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SubjectRe: [PATCH RESEND v5 -tip] x86, dumpstack: Correct stack dump info when frame pointer is available
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On Fri, 2011-03-18 at 11:40 +0900, Namhyung Kim wrote:
>
> Current stack dump code scans entire stack and check each entry
> contains a pointer to kernel code. If CONFIG_FRAME_POINTER=y it
> could mark whether the pointer is valid or not based on value of
> the frame pointer. Invalid entries could be preceded by '?' sign.
>
> However this was not going to happen because scan start point was
> always higher than the frame pointer so that they could not meet.
>
> Commit 9c0729dc8062 ("x86: Eliminate bp argument from the stack
> tracing routines") delayed bp acquisition point, so the bp was
> read in lower frame, thus all of the entries were marked invalid.
>
> This patch fixes this by reverting above commit while retaining
> stack_frame() helper as suggested by Frederic Weisbecker.
> End result looks like below:
>
> before:
> [ 3.508329] Call Trace:
> [ 3.508551] [<ffffffff814f35c9>] ? panic+0x91/0x199
> [ 3.508662] [<ffffffff814f3739>] ? printk+0x68/0x6a
> [ 3.508770] [<ffffffff81a981b2>] ? mount_block_root+0x257/0x26e
> [ 3.508876] [<ffffffff81a9821f>] ? mount_root+0x56/0x5a
> [ 3.508975] [<ffffffff81a98393>] ? prepare_namespace+0x170/0x1a9
> [ 3.509216] [<ffffffff81a9772b>] ? kernel_init+0x1d2/0x1e2
> [ 3.509335] [<ffffffff81003894>] ? kernel_thread_helper+0x4/0x10
> [ 3.509442] [<ffffffff814f6880>] ? restore_args+0x0/0x30
> [ 3.509542] [<ffffffff81a97559>] ? kernel_init+0x0/0x1e2
> [ 3.509641] [<ffffffff81003890>] ? kernel_thread_helper+0x0/0x10
>
> after:
> [ 3.522991] Call Trace:
> [ 3.523351] [<ffffffff814f35b9>] panic+0x91/0x199
> [ 3.523468] [<ffffffff814f3729>] ? printk+0x68/0x6a
> [ 3.523576] [<ffffffff81a981b2>] mount_block_root+0x257/0x26e
> [ 3.523681] [<ffffffff81a9821f>] mount_root+0x56/0x5a
> [ 3.523780] [<ffffffff81a98393>] prepare_namespace+0x170/0x1a9
> [ 3.523885] [<ffffffff81a9772b>] kernel_init+0x1d2/0x1e2
> [ 3.523987] [<ffffffff81003894>] kernel_thread_helper+0x4/0x10
> [ 3.524228] [<ffffffff814f6880>] ? restore_args+0x0/0x30
> [ 3.524345] [<ffffffff81a97559>] ? kernel_init+0x0/0x1e2
> [ 3.524445] [<ffffffff81003890>] ? kernel_thread_helper+0x0/0x10
>
> Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Soren Sandmann <ssp@redhat.com>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Cc: Robert Richter <robert.richter@amd.com>

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

Ingo, _please_, pretty _please_ merge this? These wrecked unwinds drive
me up the wall ;-)


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