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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: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200512121922.8997-8-adrian.hunter@intel.com
This commit is contained in:
Adrian Hunter 2020-05-12 15:19:14 +03:00 committed by Peter Zijlstra
parent fc0ea795f5
commit dd9ddf466a
2 changed files with 13 additions and 3 deletions
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2
include/uapi/linux/perf_event.h
View File

@ -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 */

14
kernel/trace/ftrace.c
View File

@ -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)