The patch titled x86: fix 32 bit FRAME_POINTER chasing code has been added to the -mm tree. Its filename is fix-x86-32-bit-frame_pointer-chasing-code.patch *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: x86: fix 32 bit FRAME_POINTER chasing code From: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Andi Kleen <ak@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/traps_32.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff -puN arch/x86/kernel/traps_32.c~fix-x86-32-bit-frame_pointer-chasing-code arch/x86/kernel/traps_32.c --- a/arch/x86/kernel/traps_32.c~fix-x86-32-bit-frame_pointer-chasing-code +++ a/arch/x86/kernel/traps_32.c @@ -125,7 +125,8 @@ static inline unsigned long print_contex unsigned long addr; addr = frame->return_address; - ops->address(data, addr); + if (__kernel_text_address(addr)) + ops->address(data, addr); /* * break out of recursive entries (such as * end_of_stack_stop_unwind_function). Also, @@ -133,6 +134,7 @@ static inline unsigned long print_contex * move downwards! */ next = frame->next_frame; + ebp = (unsigned long) next; if (next <= frame) break; frame = next; _ Patches currently in -mm which might be from arjan@xxxxxxxxxxxxxxx are git-input.patch git-sched.patch fix-x86-32-bit-frame_pointer-chasing-code.patch drivers-edac-use-round_jiffies_relative.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html