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 ...
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
---
arch/powerpc/include/uapi/asm/errno.h | 2 --
arch/powerpc/kernel/entry_32.S | 3 ++-
arch/powerpc/kernel/entry_64.S | 5 +++--
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/uapi/asm/errno.h
b/arch/powerpc/include/uapi/asm/errno.h
index 8c145fd17d86..e8b6b5f7de7c 100644
--- a/arch/powerpc/include/uapi/asm/errno.h
+++ b/arch/powerpc/include/uapi/asm/errno.h
@@ -6,6 +6,4 @@
#undef EDEADLOCK
#define EDEADLOCK 58 /* File locking deadlock error */
-#define _LAST_ERRNO 516
-
#endif /* _ASM_POWERPC_ERRNO_H */
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 0796c487d3db..8292581a42f1 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
@@ -279,7 +280,7 @@ 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
--
2.1.0
--
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