diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2015-07-23 20:21:01 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-07-29 11:56:11 +1000 |
| commit | c3525940cca53cf3568fefd35d169fea4f107f0a (patch) | |
| tree | ba6968be2c8b3914157f52ac05961c1e723913d6 /arch/powerpc/kernel | |
| parent | f0322f7f1e2165fbf83530a424ef6ebeacbf4bca (diff) | |
powerpc/kernel: Switch to using MAX_ERRNO
Currently on powerpc we have our own #define for the highest (negative)
errno value, called _LAST_ERRNO. This is defined to be 516, for reasons
which are not clear.
The generic code, and x86, use MAX_ERRNO, which is defined to be 4095.
In particular seccomp uses MAX_ERRNO to restrict the value that a
seccomp filter can return.
Currently with the mismatch between _LAST_ERRNO and MAX_ERRNO, a seccomp
tracer wanting to return 600, expecting it to be seen as an error, would
instead find on powerpc that userspace sees a successful syscall with a
return value of 600.
To avoid this inconsistency, switch powerpc to use MAX_ERRNO.
We are somewhat confident that generic syscalls that can return a
non-error value above negative MAX_ERRNO have already been updated to
use force_successful_syscall_return().
I have also checked all the powerpc specific syscalls, and believe that
none of them expect to return a non-error value between -MAX_ERRNO and
-516. So this change should be safe ...
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 3 | ||||
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 5 |
2 files changed, 5 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 46fc0f4d8982..67ecdf61f4e3 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -20,6 +20,7 @@ */ #include <linux/errno.h> +#include <linux/err.h> #include <linux/sys.h> #include <linux/threads.h> #include <asm/reg.h> @@ -354,7 +355,7 @@ ret_from_syscall: SYNC MTMSRD(r10) lwz r9,TI_FLAGS(r12) - li r8,-_LAST_ERRNO + li r8,-MAX_ERRNO andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) bne- syscall_exit_work cmplw 0,r3,r8 diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 579e0f9a2d57..ee15d3c62e26 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -19,6 +19,7 @@ */ #include <linux/errno.h> +#include <linux/err.h> #include <asm/unistd.h> #include <asm/processor.h> #include <asm/page.h> @@ -207,7 +208,7 @@ system_call: /* label this so stack traces look sane */ #endif /* CONFIG_PPC_BOOK3E */ ld r9,TI_FLAGS(r12) - li r11,-_LAST_ERRNO + li r11,-MAX_ERRNO andi. r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK) bne- syscall_exit_work cmpld r3,r11 @@ -277,7 +278,7 @@ syscall_exit_work: beq+ 0f REST_NVGPRS(r1) b 2f -0: cmpld r3,r11 /* r10 is -LAST_ERRNO */ +0: cmpld r3,r11 /* r11 is -MAX_ERRNO */ blt+ 1f andi. r0,r9,_TIF_NOERROR bne- 1f |