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1// SPDX-License-Identifier: GPL-2.02#include <linux/compiler.h>3#include <linux/types.h>4#include <linux/zalloc.h>5#include <inttypes.h>6#include <limits.h>7#include <unistd.h>8#include "tests.h"9#include "debug.h"10#include "machine.h"11#include "event.h"12#include "../util/unwind.h"13#include "perf_regs.h"14#include "map.h"15#include "symbol.h"16#include "thread.h"17#include "callchain.h"18#include "util/synthetic-events.h"19 20/* For bsearch. We try to unwind functions in shared object. */21#include <stdlib.h>22 23/*24 * The test will assert frames are on the stack but tail call optimizations lose25 * the frame of the caller. Clang can disable this optimization on a called26 * function but GCC currently (11/2020) lacks this attribute. The barrier is27 * used to inhibit tail calls in these cases.28 */29#ifdef __has_attribute30#if __has_attribute(disable_tail_calls)31#define NO_TAIL_CALL_ATTRIBUTE __attribute__((disable_tail_calls))32#define NO_TAIL_CALL_BARRIER33#endif34#endif35#ifndef NO_TAIL_CALL_ATTRIBUTE36#define NO_TAIL_CALL_ATTRIBUTE37#define NO_TAIL_CALL_BARRIER __asm__ __volatile__("" : : : "memory");38#endif39 40static int mmap_handler(const struct perf_tool *tool __maybe_unused,41 union perf_event *event,42 struct perf_sample *sample,43 struct machine *machine)44{45 return machine__process_mmap2_event(machine, event, sample);46}47 48static int init_live_machine(struct machine *machine)49{50 union perf_event event;51 pid_t pid = getpid();52 53 memset(&event, 0, sizeof(event));54 return perf_event__synthesize_mmap_events(NULL, &event, pid, pid,55 mmap_handler, machine, true);56}57 58/*59 * We need to keep these functions global, despite the60 * fact that they are used only locally in this object,61 * in order to keep them around even if the binary is62 * stripped. If they are gone, the unwind check for63 * symbol fails.64 */65int test_dwarf_unwind__thread(struct thread *thread);66int test_dwarf_unwind__compare(void *p1, void *p2);67int test_dwarf_unwind__krava_3(struct thread *thread);68int test_dwarf_unwind__krava_2(struct thread *thread);69int test_dwarf_unwind__krava_1(struct thread *thread);70int test__dwarf_unwind(struct test_suite *test, int subtest);71 72#define MAX_STACK 873 74static int unwind_entry(struct unwind_entry *entry, void *arg)75{76 unsigned long *cnt = (unsigned long *) arg;77 char *symbol = entry->ms.sym ? entry->ms.sym->name : NULL;78 static const char *funcs[MAX_STACK] = {79 "test__arch_unwind_sample",80 "test_dwarf_unwind__thread",81 "test_dwarf_unwind__compare",82 "bsearch",83 "test_dwarf_unwind__krava_3",84 "test_dwarf_unwind__krava_2",85 "test_dwarf_unwind__krava_1",86 "test__dwarf_unwind"87 };88 /*89 * The funcs[MAX_STACK] array index, based on the90 * callchain order setup.91 */92 int idx = callchain_param.order == ORDER_CALLER ?93 MAX_STACK - *cnt - 1 : *cnt;94 95 if (*cnt >= MAX_STACK) {96 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK);97 return -1;98 }99 100 if (!symbol) {101 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n",102 entry->ip);103 return -1;104 }105 106 (*cnt)++;107 pr_debug("got: %s 0x%" PRIx64 ", expecting %s\n",108 symbol, entry->ip, funcs[idx]);109 return strcmp((const char *) symbol, funcs[idx]);110}111 112NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__thread(struct thread *thread)113{114 struct perf_sample sample;115 unsigned long cnt = 0;116 int err = -1;117 118 memset(&sample, 0, sizeof(sample));119 120 if (test__arch_unwind_sample(&sample, thread)) {121 pr_debug("failed to get unwind sample\n");122 goto out;123 }124 125 err = unwind__get_entries(unwind_entry, &cnt, thread,126 &sample, MAX_STACK, false);127 if (err)128 pr_debug("unwind failed\n");129 else if (cnt != MAX_STACK) {130 pr_debug("got wrong number of stack entries %lu != %d\n",131 cnt, MAX_STACK);132 err = -1;133 }134 135 out:136 zfree(&sample.user_stack.data);137 zfree(&sample.user_regs.regs);138 return err;139}140 141static int global_unwind_retval = -INT_MAX;142 143NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__compare(void *p1, void *p2)144{145 /* Any possible value should be 'thread' */146 struct thread *thread = *(struct thread **)p1;147 148 if (global_unwind_retval == -INT_MAX) {149 /* Call unwinder twice for both callchain orders. */150 callchain_param.order = ORDER_CALLER;151 152 global_unwind_retval = test_dwarf_unwind__thread(thread);153 if (!global_unwind_retval) {154 callchain_param.order = ORDER_CALLEE;155 global_unwind_retval = test_dwarf_unwind__thread(thread);156 }157 }158 159 return p1 - p2;160}161 162NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_3(struct thread *thread)163{164 struct thread *array[2] = {thread, thread};165 void *fp = &bsearch;166 /*167 * make _bsearch a volatile function pointer to168 * prevent potential optimization, which may expand169 * bsearch and call compare directly from this function,170 * instead of libc shared object.171 */172 void *(*volatile _bsearch)(void *, void *, size_t,173 size_t, int (*)(void *, void *));174 175 _bsearch = fp;176 _bsearch(array, &thread, 2, sizeof(struct thread **),177 test_dwarf_unwind__compare);178 return global_unwind_retval;179}180 181NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_2(struct thread *thread)182{183 int ret;184 185 ret = test_dwarf_unwind__krava_3(thread);186 NO_TAIL_CALL_BARRIER;187 return ret;188}189 190NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_1(struct thread *thread)191{192 int ret;193 194 ret = test_dwarf_unwind__krava_2(thread);195 NO_TAIL_CALL_BARRIER;196 return ret;197}198 199noinline int test__dwarf_unwind(struct test_suite *test __maybe_unused,200 int subtest __maybe_unused)201{202 struct machine *machine;203 struct thread *thread;204 int err = -1;205 206 machine = machine__new_host();207 if (!machine) {208 pr_err("Could not get machine\n");209 return -1;210 }211 212 if (machine__create_kernel_maps(machine)) {213 pr_err("Failed to create kernel maps\n");214 return -1;215 }216 217 callchain_param.record_mode = CALLCHAIN_DWARF;218 dwarf_callchain_users = true;219 220 if (init_live_machine(machine)) {221 pr_err("Could not init machine\n");222 goto out;223 }224 225 if (verbose > 1)226 machine__fprintf(machine, stderr);227 228 thread = machine__find_thread(machine, getpid(), getpid());229 if (!thread) {230 pr_err("Could not get thread\n");231 goto out;232 }233 234 err = test_dwarf_unwind__krava_1(thread);235 thread__put(thread);236 237 out:238 machine__delete(machine);239 return err;240}241 242DEFINE_SUITE("Test dwarf unwind", dwarf_unwind);243