powerpc: Provide syscall wrapper

Implement syscall wrapper as per s390, x86, arm64. When enabled
cause handlers to accept parameters from a stack frame rather than
from user scratch register state.

powerpc: Provide syscall wrapper

Implement syscall wrapper as per s390, x86, arm64. When enabled
cause handlers to accept parameters from a stack frame rather than
from user scratch register state. This allows for user registers to be
safely cleared in order to reduce caller influence on speculation
within syscall routine. The wrapper is a macro that emits syscall
handler symbols that call into the target handler, obtaining its
parameters from a struct pt_regs on the stack.

As registers are already saved to the stack prior to calling
system_call_exception, it appears that this function is executed more
efficiently with the new stack-pointer convention than with parameters
passed by registers, avoiding the allocation of a stack frame for this
method. On a 32-bit system, we see >20% performance increases on the
null_syscall microbenchmark, and on a Power 8 the performance gains
amortise the cost of clearing and restoring registers which is
implemented at the end of this series, seeing final result of ~5.6%
performance improvement on null_syscall.

Syscalls are wrapped in this fashion on all platforms except for the
Cell processor as this commit does not provide SPU support. This can be
quickly fixed in a successive patch, but requires spu_sys_callback to
allocate a pt_regs structure to satisfy the wrapped calling convention.

Co-developed-by: Andrew Donnellan <[email protected]>
Signed-off-by: Andrew Donnellan <[email protected]>
Signed-off-by: Rohan McLure <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
[mpe: Make incompatible with COMPAT to retain clearing of high bits of args]
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

powerpc: Use common syscall handler type

Cause syscall handlers to be typed as follows when called indirectly
throughout the kernel. This is to allow for better type checking.

typedef long (*syscal

powerpc: Use common syscall handler type

Cause syscall handlers to be typed as follows when called indirectly
throughout the kernel. This is to allow for better type checking.

typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long,
unsigned long, unsigned long, unsigned long);

Since both 32 and 64-bit abis allow for at least the first six
machine-word length parameters to a function to be passed by registers,
even handlers which admit fewer than six parameters may be viewed as
having the above type.

Coercing syscalls to syscall_fn requires a cast to void* to avoid
-Wcast-function-type.

Fixup comparisons in VDSO to avoid pointer-integer comparison. Introduce
explicit cast on systems with SPUs.

Signed-off-by: Rohan McLure <[email protected]>
Reviewed-by: Nicholas Piggin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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powerpc/audit: Fix syscall_get_arch()

Commit 770cec16cdc9 ("powerpc/audit: Simplify syscall_get_arch()")
and commit 898a1ef06ad4 ("powerpc/audit: Avoid unneccessary #ifdef
in syscall_get_arguments()

powerpc/audit: Fix syscall_get_arch()

Commit 770cec16cdc9 ("powerpc/audit: Simplify syscall_get_arch()")
and commit 898a1ef06ad4 ("powerpc/audit: Avoid unneccessary #ifdef
in syscall_get_arguments()")
replaced test_tsk_thread_flag(task, TIF_32BIT)) by is_32bit_task().

But is_32bit_task() applies on current task while be want the test
done on task 'task'

So add a new macro is_tsk_32bit_task() to check any task.

Fixes: 770cec16cdc9 ("powerpc/audit: Simplify syscall_get_arch()")
Fixes: 898a1ef06ad4 ("powerpc/audit: Avoid unneccessary #ifdef in syscall_get_arguments()")
Cc: [email protected]
Reported-by: Dmitry V. Levin <[email protected]>
Signed-off-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/c55cddb8f65713bf5859ed675d75a50cb37d5995.1642159570.git.christophe.leroy@csgroup.eu

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arch: remove unused function syscall_set_arguments()

This function appears to have been unused since it was first introduced in
commit 828c365cc8b8 ("tracehook: asm/syscall.h").

Signed-off-by: Pete

arch: remove unused function syscall_set_arguments()

This function appears to have been unused since it was first introduced in
commit 828c365cc8b8 ("tracehook: asm/syscall.h").

Signed-off-by: Peter Collingbourne <[email protected]>
Link: https://linux-review.googlesource.com/id/I8ce04f002903a37c0b6c1d16e9b2a3afa716c097
Signed-off-by: Arnd Bergmann <[email protected]>

show more ...

powerpc/audit: Simplify syscall_get_arch()

Make use of is_32bit_task() and CONFIG_CPU_LITTLE_ENDIAN
to simplify syscall_get_arch().

Signed-off-by: Christophe Leroy <[email protected]>
Sig

powerpc/audit: Simplify syscall_get_arch()

Make use of is_32bit_task() and CONFIG_CPU_LITTLE_ENDIAN
to simplify syscall_get_arch().

Signed-off-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/4be53b9187a4d8c163968f4d224267e41a7fcc33.1629451479.git.christophe.leroy@csgroup.eu

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powerpc/audit: Avoid unneccessary #ifdef in syscall_get_arguments()

Use is_32bit_task() which already handles CONFIG_COMPAT.

Signed-off-by: Christophe Leroy <[email protected]>
Signed-off

powerpc/audit: Avoid unneccessary #ifdef in syscall_get_arguments()

Use is_32bit_task() which already handles CONFIG_COMPAT.

Signed-off-by: Christophe Leroy <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/ba49cdd574558a0363300c3f6b5b062b397cb071.1629451483.git.christophe.leroy@csgroup.eu

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powerpc/64s/syscall: Fix ptrace syscall info with scv syscalls

The scv implementation missed updating syscall return value and error
value get/set functions to deal with the changed register ABI. Th

powerpc/64s/syscall: Fix ptrace syscall info with scv syscalls

The scv implementation missed updating syscall return value and error
value get/set functions to deal with the changed register ABI. This
broke ptrace PTRACE_GET_SYSCALL_INFO as well as some kernel auditing
and tracing functions.

Fix. tools/testing/selftests/ptrace/get_syscall_info now passes when
scv is used.

Fixes: 7fa95f9adaee ("powerpc/64s: system call support for scv/rfscv instructions")
Cc: [email protected] # v5.9+
Reported-by: "Dmitry V. Levin" <[email protected]>
Signed-off-by: Nicholas Piggin <[email protected]>
Reviewed-by: Dmitry V. Levin <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

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powerpc: trap_is_syscall() helper to hide syscall trap number

A new system call interrupt will be added with a new trap number.
Hide the explicit 0xc00 test behind an accessor to reduce churn
in cal

powerpc: trap_is_syscall() helper to hide syscall trap number

A new system call interrupt will be added with a new trap number.
Hide the explicit 0xc00 test behind an accessor to reduce churn
in callers.

Signed-off-by: Nicholas Piggin <[email protected]>
[mpe: Make it a static inline]
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

show more ...

powerpc: define syscall_get_error()

syscall_get_error() is required to be implemented on this architecture in
addition to already implemented syscall_get_nr(), syscall_get_arguments(),
syscall_get_r

powerpc: define syscall_get_error()

syscall_get_error() is required to be implemented on this architecture in
addition to already implemented syscall_get_nr(), syscall_get_arguments(),
syscall_get_return_value(), and syscall_get_arch() functions in order to
extend the generic ptrace API with PTRACE_GET_SYSCALL_INFO request.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Dmitry V. Levin <[email protected]>
Acked-by: Michael Ellerman <[email protected]>
Cc: Elvira Khabirova <[email protected]>
Cc: Eugene Syromyatnikov <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Greentime Hu <[email protected]>
Cc: Helge Deller <[email protected]> [parisc]
Cc: James E.J. Bottomley <[email protected]>
Cc: James Hogan <[email protected]>
Cc: kbuild test robot <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Richard Kuo <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Vincent Chen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 193

Based on 1 normalized pattern(s):

this copyrighted material is made available to anyone wishing to use
modify copy or redistri

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 193

Based on 1 normalized pattern(s):

this copyrighted material is made available to anyone wishing to use
modify copy or redistribute it subject to the terms and conditions
of the gnu general public license v 2

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 45 file(s).

Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Richard Fontana <[email protected]>
Reviewed-by: Allison Randal <[email protected]>
Reviewed-by: Steve Winslow <[email protected]>
Reviewed-by: Alexios Zavras <[email protected]>
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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syscalls: Remove start and number from syscall_set_arguments() args

After removing the start and count arguments of syscall_get_arguments() it
seems reasonable to remove them from syscall_set_argume

syscalls: Remove start and number from syscall_set_arguments() args

After removing the start and count arguments of syscall_get_arguments() it
seems reasonable to remove them from syscall_set_arguments(). Note, as of
today, there are no users of syscall_set_arguments(). But we are told that
there will be soon. But for now, at least make it consistent with
syscall_get_arguments().

Link: http://lkml.kernel.org/r/[email protected]

Cc: Oleg Nesterov <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dominik Brodowski <[email protected]>
Cc: Dave Martin <[email protected]>
Cc: "Dmitry V. Levin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Acked-by: Max Filippov <[email protected]> # For xtensa changes
Acked-by: Will Deacon <[email protected]> # For the arm64 bits
Reviewed-by: Thomas Gleixner <[email protected]> # for x86
Reviewed-by: Dmitry V. Levin <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

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syscalls: Remove start and number from syscall_get_arguments() args

At Linux Plumbers, Andy Lutomirski approached me and pointed out that the
function call syscall_get_arguments() implemented in x86

syscalls: Remove start and number from syscall_get_arguments() args

At Linux Plumbers, Andy Lutomirski approached me and pointed out that the
function call syscall_get_arguments() implemented in x86 was horribly
written and not optimized for the standard case of passing in 0 and 6 for
the starting index and the number of system calls to get. When looking at
all the users of this function, I discovered that all instances pass in only
0 and 6 for these arguments. Instead of having this function handle
different cases that are never used, simply rewrite it to return the first 6
arguments of a system call.

This should help out the performance of tracing system calls by ptrace,
ftrace and perf.

Link: http://lkml.kernel.org/r/[email protected]

Cc: Oleg Nesterov <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dominik Brodowski <[email protected]>
Cc: Dave Martin <[email protected]>
Cc: "Dmitry V. Levin" <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Acked-by: Paul Burton <[email protected]> # MIPS parts
Acked-by: Max Filippov <[email protected]> # For xtensa changes
Acked-by: Will Deacon <[email protected]> # For the arm64 bits
Reviewed-by: Thomas Gleixner <[email protected]> # for x86
Reviewed-by: Dmitry V. Levin <[email protected]>
Reported-by: Andy Lutomirski <[email protected]>
Signed-off-by: Steven Rostedt (VMware) <[email protected]>

show more ...

syscall_get_arch: add "struct task_struct *" argument

This argument is required to extend the generic ptrace API with
PTRACE_GET_SYSCALL_INFO request: syscall_get_arch() is going
to be called from p

syscall_get_arch: add "struct task_struct *" argument

This argument is required to extend the generic ptrace API with
PTRACE_GET_SYSCALL_INFO request: syscall_get_arch() is going
to be called from ptrace_request() along with syscall_get_nr(),
syscall_get_arguments(), syscall_get_error(), and
syscall_get_return_value() functions with a tracee as their argument.

The primary intent is that the triple (audit_arch, syscall_nr, arg1..arg6)
should describe what system call is being called and what its arguments
are.

Reverts: 5e937a9ae913 ("syscall_get_arch: remove useless function arguments")
Reverts: 1002d94d3076 ("syscall.h: fix doc text for syscall_get_arch()")
Reviewed-by: Andy Lutomirski <[email protected]> # for x86
Reviewed-by: Palmer Dabbelt <[email protected]>
Acked-by: Paul Moore <[email protected]>
Acked-by: Paul Burton <[email protected]> # MIPS parts
Acked-by: Michael Ellerman <[email protected]> (powerpc)
Acked-by: Kees Cook <[email protected]> # seccomp parts
Acked-by: Mark Salter <[email protected]> # for the c6x bit
Cc: Elvira Khabirova <[email protected]>
Cc: Eugene Syromyatnikov <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Dmitry V. Levin <[email protected]>
Signed-off-by: Paul Moore <[email protected]>

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powerpc: split compat syscall table out from native table

PowerPC uses a syscall table with native and compat calls
interleaved, which is a slightly simpler way to define two
matching tables.

As we

powerpc: split compat syscall table out from native table

PowerPC uses a syscall table with native and compat calls
interleaved, which is a slightly simpler way to define two
matching tables.

As we move to having the tables generated, that advantage
is no longer important, but the interleaved table gets in
the way of using the same scripts as on the other archit-
ectures.

Split out a new compat_sys_call_table symbol that contains
all the compat calls, and leave the main table for the nat-
ive calls, to more closely match the method we use every-
where else.

Suggested-by: Arnd Bergmann <[email protected]>
Signed-off-by: Firoz Khan <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>

show more ...

powerpc: Change syscall_get_nr() to return int

The documentation for syscall_get_nr() in asm-generic says:

Note this returns int even on 64-bit machines. Only 32 bits of
system call number can be

powerpc: Change syscall_get_nr() to return int

The documentation for syscall_get_nr() in asm-generic says:

Note this returns int even on 64-bit machines. Only 32 bits of
system call number can be meaningful. If the actual arch value
is 64 bits, this truncates to 32 bits so 0xffffffff means -1.

However our implementation was never updated to reflect this.

Generally it's not important, but there is once case where it matters.

For seccomp filter with SECCOMP_RET_TRACE, the tracer will set
regs->gpr[0] to -1 to reject the syscall. When the task is a compat
task, this means we end up with 0xffffffff in r0 because ptrace will
zero extend the 32-bit value.

If syscall_get_nr() returns an unsigned long, then a 64-bit kernel will
see a positive value in r0 and will incorrectly allow the syscall
through seccomp.

Signed-off-by: Michael Ellerman <[email protected]>
Reviewed-by: Kees Cook <[email protected]>

show more ...

powerpc: Use orig_gpr3 in syscall_get_arguments()

Currently syscall_get_arguments() is used by syscall tracepoints, and
collect_syscall() which is used in some debugging as well as
/proc/pid/syscall

powerpc: Use orig_gpr3 in syscall_get_arguments()

Currently syscall_get_arguments() is used by syscall tracepoints, and
collect_syscall() which is used in some debugging as well as
/proc/pid/syscall.

The current implementation just copies regs->gpr[3 .. 5] out, which is
fine for all the current use cases.

When we enable seccomp filter, that will also start using
syscall_get_arguments(). However for seccomp filter we want to use r3
as the return value of the syscall, and orig_gpr3 as the first
parameter. This will allow seccomp to modify the return value in r3.

To support this we need to modify syscall_get_arguments() to return
orig_gpr3 instead of r3. This is safe for all uses because orig_gpr3
always contains the r3 value that was passed to the syscall. We store it
in the syscall entry path and never modify it.

Update syscall_set_arguments() while we're here, even though it's never
used.

Signed-off-by: Michael Ellerman <[email protected]>
Reviewed-by: Kees Cook <[email protected]>

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powerpc: Rework syscall_get_arguments() so there is only one loop

Currently syscall_get_arguments() has two loops, one for compat and one
for regular tasks. In prepartion for the next patch, which c

powerpc: Rework syscall_get_arguments() so there is only one loop

Currently syscall_get_arguments() has two loops, one for compat and one
for regular tasks. In prepartion for the next patch, which changes which
registers we use, switch it to only have one loop, so we only have one
place to update.

Signed-off-by: Michael Ellerman <[email protected]>
Reviewed-by: Kees Cook <[email protected]>

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powerpc: Don't negate error in syscall_set_return_value()

Currently the only caller of syscall_set_return_value() is seccomp
filter, which is not enabled on powerpc.

This means we have not noticed

powerpc: Don't negate error in syscall_set_return_value()

Currently the only caller of syscall_set_return_value() is seccomp
filter, which is not enabled on powerpc.

This means we have not noticed that our implementation of
syscall_set_return_value() negates error, even though the value passed
in is already negative.

So remove the negation in syscall_set_return_value(), and expect the
caller to do it like all other implementations do.

Also add a comment about the ccr handling.

Signed-off-by: Michael Ellerman <[email protected]>
Reviewed-by: Kees Cook <[email protected]>

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powerpc: Drop unused syscall_get_error()

syscall_get_error() is unused, and never has been.

It's also probably wrong, as it negates r3 before returning it, but that
depends on what the caller is ex

powerpc: Drop unused syscall_get_error()

syscall_get_error() is unused, and never has been.

It's also probably wrong, as it negates r3 before returning it, but that
depends on what the caller is expecting.

It also doesn't deal with compat, and doesn't deal with TIF_NOERROR.

Although we could fix those, until it has a caller and it's clear what
semantics the caller wants it's just untested code. So drop it.

Signed-off-by: Michael Ellerman <[email protected]>
Reviewed-by: Kees Cook <[email protected]>

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powerpc: add little endian flag to syscall_get_arch()

Since both ppc and ppc64 have LE variants which are now reported by uname, add
that flag (__AUDIT_ARCH_LE) to syscall_get_arch() and add AUDIT_A

powerpc: add little endian flag to syscall_get_arch()

Since both ppc and ppc64 have LE variants which are now reported by uname, add
that flag (__AUDIT_ARCH_LE) to syscall_get_arch() and add AUDIT_ARCH_PPC64LE
variant.

Without this, perf trace and auditctl fail.

Mainline kernel reports ppc64le (per a058801) but there is no matching
AUDIT_ARCH_PPC64LE.

Since 32-bit PPC LE is not supported by audit, don't advertise it in
AUDIT_ARCH_PPC* variants.

See:
https://www.redhat.com/archives/linux-audit/2014-August/msg00082.html
https://www.redhat.com/archives/linux-audit/2014-December/msg00004.html

Signed-off-by: Richard Guy Briggs <[email protected]>
Acked-by: Paul Moore <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>

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powerpc: Fix sys_call_table declaration to enable syscall tracing

Declaring sys_call_table as a pointer causes the compiler to generate
the wrong lookup code in arch_syscall_addr().

<arch_sysc

powerpc: Fix sys_call_table declaration to enable syscall tracing

Declaring sys_call_table as a pointer causes the compiler to generate
the wrong lookup code in arch_syscall_addr().

<arch_syscall_addr>:
lis r9,-16384
rlwinm r3,r3,2,0,29
- lwz r11,30640(r9)
- lwzx r3,r11,r3
+ addi r9,r9,30640
+ lwzx r3,r9,r3
blr

The actual sys_call_table symbol, declared in assembler, is an
array. If we lie about that to the compiler we get the wrong code
generated, as above.

This definition seems only to be used by the syscall tracing code in
kernel/trace/trace_syscalls.c. With this patch I can successfully use
the syscall tracepoints:

bash-3815 [002] .... 333.239082: sys_write -> 0x2
bash-3815 [002] .... 333.239087: sys_dup2(oldfd: a, newfd: 1)
bash-3815 [002] .... 333.239088: sys_dup2 -> 0x1
bash-3815 [002] .... 333.239092: sys_fcntl(fd: a, cmd: 1, arg: 0)
bash-3815 [002] .... 333.239093: sys_fcntl -> 0x1
bash-3815 [002] .... 333.239094: sys_close(fd: a)
bash-3815 [002] .... 333.239094: sys_close -> 0x0

Signed-off-by: Romeo Cane <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>

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sparc: simplify syscall_get_arch()

Include linux/thread_info.h so we can use is_32_bit_task() cleanly.
Then just simplify syscall_get_arch() since is_32_bit_task() works for
all configuration option

sparc: simplify syscall_get_arch()

Include linux/thread_info.h so we can use is_32_bit_task() cleanly.
Then just simplify syscall_get_arch() since is_32_bit_task() works for
all configuration options.

Suggested-by: Stephen Rothwell <[email protected]>
Signed-off-by: Eric Paris <[email protected]>

show more ...

ARCH: AUDIT: implement syscall_get_arch for all arches

For all arches which support audit implement syscall_get_arch()
They are all pretty easy and straight forward, stolen from how the call
to audi

ARCH: AUDIT: implement syscall_get_arch for all arches

For all arches which support audit implement syscall_get_arch()
They are all pretty easy and straight forward, stolen from how the call
to audit_syscall_entry() determines the arch.

Based-on-patch-by: Richard Briggs <[email protected]>
Signed-off-by: Eric Paris <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]

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powerpc/ftrace: Implement raw syscall tracepoints on PowerPC

This patch implements the raw syscall tracepoints on PowerPC and exports
them for ftrace syscalls to use.

To minimise reworking existing

powerpc/ftrace: Implement raw syscall tracepoints on PowerPC

This patch implements the raw syscall tracepoints on PowerPC and exports
them for ftrace syscalls to use.

To minimise reworking existing code, I slightly re-ordered the thread
info flags such that the new TIF_SYSCALL_TRACEPOINT bit would still fit
within the 16 bits of the andi. instruction's UI field. The instructions
in question are in /arch/powerpc/kernel/entry_{32,64}.S to and the
_TIF_SYSCALL_T_OR_A with the thread flags to see if system call tracing
is enabled.

In the case of 64bit PowerPC, arch_syscall_addr and
arch_syscall_match_sym_name are overridden to allow ftrace syscalls to
work given the unusual system call table structure and symbol names that
start with a period.

Signed-off-by: Ian Munsie <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>

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powerpc: Use correct ccr bit for syscall error status

The powerpc implementations of syscall_get_error and
syscall_set_return_value should use CCR0:S0 (0x10000000) for testing
and setting syscall er

powerpc: Use correct ccr bit for syscall error status

The powerpc implementations of syscall_get_error and
syscall_set_return_value should use CCR0:S0 (0x10000000) for testing
and setting syscall error status. Fortunately these APIs don't seem
to be used at the moment.

Signed-off-by: Nathan Lynch <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>

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