Commit dd9ddf46 authored by Adrian Hunter's avatar Adrian Hunter Committed by Peter Zijlstra
Browse files

ftrace: Add perf ksymbol events for ftrace trampolines 



Symbols are needed for tools to describe instruction addresses. Pages
allocated for ftrace's purposes need symbols to be created for them.
Add such symbols to be visible via perf ksymbol events.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200512121922.8997-8-adrian.hunter@intel.com
parent fc0ea795

include/uapi/linux/perf_event.h

+1 −1
Original line number Diff line number Diff line
@@ -1051,7 +1051,7 @@ enum perf_record_ksymbol_type { 
	PERF_RECORD_KSYMBOL_TYPE_BPF		= 1,

	/*

	 * Out of line code such as kprobe-replaced instructions or optimized

	 * kprobes.

	 * kprobes or ftrace trampolines.

	 */

	PERF_RECORD_KSYMBOL_TYPE_OOL		= 2,

	PERF_RECORD_KSYMBOL_TYPE_MAX		/* non-ABI */

kernel/trace/ftrace.c

+12 −2
Original line number Diff line number Diff line
@@ -2790,8 +2790,13 @@ static void ftrace_remove_trampoline_from_kallsyms(struct ftrace_ops *ops) 
static void ftrace_trampoline_free(struct ftrace_ops *ops)

{

	if (ops && (ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP) &&

	    ops->trampoline)

	    ops->trampoline) {

		perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,

				   ops->trampoline, ops->trampoline_size,

				   true, FTRACE_TRAMPOLINE_SYM);

		/* Remove from kallsyms after the perf events */

		ftrace_remove_trampoline_from_kallsyms(ops);

	}



	arch_ftrace_trampoline_free(ops);

}
@@ -6805,8 +6810,13 @@ static void ftrace_update_trampoline(struct ftrace_ops *ops) 


	arch_ftrace_update_trampoline(ops);

	if (ops->trampoline && ops->trampoline != trampoline &&

	    (ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))

	    (ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) {

		/* Add to kallsyms before the perf events */

		ftrace_add_trampoline_to_kallsyms(ops);

		perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,

				   ops->trampoline, ops->trampoline_size, false,

				   FTRACE_TRAMPOLINE_SYM);

	}

}



void ftrace_init_trace_array(struct trace_array *tr)

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