From 9135c3cc5acf344eb28735681d8bebdb98a2c216 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 15 Sep 2009 08:20:15 -0700 Subject: powerpc/ftrace: show real return addresses in modules When the function graph tracer is enabled, it replaces the return address with a hook back to the tracer. This makes back traces see the hook instead of the actual return address. The current code also shows the real address by checking if the return address jumps to the return_to_handler. If it is, is also prints out the saved real return address. On powerpc64, some modules may return to mod_return_to_handler, which is not checked. This patch will also show the real address if a return is to mod_return_to_handler as well. Signed-off-by: Steven Rostedt --- arch/powerpc/kernel/process.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 1168c5f440ab..2ec1eaed19ca 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1016,9 +1016,13 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) #ifdef CONFIG_FUNCTION_GRAPH_TRACER int curr_frame = current->curr_ret_stack; extern void return_to_handler(void); - unsigned long addr = (unsigned long)return_to_handler; + unsigned long rth = (unsigned long)return_to_handler; + unsigned long mrth = -1; #ifdef CONFIG_PPC64 - addr = *(unsigned long*)addr; + extern void mod_return_to_handler(void); + rth = *(unsigned long *)rth; + mrth = (unsigned long)mod_return_to_handler; + mrth = *(unsigned long *)mrth; #endif #endif @@ -1044,7 +1048,7 @@ void show_stack(struct task_struct *tsk, unsigned long *stack) if (!firstframe || ip != lr) { printk("["REG"] ["REG"] %pS", sp, ip, (void *)ip); #ifdef CONFIG_FUNCTION_GRAPH_TRACER - if (ip == addr && curr_frame >= 0) { + if ((ip == rth || ip == mrth) && curr_frame >= 0) { printk(" (%pS)", (void *)current->ret_stack[curr_frame].ret); curr_frame--; -- cgit v1.2.1 From be10ab109099f8bd8dd365677a9fe641584c1b5b Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 15 Sep 2009 08:30:14 -0700 Subject: powerpc64/ftrace: use PACA to retrieve TOC in mod_return_to_handler The mod_return_to_handler needs to switch to the kernel TOC before jumping to a the kernel code. It currently does this by looking at the kernel function data and retrieves the TOC that way. Not only is this inefficient, it also breaks with a relocatable kernel. The PACA contains the kernel TOC and we can easily retrieve it that way. Reported-by: Sachin Sant Signed-off-by: Steven Rostedt --- arch/powerpc/kernel/entry_64.S | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index 900e0eea0099..f9fd54bfcc84 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1038,8 +1038,7 @@ _GLOBAL(mod_return_to_handler) * We are in a module using the module's TOC. * Switch to our TOC to run inside the core kernel. */ - LOAD_REG_IMMEDIATE(r4,ftrace_return_to_handler) - ld r2, 8(r4) + ld r2, PACATOC(r13) bl .ftrace_return_to_handler nop -- cgit v1.2.1