1 files changed, 571 insertions, 0 deletions

diff --git a/tools/perf/util/unwind.c b/tools/perf/util/unwind.c
new file mode 100644
index 000000000000..958723ba3d2e
--- /dev/null
+++ b/tools/perf/util/unwind.c
@@ -0,0 +1,571 @@
+/*
+ * 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 __maybe_unused as,
+                        unw_regnum_t __maybe_unused num,
+                        unw_fpreg_t __maybe_unused *val,
+                        int __maybe_unused __write,
+                        void __maybe_unused *arg)
+{
+        pr_err("unwind: access_fpreg unsupported\n");
+        return -UNW_EINVAL;
+}
+
+static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
+                                  unw_word_t __maybe_unused *dil_addr,
+                                  void __maybe_unused *arg)
+{
+        return -UNW_ENOINFO;
+}
+
+static int resume(unw_addr_space_t __maybe_unused as,
+                  unw_cursor_t __maybe_unused *cu,
+                  void __maybe_unused *arg)
+{
+        pr_err("unwind: resume unsupported\n");
+        return -UNW_EINVAL;
+}
+
+static int
+get_proc_name(unw_addr_space_t __maybe_unused as,
+              unw_word_t __maybe_unused addr,
+                char __maybe_unused *bufp, size_t __maybe_unused buf_len,
+                unw_word_t __maybe_unused *offp, void __maybe_unused *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 __maybe_unused 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 __maybe_unused 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 __maybe_unused as,
+                            unw_proc_info_t *pi __maybe_unused,
+                            void *arg __maybe_unused)
+{
+        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);
+}