user/sven/linux.git/arch/powerpc/kernel/stacktrace.c, branch v4.9.296

powerpc: Implement save_stack_trace_regs() to enable kprobe stack tracing

2016-01-11T03:27:28Z

It has come to my attention that kprobe event stack tracing does not work on powerpc. You can see with the following: # cd /sys/kernel/debug/tracing # echo stacktrace > trace_options # echo 'p kfree' > kprobe_events # echo 1 > events/kprobes/enable Will print the following warning: save_stack_trace_regs() not implemented yet. Although save_stack_trace() (which normal event stack traces use) is implemented, save_stack_trace_regs() which kprobe events use is not. This is a cheap attempt to implement that function. Note, This may have issues if a task tries to get a stack trace from another task with its regs, because it just passes in "current" to save_context_stack(). But this does solve the issue with stack tracing kprobe events. Reported-by: Chunyu Hu Signed-off-by: Steven Rostedt Signed-off-by: Michael Ellerman

powerpc: Rename __get_SP() to current_stack_pointer()

2014-10-15T00:23:20Z

Michael points out that __get_SP() is a pretty horrible function name. Let's give it a better name. Signed-off-by: Anton Blanchard Signed-off-by: Michael Ellerman

powerpc: Reimplement __get_SP() as a function not a define

2014-10-15T00:23:19Z

Li Zhong points out an issue with our current __get_SP() implementation. If ftrace function tracing is enabled (ie -pg profiling using _mcount) we spill a stack frame on 64bit all the time. If a function calls __get_SP() and later calls a function that is tail call optimised, we will pop the stack frame and the value returned by __get_SP() is no longer valid. An example from Li can be found in save_stack_trace -> save_context_stack: c0000000000432c0 <.save_stack_trace>: c0000000000432c0: mflr r0 c0000000000432c4: std r0,16(r1) c0000000000432c8: stdu r1,-128(r1) <-- stack frame for _mcount c0000000000432cc: std r3,112(r1) c0000000000432d0: bl <._mcount> c0000000000432d4: nop c0000000000432d8: mr r4,r1 <-- __get_SP() c0000000000432dc: ld r5,632(r13) c0000000000432e0: ld r3,112(r1) c0000000000432e4: li r6,1 c0000000000432e8: addi r1,r1,128 <-- pop stack frame c0000000000432ec: ld r0,16(r1) c0000000000432f0: mtlr r0 c0000000000432f4: b <.save_context_stack> <-- tail call optimized save_context_stack ends up with a stack pointer below the current one, and it is likely to be scribbled over. Fix this by making __get_SP() a function which returns the callers stack frame. Also replace inline assembly which grabs the stack pointer in save_stack_trace and show_stack with __get_SP(). This also fixes an issue with perf_arch_fetch_caller_regs(). It currently unwinds the stack once, which will skip a valid stack frame on a leaf function. With the __get_SP() fixes in this patch, we never need to unwind the stack frame to get to the first interesting frame. We have to export __get_SP() because perf_arch_fetch_caller_regs() (which is used in modules) calls it from a header file. Reported-by: Li Zhong Signed-off-by: Anton Blanchard Signed-off-by: Michael Ellerman

powerpc: various straight conversions from module.h --> export.h

2011-10-31T23:30:44Z

All these files were including module.h just for the basic EXPORT_SYMBOL infrastructure. We can shift them off to the export.h header which is a way smaller footprint and thus realize some compile time gains. Signed-off-by: Paul Gortmaker

powerpc: Removed duplicated include in stacktrace.c

2008-07-28T06:30:47Z

Removed duplicated include file in arch/powerpc/kernel/stacktrace.c. Signed-off-by: Huang Weiyi Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix support for latencytop

2008-07-22T00:39:33Z

We need to pass the kernel stack pointer instead of the user space stack pointer in save_stack_trace_tsk(). Signed-off-by: Arnd Bergmann Signed-off-by: Benjamin Herrenschmidt

Merge commit 'origin/master'

2008-07-16T01:07:59Z

Manual merge of: arch/powerpc/Kconfig arch/powerpc/kernel/stacktrace.c arch/powerpc/mm/slice.c arch/ppc/kernel/smp.c

powerpc: support for latencytop

2008-07-15T02:29:15Z

Implement save_stack_trace_tsk on powerpc, so that we can run with latencytop. Signed-off-by: Arnd Bergmann Signed-off-by: Benjamin Herrenschmidt

generic-ipi: powerpc/generic-ipi tree build failure

2008-07-14T15:54:22Z

Today's linux-next build (powerpc allmodconfig) failed like this: ERROR: ".save_stack_trace" [tests/backtracetest.ko] undefined! But save_stack_trace is exported in arch/powerpc/kernel/stacktrace.c I couldn't figure it out until I noticed these earlier warnings: arch/powerpc/kernel/stacktrace.c:47: warning: data definition has no type or storage class arch/powerpc/kernel/stacktrace.c:47: warning: type defaults to 'int' in declaration of 'EXPORT_SYMBOL_GPL' arch/powerpc/kernel/stacktrace.c:47: warning: parameter names (without types) in function declaration I applied the patch below. Signed-off-by: Stephen Rothwell Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Signed-off-by: Ingo Molnar

stacktrace: export save_stack_trace[_tsk]

2008-07-03T07:17:55Z

Andrew Morton reported this against linux-next: ERROR: ".save_stack_trace" [tests/backtracetest.ko] undefined! Reported-by: Andrew Morton Signed-off-by: Ingo Molnar