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docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
===================================
Light-weight System Calls for IA-64
===================================
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
Started: 13-Jan-2003
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
Last update: 27-Sep-2003
David Mosberger-Tang
<davidm@hpl.hp.com>
Using the "epc" instruction effectively introduces a new mode of
execution to the ia64 linux kernel. We call this mode the
"fsys-mode". To recap, the normal states of execution are:
- kernel mode:
Both the register stack and the memory stack have been
switched over to kernel memory. The user-level state is saved
in a pt-regs structure at the top of the kernel memory stack.
- user mode:
Both the register stack and the kernel stack are in
user memory. The user-level state is contained in the
CPU registers.
- bank 0 interruption-handling mode:
This is the non-interruptible state which all
interruption-handlers start execution in. The user-level
state remains in the CPU registers and some kernel state may
be stored in bank 0 of registers r16-r31.
In contrast, fsys-mode has the following special properties:
- execution is at privilege level 0 (most-privileged)
- CPU registers may contain a mixture of user-level and kernel-level
state (it is the responsibility of the kernel to ensure that no
security-sensitive kernel-level state is leaked back to
user-level)
- execution is interruptible and preemptible (an fsys-mode handler
can disable interrupts and avoid all other interruption-sources
to avoid preemption)
- neither the memory-stack nor the register-stack can be trusted while
in fsys-mode (they point to the user-level stacks, which may
be invalid, or completely bogus addresses)
In summary, fsys-mode is much more similar to running in user-mode
than it is to running in kernel-mode. Of course, given that the
privilege level is at level 0, this means that fsys-mode requires some
care (see below).
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
How to tell fsys-mode
=====================
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2005-04-17 06:20:36 +08:00
Linux operates in fsys-mode when (a) the privilege level is 0 (most
privileged) and (b) the stacks have NOT been switched to kernel memory
yet. For convenience, the header file <asm-ia64/ptrace.h> provides
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
three macros::
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2005-04-17 06:20:36 +08:00
user_mode(regs)
user_stack(task,regs)
fsys_mode(task,regs)
The "regs" argument is a pointer to a pt_regs structure. The "task"
argument is a pointer to the task structure to which the "regs"
pointer belongs to. user_mode() returns TRUE if the CPU state pointed
to by "regs" was executing in user mode (privilege level 3).
user_stack() returns TRUE if the state pointed to by "regs" was
executing on the user-level stack(s). Finally, fsys_mode() returns
TRUE if the CPU state pointed to by "regs" was executing in fsys-mode.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
The fsys_mode() macro is equivalent to the expression::
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2005-04-17 06:20:36 +08:00
!user_mode(regs) && user_stack(task,regs)
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2019-04-18 21:10:33 +08:00
How to write an fsyscall handler
================================
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2005-04-17 06:20:36 +08:00
The file arch/ia64/kernel/fsys.S contains a table of fsyscall-handlers
(fsyscall_table). This table contains one entry for each system call.
By default, a system call is handled by fsys_fallback_syscall(). This
routine takes care of entering (full) kernel mode and calling the
normal Linux system call handler. For performance-critical system
calls, it is possible to write a hand-tuned fsyscall_handler. For
example, fsys.S contains fsys_getpid(), which is a hand-tuned version
of the getpid() system call.
The entry and exit-state of an fsyscall handler is as follows:
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
Machine state on entry to fsyscall handler
------------------------------------------
========= ===============================================================
r10 0
r11 saved ar.pfs (a user-level value)
r15 system call number
r16 "current" task pointer (in normal kernel-mode, this is in r13)
r32-r39 system call arguments
b6 return address (a user-level value)
ar.pfs previous frame-state (a user-level value)
PSR.be cleared to zero (i.e., little-endian byte order is in effect)
- all other registers may contain values passed in from user-mode
========= ===============================================================
Required machine state on exit to fsyscall handler
--------------------------------------------------
========= ===========================================================
r11 saved ar.pfs (as passed into the fsyscall handler)
r15 system call number (as passed into the fsyscall handler)
r32-r39 system call arguments (as passed into the fsyscall handler)
b6 return address (as passed into the fsyscall handler)
ar.pfs previous frame-state (as passed into the fsyscall handler)
========= ===========================================================
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2005-04-17 06:20:36 +08:00
Fsyscall handlers can execute with very little overhead, but with that
speed comes a set of restrictions:
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers MUST check for any pending work in the flags
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
member of the thread-info structure and if any of the
TIF_ALLWORK_MASK flags are set, the handler needs to fall back on
doing a full system call (by calling fsys_fallback_syscall).
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers MUST preserve incoming arguments (r32-r39, r11,
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
r15, b6, and ar.pfs) because they will be needed in case of a
system call restart. Of course, all "preserved" registers also
must be preserved, in accordance to the normal calling conventions.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers MUST check argument registers for containing a
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
NaT value before using them in any way that could trigger a
NaT-consumption fault. If a system call argument is found to
contain a NaT value, an fsyscall-handler may return immediately
with r8=EINVAL, r10=-1.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers MUST NOT use the "alloc" instruction or perform
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
any other operation that would trigger mandatory RSE
(register-stack engine) traffic.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers MUST NOT write to any stacked registers because
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
it is not safe to assume that user-level called a handler with the
proper number of arguments.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers need to be careful when accessing per-CPU variables:
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
unless proper safe-guards are taken (e.g., interruptions are avoided),
execution may be pre-empted and resumed on another CPU at any given
time.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers must be careful not to leak sensitive kernel'
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
information back to user-level. In particular, before returning to
user-level, care needs to be taken to clear any scratch registers
that could contain sensitive information (note that the current
task pointer is not considered sensitive: it's already exposed
through ar.k6).
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* Fsyscall-handlers MUST NOT access user-memory without first
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
validating access-permission (this can be done typically via
probe.r.fault and/or probe.w.fault) and without guarding against
memory access exceptions (this can be done with the EX() macros
defined by asmmacro.h).
The above restrictions may seem draconian, but remember that it's
possible to trade off some of the restrictions by paying a slightly
higher overhead. For example, if an fsyscall-handler could benefit
from the shadow register bank, it could temporarily disable PSR.i and
PSR.ic, switch to bank 0 (bsw.0) and then use the shadow registers as
needed. In other words, following the above rules yields extremely
fast system call execution (while fully preserving system call
semantics), but there is also a lot of flexibility in handling more
complicated cases.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
Signal handling
===============
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
The delivery of (asynchronous) signals must be delayed until fsys-mode
Fix some typos in Documentation/: 'A' This patch fixes typos in various Documentation txts. This patch addresses some words starting with the letter 'A'. Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com> Acked-by: Randy Dunlap <rdunlap@xenotime.net> Acked-by: Alan Cox <alan@redhat.com> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-10-04 04:45:33 +08:00
is exited. This is accomplished with the help of the lower-privilege
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
transfer trap: arch/ia64/kernel/process.c:do_notify_resume_user()
checks whether the interrupted task was in fsys-mode and, if so, sets
PSR.lp and returns immediately. When fsys-mode is exited via the
"br.ret" instruction that lowers the privilege level, a trap will
occur. The trap handler clears PSR.lp again and returns immediately.
The kernel exit path then checks for and delivers any pending signals.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
PSR Handling
============
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
The "epc" instruction doesn't change the contents of PSR at all. This
is in contrast to a regular interruption, which clears almost all
bits. Because of that, some care needs to be taken to ensure things
work as expected. The following discussion describes how each PSR bit
is handled.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
======= =======================================================================
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
PSR.be Cleared when entering fsys-mode. A srlz.d instruction is used
to ensure the CPU is in little-endian mode before the first
load/store instruction is executed. PSR.be is normally NOT
restored upon return from an fsys-mode handler. In other
words, user-level code must not rely on PSR.be being preserved
across a system call.
PSR.up Unchanged.
PSR.ac Unchanged.
PSR.mfl Unchanged. Note: fsys-mode handlers must not write-registers!
PSR.mfh Unchanged. Note: fsys-mode handlers must not write-registers!
PSR.ic Unchanged. Note: fsys-mode handlers can clear the bit, if needed.
PSR.i Unchanged. Note: fsys-mode handlers can clear the bit, if needed.
PSR.pk Unchanged.
PSR.dt Unchanged.
PSR.dfl Unchanged. Note: fsys-mode handlers must not write-registers!
PSR.dfh Unchanged. Note: fsys-mode handlers must not write-registers!
PSR.sp Unchanged.
PSR.pp Unchanged.
PSR.di Unchanged.
PSR.si Unchanged.
PSR.db Unchanged. The kernel prevents user-level from setting a hardware
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
breakpoint that triggers at any privilege level other than
3 (user-mode).
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
PSR.lp Unchanged.
PSR.tb Lazy redirect. If a taken-branch trap occurs while in
fsys-mode, the trap-handler modifies the saved machine state
such that execution resumes in the gate page at
syscall_via_break(), with privilege level 3. Note: the
taken branch would occur on the branch invoking the
fsyscall-handler, at which point, by definition, a syscall
restart is still safe. If the system call number is invalid,
the fsys-mode handler will return directly to user-level. This
return will trigger a taken-branch trap, but since the trap is
taken _after_ restoring the privilege level, the CPU has already
left fsys-mode, so no special treatment is needed.
PSR.rt Unchanged.
PSR.cpl Cleared to 0.
PSR.is Unchanged (guaranteed to be 0 on entry to the gate page).
PSR.mc Unchanged.
PSR.it Unchanged (guaranteed to be 1).
PSR.id Unchanged. Note: the ia64 linux kernel never sets this bit.
PSR.da Unchanged. Note: the ia64 linux kernel never sets this bit.
PSR.dd Unchanged. Note: the ia64 linux kernel never sets this bit.
PSR.ss Lazy redirect. If set, "epc" will cause a Single Step Trap to
be taken. The trap handler then modifies the saved machine
state such that execution resumes in the gate page at
syscall_via_break(), with privilege level 3.
PSR.ri Unchanged.
PSR.ed Unchanged. Note: This bit could only have an effect if an fsys-mode
handler performed a speculative load that gets NaTted. If so, this
would be the normal & expected behavior, so no special treatment is
needed.
PSR.bn Unchanged. Note: fsys-mode handlers may clear the bit, if needed.
Doing so requires clearing PSR.i and PSR.ic as well.
PSR.ia Unchanged. Note: the ia64 linux kernel never sets this bit.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
======= =======================================================================
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
Using fast system calls
=======================
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
To use fast system calls, userspace applications need simply call
__kernel_syscall_via_epc(). For example
-- example fgettimeofday() call --
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
-- fgettimeofday.S --
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
::
#include <asm/asmmacro.h>
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
GLOBAL_ENTRY(fgettimeofday)
.prologue
.save ar.pfs, r11
mov r11 = ar.pfs
.body
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
mov r2 = 0xa000000000020660;; // gate address
// found by inspection of System.map for the
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
// __kernel_syscall_via_epc() function. See
// below for how to do this for real.
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
mov b7 = r2
mov r15 = 1087 // gettimeofday syscall
;;
br.call.sptk.many b6 = b7
;;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
.restore sp
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
mov ar.pfs = r11
br.ret.sptk.many rp;; // return to caller
END(fgettimeofday)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
-- end fgettimeofday.S --
In reality, getting the gate address is accomplished by two extra
values passed via the ELF auxiliary vector (include/asm-ia64/elf.h)
docs: ia64: convert to ReST Rename the ia64 documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. There are two upper case file names. Rename them to lower case, as we're working to avoid upper case file names at Documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-04-18 21:10:33 +08:00
* AT_SYSINFO : is the address of __kernel_syscall_via_epc()
* AT_SYSINFO_EHDR : is the address of the kernel gate ELF DSO
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-17 06:20:36 +08:00
The ELF DSO is a pre-linked library that is mapped in by the kernel at
the gate page. It is a proper ELF shared object so, with a dynamic
loader that recognises the library, you should be able to make calls to
the exported functions within it as with any other shared library.
AT_SYSINFO points into the kernel DSO at the
__kernel_syscall_via_epc() function for historical reasons (it was
used before the kernel DSO) and as a convenience.