1 #include <linux/compiler.h> 2 #include <elfutils/libdw.h> 3 #include <elfutils/libdwfl.h> 4 #include <inttypes.h> 5 #include <errno.h> 6 #include "debug.h" 7 #include "unwind.h" 8 #include "unwind-libdw.h" 9 #include "machine.h" 10 #include "thread.h" 11 #include <linux/types.h> 12 #include "event.h" 13 #include "perf_regs.h" 14 15 static char *debuginfo_path; 16 17 static const Dwfl_Callbacks offline_callbacks = { 18 .find_debuginfo = dwfl_standard_find_debuginfo, 19 .debuginfo_path = &debuginfo_path, 20 .section_address = dwfl_offline_section_address, 21 }; 22 23 static int __report_module(struct addr_location *al, u64 ip, 24 struct unwind_info *ui) 25 { 26 Dwfl_Module *mod; 27 struct dso *dso = NULL; 28 29 thread__find_addr_location(ui->thread, 30 PERF_RECORD_MISC_USER, 31 MAP__FUNCTION, ip, al); 32 33 if (al->map) 34 dso = al->map->dso; 35 36 if (!dso) 37 return 0; 38 39 mod = dwfl_addrmodule(ui->dwfl, ip); 40 if (!mod) 41 mod = dwfl_report_elf(ui->dwfl, dso->short_name, 42 dso->long_name, -1, al->map->start, 43 false); 44 45 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; 46 } 47 48 static int report_module(u64 ip, struct unwind_info *ui) 49 { 50 struct addr_location al; 51 52 return __report_module(&al, ip, ui); 53 } 54 55 static int entry(u64 ip, struct unwind_info *ui) 56 57 { 58 struct unwind_entry e; 59 struct addr_location al; 60 61 if (__report_module(&al, ip, ui)) 62 return -1; 63 64 e.ip = ip; 65 e.map = al.map; 66 e.sym = al.sym; 67 68 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", 69 al.sym ? al.sym->name : "''", 70 ip, 71 al.map ? al.map->map_ip(al.map, ip) : (u64) 0); 72 73 return ui->cb(&e, ui->arg); 74 } 75 76 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) 77 { 78 /* We want only single thread to be processed. */ 79 if (*thread_argp != NULL) 80 return 0; 81 82 *thread_argp = arg; 83 return dwfl_pid(dwfl); 84 } 85 86 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, 87 Dwarf_Word *data) 88 { 89 struct addr_location al; 90 ssize_t size; 91 92 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER, 93 MAP__FUNCTION, addr, &al); 94 if (!al.map) { 95 pr_debug("unwind: no map for %lx\n", (unsigned long)addr); 96 return -1; 97 } 98 99 if (!al.map->dso) 100 return -1; 101 102 size = dso__data_read_addr(al.map->dso, al.map, ui->machine, 103 addr, (u8 *) data, sizeof(*data)); 104 105 return !(size == sizeof(*data)); 106 } 107 108 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, 109 void *arg) 110 { 111 struct unwind_info *ui = arg; 112 struct stack_dump *stack = &ui->sample->user_stack; 113 u64 start, end; 114 int offset; 115 int ret; 116 117 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); 118 if (ret) 119 return false; 120 121 end = start + stack->size; 122 123 /* Check overflow. */ 124 if (addr + sizeof(Dwarf_Word) < addr) 125 return false; 126 127 if (addr < start || addr + sizeof(Dwarf_Word) > end) { 128 ret = access_dso_mem(ui, addr, result); 129 if (ret) { 130 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" 131 " 0x%" PRIx64 "-0x%" PRIx64 "\n", 132 addr, start, end); 133 return false; 134 } 135 return true; 136 } 137 138 offset = addr - start; 139 *result = *(Dwarf_Word *)&stack->data[offset]; 140 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", 141 addr, (unsigned long)*result, offset); 142 return true; 143 } 144 145 static const Dwfl_Thread_Callbacks callbacks = { 146 .next_thread = next_thread, 147 .memory_read = memory_read, 148 .set_initial_registers = libdw__arch_set_initial_registers, 149 }; 150 151 static int 152 frame_callback(Dwfl_Frame *state, void *arg) 153 { 154 struct unwind_info *ui = arg; 155 Dwarf_Addr pc; 156 157 if (!dwfl_frame_pc(state, &pc, NULL)) { 158 pr_err("%s", dwfl_errmsg(-1)); 159 return DWARF_CB_ABORT; 160 } 161 162 return entry(pc, ui) || !(--ui->max_stack) ? 163 DWARF_CB_ABORT : DWARF_CB_OK; 164 } 165 166 int unwind__get_entries(unwind_entry_cb_t cb, void *arg, 167 struct thread *thread, 168 struct perf_sample *data, 169 int max_stack) 170 { 171 struct unwind_info ui = { 172 .sample = data, 173 .thread = thread, 174 .machine = thread->mg->machine, 175 .cb = cb, 176 .arg = arg, 177 .max_stack = max_stack, 178 }; 179 Dwarf_Word ip; 180 int err = -EINVAL; 181 182 if (!data->user_regs.regs) 183 return -EINVAL; 184 185 ui.dwfl = dwfl_begin(&offline_callbacks); 186 if (!ui.dwfl) 187 goto out; 188 189 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); 190 if (err) 191 goto out; 192 193 err = report_module(ip, &ui); 194 if (err) 195 goto out; 196 197 if (!dwfl_attach_state(ui.dwfl, EM_NONE, thread->tid, &callbacks, &ui)) 198 goto out; 199 200 err = dwfl_getthread_frames(ui.dwfl, thread->tid, frame_callback, &ui); 201 202 if (err && !ui.max_stack) 203 err = 0; 204 205 out: 206 if (err) 207 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); 208 209 dwfl_end(ui.dwfl); 210 return 0; 211 } 212