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>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 356d2ec..fcf12af 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -33,6 +33,7 @@
select HAVE_DYNAMIC_FTRACE
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
+ select HAVE_FUNCTION_GRAPH_FP_TEST
select HAVE_FUNCTION_TRACE_MCOUNT_TEST
select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
select HAVE_FTRACE_SYSCALLS
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index c929add..0d4b285 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1154,6 +1154,7 @@
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 @@
pushl %eax
pushl %ecx
pushl %edx
+ movl %ebp, %eax
call ftrace_return_to_handler
movl %eax, 0xc(%esp)
popl %edx
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index de74f0a..c251be7 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -135,6 +135,7 @@
leaq 8(%rbp), %rdi
movq 0x38(%rsp), %rsi
+ movq (%rbp), %rdx
subq $MCOUNT_INSN_SIZE, %rsi
call prepare_ftrace_return
@@ -150,6 +151,7 @@
/* Save the return values */
movq %rax, (%rsp)
movq %rdx, 8(%rsp)
+ movq %rbp, %rdi
call ftrace_return_to_handler
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index b79c553..d94e1ea 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -408,7 +408,8 @@
* Hook the return address and push it in the stack of return addrs
* in current thread info.
*/
-void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+ unsigned long frame_pointer)
{
unsigned long old;
int faulted;
@@ -453,7 +454,8 @@
return;
}
- if (ftrace_push_return_trace(old, self_addr, &trace.depth) == -EBUSY) {
+ if (ftrace_push_return_trace(old, self_addr, &trace.depth,
+ frame_pointer) == -EBUSY) {
*parent = old;
return;
}