tracing/function: Introduce persistent trace option
This patch introduces 'func_ptrace' option, now available in /sys/kernel/debug/tracing/options when function tracer is selected. The patch also adds some tiny code that calls back to pstore to record the trace. The callback is no-op when PSTORE=n. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -13,6 +13,7 @@
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <linux/pstore.h>
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#include <linux/fs.h>
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#include "trace.h"
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@ -74,6 +75,14 @@ function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip)
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preempt_enable_notrace();
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}
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/* Our two options */
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enum {
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TRACE_FUNC_OPT_STACK = 0x1,
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TRACE_FUNC_OPT_PSTORE = 0x2,
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};
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static struct tracer_flags func_flags;
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static void
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function_trace_call(unsigned long ip, unsigned long parent_ip)
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{
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@ -97,6 +106,12 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
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disabled = atomic_inc_return(&data->disabled);
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if (likely(disabled == 1)) {
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/*
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* So far tracing doesn't support multiple buffers, so
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* we make an explicit call for now.
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*/
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if (unlikely(func_flags.val & TRACE_FUNC_OPT_PSTORE))
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pstore_ftrace_call(ip, parent_ip);
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pc = preempt_count();
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trace_function(tr, ip, parent_ip, flags, pc);
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}
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@ -158,14 +173,12 @@ static struct ftrace_ops trace_stack_ops __read_mostly =
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.flags = FTRACE_OPS_FL_GLOBAL,
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};
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/* Our two options */
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enum {
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TRACE_FUNC_OPT_STACK = 0x1,
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};
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static struct tracer_opt func_opts[] = {
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#ifdef CONFIG_STACKTRACE
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{ TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) },
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#endif
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#ifdef CONFIG_PSTORE_FTRACE
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{ TRACER_OPT(func_pstore, TRACE_FUNC_OPT_PSTORE) },
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#endif
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{ } /* Always set a last empty entry */
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};
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@ -217,6 +230,8 @@ static int func_set_flag(u32 old_flags, u32 bit, int set)
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register_ftrace_function(&trace_ops);
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}
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return 0;
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} else if (bit == TRACE_FUNC_OPT_PSTORE) {
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return 0;
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}
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