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author | Matt Fleming <matt@console-pimps.org> | 2009-07-11 02:29:04 +0200 |
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committer | Paul Mundt <lethal@linux-sh.org> | 2009-07-11 03:08:06 +0200 |
commit | 7816fecd03e480ed0b47d674ed772ca0b45e1b5e (patch) | |
tree | 33ed6c1780f3ebccd5915f724e7345875bee93b1 /arch/sh | |
parent | sh: Function graph tracer support (diff) | |
download | linux-7816fecd03e480ed0b47d674ed772ca0b45e1b5e.tar.xz linux-7816fecd03e480ed0b47d674ed772ca0b45e1b5e.zip |
sh: Mark __switch_to() as __notrace_funcgraph
Annotate __switch_to() so that the function graph tracer does not try to
trace it. Use __notrace_funcgraph, as opposed to notrace, so that other
tracers can continue to trace __switch_to().
The reason that we don't want to trace __switch_to() with the function
graph tracer is because of how the return address stack in task_struct
is implemented. When we enter __switch_to we store the real return
address on prev's ret_stack. When we return from __switch_to() we've
patched the return address on the kernel stack to be
return_to_handler. Calling return_to_handler we do,
-> ftrace_return_to_handler()
-> ftrace_pop_return_ftrace()
Which tries to pop the real return address from current->ret_stack. The
problem being that we stored the return address on prev->ret_stack, but
current now points to next, and next->ret_stack doesn't contain the
correct return address (and is possibly even empty).
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to 'arch/sh')
-rw-r--r-- | arch/sh/kernel/process_32.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c index 92d7740faab1..9fee977f176b 100644 --- a/arch/sh/kernel/process_32.c +++ b/arch/sh/kernel/process_32.c @@ -23,6 +23,7 @@ #include <linux/tick.h> #include <linux/reboot.h> #include <linux/fs.h> +#include <linux/ftrace.h> #include <linux/preempt.h> #include <asm/uaccess.h> #include <asm/mmu_context.h> @@ -264,8 +265,8 @@ static void ubc_set_tracing(int asid, unsigned long pc) * switch_to(x,y) should switch tasks from x to y. * */ -struct task_struct *__switch_to(struct task_struct *prev, - struct task_struct *next) +__notrace_funcgraph struct task_struct * +__switch_to(struct task_struct *prev, struct task_struct *next) { #if defined(CONFIG_SH_FPU) unlazy_fpu(prev, task_pt_regs(prev)); |