1 // SPDX-License-Identifier: GPL-2.0 2 #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 "env.h" 11 #include "machine.h" 12 #include "event.h" 13 #include "../util/unwind.h" 14 #include "perf_regs.h" 15 #include "map.h" 16 #include "symbol.h" 17 #include "thread.h" 18 #include "callchain.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 lose 25 * the frame of the caller. Clang can disable this optimization on a called 26 * function but GCC currently (11/2020) lacks this attribute. The barrier is 27 * used to inhibit tail calls in these cases. 28 */ 29 #ifdef __has_attribute 30 #if __has_attribute(disable_tail_calls) 31 #define NO_TAIL_CALL_ATTRIBUTE __attribute__((disable_tail_calls)) 32 #define NO_TAIL_CALL_BARRIER 33 #endif 34 #endif 35 #ifndef NO_TAIL_CALL_ATTRIBUTE 36 #define NO_TAIL_CALL_ATTRIBUTE 37 #define NO_TAIL_CALL_BARRIER __asm__ __volatile__("" : : : "memory"); 38 #endif 39 40 /* 41 * We need to keep these functions global, despite the 42 * fact that they are used only locally in this object, 43 * in order to keep them around even if the binary is 44 * stripped. If they are gone, the unwind check for 45 * symbol fails. 46 */ 47 int test_dwarf_unwind__thread(struct thread *thread); 48 int test_dwarf_unwind__compare(void *p1, void *p2); 49 int test_dwarf_unwind__krava_3(struct thread *thread); 50 int test_dwarf_unwind__krava_2(struct thread *thread); 51 int test_dwarf_unwind__krava_1(struct thread *thread); 52 int test__dwarf_unwind(struct test_suite *test, int subtest); 53 54 #define MAX_STACK 8 55 56 static int unwind_entry(struct unwind_entry *entry, void *arg) 57 { 58 unsigned long *cnt = (unsigned long *) arg; 59 char *symbol = entry->ms.sym ? entry->ms.sym->name : NULL; 60 static const char *funcs[MAX_STACK] = { 61 "test__arch_unwind_sample", 62 "test_dwarf_unwind__thread", 63 "test_dwarf_unwind__compare", 64 "bsearch", 65 "test_dwarf_unwind__krava_3", 66 "test_dwarf_unwind__krava_2", 67 "test_dwarf_unwind__krava_1", 68 "test__dwarf_unwind" 69 }; 70 /* 71 * The funcs[MAX_STACK] array index, based on the 72 * callchain order setup. 73 */ 74 int idx = callchain_param.order == ORDER_CALLER ? 75 MAX_STACK - *cnt - 1 : *cnt; 76 77 if (*cnt >= MAX_STACK) { 78 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK); 79 return -1; 80 } 81 82 if (!symbol) { 83 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n", 84 entry->ip); 85 return -1; 86 } 87 88 (*cnt)++; 89 pr_debug("got: %s 0x%" PRIx64 ", expecting %s\n", 90 symbol, entry->ip, funcs[idx]); 91 return strcmp((const char *) symbol, funcs[idx]); 92 } 93 94 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__thread(struct thread *thread) 95 { 96 struct perf_sample sample; 97 unsigned long cnt = 0; 98 int err = -1; 99 100 perf_sample__init(&sample, /*all=*/true); 101 if (test__arch_unwind_sample(&sample, thread)) { 102 pr_debug("failed to get unwind sample\n"); 103 goto out; 104 } 105 106 err = unwind__get_entries(unwind_entry, &cnt, thread, 107 &sample, MAX_STACK, false); 108 if (err) 109 pr_debug("unwind failed\n"); 110 else if (cnt != MAX_STACK) { 111 pr_debug("got wrong number of stack entries %lu != %d\n", 112 cnt, MAX_STACK); 113 err = -1; 114 } 115 116 out: 117 zfree(&sample.user_stack.data); 118 zfree(&sample.user_regs->regs); 119 perf_sample__exit(&sample); 120 return err; 121 } 122 123 static int global_unwind_retval = -INT_MAX; 124 125 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__compare(void *p1, void *p2) 126 { 127 /* Any possible value should be 'thread' */ 128 struct thread *thread = *(struct thread **)p1; 129 130 if (global_unwind_retval == -INT_MAX) { 131 /* Call unwinder twice for both callchain orders. */ 132 callchain_param.order = ORDER_CALLER; 133 134 global_unwind_retval = test_dwarf_unwind__thread(thread); 135 if (!global_unwind_retval) { 136 callchain_param.order = ORDER_CALLEE; 137 global_unwind_retval = test_dwarf_unwind__thread(thread); 138 } 139 } 140 141 return p1 - p2; 142 } 143 144 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_3(struct thread *thread) 145 { 146 struct thread *array[2] = {thread, thread}; 147 void *fp = &bsearch; 148 /* 149 * make _bsearch a volatile function pointer to 150 * prevent potential optimization, which may expand 151 * bsearch and call compare directly from this function, 152 * instead of libc shared object. 153 */ 154 void *(*volatile _bsearch)(void *, void *, size_t, 155 size_t, int (*)(void *, void *)); 156 157 _bsearch = fp; 158 _bsearch(array, &thread, 2, sizeof(struct thread **), 159 test_dwarf_unwind__compare); 160 return global_unwind_retval; 161 } 162 163 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_2(struct thread *thread) 164 { 165 int ret; 166 167 ret = test_dwarf_unwind__krava_3(thread); 168 NO_TAIL_CALL_BARRIER; 169 return ret; 170 } 171 172 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_1(struct thread *thread) 173 { 174 int ret; 175 176 ret = test_dwarf_unwind__krava_2(thread); 177 NO_TAIL_CALL_BARRIER; 178 return ret; 179 } 180 181 noinline int test__dwarf_unwind(struct test_suite *test __maybe_unused, 182 int subtest __maybe_unused) 183 { 184 struct perf_env host_env; 185 struct machine *machine; 186 struct thread *thread; 187 int err = -1; 188 pid_t pid = getpid(); 189 190 callchain_param.record_mode = CALLCHAIN_DWARF; 191 dwarf_callchain_users = true; 192 193 perf_env__init(&host_env); 194 machine = machine__new_live(&host_env, /*kernel_maps=*/true, pid); 195 if (!machine) { 196 pr_err("Could not get machine\n"); 197 goto out; 198 } 199 200 if (machine__create_kernel_maps(machine)) { 201 pr_err("Failed to create kernel maps\n"); 202 goto out; 203 } 204 205 if (verbose > 1) 206 machine__fprintf(machine, stderr); 207 208 thread = machine__find_thread(machine, pid, pid); 209 if (!thread) { 210 pr_err("Could not get thread\n"); 211 goto out; 212 } 213 214 err = test_dwarf_unwind__krava_1(thread); 215 thread__put(thread); 216 217 out: 218 machine__delete(machine); 219 perf_env__exit(&host_env); 220 return err; 221 } 222 223 DEFINE_SUITE("Test dwarf unwind", dwarf_unwind); 224