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authorMichael Ellerman <mpe@ellerman.id.au>2015-07-23 20:21:01 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2015-07-29 11:56:11 +1000
commitc3525940cca53cf3568fefd35d169fea4f107f0a (patch)
treeba6968be2c8b3914157f52ac05961c1e723913d6 /arch/powerpc/kernel
parentf0322f7f1e2165fbf83530a424ef6ebeacbf4bca (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.S3
-rw-r--r--arch/powerpc/kernel/entry_64.S5
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