From: Tong Li <tong.n.li@intel.com>
Date: Fri, 3 Feb 2006 11:04:09 +0000 (-0800)
Subject: [PATCH] OProfile: fixed x86_64 incorrect kernel call graphs
X-Git-Tag: v2.6.16-rc3~265
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=23332c2e9da16b717f18fd95bc90211a663aa6ee;p=pandora-kernel.git

[PATCH] OProfile: fixed x86_64 incorrect kernel call graphs

Fix the problem in kernel 2.6.15.1 (and early versions) that OProfile on
x86_64 does not correctly collect the stack traces for kernel functions.

The original code in valid_kernel_stack() in arch/i386/oprofile/backtrace.c
assumes that the frame pointer (headaddr) should be greater than stack
(i.e., regs).

This assumption is wrong for x86_64 because NMIs in x86_64 use a seperate
stack different from the kernel stack.  Therefore, the variable stack now
points to some location on the NMI stack, which turns out to be at a higher
address than the frame pointer (headaddr) on the kernel stack.  The correct
comparison here should be between headaddr and regs->rsp for x86_64.

Signed-off-by: Tong Li <tong.n.li@intel.com>
Cc: John Levon <levon@movementarian.org>
Cc: Philippe Elie <phil.el@wanadoo.fr>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

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