lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

[PATCH] kprobes: fix race in recovery of reentrant probe

Browse Source 
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>
This commit is contained in:
Keshavamurthy Anil S
2006-01-11 12:17:42 -08:00
committed by Linus Torvalds
parent df019b1d8b
commit eb3a72921c
5 changed files with 49 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
arch/powerpc/kernel/kprobes.c
View File

@ -179,6 +179,18 @@ static inline int kprobe_handler(struct pt_regs *regs)
kcb->kprobe_status = KPROBE_REENTER;
return 1;
} else {
if (*addr != BREAKPOINT_INSTRUCTION) {
/* If trap variant, then it belongs not to us */
kprobe_opcode_t cur_insn = *addr;
if (is_trap(cur_insn))
goto no_kprobe;
/* The breakpoint instruction was removed by
* another cpu right after we hit, no further
* handling of this interrupt is appropriate
*/
ret = 1;
goto no_kprobe;
}
p = __get_cpu_var(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
goto ss_probe;