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35de3b1aa1
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 <chuhu@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
71 lines
1.6 KiB
C
71 lines
1.6 KiB
C
/*
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* Stack trace utility
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*
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* Copyright 2008 Christoph Hellwig, IBM Corp.
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*
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/stacktrace.h>
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#include <asm/ptrace.h>
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#include <asm/processor.h>
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/*
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* Save stack-backtrace addresses into a stack_trace buffer.
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*/
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static void save_context_stack(struct stack_trace *trace, unsigned long sp,
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struct task_struct *tsk, int savesched)
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{
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for (;;) {
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unsigned long *stack = (unsigned long *) sp;
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unsigned long newsp, ip;
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if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
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return;
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newsp = stack[0];
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ip = stack[STACK_FRAME_LR_SAVE];
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if (savesched || !in_sched_functions(ip)) {
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if (!trace->skip)
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trace->entries[trace->nr_entries++] = ip;
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else
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trace->skip--;
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}
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if (trace->nr_entries >= trace->max_entries)
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return;
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sp = newsp;
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}
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}
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void save_stack_trace(struct stack_trace *trace)
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{
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unsigned long sp;
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sp = current_stack_pointer();
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save_context_stack(trace, sp, current, 1);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace);
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void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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{
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save_context_stack(trace, tsk->thread.ksp, tsk, 0);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
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void
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save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
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{
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save_context_stack(trace, regs->gpr[1], current, 0);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_regs);
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