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 "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 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 static int mmap_handler(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 48 static 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 the 60 * fact that they are used only locally in this object, 61 * in order to keep them around even if the binary is 62 * stripped. If they are gone, the unwind check for 63 * symbol fails. 64 */ 65 int test_dwarf_unwind__thread(struct thread *thread); 66 int test_dwarf_unwind__compare(void *p1, void *p2); 67 int test_dwarf_unwind__krava_3(struct thread *thread); 68 int test_dwarf_unwind__krava_2(struct thread *thread); 69 int test_dwarf_unwind__krava_1(struct thread *thread); 70 71 #define MAX_STACK 8 72 73 static int unwind_entry(struct unwind_entry *entry, void *arg) 74 { 75 unsigned long *cnt = (unsigned long *) arg; 76 char *symbol = entry->ms.sym ? entry->ms.sym->name : NULL; 77 static const char *funcs[MAX_STACK] = { 78 "test__arch_unwind_sample", 79 "test_dwarf_unwind__thread", 80 "test_dwarf_unwind__compare", 81 "bsearch", 82 "test_dwarf_unwind__krava_3", 83 "test_dwarf_unwind__krava_2", 84 "test_dwarf_unwind__krava_1", 85 "test__dwarf_unwind" 86 }; 87 /* 88 * The funcs[MAX_STACK] array index, based on the 89 * callchain order setup. 90 */ 91 int idx = callchain_param.order == ORDER_CALLER ? 92 MAX_STACK - *cnt - 1 : *cnt; 93 94 if (*cnt >= MAX_STACK) { 95 pr_debug("failed: crossed the max stack value %d\n", MAX_STACK); 96 return -1; 97 } 98 99 if (!symbol) { 100 pr_debug("failed: got unresolved address 0x%" PRIx64 "\n", 101 entry->ip); 102 return -1; 103 } 104 105 (*cnt)++; 106 pr_debug("got: %s 0x%" PRIx64 ", expecting %s\n", 107 symbol, entry->ip, funcs[idx]); 108 return strcmp((const char *) symbol, funcs[idx]); 109 } 110 111 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__thread(struct thread *thread) 112 { 113 struct perf_sample sample; 114 unsigned long cnt = 0; 115 int err = -1; 116 117 memset(&sample, 0, sizeof(sample)); 118 119 if (test__arch_unwind_sample(&sample, thread)) { 120 pr_debug("failed to get unwind sample\n"); 121 goto out; 122 } 123 124 err = unwind__get_entries(unwind_entry, &cnt, thread, 125 &sample, MAX_STACK); 126 if (err) 127 pr_debug("unwind failed\n"); 128 else if (cnt != MAX_STACK) { 129 pr_debug("got wrong number of stack entries %lu != %d\n", 130 cnt, MAX_STACK); 131 err = -1; 132 } 133 134 out: 135 zfree(&sample.user_stack.data); 136 zfree(&sample.user_regs.regs); 137 return err; 138 } 139 140 static int global_unwind_retval = -INT_MAX; 141 142 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__compare(void *p1, void *p2) 143 { 144 /* Any possible value should be 'thread' */ 145 struct thread *thread = *(struct thread **)p1; 146 147 if (global_unwind_retval == -INT_MAX) { 148 /* Call unwinder twice for both callchain orders. */ 149 callchain_param.order = ORDER_CALLER; 150 151 global_unwind_retval = test_dwarf_unwind__thread(thread); 152 if (!global_unwind_retval) { 153 callchain_param.order = ORDER_CALLEE; 154 global_unwind_retval = test_dwarf_unwind__thread(thread); 155 } 156 } 157 158 return p1 - p2; 159 } 160 161 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_3(struct thread *thread) 162 { 163 struct thread *array[2] = {thread, thread}; 164 void *fp = &bsearch; 165 /* 166 * make _bsearch a volatile function pointer to 167 * prevent potential optimization, which may expand 168 * bsearch and call compare directly from this function, 169 * instead of libc shared object. 170 */ 171 void *(*volatile _bsearch)(void *, void *, size_t, 172 size_t, int (*)(void *, void *)); 173 174 _bsearch = fp; 175 _bsearch(array, &thread, 2, sizeof(struct thread **), 176 test_dwarf_unwind__compare); 177 return global_unwind_retval; 178 } 179 180 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_2(struct thread *thread) 181 { 182 int ret; 183 184 ret = test_dwarf_unwind__krava_3(thread); 185 NO_TAIL_CALL_BARRIER; 186 return ret; 187 } 188 189 NO_TAIL_CALL_ATTRIBUTE noinline int test_dwarf_unwind__krava_1(struct thread *thread) 190 { 191 int ret; 192 193 ret = test_dwarf_unwind__krava_2(thread); 194 NO_TAIL_CALL_BARRIER; 195 return ret; 196 } 197 198 int test__dwarf_unwind(struct test *test __maybe_unused, int subtest __maybe_unused) 199 { 200 struct machine *machine; 201 struct thread *thread; 202 int err = -1; 203 204 machine = machine__new_host(); 205 if (!machine) { 206 pr_err("Could not get machine\n"); 207 return -1; 208 } 209 210 if (machine__create_kernel_maps(machine)) { 211 pr_err("Failed to create kernel maps\n"); 212 return -1; 213 } 214 215 callchain_param.record_mode = CALLCHAIN_DWARF; 216 dwarf_callchain_users = true; 217 218 if (init_live_machine(machine)) { 219 pr_err("Could not init machine\n"); 220 goto out; 221 } 222 223 if (verbose > 1) 224 machine__fprintf(machine, stderr); 225 226 thread = machine__find_thread(machine, getpid(), getpid()); 227 if (!thread) { 228 pr_err("Could not get thread\n"); 229 goto out; 230 } 231 232 err = test_dwarf_unwind__krava_1(thread); 233 thread__put(thread); 234 235 out: 236 machine__delete_threads(machine); 237 machine__delete(machine); 238 return err; 239 } 240