UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

x86-64: Move vread_tsc and vread_hpet into the vDSO 

The vsyscall page now consists entirely of trap instructions.

Cc: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/637648f303f2ef93af93bae25186e9a1bea093f5.1310639973.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Andy Lutomirski 2011-07-14 06:47:22 -04:00 committed by H. Peter Anvin
parent 433bd805e5
commit 98d0ac38ca
12 changed files with 57 additions and 79 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/clocksource.h
View File

@ -7,8 +7,12 @@
#define __ARCH_HAS_CLOCKSOURCE_DATA
#define VCLOCK_NONE 0 /* No vDSO clock available. */
#define VCLOCK_TSC 1 /* vDSO should use vread_tsc. */
#define VCLOCK_HPET 2 /* vDSO should use vread_hpet. */
struct arch_clocksource_data {
cycle_t (*vread)(void);
int vclock_mode;
};
#endif /* CONFIG_X86_64 */

4
arch/x86/include/asm/tsc.h
View File

@ -51,10 +51,6 @@ extern int unsynchronized_tsc(void);
extern int check_tsc_unstable(void);
extern unsigned long native_calibrate_tsc(void);
#ifdef CONFIG_X86_64
extern cycles_t vread_tsc(void);
#endif
/*
* Boot-time check whether the TSCs are synchronized across
* all CPUs/cores:

2
arch/x86/include/asm/vgtod.h
View File

@ -13,7 +13,7 @@ struct vsyscall_gtod_data {
struct timezone sys_tz;
struct { /* extract of a clocksource struct */
cycle_t (*vread)(void);
int vclock_mode;
cycle_t cycle_last;
cycle_t mask;
u32 mult;

4
arch/x86/include/asm/vsyscall.h
View File

@ -16,10 +16,6 @@ enum vsyscall_num {
#ifdef __KERNEL__
#include <linux/seqlock.h>
/* Definitions for CONFIG_GENERIC_TIME definitions */
#define __vsyscall_fn \
__attribute__ ((unused, __section__(".vsyscall_fn"))) notrace
#define VGETCPU_RDTSCP 1
#define VGETCPU_LSL 2

7
arch/x86/kernel/Makefile
View File

@ -24,17 +24,12 @@ endif
nostackp := $(call cc-option, -fno-stack-protector)
CFLAGS_vsyscall_64.o := $(PROFILING) -g0 $(nostackp)
CFLAGS_hpet.o := $(nostackp)
CFLAGS_vread_tsc_64.o := $(nostackp)
CFLAGS_paravirt.o := $(nostackp)
GCOV_PROFILE_vsyscall_64.o := n
GCOV_PROFILE_hpet.o := n
GCOV_PROFILE_tsc.o := n
GCOV_PROFILE_vread_tsc_64.o := n
GCOV_PROFILE_paravirt.o := n
# vread_tsc_64 is hot and should be fully optimized:
CFLAGS_REMOVE_vread_tsc_64.o = -pg -fno-optimize-sibling-calls
obj-y := process_$(BITS).o signal.o entry_$(BITS).o
obj-y += traps.o irq.o irq_$(BITS).o dumpstack_$(BITS).o
obj-y += time.o ioport.o ldt.o dumpstack.o
@ -43,7 +38,7 @@ obj-$(CONFIG_IRQ_WORK) += irq_work.o
obj-y += probe_roms.o
obj-$(CONFIG_X86_32) += sys_i386_32.o i386_ksyms_32.o
obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o vread_tsc_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o
obj-$(CONFIG_X86_64) += vsyscall_emu_64.o
obj-y += bootflag.o e820.o
obj-y += pci-dma.o quirks.o topology.o kdebugfs.o

8
arch/x86/kernel/alternative.c
View File

@ -14,7 +14,6 @@
#include <asm/pgtable.h>
#include <asm/mce.h>
#include <asm/nmi.h>
#include <asm/vsyscall.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/io.h>
@ -250,7 +249,6 @@ static void __init_or_module add_nops(void *insns, unsigned int len)
extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
extern s32 __smp_locks[], __smp_locks_end[];
extern char __vsyscall_0;
void *text_poke_early(void *addr, const void *opcode, size_t len);
/* Replace instructions with better alternatives for this CPU type.
@ -294,12 +292,6 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
add_nops(insnbuf + a->replacementlen,
a->instrlen - a->replacementlen);
#ifdef CONFIG_X86_64
/* vsyscall code is not mapped yet. resolve it manually. */
if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END) {
instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0));
}
#endif
text_poke_early(instr, insnbuf, a->instrlen);
}
}

9
arch/x86/kernel/hpet.c
View File

@ -738,13 +738,6 @@ static cycle_t read_hpet(struct clocksource *cs)
return (cycle_t)hpet_readl(HPET_COUNTER);
}
#ifdef CONFIG_X86_64
static cycle_t __vsyscall_fn vread_hpet(void)
{
return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
}
#endif
static struct clocksource clocksource_hpet = {
.name = "hpet",
.rating = 250,
@ -753,7 +746,7 @@ static struct clocksource clocksource_hpet = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.resume = hpet_resume_counter,
#ifdef CONFIG_X86_64
.archdata = { .vread = vread_hpet },
.archdata = { .vclock_mode = VCLOCK_HPET },
#endif
};

2
arch/x86/kernel/tsc.c
View File

@ -777,7 +777,7 @@ static struct clocksource clocksource_tsc = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_MUST_VERIFY,
#ifdef CONFIG_X86_64
.archdata = { .vread = vread_tsc },
.archdata = { .vclock_mode = VCLOCK_TSC },
#endif
};

3
arch/x86/kernel/vmlinux.lds.S
View File

@ -169,9 +169,6 @@ SECTIONS
.vsyscall : AT(VLOAD(.vsyscall)) {
*(.vsyscall_0)
. = ALIGN(L1_CACHE_BYTES);
*(.vsyscall_fn)
. = 1024;
*(.vsyscall_1)

36
arch/x86/kernel/vread_tsc_64.c
View File

@ -1,36 +0,0 @@
/* This code runs in userspace. */
#define DISABLE_BRANCH_PROFILING
#include <asm/vgtod.h>
notrace cycle_t __vsyscall_fn vread_tsc(void)
{
cycle_t ret;
u64 last;
/*
* Empirically, a fence (of type that depends on the CPU)
* before rdtsc is enough to ensure that rdtsc is ordered
* with respect to loads. The various CPU manuals are unclear
* as to whether rdtsc can be reordered with later loads,
* but no one has ever seen it happen.
*/
rdtsc_barrier();
ret = (cycle_t)vget_cycles();
last = VVAR(vsyscall_gtod_data).clock.cycle_last;
if (likely(ret >= last))
return ret;
/*
* GCC likes to generate cmov here, but this branch is extremely
* predictable (it's just a funciton of time and the likely is
* very likely) and there's a data dependence, so force GCC
* to generate a branch instead. I don't barrier() because
* we don't actually need a barrier, and if this function
* ever gets inlined it will generate worse code.
*/
asm volatile ("");
return last;
}

2
arch/x86/kernel/vsyscall_64.c
View File

@ -74,7 +74,7 @@ void update_vsyscall(struct timespec *wall_time, struct timespec *wtm,
write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags);
/* copy vsyscall data */
vsyscall_gtod_data.clock.vread = clock->archdata.vread;
vsyscall_gtod_data.clock.vclock_mode = clock->archdata.vclock_mode;
vsyscall_gtod_data.clock.cycle_last = clock->cycle_last;
vsyscall_gtod_data.clock.mask = clock->mask;
vsyscall_gtod_data.clock.mult = mult;

53
arch/x86/vdso/vclock_gettime.c
View File

@ -17,6 +17,7 @@
#include <linux/time.h>
#include <linux/string.h>
#include <asm/vsyscall.h>
#include <asm/fixmap.h>
#include <asm/vgtod.h>
#include <asm/timex.h>
#include <asm/hpet.h>
@ -25,6 +26,43 @@
#define gtod (&VVAR(vsyscall_gtod_data))
notrace static cycle_t vread_tsc(void)
{
cycle_t ret;
u64 last;
/*
* Empirically, a fence (of type that depends on the CPU)
* before rdtsc is enough to ensure that rdtsc is ordered
* with respect to loads. The various CPU manuals are unclear
* as to whether rdtsc can be reordered with later loads,
* but no one has ever seen it happen.
*/
rdtsc_barrier();
ret = (cycle_t)vget_cycles();
last = VVAR(vsyscall_gtod_data).clock.cycle_last;
if (likely(ret >= last))
return ret;
/*
* GCC likes to generate cmov here, but this branch is extremely
* predictable (it's just a funciton of time and the likely is
* very likely) and there's a data dependence, so force GCC
* to generate a branch instead. I don't barrier() because
* we don't actually need a barrier, and if this function
* ever gets inlined it will generate worse code.
*/
asm volatile ("");
return last;
}
static notrace cycle_t vread_hpet(void)
{
return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
}
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
{
long ret;
@ -36,9 +74,12 @@ notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
notrace static inline long vgetns(void)
{
long v;
cycles_t (*vread)(void);
vread = gtod->clock.vread;
v = (vread() - gtod->clock.cycle_last) & gtod->clock.mask;
cycles_t cycles;
if (gtod->clock.vclock_mode == VCLOCK_TSC)
cycles = vread_tsc();
else
cycles = vread_hpet();
v = (cycles - gtod->clock.cycle_last) & gtod->clock.mask;
return (v * gtod->clock.mult) >> gtod->clock.shift;
}
@ -118,11 +159,11 @@ notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts)
{
switch (clock) {
case CLOCK_REALTIME:
if (likely(gtod->clock.vread))
if (likely(gtod->clock.vclock_mode != VCLOCK_NONE))
return do_realtime(ts);
break;
case CLOCK_MONOTONIC:
if (likely(gtod->clock.vread))
if (likely(gtod->clock.vclock_mode != VCLOCK_NONE))
return do_monotonic(ts);
break;
case CLOCK_REALTIME_COARSE:
@ -139,7 +180,7 @@ int clock_gettime(clockid_t, struct timespec *)
notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
{
long ret;
if (likely(gtod->clock.vread)) {
if (likely(gtod->clock.vclock_mode != VCLOCK_NONE)) {
if (likely(tv != NULL)) {
BUILD_BUG_ON(offsetof(struct timeval, tv_usec) !=
offsetof(struct timespec, tv_nsec) ||