summaryrefslogtreecommitdiffstats
path: root/tools/perf/util/unwind.c
diff options
context:
space:
mode:
Diffstat (limited to 'tools/perf/util/unwind.c')
-rw-r--r--tools/perf/util/unwind.c567
1 files changed, 567 insertions, 0 deletions
diff --git a/tools/perf/util/unwind.c b/tools/perf/util/unwind.c
new file mode 100644
index 000000000000..00a42aa8d5c1
--- /dev/null
+++ b/tools/perf/util/unwind.c
@@ -0,0 +1,567 @@
+/*
+ * Post mortem Dwarf CFI based unwinding on top of regs and stack dumps.
+ *
+ * Lots of this code have been borrowed or heavily inspired from parts of
+ * the libunwind 0.99 code which are (amongst other contributors I may have
+ * forgotten):
+ *
+ * Copyright (C) 2002-2007 Hewlett-Packard Co
+ * Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
+ *
+ * And the bugs have been added by:
+ *
+ * Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com>
+ * Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com>
+ *
+ */
+
+#include <elf.h>
+#include <gelf.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <linux/list.h>
+#include <libunwind.h>
+#include <libunwind-ptrace.h>
+#include "thread.h"
+#include "session.h"
+#include "perf_regs.h"
+#include "unwind.h"
+#include "util.h"
+
+extern int
+UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
+ unw_word_t ip,
+ unw_dyn_info_t *di,
+ unw_proc_info_t *pi,
+ int need_unwind_info, void *arg);
+
+#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
+
+#define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */
+#define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */
+
+/* Pointer-encoding formats: */
+#define DW_EH_PE_omit 0xff
+#define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */
+#define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */
+#define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */
+#define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */
+#define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */
+
+/* Pointer-encoding application: */
+#define DW_EH_PE_absptr 0x00 /* absolute value */
+#define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */
+
+/*
+ * The following are not documented by LSB v1.3, yet they are used by
+ * GCC, presumably they aren't documented by LSB since they aren't
+ * used on Linux:
+ */
+#define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */
+#define DW_EH_PE_aligned 0x50 /* aligned pointer */
+
+/* Flags intentionaly not handled, since they're not needed:
+ * #define DW_EH_PE_indirect 0x80
+ * #define DW_EH_PE_uleb128 0x01
+ * #define DW_EH_PE_udata2 0x02
+ * #define DW_EH_PE_sleb128 0x09
+ * #define DW_EH_PE_sdata2 0x0a
+ * #define DW_EH_PE_textrel 0x20
+ * #define DW_EH_PE_datarel 0x30
+ */
+
+struct unwind_info {
+ struct perf_sample *sample;
+ struct machine *machine;
+ struct thread *thread;
+ u64 sample_uregs;
+};
+
+#define dw_read(ptr, type, end) ({ \
+ type *__p = (type *) ptr; \
+ type __v; \
+ if ((__p + 1) > (type *) end) \
+ return -EINVAL; \
+ __v = *__p++; \
+ ptr = (typeof(ptr)) __p; \
+ __v; \
+ })
+
+static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val,
+ u8 encoding)
+{
+ u8 *cur = *p;
+ *val = 0;
+
+ switch (encoding) {
+ case DW_EH_PE_omit:
+ *val = 0;
+ goto out;
+ case DW_EH_PE_ptr:
+ *val = dw_read(cur, unsigned long, end);
+ goto out;
+ default:
+ break;
+ }
+
+ switch (encoding & DW_EH_PE_APPL_MASK) {
+ case DW_EH_PE_absptr:
+ break;
+ case DW_EH_PE_pcrel:
+ *val = (unsigned long) cur;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if ((encoding & 0x07) == 0x00)
+ encoding |= DW_EH_PE_udata4;
+
+ switch (encoding & DW_EH_PE_FORMAT_MASK) {
+ case DW_EH_PE_sdata4:
+ *val += dw_read(cur, s32, end);
+ break;
+ case DW_EH_PE_udata4:
+ *val += dw_read(cur, u32, end);
+ break;
+ case DW_EH_PE_sdata8:
+ *val += dw_read(cur, s64, end);
+ break;
+ case DW_EH_PE_udata8:
+ *val += dw_read(cur, u64, end);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ out:
+ *p = cur;
+ return 0;
+}
+
+#define dw_read_encoded_value(ptr, end, enc) ({ \
+ u64 __v; \
+ if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
+ return -EINVAL; \
+ } \
+ __v; \
+ })
+
+static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
+ GElf_Shdr *shp, const char *name)
+{
+ Elf_Scn *sec = NULL;
+
+ while ((sec = elf_nextscn(elf, sec)) != NULL) {
+ char *str;
+
+ gelf_getshdr(sec, shp);
+ str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
+ if (!strcmp(name, str))
+ break;
+ }
+
+ return sec;
+}
+
+static u64 elf_section_offset(int fd, const char *name)
+{
+ Elf *elf;
+ GElf_Ehdr ehdr;
+ GElf_Shdr shdr;
+ u64 offset = 0;
+
+ elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+ if (elf == NULL)
+ return 0;
+
+ do {
+ if (gelf_getehdr(elf, &ehdr) == NULL)
+ break;
+
+ if (!elf_section_by_name(elf, &ehdr, &shdr, name))
+ break;
+
+ offset = shdr.sh_offset;
+ } while (0);
+
+ elf_end(elf);
+ return offset;
+}
+
+struct table_entry {
+ u32 start_ip_offset;
+ u32 fde_offset;
+};
+
+struct eh_frame_hdr {
+ unsigned char version;
+ unsigned char eh_frame_ptr_enc;
+ unsigned char fde_count_enc;
+ unsigned char table_enc;
+
+ /*
+ * The rest of the header is variable-length and consists of the
+ * following members:
+ *
+ * encoded_t eh_frame_ptr;
+ * encoded_t fde_count;
+ */
+
+ /* A single encoded pointer should not be more than 8 bytes. */
+ u64 enc[2];
+
+ /*
+ * struct {
+ * encoded_t start_ip;
+ * encoded_t fde_addr;
+ * } binary_search_table[fde_count];
+ */
+ char data[0];
+} __packed;
+
+static int unwind_spec_ehframe(struct dso *dso, struct machine *machine,
+ u64 offset, u64 *table_data, u64 *segbase,
+ u64 *fde_count)
+{
+ struct eh_frame_hdr hdr;
+ u8 *enc = (u8 *) &hdr.enc;
+ u8 *end = (u8 *) &hdr.data;
+ ssize_t r;
+
+ r = dso__data_read_offset(dso, machine, offset,
+ (u8 *) &hdr, sizeof(hdr));
+ if (r != sizeof(hdr))
+ return -EINVAL;
+
+ /* We dont need eh_frame_ptr, just skip it. */
+ dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
+
+ *fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
+ *segbase = offset;
+ *table_data = (enc - (u8 *) &hdr) + offset;
+ return 0;
+}
+
+static int read_unwind_spec(struct dso *dso, struct machine *machine,
+ u64 *table_data, u64 *segbase, u64 *fde_count)
+{
+ int ret = -EINVAL, fd;
+ u64 offset;
+
+ fd = dso__data_fd(dso, machine);
+ if (fd < 0)
+ return -EINVAL;
+
+ offset = elf_section_offset(fd, ".eh_frame_hdr");
+ close(fd);
+
+ if (offset)
+ ret = unwind_spec_ehframe(dso, machine, offset,
+ table_data, segbase,
+ fde_count);
+
+ /* TODO .debug_frame check if eh_frame_hdr fails */
+ return ret;
+}
+
+static struct map *find_map(unw_word_t ip, struct unwind_info *ui)
+{
+ struct addr_location al;
+
+ thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
+ MAP__FUNCTION, ip, &al);
+ return al.map;
+}
+
+static int
+find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
+ int need_unwind_info, void *arg)
+{
+ struct unwind_info *ui = arg;
+ struct map *map;
+ unw_dyn_info_t di;
+ u64 table_data, segbase, fde_count;
+
+ map = find_map(ip, ui);
+ if (!map || !map->dso)
+ return -EINVAL;
+
+ pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
+
+ if (read_unwind_spec(map->dso, ui->machine,
+ &table_data, &segbase, &fde_count))
+ return -EINVAL;
+
+ memset(&di, 0, sizeof(di));
+ di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
+ di.start_ip = map->start;
+ di.end_ip = map->end;
+ di.u.rti.segbase = map->start + segbase;
+ di.u.rti.table_data = map->start + table_data;
+ di.u.rti.table_len = fde_count * sizeof(struct table_entry)
+ / sizeof(unw_word_t);
+ return dwarf_search_unwind_table(as, ip, &di, pi,
+ need_unwind_info, arg);
+}
+
+static int access_fpreg(unw_addr_space_t __used as, unw_regnum_t __used num,
+ unw_fpreg_t __used *val, int __used __write,
+ void __used *arg)
+{
+ pr_err("unwind: access_fpreg unsupported\n");
+ return -UNW_EINVAL;
+}
+
+static int get_dyn_info_list_addr(unw_addr_space_t __used as,
+ unw_word_t __used *dil_addr,
+ void __used *arg)
+{
+ return -UNW_ENOINFO;
+}
+
+static int resume(unw_addr_space_t __used as, unw_cursor_t __used *cu,
+ void __used *arg)
+{
+ pr_err("unwind: resume unsupported\n");
+ return -UNW_EINVAL;
+}
+
+static int
+get_proc_name(unw_addr_space_t __used as, unw_word_t __used addr,
+ char __used *bufp, size_t __used buf_len,
+ unw_word_t __used *offp, void __used *arg)
+{
+ pr_err("unwind: get_proc_name unsupported\n");
+ return -UNW_EINVAL;
+}
+
+static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
+ unw_word_t *data)
+{
+ struct addr_location al;
+ ssize_t size;
+
+ thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER,
+ MAP__FUNCTION, addr, &al);
+ if (!al.map) {
+ pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
+ return -1;
+ }
+
+ if (!al.map->dso)
+ return -1;
+
+ size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
+ addr, (u8 *) data, sizeof(*data));
+
+ return !(size == sizeof(*data));
+}
+
+static int reg_value(unw_word_t *valp, struct regs_dump *regs, int id,
+ u64 sample_regs)
+{
+ int i, idx = 0;
+
+ if (!(sample_regs & (1 << id)))
+ return -EINVAL;
+
+ for (i = 0; i < id; i++) {
+ if (sample_regs & (1 << i))
+ idx++;
+ }
+
+ *valp = regs->regs[idx];
+ return 0;
+}
+
+static int access_mem(unw_addr_space_t __used as,
+ unw_word_t addr, unw_word_t *valp,
+ int __write, void *arg)
+{
+ struct unwind_info *ui = arg;
+ struct stack_dump *stack = &ui->sample->user_stack;
+ unw_word_t start, end;
+ int offset;
+ int ret;
+
+ /* Don't support write, probably not needed. */
+ if (__write || !stack || !ui->sample->user_regs.regs) {
+ *valp = 0;
+ return 0;
+ }
+
+ ret = reg_value(&start, &ui->sample->user_regs, PERF_REG_SP,
+ ui->sample_uregs);
+ if (ret)
+ return ret;
+
+ end = start + stack->size;
+
+ /* Check overflow. */
+ if (addr + sizeof(unw_word_t) < addr)
+ return -EINVAL;
+
+ if (addr < start || addr + sizeof(unw_word_t) >= end) {
+ ret = access_dso_mem(ui, addr, valp);
+ if (ret) {
+ pr_debug("unwind: access_mem %p not inside range %p-%p\n",
+ (void *)addr, (void *)start, (void *)end);
+ *valp = 0;
+ return ret;
+ }
+ return 0;
+ }
+
+ offset = addr - start;
+ *valp = *(unw_word_t *)&stack->data[offset];
+ pr_debug("unwind: access_mem addr %p, val %lx, offset %d\n",
+ (void *)addr, (unsigned long)*valp, offset);
+ return 0;
+}
+
+static int access_reg(unw_addr_space_t __used as,
+ unw_regnum_t regnum, unw_word_t *valp,
+ int __write, void *arg)
+{
+ struct unwind_info *ui = arg;
+ int id, ret;
+
+ /* Don't support write, I suspect we don't need it. */
+ if (__write) {
+ pr_err("unwind: access_reg w %d\n", regnum);
+ return 0;
+ }
+
+ if (!ui->sample->user_regs.regs) {
+ *valp = 0;
+ return 0;
+ }
+
+ id = unwind__arch_reg_id(regnum);
+ if (id < 0)
+ return -EINVAL;
+
+ ret = reg_value(valp, &ui->sample->user_regs, id, ui->sample_uregs);
+ if (ret) {
+ pr_err("unwind: can't read reg %d\n", regnum);
+ return ret;
+ }
+
+ pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
+ return 0;
+}
+
+static void put_unwind_info(unw_addr_space_t __used as,
+ unw_proc_info_t *pi __used,
+ void *arg __used)
+{
+ pr_debug("unwind: put_unwind_info called\n");
+}
+
+static int entry(u64 ip, struct thread *thread, struct machine *machine,
+ unwind_entry_cb_t cb, void *arg)
+{
+ struct unwind_entry e;
+ struct addr_location al;
+
+ thread__find_addr_location(thread, machine,
+ PERF_RECORD_MISC_USER,
+ MAP__FUNCTION, ip, &al, NULL);
+
+ e.ip = ip;
+ e.map = al.map;
+ e.sym = al.sym;
+
+ pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
+ al.sym ? al.sym->name : "''",
+ ip,
+ al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
+
+ return cb(&e, arg);
+}
+
+static void display_error(int err)
+{
+ switch (err) {
+ case UNW_EINVAL:
+ pr_err("unwind: Only supports local.\n");
+ break;
+ case UNW_EUNSPEC:
+ pr_err("unwind: Unspecified error.\n");
+ break;
+ case UNW_EBADREG:
+ pr_err("unwind: Register unavailable.\n");
+ break;
+ default:
+ break;
+ }
+}
+
+static unw_accessors_t accessors = {
+ .find_proc_info = find_proc_info,
+ .put_unwind_info = put_unwind_info,
+ .get_dyn_info_list_addr = get_dyn_info_list_addr,
+ .access_mem = access_mem,
+ .access_reg = access_reg,
+ .access_fpreg = access_fpreg,
+ .resume = resume,
+ .get_proc_name = get_proc_name,
+};
+
+static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
+ void *arg)
+{
+ unw_addr_space_t addr_space;
+ unw_cursor_t c;
+ int ret;
+
+ addr_space = unw_create_addr_space(&accessors, 0);
+ if (!addr_space) {
+ pr_err("unwind: Can't create unwind address space.\n");
+ return -ENOMEM;
+ }
+
+ ret = unw_init_remote(&c, addr_space, ui);
+ if (ret)
+ display_error(ret);
+
+ while (!ret && (unw_step(&c) > 0)) {
+ unw_word_t ip;
+
+ unw_get_reg(&c, UNW_REG_IP, &ip);
+ ret = entry(ip, ui->thread, ui->machine, cb, arg);
+ }
+
+ unw_destroy_addr_space(addr_space);
+ return ret;
+}
+
+int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
+ struct machine *machine, struct thread *thread,
+ u64 sample_uregs, struct perf_sample *data)
+{
+ unw_word_t ip;
+ struct unwind_info ui = {
+ .sample = data,
+ .sample_uregs = sample_uregs,
+ .thread = thread,
+ .machine = machine,
+ };
+ int ret;
+
+ if (!data->user_regs.regs)
+ return -EINVAL;
+
+ ret = reg_value(&ip, &data->user_regs, PERF_REG_IP, sample_uregs);
+ if (ret)
+ return ret;
+
+ ret = entry(ip, thread, machine, cb, arg);
+ if (ret)
+ return -ENOMEM;
+
+ return get_entries(&ui, cb, arg);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-16 12:36:01 +0000