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OpenCloudOS-Kernel/arch/arm64/kernel/vdso/gettimeofday.S

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arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
/*
* Userspace implementations of gettimeofday() and friends.
*
* Copyright (C) 2012 ARM Limited
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Will Deacon <will.deacon@arm.com>
*/
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
#define NSEC_PER_SEC_LO16 0xca00
#define NSEC_PER_SEC_HI16 0x3b9a
vdso_data .req x6
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
seqcnt .req w7
w_tmp .req w8
x_tmp .req x8
/*
* Conventions for macro arguments:
* - An argument is write-only if its name starts with "res".
* - All other arguments are read-only, unless otherwise specified.
*/
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
.macro seqcnt_acquire
9999: ldr seqcnt, [vdso_data, #VDSO_TB_SEQ_COUNT]
tbnz seqcnt, #0, 9999b
dmb ishld
.endm
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
.macro seqcnt_check fail
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
dmb ishld
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ldr w_tmp, [vdso_data, #VDSO_TB_SEQ_COUNT]
cmp w_tmp, seqcnt
b.ne \fail
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
.endm
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
.macro syscall_check fail
ldr w_tmp, [vdso_data, #VDSO_USE_SYSCALL]
cbnz w_tmp, \fail
.endm
.macro get_nsec_per_sec res
mov \res, #NSEC_PER_SEC_LO16
movk \res, #NSEC_PER_SEC_HI16, lsl #16
.endm
/*
* Returns the clock delta, in nanoseconds left-shifted by the clock
* shift.
*/
.macro get_clock_shifted_nsec res, cycle_last, mult
/* Read the virtual counter. */
isb
mrs x_tmp, cntvct_el0
/* Calculate cycle delta and convert to ns. */
sub \res, x_tmp, \cycle_last
/* We can only guarantee 56 bits of precision. */
movn x_tmp, #0xff00, lsl #48
and \res, x_tmp, \res
mul \res, \res, \mult
.endm
/*
* Returns in res_{sec,nsec} the REALTIME timespec, based on the
* "wall time" (xtime) and the clock_mono delta.
*/
.macro get_ts_realtime res_sec, res_nsec, \
clock_nsec, xtime_sec, xtime_nsec, nsec_to_sec
add \res_nsec, \clock_nsec, \xtime_nsec
udiv x_tmp, \res_nsec, \nsec_to_sec
add \res_sec, \xtime_sec, x_tmp
msub \res_nsec, x_tmp, \nsec_to_sec, \res_nsec
.endm
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
/*
* Returns in res_{sec,nsec} the timespec based on the clock_raw delta,
* used for CLOCK_MONOTONIC_RAW.
*/
.macro get_ts_clock_raw res_sec, res_nsec, clock_nsec, nsec_to_sec
udiv \res_sec, \clock_nsec, \nsec_to_sec
msub \res_nsec, \res_sec, \nsec_to_sec, \clock_nsec
.endm
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
/* sec and nsec are modified in place. */
.macro add_ts sec, nsec, ts_sec, ts_nsec, nsec_to_sec
/* Add timespec. */
add \sec, \sec, \ts_sec
add \nsec, \nsec, \ts_nsec
/* Normalise the new timespec. */
cmp \nsec, \nsec_to_sec
b.lt 9999f
sub \nsec, \nsec, \nsec_to_sec
add \sec, \sec, #1
9999:
cmp \nsec, #0
b.ge 9998f
add \nsec, \nsec, \nsec_to_sec
sub \sec, \sec, #1
9998:
.endm
.macro clock_gettime_return, shift=0
.if \shift == 1
lsr x11, x11, x12
.endif
stp x10, x11, [x1, #TSPEC_TV_SEC]
mov x0, xzr
ret
.endm
.macro jump_slot jumptable, index, label
.if (. - \jumptable) != 4 * (\index)
.error "Jump slot index mismatch"
.endif
b \label
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
.endm
.text
/* int __kernel_gettimeofday(struct timeval *tv, struct timezone *tz); */
ENTRY(__kernel_gettimeofday)
.cfi_startproc
adr vdso_data, _vdso_data
/* If tv is NULL, skip to the timezone code. */
cbz x0, 2f
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
/* Compute the time of day. */
1: seqcnt_acquire
syscall_check fail=4f
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
/* w11 = cs_mono_mult, w12 = cs_shift */
ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
seqcnt_check fail=1b
get_nsec_per_sec res=x9
lsl x9, x9, x12
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
get_ts_realtime res_sec=x10, res_nsec=x11, \
clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
/* Convert ns to us. */
arm64: vdso: rework __do_get_tspec register allocation and return shift In preparation for sub-ns precision in the vdso timespec maths, change the __do_get_tspec register allocation so that we return the clocksource shift value instead of the unused xtime tspec. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-11-30 06:19:01 +08:00
mov x13, #1000
arm64: vdso: defer shifting of nanosecond component of timespec Shifting the nanosecond component of the computed timespec early can lead to sub-ns inaccuracies when using the truncated value as input to further arithmetic for things like conversions to monotonic time. This patch defers the timespec shifting until after the final value has been computed. Reported-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-11-30 06:33:29 +08:00
lsl x13, x13, x12
arm64: vdso: rework __do_get_tspec register allocation and return shift In preparation for sub-ns precision in the vdso timespec maths, change the __do_get_tspec register allocation so that we return the clocksource shift value instead of the unused xtime tspec. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-11-30 06:19:01 +08:00
udiv x11, x11, x13
stp x10, x11, [x0, #TVAL_TV_SEC]
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
2:
/* If tz is NULL, return 0. */
cbz x1, 3f
ldp w4, w5, [vdso_data, #VDSO_TZ_MINWEST]
stp w4, w5, [x1, #TZ_MINWEST]
3:
mov x0, xzr
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ret
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
4:
/* Syscall fallback. */
mov x8, #__NR_gettimeofday
svc #0
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ret
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
.cfi_endproc
ENDPROC(__kernel_gettimeofday)
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
#define JUMPSLOT_MAX CLOCK_MONOTONIC_COARSE
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
/* int __kernel_clock_gettime(clockid_t clock_id, struct timespec *tp); */
ENTRY(__kernel_clock_gettime)
.cfi_startproc
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
cmp w0, #JUMPSLOT_MAX
b.hi syscall
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
adr vdso_data, _vdso_data
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
adr x_tmp, jumptable
add x_tmp, x_tmp, w0, uxtw #2
br x_tmp
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ALIGN
jumptable:
jump_slot jumptable, CLOCK_REALTIME, realtime
jump_slot jumptable, CLOCK_MONOTONIC, monotonic
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
b syscall
b syscall
jump_slot jumptable, CLOCK_MONOTONIC_RAW, monotonic_raw
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
jump_slot jumptable, CLOCK_REALTIME_COARSE, realtime_coarse
jump_slot jumptable, CLOCK_MONOTONIC_COARSE, monotonic_coarse
.if (. - jumptable) != 4 * (JUMPSLOT_MAX + 1)
.error "Wrong jumptable size"
.endif
ALIGN
realtime:
seqcnt_acquire
syscall_check fail=syscall
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
/* w11 = cs_mono_mult, w12 = cs_shift */
ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
seqcnt_check fail=realtime
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
/* All computations are done with left-shifted nsecs. */
get_nsec_per_sec res=x9
lsl x9, x9, x12
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
get_ts_realtime res_sec=x10, res_nsec=x11, \
clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
clock_gettime_return, shift=1
arm64: vdso: fix coarse clock handling When __kernel_clock_gettime is called with a CLOCK_MONOTONIC_COARSE or CLOCK_REALTIME_COARSE clock id, it returns incorrectly to whatever the caller has placed in x2 ("ret x2" to return from the fast path). Fix this by saving x30/LR to x2 only in code that will call __do_get_tspec, restoring x30 afterward, and using a plain "ret" to return from the routine. Also: while the resulting tv_nsec value for CLOCK_REALTIME and CLOCK_MONOTONIC must be computed using intermediate values that are left-shifted by cs_shift (x12, set by __do_get_tspec), the results for coarse clocks should be calculated using unshifted values (xtime_coarse_nsec is in units of actual nanoseconds). The current code shifts intermediate values by x12 unconditionally, but x12 is uninitialized when servicing a coarse clock. Fix this by setting x12 to 0 once we know we are dealing with a coarse clock id. Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-02-05 13:53:04 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ALIGN
monotonic:
seqcnt_acquire
syscall_check fail=syscall
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
/* w11 = cs_mono_mult, w12 = cs_shift */
ldp w11, w12, [vdso_data, #VDSO_CS_MONO_MULT]
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ldp x13, x14, [vdso_data, #VDSO_XTIME_CLK_SEC]
ldp x3, x4, [vdso_data, #VDSO_WTM_CLK_SEC]
seqcnt_check fail=monotonic
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
/* All computations are done with left-shifted nsecs. */
lsl x4, x4, x12
get_nsec_per_sec res=x9
lsl x9, x9, x12
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
get_ts_realtime res_sec=x10, res_nsec=x11, \
clock_nsec=x15, xtime_sec=x13, xtime_nsec=x14, nsec_to_sec=x9
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
add_ts sec=x10, nsec=x11, ts_sec=x3, ts_nsec=x4, nsec_to_sec=x9
clock_gettime_return, shift=1
arm64: vdso: fix coarse clock handling When __kernel_clock_gettime is called with a CLOCK_MONOTONIC_COARSE or CLOCK_REALTIME_COARSE clock id, it returns incorrectly to whatever the caller has placed in x2 ("ret x2" to return from the fast path). Fix this by saving x30/LR to x2 only in code that will call __do_get_tspec, restoring x30 afterward, and using a plain "ret" to return from the routine. Also: while the resulting tv_nsec value for CLOCK_REALTIME and CLOCK_MONOTONIC must be computed using intermediate values that are left-shifted by cs_shift (x12, set by __do_get_tspec), the results for coarse clocks should be calculated using unshifted values (xtime_coarse_nsec is in units of actual nanoseconds). The current code shifts intermediate values by x12 unconditionally, but x12 is uninitialized when servicing a coarse clock. Fix this by setting x12 to 0 once we know we are dealing with a coarse clock id. Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com> Acked-by: Will Deacon <will.deacon@arm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-02-05 13:53:04 +08:00
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
ALIGN
monotonic_raw:
seqcnt_acquire
syscall_check fail=syscall
ldr x10, [vdso_data, #VDSO_CS_CYCLE_LAST]
/* w11 = cs_raw_mult, w12 = cs_shift */
ldp w12, w11, [vdso_data, #VDSO_CS_SHIFT]
ldp x13, x14, [vdso_data, #VDSO_RAW_TIME_SEC]
seqcnt_check fail=monotonic_raw
/* All computations are done with left-shifted nsecs. */
get_nsec_per_sec res=x9
lsl x9, x9, x12
get_clock_shifted_nsec res=x15, cycle_last=x10, mult=x11
get_ts_clock_raw res_sec=x10, res_nsec=x11, \
clock_nsec=x15, nsec_to_sec=x9
add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
clock_gettime_return, shift=1
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ALIGN
realtime_coarse:
seqcnt_acquire
arm64: vdso: rework __do_get_tspec register allocation and return shift In preparation for sub-ns precision in the vdso timespec maths, change the __do_get_tspec register allocation so that we return the clocksource shift value instead of the unused xtime tspec. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-11-30 06:19:01 +08:00
ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
seqcnt_check fail=realtime_coarse
clock_gettime_return
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ALIGN
monotonic_coarse:
seqcnt_acquire
ldp x10, x11, [vdso_data, #VDSO_XTIME_CRS_SEC]
arm64: vdso: rework __do_get_tspec register allocation and return shift In preparation for sub-ns precision in the vdso timespec maths, change the __do_get_tspec register allocation so that we return the clocksource shift value instead of the unused xtime tspec. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2012-11-30 06:19:01 +08:00
ldp x13, x14, [vdso_data, #VDSO_WTM_CLK_SEC]
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
seqcnt_check fail=monotonic_coarse
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
/* Computations are done in (non-shifted) nsecs. */
get_nsec_per_sec res=x9
add_ts sec=x10, nsec=x11, ts_sec=x13, ts_nsec=x14, nsec_to_sec=x9
clock_gettime_return
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
arm64: Refactor vDSO time functions Time functions are directly implemented in assembly in arm64, and it is desirable to keep it this way for performance reasons (everything fits in registers, so that the stack is not used at all). However, the current implementation is quite difficult to read and understand (even considering it's assembly). Additionally, due to the structure of __kernel_clock_gettime, which heavily uses conditional branches to share code between the different clocks, it is difficult to support a new clock without making the branches even harder to follow. This commit completely refactors the structure of clock_gettime (and gettimeofday along the way) while keeping exactly the same algorithms. We no longer try to share code; instead, macros provide common operations. This new approach comes with a number of advantages: - In clock_gettime, clock implementations are no longer interspersed, making them much more readable. Additionally, macros only use registers passed as arguments or reserved with .req, this way it is easy to make sure that registers are properly allocated. To avoid a large number of branches in a given execution path, a jump table is used; a normal execution uses 3 unconditional branches. - __do_get_tspec has been replaced with 2 macros (get_ts_clock_mono, get_clock_shifted_nsec) and explicit loading of data from the vDSO page. Consequently, clock_gettime and gettimeofday are now leaf functions, and saving x30 (lr) is no longer necessary. - Variables protected by tb_seq_count are now loaded all at once, allowing to merge the seqcnt_read macro into seqcnt_check. - For CLOCK_REALTIME_COARSE, removed an unused load of the wall to monotonic timespec. - For CLOCK_MONOTONIC_COARSE, removed a few shift instructions. Obviously, the downside of sharing less code is an increase in code size. However since the vDSO has its own code page, this does not really matter, as long as the size of the DSO remains below 4 kB. For now this should be all right: Before After vdso.so size (B) 2776 3000 Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:23:59 +08:00
ALIGN
syscall: /* Syscall fallback. */
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
mov x8, #__NR_clock_gettime
svc #0
ret
.cfi_endproc
ENDPROC(__kernel_clock_gettime)
/* int __kernel_clock_getres(clockid_t clock_id, struct timespec *res); */
ENTRY(__kernel_clock_getres)
.cfi_startproc
cmp w0, #CLOCK_REALTIME
ccmp w0, #CLOCK_MONOTONIC, #0x4, ne
arm64: Add support for CLOCK_MONOTONIC_RAW in clock_gettime() vDSO So far the arm64 clock_gettime() vDSO implementation only supported the following clocks, falling back to the syscall for the others: - CLOCK_REALTIME{,_COARSE} - CLOCK_MONOTONIC{,_COARSE} This patch adds support for the CLOCK_MONOTONIC_RAW clock, taking advantage of the recent refactoring of the vDSO time functions. Like the non-_COARSE clocks, this only works when the "arch_sys_counter" clocksource is in use (allowing us to read the current time from the virtual counter register), otherwise we also have to fall back to the syscall. Most of the data is shared with CLOCK_MONOTONIC, and the algorithm is similar. The reference implementation in kernel/time/timekeeping.c shows that: - CLOCK_MONOTONIC = tk->wall_to_monotonic + tk->xtime_sec + timekeeping_get_ns(&tk->tkr_mono) - CLOCK_MONOTONIC_RAW = tk->raw_time + timekeeping_get_ns(&tk->tkr_raw) - tkr_mono and tkr_raw are identical (in particular, same clocksource), except these members: * mult (only mono's multiplier is NTP-adjusted) * xtime_nsec (always 0 for raw) Therefore, tk->raw_time and tkr_raw->mult are now also stored in the vDSO data page. Cc: Ali Saidi <ali.saidi@arm.com> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2016-07-12 18:24:00 +08:00
ccmp w0, #CLOCK_MONOTONIC_RAW, #0x4, ne
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
b.ne 1f
ldr x2, 5f
b 2f
1:
cmp w0, #CLOCK_REALTIME_COARSE
ccmp w0, #CLOCK_MONOTONIC_COARSE, #0x4, ne
b.ne 4f
ldr x2, 6f
2:
arm64: vdso: fix clock_getres for 4GiB-aligned res The vdso tries to check for a NULL res pointer in __kernel_clock_getres, but only checks the lower 32 bits as is uses CBZ on the W register the res pointer is held in. Thus, if the res pointer happened to be aligned to a 4GiB boundary, we'd spuriously skip storing the timespec to it, while returning a zero error code to the caller. Prevent this by checking the whole pointer, using CBZ on the X register the res pointer is held in. Fixes: 9031fefde6f2ac1d ("arm64: VDSO support") Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reported-by: Andrew Pinski <apinski@cavium.com> Reported-by: Mark Salyzyn <salyzyn@android.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2017-10-31 05:23:19 +08:00
cbz x1, 3f
arm64: VDSO support This patch adds VDSO support for 64-bit applications. The VDSO code is currently used for sys_rt_sigreturn() and optimised gettimeofday() (using the user-accessible generic counter). Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Tony Lindgren <tony@atomide.com> Acked-by: Nicolas Pitre <nico@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
2012-03-05 19:49:31 +08:00
stp xzr, x2, [x1]
3: /* res == NULL. */
mov w0, wzr
ret
4: /* Syscall fallback. */
mov x8, #__NR_clock_getres
svc #0
ret
5:
.quad CLOCK_REALTIME_RES
6:
.quad CLOCK_COARSE_RES
.cfi_endproc
ENDPROC(__kernel_clock_getres)