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author | Michael Ellerman <mpe@ellerman.id.au> | 2015-07-23 13:21:06 +0300 |
---|---|---|
committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-07-29 04:56:13 +0300 |
commit | 1cb9839b73e7f2b006a1cc9452c30f15ff8b1748 (patch) | |
tree | 6e508e8421b0e55e3c7417e670ec7aa4a19a9bb6 /arch/powerpc/include/asm/syscall.h | |
parent | a7657844296e796bf33922192743ddeacbcd4d7a (diff) | |
download | linux-1cb9839b73e7f2b006a1cc9452c30f15ff8b1748.tar.xz |
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 <mpe@ellerman.id.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'arch/powerpc/include/asm/syscall.h')
-rw-r--r-- | arch/powerpc/include/asm/syscall.h | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h index 403e2303fe18..8d79a87c0511 100644 --- a/arch/powerpc/include/asm/syscall.h +++ b/arch/powerpc/include/asm/syscall.h @@ -64,7 +64,7 @@ static inline void syscall_get_arguments(struct task_struct *task, unsigned int i, unsigned int n, unsigned long *args) { - unsigned long mask = -1UL; + unsigned long val, mask = -1UL; BUG_ON(i + n > 6); @@ -72,8 +72,14 @@ static inline void syscall_get_arguments(struct task_struct *task, if (test_tsk_thread_flag(task, TIF_32BIT)) mask = 0xffffffff; #endif - while (n--) - args[n] = regs->gpr[3 + i + n] & mask; + while (n--) { + if (n == 0 && i == 0) + val = regs->orig_gpr3; + else + val = regs->gpr[3 + i + n]; + + args[n] = val & mask; + } } static inline void syscall_set_arguments(struct task_struct *task, @@ -83,6 +89,10 @@ static inline void syscall_set_arguments(struct task_struct *task, { BUG_ON(i + n > 6); memcpy(®s->gpr[3 + i], args, n * sizeof(args[0])); + + /* Also copy the first argument into orig_gpr3 */ + if (i == 0 && n > 0) + regs->orig_gpr3 = args[0]; } static inline int syscall_get_arch(void) |