Messages in this thread Patch in this message | | | Date | Sun, 20 Apr 2008 23:18:38 +0300 | From | Pekka Paalanen <> | Subject | Re: [PATCH] Check for breakpoint in text_poke to eliminate bug_on |
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On Sun, 20 Apr 2008 15:44:40 -0400 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:
> Can you test this new version ? The check was buggy when it fell on a > code boundary : the addr - 1 wan't always a valid address. >
Sorry, still the same. Btw. I had to apply your patch by hand on top of your previous patch, and it ended up as just
--- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -520,11 +520,6 @@ void *__kprobes text_poke(void *addr, const void *opcode, size_t len) struct page *pages[2]; int i; - if (*((uint8_t *)addr - 1) != BREAKPOINT_INSTRUCTION) { - BUG_ON(len > sizeof(long)); - BUG_ON((((long)addr + len - 1) & ~(sizeof(long) - 1)) - - ((long)addr & ~(sizeof(long) - 1))); - } if (!core_kernel_text((unsigned long)addr)) {
Now I took a log of echo 0, echo 1 cycle with 2.6.24-gentoo-r1-trace kernel: [ 203.448534] CPU 1 is now offline [ 203.448975] SMP alternatives: switching to UP code [ 217.888298] SMP alternatives: switching to SMP code [ 217.889285] Booting processor 1/2 APIC 0x1 [ 217.901404] Initializing CPU#1 [ 217.982081] Calibrating delay using timer specific routine.. 3991.35 BogoMIPS (lpj=6650167) [ 217.982088] CPU: L1 I cache: 32K, L1 D cache: 32K [ 217.982089] CPU: L2 cache: 4096K [ 217.982091] CPU: Physical Processor ID: 0 [ 217.982092] CPU: Processor Core ID: 1 [ 217.982593] Intel(R) Core(TM)2 Duo CPU T7300 @ 2.00GHz stepping 0a [ 217.982644] Switched to high resolution mode on CPU 1
And the failing log from the latest try is: [ 87.064970] CPU 1 is now offline [ 87.065311] lockdep: fixing up alternatives. [ 87.065694] SMP alternatives: switching to UP code [ 97.192213] lockdep: fixing up alternatives. [ 97.192532] SMP alternatives: switching to SMP code [ 97.203495] Booting processor 1/1 ip 6000 and it hangs and reboots.
Does it make sense to bisect on sched-devel/latest? I think I could try that after a sleep&work cycle. Luckily this bug is easy to reproduce.
Thanks.
-- Pekka Paalanen http://www.iki.fi/pq/
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