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authorSteven Rostedt <srostedt@redhat.com>2009-06-18 12:45:08 -0400
committerSteven Rostedt <rostedt@goodmis.org>2009-06-18 18:40:18 -0400
commit71e308a239c098673570d0b417d42262bb535909 (patch)
treea9e415d0ae6302e820a1f9d4ff55a724b3a12cf6 /arch/x86/kernel/entry_32.S
parenteb4a03780d4c4464ef2ad86d80cca3f3284fe81d (diff)
function-graph: add stack frame test
In case gcc does something funny with the stack frames, or the return from function code, we would like to detect that. An arch may implement passing of a variable that is unique to the function and can be saved on entering a function and can be tested when exiting the function. Usually the frame pointer can be used for this purpose. This patch also implements this for x86. Where it passes in the stack frame of the parent function, and will test that frame on exit. There was a case in x86_32 with optimize for size (-Os) where, for a few functions, gcc would align the stack frame and place a copy of the return address into it. The function graph tracer modified the copy and not the actual return address. On return from the funtion, it did not go to the tracer hook, but returned to the parent. This broke the function graph tracer, because the return of the parent (where gcc did not do this funky manipulation) returned to the location that the child function was suppose to. This caused strange kernel crashes. This test detected the problem and pointed out where the issue was. This modifies the parameters of one of the functions that the arch specific code calls, so it includes changes to arch code to accommodate the new prototype. Note, I notice that the parsic arch implements its own push_return_trace. This is now a generic function and the ftrace_push_return_trace should be used instead. This patch does not touch that code. Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Helge Deller <deller@gmx.de> Cc: Kyle McMartin <kyle@mcmartin.ca> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch/x86/kernel/entry_32.S')
-rw-r--r--arch/x86/kernel/entry_32.S2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index c929add475c9..0d4b28564c14 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1154,6 +1154,7 @@ ENTRY(ftrace_graph_caller)
pushl %edx
movl 0xc(%esp), %edx
lea 0x4(%ebp), %eax
+ movl (%ebp), %ecx
subl $MCOUNT_INSN_SIZE, %edx
call prepare_ftrace_return
popl %edx
@@ -1168,6 +1169,7 @@ return_to_handler:
pushl %eax
pushl %ecx
pushl %edx
+ movl %ebp, %eax
call ftrace_return_to_handler
movl %eax, 0xc(%esp)
popl %edx