arch/riscv/kernel/perf_callchain.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
   3
   4 #include <linux/perf_event.h>
   5 #include <linux/uaccess.h>
   6
   7 #include <asm/stacktrace.h>
   8
   9 static bool fill_callchain(void *entry, unsigned long pc)
  10 {
  11         return perf_callchain_store(entry, pc) == 0;
  12 }
  13
  14 /*
  15  * This will be called when the target is in user mode
  16  * This function will only be called when we use
  17  * "PERF_SAMPLE_CALLCHAIN" in
  18  * kernel/events/core.c:perf_prepare_sample()
  19  *
  20  * How to trigger perf_callchain_[user/kernel] :
  21  * $ perf record -e cpu-clock --call-graph fp ./program
  22  * $ perf report --call-graph
  23  *
  24  * On RISC-V platform, the program being sampled and the C library
  25  * need to be compiled with -fno-omit-frame-pointer, otherwise
  26  * the user stack will not contain function frame.
  27  */
  28 void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
  29                          struct pt_regs *regs)
  30 {
  31         arch_stack_walk_user(fill_callchain, entry, regs);
  32 }
  33
  34 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
  35                            struct pt_regs *regs)
  36 {
  37         walk_stackframe(NULL, regs, fill_callchain, entry);
  38 }