PERF_SAMPLE_REGS_INTR demo

gistfile1.txt

$ ./perf_sample_regs_intr_demo 
data_head is at ff0
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0x4005b0
rax=0xfffffffffffffff7 rbp=0xffffa5fc43efff48 rsp=0xffffa5fc43efff28 rip=0xffffffff97c55f1d
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0xffff8fc3ba3b79c0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef0 rip=0xffffffff97c745c9
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0x0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef8 rip=0xffffffff97c75049
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce15
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040c0 rip=0x4007d5
rax=0xfffffffffffffff7 rbp=0xffffa5fc43efff48 rsp=0xffffa5fc43efff10 rip=0xffffffff97c55f43
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0xffff8fc3ba3b79c0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef0 rip=0xffffffff97c745c9
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0x0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef8 rip=0xffffffff97c75049
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce15
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040c0 rip=0x4007d5
rax=0xfffffffffffffff7 rbp=0xffffa5fc43efff48 rsp=0xffffa5fc43efff10 rip=0xffffffff97c55f43
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0x0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef8 rip=0xffffffff97c75049
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce15
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040c0 rip=0x4007d5
rax=0xfffffffffffffff7 rbp=0xffffa5fc43efff48 rsp=0xffffa5fc43efff10 rip=0xffffffff97c55f43
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce18
rax=0x0 rbp=0xffffa5fc43efff00 rsp=0xffffa5fc43effef8 rip=0xffffffff97c75049
rax=0xfffffffffffffff7 rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0xffffffff9862ce15
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040c0 rip=0x4007d5
rax=0xfffffffffffffff7 rbp=0xffffa5fc43efff48 rsp=0xffffa5fc43efff10 rip=0xffffffff97c55f43
rax=0xffffffffffffffff rbp=0x7ffc9ec04170 rsp=0x7ffc9ec040b8 rip=0x4005b0
[...]

perf_sample_regs_intr_demo.c

// compile with:
// gcc -Wall -std=gnu99 -o perf_sample_regs_intr_demo perf_sample_regs_intr_demo.c
#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <err.h>
#include <inttypes.h>
#include <assert.h>
#include <errno.h>
#include <time.h>
#include <stdlib.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/wait.h>

#include <linux/perf_event.h>
#include <asm/perf_regs.h>

struct my_event {
        struct perf_event_header header;
        uint64_t   abi;
        uint64_t   regs[4];
};

long perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu, int group_fd, unsigned long flags) {
        return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
}

int main(void) {
        int status;

        pid_t child = fork();
        if (child == -1)
                err(1, "fork");
        if (child == 0) {
                sleep(1); /* quick-and-dirty way to wait for the parent to attach */
                for (int i=0; i<1000000; i++) {
                        write(100000, NULL, 1);
                }
                return 0;
        }
        struct perf_event_attr attr = {
                .type = PERF_TYPE_HARDWARE,
                .config = PERF_COUNT_HW_INSTRUCTIONS,
                .size = sizeof(struct perf_event_attr),
                .sample_period = 100000,
                .sample_type = PERF_SAMPLE_REGS_INTR,
                .precise_ip = 2,
                .sample_regs_intr =
                        (1<<PERF_REG_X86_AX) |
                        (1<<PERF_REG_X86_BP) |
                        (1<<PERF_REG_X86_SP) |
                        (1<<PERF_REG_X86_IP)
        };
        int perf_fd = perf_event_open(&attr, child, -1, -1, 0);
        if (perf_fd == -1)
                err(1, "perf_event_open");
        struct perf_event_mmap_page *meta_page = mmap(NULL, 2*4096, PROT_READ|PROT_WRITE, MAP_SHARED, perf_fd, 0);
        if (meta_page == MAP_FAILED)
                err(1, "mmap");

        if (waitpid(child, &status, 0) != child)
                err(1, "waitpid");

        uint64_t data_head = meta_page->data_head;
        if (data_head == 0) {
                puts("no data!");
                return 0;
        }

        printf("data_head is at %lx\n", (unsigned long)data_head);
        struct perf_event_header *head = (void*)((char*)meta_page + 4096);
        while ((char*)head + head->size < (char*)meta_page + 4096 + data_head) {
                if (head->type == PERF_RECORD_SAMPLE) {
                        struct my_event *ev = (void*)head;
                        printf("rax=0x%lx rbp=0x%lx rsp=0x%lx rip=0x%lx\n",
                                ev->regs[0], ev->regs[1], ev->regs[2], ev->regs[3]);
                }
                head = (void*)((char*)head + head->size);
        }
        return 0;
}