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authorHeiko Carstens <hca@linux.ibm.com>2023-04-05 16:08:41 +0300
committerVasily Gorbik <gor@linux.ibm.com>2023-04-20 12:36:35 +0300
commit2a405f6bb3a5b2baaa74dfc5aaa0e1b99145bd1b (patch)
tree6481ca657215160fa0914083d4c81ce40caf854d /arch/s390/include/asm/processor.h
parent491a78663e039fabc58c892ca8f2c2e08caaf4f8 (diff)
downloadlinux-2a405f6bb3a5b2baaa74dfc5aaa0e1b99145bd1b.tar.xz
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/include/asm/processor.h')
-rw-r--r--arch/s390/include/asm/processor.h35
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
*/