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![Steven Rostedt (Red Hat)](/assets/img/avatar_default.png)
Nothing sets function_trace_stop to disable function tracing anymore. Remove the check for it in the arch code. Link: http://lkml.kernel.org/r/53B08317.7010501@gmx.de Cc: Kyle McMartin <kyle@mcmartin.ca> Acked-by: Helge Deller <deller@gmx.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
185 lines
4.3 KiB
C
185 lines
4.3 KiB
C
/*
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* Code for tracing calls in Linux kernel.
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* Copyright (C) 2009 Helge Deller <deller@gmx.de>
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*
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* based on code for x86 which is:
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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*
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* future possible enhancements:
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* - add CONFIG_DYNAMIC_FTRACE
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* - add CONFIG_STACK_TRACER
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*/
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#include <linux/init.h>
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#include <linux/ftrace.h>
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#include <asm/sections.h>
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#include <asm/ftrace.h>
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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/* Add a function return address to the trace stack on thread info.*/
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static int push_return_trace(unsigned long ret, unsigned long long time,
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unsigned long func, int *depth)
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{
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int index;
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if (!current->ret_stack)
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return -EBUSY;
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/* The return trace stack is full */
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if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
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atomic_inc(¤t->trace_overrun);
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return -EBUSY;
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}
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index = ++current->curr_ret_stack;
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barrier();
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current->ret_stack[index].ret = ret;
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current->ret_stack[index].func = func;
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current->ret_stack[index].calltime = time;
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*depth = index;
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return 0;
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}
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/* Retrieve a function return address to the trace stack on thread info.*/
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static void pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
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{
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int index;
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index = current->curr_ret_stack;
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if (unlikely(index < 0)) {
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ftrace_graph_stop();
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WARN_ON(1);
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/* Might as well panic, otherwise we have no where to go */
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*ret = (unsigned long)
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dereference_function_descriptor(&panic);
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return;
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}
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*ret = current->ret_stack[index].ret;
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trace->func = current->ret_stack[index].func;
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trace->calltime = current->ret_stack[index].calltime;
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trace->overrun = atomic_read(¤t->trace_overrun);
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trace->depth = index;
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barrier();
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current->curr_ret_stack--;
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}
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/*
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* Send the trace to the ring-buffer.
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* @return the original return address.
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*/
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unsigned long ftrace_return_to_handler(unsigned long retval0,
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unsigned long retval1)
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{
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struct ftrace_graph_ret trace;
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unsigned long ret;
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pop_return_trace(&trace, &ret);
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trace.rettime = local_clock();
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ftrace_graph_return(&trace);
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if (unlikely(!ret)) {
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ftrace_graph_stop();
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WARN_ON(1);
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/* Might as well panic. What else to do? */
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ret = (unsigned long)
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dereference_function_descriptor(&panic);
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}
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/* HACK: we hand over the old functions' return values
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in %r23 and %r24. Assembly in entry.S will take care
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and move those to their final registers %ret0 and %ret1 */
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asm( "copy %0, %%r23 \n\t"
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"copy %1, %%r24 \n" : : "r" (retval0), "r" (retval1) );
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return ret;
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}
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/*
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* Hook the return address and push it in the stack of return addrs
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* in current thread info.
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*/
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void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
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{
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unsigned long old;
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unsigned long long calltime;
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struct ftrace_graph_ent trace;
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if (unlikely(ftrace_graph_is_dead()))
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return;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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old = *parent;
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*parent = (unsigned long)
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dereference_function_descriptor(&return_to_handler);
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if (unlikely(!__kernel_text_address(old))) {
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ftrace_graph_stop();
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*parent = old;
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WARN_ON(1);
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return;
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}
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calltime = local_clock();
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if (push_return_trace(old, calltime,
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self_addr, &trace.depth) == -EBUSY) {
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*parent = old;
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return;
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}
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trace.func = self_addr;
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/* Only trace if the calling function expects to */
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if (!ftrace_graph_entry(&trace)) {
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current->curr_ret_stack--;
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*parent = old;
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}
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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void ftrace_function_trampoline(unsigned long parent,
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unsigned long self_addr,
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unsigned long org_sp_gr3)
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{
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extern ftrace_func_t ftrace_trace_function;
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if (ftrace_trace_function != ftrace_stub) {
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ftrace_trace_function(parent, self_addr);
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return;
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}
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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if (ftrace_graph_entry && ftrace_graph_return) {
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unsigned long sp;
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unsigned long *parent_rp;
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asm volatile ("copy %%r30, %0" : "=r"(sp));
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/* sanity check: is stack pointer which we got from
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assembler function in entry.S in a reasonable
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range compared to current stack pointer? */
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if ((sp - org_sp_gr3) > 0x400)
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return;
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/* calculate pointer to %rp in stack */
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parent_rp = (unsigned long *) org_sp_gr3 - 0x10;
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/* sanity check: parent_rp should hold parent */
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if (*parent_rp != parent)
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return;
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prepare_ftrace_return(parent_rp, self_addr);
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return;
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}
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#endif
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}
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