Commit:     3d1f7cae883ce4aac99c661562111a25d52effe0
Parent:     076f9776f5d8d131b36955db8641aba3893c2c1b
Author:     Arjan van de Ven <[EMAIL PROTECTED]>
AuthorDate: Wed Jan 30 13:33:06 2008 +0100
Committer:  Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 13:33:06 2008 +0100

    x86: fix 32-bit FRAME_POINTER chasing code
    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
    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 
    Signed-off-by: Arjan van de Ven <[EMAIL PROTECTED]>
    Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
    Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
 arch/x86/kernel/traps_32.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 83df0f3..acc9af2 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -125,7 +125,8 @@ static inline unsigned long print_context_stack(struct 
thread_info *tinfo,
                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_context_stack(struct 
thread_info *tinfo,
                 * move downwards!
                next = frame->next_frame;
+               bp = (unsigned long) next;
                if (next <= frame)
                frame = next;
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