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    Subject[PATCH -tip v3 08/11] perf-probe: Show appropriate symbol for ref_reloc_sym based kprobes
    From
    Date
    Show appropriate symbol for ref_reloc_sym based kprobes instead
    of refpoint+offset when perf-probe -l runs without debuginfo.

    Without this change:
    # ./perf probe -l
    probe:t_show (on _stext+889880 with m v)
    probe:t_show_1 (on _stext+928568 with m v t)
    probe:t_show_2 (on _stext+969512 with m v fmt)
    probe:t_show_3 (on _stext+1001416 with m v file)

    With this change:
    # ./perf probe -l
    probe:t_show (on t_show with m v)
    probe:t_show_1 (on t_show with m v t)
    probe:t_show_2 (on t_show with m v fmt)
    probe:t_show_3 (on t_show with m v file)

    Changes from v2:
    - Check ref_reloc_sym to find correct unrelocated address.

    Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    ---
    tools/perf/util/probe-event.c | 83 +++++++++++++++++++++++++++--------------
    1 file changed, 55 insertions(+), 28 deletions(-)

    diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
    index 8e34c8d..f86820c 100644
    --- a/tools/perf/util/probe-event.c
    +++ b/tools/perf/util/probe-event.c
    @@ -121,6 +121,42 @@ static struct symbol *__find_kernel_function_by_name(const char *name,
    NULL);
    }

    +static struct symbol *__find_kernel_function(u64 addr, struct map **mapp)
    +{
    + return machine__find_kernel_function(host_machine, addr, mapp, NULL);
    +}
    +
    +static struct ref_reloc_sym *kernel_get_ref_reloc_sym(void)
    +{
    + /* kmap->ref_reloc_sym should be set if host_machine is initialized */
    + struct kmap *kmap;
    +
    + if (map__load(host_machine->vmlinux_maps[MAP__FUNCTION], NULL) < 0)
    + return NULL;
    +
    + kmap = map__kmap(host_machine->vmlinux_maps[MAP__FUNCTION]);
    + return kmap->ref_reloc_sym;
    +}
    +
    +static u64 kernel_get_symbol_address_by_name(const char *name, bool reloc)
    +{
    + struct ref_reloc_sym *reloc_sym;
    + struct symbol *sym;
    + struct map *map;
    +
    + /* ref_reloc_sym is just a label. Need a special fix*/
    + reloc_sym = kernel_get_ref_reloc_sym();
    + if (reloc_sym && strcmp(name, reloc_sym->name) == 0)
    + return (reloc) ? reloc_sym->addr : reloc_sym->unrelocated_addr;
    + else {
    + sym = __find_kernel_function_by_name(name, &map);
    + if (sym)
    + return map->unmap_ip(map, sym->start) -
    + (reloc) ? 0 : map->reloc;
    + }
    + return 0;
    +}
    +
    static struct map *kernel_get_module_map(const char *module)
    {
    struct rb_node *nd;
    @@ -216,12 +252,26 @@ out:
    static int convert_to_perf_probe_point(struct probe_trace_point *tp,
    struct perf_probe_point *pp)
    {
    - pp->function = strdup(tp->symbol);
    + struct symbol *sym;
    + struct map *map;
    + u64 addr = kernel_get_symbol_address_by_name(tp->symbol, true);
    +
    + if (addr) {
    + addr += tp->offset;
    + sym = __find_kernel_function(addr, &map);
    + if (!sym)
    + goto failed;
    + pp->function = strdup(sym->name);
    + pp->offset = addr - map->unmap_ip(map, sym->start);
    + } else {
    +failed:
    + pp->function = strdup(tp->symbol);
    + pp->offset = tp->offset;
    + }

    if (pp->function == NULL)
    return -ENOMEM;

    - pp->offset = tp->offset;
    pp->retprobe = tp->retprobe;

    return 0;
    @@ -248,18 +298,6 @@ static struct debuginfo *open_debuginfo(const char *module)
    return debuginfo__new(path);
    }

    -static struct ref_reloc_sym *__kernel_get_ref_reloc_sym(void)
    -{
    - /* kmap->ref_reloc_sym should be set if host_machine is initialized */
    - struct kmap *kmap;
    -
    - if (map__load(host_machine->vmlinux_maps[MAP__FUNCTION], NULL) < 0)
    - return NULL;
    -
    - kmap = map__kmap(host_machine->vmlinux_maps[MAP__FUNCTION]);
    - return kmap->ref_reloc_sym;
    -}
    -
    /*
    * Convert trace point to probe point with debuginfo
    * Currently only handles kprobes.
    @@ -267,24 +305,13 @@ static struct ref_reloc_sym *__kernel_get_ref_reloc_sym(void)
    static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
    struct perf_probe_point *pp)
    {
    - struct symbol *sym;
    - struct ref_reloc_sym *reloc_sym;
    - struct map *map;
    u64 addr = 0;
    int ret = -ENOENT;
    struct debuginfo *dinfo;

    - /* ref_reloc_sym is just a label. Need a special fix*/
    - reloc_sym = __kernel_get_ref_reloc_sym();
    - if (reloc_sym && strcmp(tp->symbol, reloc_sym->name) == 0)
    - addr = reloc_sym->unrelocated_addr + tp->offset;
    - else {
    - sym = __find_kernel_function_by_name(tp->symbol, &map);
    - if (sym)
    - addr = map->unmap_ip(map, sym->start + tp->offset) -
    - map->reloc;
    - }
    + addr = kernel_get_symbol_address_by_name(tp->symbol, false);
    if (addr) {
    + addr += tp->offset;
    pr_debug("try to find %s+%ld@%" PRIx64 "\n", tp->symbol,
    tp->offset, addr);

    @@ -420,7 +447,7 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs,
    if (module)
    return add_module_to_probe_trace_events(tevs, ntevs, module);

    - reloc_sym = __kernel_get_ref_reloc_sym();
    + reloc_sym = kernel_get_ref_reloc_sym();
    if (!reloc_sym) {
    pr_warning("Relocated base symbol is not found!\n");
    return -EINVAL;



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