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authorKeshavamurthy Anil S <anil.s.keshavamurthy@intel.com>2006-01-11 15:17:42 -0500
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-11 21:42:12 -0500
commiteb3a72921c8276bf2cd028a458bb83435f16c91c (patch)
tree634eff43e1926bdb400d038eb08115193b6a7506 /arch/ia64
parentdf019b1d8b893d0f0ee5a9b0f71486f0892561ae (diff)
[PATCH] kprobes: fix race in recovery of reentrant probe
There is a window where a probe gets removed right after the probe is hit on some different cpu. In this case probe handlers can't find a matching probe instance related to break address. In this case we need to read the original instruction at break address to see if that is not a break/int3 instruction and recover safely. Previous code had a bug where we were not checking for the above race in case of reentrant probes and the below patch fixes this race. Tested on IA64, Powerpc, x86_64. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'arch/ia64')
-rw-r--r--arch/ia64/kernel/kprobes.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c
index 4de7f6759093..346fedf9ea47 100644
--- a/arch/ia64/kernel/kprobes.c
+++ b/arch/ia64/kernel/kprobes.c
@@ -638,6 +638,13 @@ static int __kprobes pre_kprobes_handler(struct die_args *args)
638 if (p->break_handler && p->break_handler(p, regs)) { 638 if (p->break_handler && p->break_handler(p, regs)) {
639 goto ss_probe; 639 goto ss_probe;
640 } 640 }
641 } else if (!is_ia64_break_inst(regs)) {
642 /* The breakpoint instruction was removed by
643 * another cpu right after we hit, no further
644 * handling of this interrupt is appropriate
645 */
646 ret = 1;
647 goto no_kprobe;
641 } else { 648 } else {
642 /* Not our break */ 649 /* Not our break */
643 goto no_kprobe; 650 goto no_kprobe;