From b70842df77615309d76bcdd63bd289993e0844f2 Mon Sep 17 00:00:00 2001 From: David Wilder Date: Mon, 26 Mar 2007 20:42:40 +0200 Subject: [PATCH] [S390] kprobes: Align probe address. Running a probe on s390 with a probe address that is not 4 byte aligned results in a Kernel BUG. The problem is that the stura instruction used by swap_instruction requires the destination address to be 4 byte aligned. As stura only writes 4 bytes, aligning to the next 4 byte aligned address results in the breakpoint instruction being stored past the probe address. The fix is to align the address backward (to the previous 4 byte aligned address) and writing the two byte breakpoint instruction in the appropriate bytes. Cc: Martin Schwidefsky Signed-off-by: David Wilder Signed-off-by: Heiko Carstens --- arch/s390/kernel/kprobes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c index 8af549e957..993f353814 100644 --- a/arch/s390/kernel/kprobes.c +++ b/arch/s390/kernel/kprobes.c @@ -167,7 +167,7 @@ static int __kprobes swap_instruction(void *aref) * shall not cross any page boundaries (vmalloc area!) when writing * the new instruction. */ - addr = (u32 *)ALIGN((unsigned long)args->ptr, 4); + addr = (u32 *)((unsigned long)args->ptr & -4UL); if ((unsigned long)args->ptr & 2) instr = ((*addr) & 0xffff0000) | args->new; else -- 2.39.5