diff options
| author | Heiko Carstens | 2023-04-05 15:08:41 +0200 |
|---|---|---|
| committer | Vasily Gorbik | 2023-04-20 11:36:35 +0200 |
| commit | 2a405f6bb3a5b2baaa74dfc5aaa0e1b99145bd1b (patch) | |
| tree | 6481ca657215160fa0914083d4c81ce40caf854d /arch/s390 | |
| parent | 491a78663e039fabc58c892ca8f2c2e08caaf4f8 (diff) | |
s390/stackleak: provide fast __stackleak_poison() implementation
Provide an s390 specific __stackleak_poison() implementation which is
faster than the generic variant.
For the original implementation with an enforced 4kb stackframe for the
getpid() system call the system call overhead increases by a factor of 3 if
the stackleak feature is enabled. Using the s390 mvc based variant this is
reduced to an increase of 25% instead.
This is within the expected area, since the mvc based implementation is
more or less a memset64() variant which comes with similar results. See
commit 0b77d6701cf8 ("s390: implement memset16, memset32 & memset64").
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20230405130841.1350565-3-hca@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/include/asm/processor.h | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h index efffc28cbad8..dc17896a001a 100644 --- a/arch/s390/include/asm/processor.h +++ b/arch/s390/include/asm/processor.h @@ -118,6 +118,41 @@ unsigned long vdso_size(void); #define HAVE_ARCH_PICK_MMAP_LAYOUT +#define __stackleak_poison __stackleak_poison +static __always_inline void __stackleak_poison(unsigned long erase_low, + unsigned long erase_high, + unsigned long poison) +{ + unsigned long tmp, count; + + count = erase_high - erase_low; + if (!count) + return; + asm volatile( + " cghi %[count],8\n" + " je 2f\n" + " aghi %[count],-(8+1)\n" + " srlg %[tmp],%[count],8\n" + " ltgr %[tmp],%[tmp]\n" + " jz 1f\n" + "0: stg %[poison],0(%[addr])\n" + " mvc 8(256-8,%[addr]),0(%[addr])\n" + " la %[addr],256(%[addr])\n" + " brctg %[tmp],0b\n" + "1: stg %[poison],0(%[addr])\n" + " larl %[tmp],3f\n" + " ex %[count],0(%[tmp])\n" + " j 4f\n" + "2: stg %[poison],0(%[addr])\n" + " j 4f\n" + "3: mvc 8(1,%[addr]),0(%[addr])\n" + "4:\n" + : [addr] "+&a" (erase_low), [count] "+&d" (count), [tmp] "=&a" (tmp) + : [poison] "d" (poison) + : "memory", "cc" + ); +} + /* * Thread structure */ |