diff options
| author | Sam bobroff <sam.bobroff@au1.ibm.com> | 2015-04-10 07:16:47 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-04-11 13:49:19 +0300 |
| commit | feba40362b11341bee6d8ed58d54b896abbd9f84 (patch) | |
| tree | 1260122ddfe4ae26ad224367097e2ca38fc8c6be /arch/powerpc/include/uapi/asm/tm.h | |
| parent | 771e569e8200ab6f5cdbcd6513f7a476718bb44d (diff) | |
| download | linux-feba40362b11341bee6d8ed58d54b896abbd9f84.tar.xz | |
powerpc/tm: Abort syscalls in active transactions
This patch changes the syscall handler to doom (tabort) active
transactions when a syscall is made and return immediately without
performing the syscall.
Currently, the system call instruction automatically suspends an
active transaction which causes side effects to persist when an active
transaction fails.
This does change the kernel's behaviour, but in a way that was
documented as unsupported. It doesn't reduce functionality because
syscalls will still be performed after tsuspend. It also provides a
consistent interface and makes the behaviour of user code
substantially the same across powerpc and platforms that do not
support suspended transactions (e.g. x86 and s390).
Performance measurements using
http://ozlabs.org/~anton/junkcode/null_syscall.c
indicate the cost of a system call increases by about 0.5%.
Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com>
Acked-By: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/uapi/asm/tm.h')
| -rw-r--r-- | arch/powerpc/include/uapi/asm/tm.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/include/uapi/asm/tm.h b/arch/powerpc/include/uapi/asm/tm.h index 5d836b7c1176..5047659815a5 100644 --- a/arch/powerpc/include/uapi/asm/tm.h +++ b/arch/powerpc/include/uapi/asm/tm.h @@ -11,7 +11,7 @@ #define TM_CAUSE_RESCHED 0xde #define TM_CAUSE_TLBI 0xdc #define TM_CAUSE_FAC_UNAV 0xda -#define TM_CAUSE_SYSCALL 0xd8 /* future use */ +#define TM_CAUSE_SYSCALL 0xd8 #define TM_CAUSE_MISC 0xd6 /* future use */ #define TM_CAUSE_SIGNAL 0xd4 #define TM_CAUSE_ALIGNMENT 0xd2 |