forked from Minki/linux
3d1f7cae88
The current x86 32 bit FRAME_POINTER chasing code has a nasty bug in that the EBP tracer doesn't actually update the value of EBP it is tracing, so that the code doesn't actually switch to the irq stack properly. The result is a truncated backtrace: WARNING: at timeroops.c:8 kerneloops_regression_test() (Not tainted) Pid: 0, comm: swapper Not tainted 2.6.24-0.77.rc4.git4.fc9 #1 [<c040649a>] show_trace_log_lvl+0x1a/0x2f [<c0406d41>] show_trace+0x12/0x14 [<c0407061>] dump_stack+0x6c/0x72 [<e0258049>] kerneloops_regression_test+0x44/0x46 [timeroops] [<c04371ac>] run_timer_softirq+0x127/0x18f [<c0434685>] __do_softirq+0x78/0xff [<c0407759>] do_softirq+0x74/0xf7 ======================= This patch fixes the code to update EBP properly, and to check the EIP before printing (as the non-framepointer backtracer does) so that the same test backtrace now looks like this: WARNING: at timeroops.c:8 kerneloops_regression_test() Pid: 0, comm: swapper Not tainted 2.6.24-rc7 #4 [<c0405d17>] show_trace_log_lvl+0x1a/0x2f [<c0406681>] show_trace+0x12/0x14 [<c0406ef2>] dump_stack+0x6a/0x70 [<e01f6040>] kerneloops_regression_test+0x3b/0x3d [timeroops] [<c0426f07>] run_timer_softirq+0x11b/0x17c [<c04243ac>] __do_softirq+0x42/0x94 [<c040704c>] do_softirq+0x50/0xb6 [<c04242a9>] irq_exit+0x37/0x67 [<c040714c>] do_IRQ+0x9a/0xaf [<c04057da>] common_interrupt+0x2e/0x34 [<c05807fe>] cpuidle_idle_call+0x52/0x78 [<c04034f3>] cpu_idle+0x46/0x60 [<c05fbbd3>] rest_init+0x43/0x45 [<c070aa3d>] start_kernel+0x279/0x27f ======================= This shows that the backtrace goes all the way down to user context now. This bug was found during the port to 64 bit of the frame pointer backtracer. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
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