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    Subject[PATCHv2 5/8] perf probe powerpc: Allow matching against dot symbols
    Date
    Allow perf probe to work on powerpc ABIv1 without the need to specify
    the leading dot '.' for functions. 'perf probe do_fork' works with this
    patch.

    Introduce HAVE_ARCH_SYMBOL_HANDLING to indicate need for special
    handling of symbols. In this patch, we override probe_function_filter()
    on powerpc to account for dot symbols.

    Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
    ---
    Changes from the previous patchset:
    Introduced arch helper to override the way probe function filter works.

    tools/perf/arch/powerpc/Makefile | 1 +
    tools/perf/arch/powerpc/util/sym-handling.c | 28 ++++++++++++++++++++++++++++
    tools/perf/config/Makefile | 1 +
    tools/perf/util/probe-event.c | 10 +++++-----
    tools/perf/util/probe-event.h | 5 +++++
    5 files changed, 40 insertions(+), 5 deletions(-)
    create mode 100644 tools/perf/arch/powerpc/util/sym-handling.c

    diff --git a/tools/perf/arch/powerpc/Makefile b/tools/perf/arch/powerpc/Makefile
    index 6f7782b..1c3d435 100644
    --- a/tools/perf/arch/powerpc/Makefile
    +++ b/tools/perf/arch/powerpc/Makefile
    @@ -3,4 +3,5 @@ PERF_HAVE_DWARF_REGS := 1
    LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
    LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/skip-callchain-idx.o
    endif
    +LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/sym-handling.o
    LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/header.o
    diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c
    new file mode 100644
    index 0000000..0a77825
    --- /dev/null
    +++ b/tools/perf/arch/powerpc/util/sym-handling.c
    @@ -0,0 +1,28 @@
    +/*
    + * Special symbol handling for PowerPC:
    + * - Handle dot symbols on ABIv1
    + *
    + * Copyright (C) 2014 Naveen N Rao, IBM Corporation.
    + *
    + * This program is free software; you can redistribute it and/or
    + * modify it under the terms of the GNU General Public License
    + * as published by the Free Software Foundation; either version
    + * 2 of the License, or (at your option) any later version.
    + */
    +
    +#include "map.h"
    +#include "symbol.h"
    +#include "probe-event.h"
    +
    +int probe_function_filter(struct map *map __maybe_unused, struct symbol *sym)
    +{
    + if (sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) {
    + if ((strcmp(looking_function_name, sym->name) == 0) ||
    + (sym->name[0] == '.' && looking_function_name[0] != '.' &&
    + strcmp(looking_function_name, sym->name+1) == 0)) {
    + num_matched_functions++;
    + return 0;
    + }
    + }
    + return 1;
    +}
    diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
    index 5d4b039..35cf934 100644
    --- a/tools/perf/config/Makefile
    +++ b/tools/perf/config/Makefile
    @@ -383,6 +383,7 @@ ifeq ($(ARCH),powerpc)
    ifndef NO_DWARF
    CFLAGS += -DHAVE_SKIP_CALLCHAIN_IDX
    endif
    + CFLAGS += -DHAVE_ARCH_SYMBOL_HANDLING
    endif

    ifndef NO_LIBUNWIND
    diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
    index 74b7fef..7eb9b27 100644
    --- a/tools/perf/util/probe-event.c
    +++ b/tools/perf/util/probe-event.c
    @@ -50,6 +50,8 @@
    #define PERFPROBE_GROUP "probe"

    bool probe_event_dry_run; /* Dry run flag */
    +char *looking_function_name;
    +int num_matched_functions;

    #define semantic_error(msg ...) pr_err("Semantic error :" msg)

    @@ -2210,11 +2212,8 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
    return ret;
    }

    -static char *looking_function_name;
    -static int num_matched_functions;
    -
    -static int probe_function_filter(struct map *map __maybe_unused,
    - struct symbol *sym)
    +#ifndef HAVE_ARCH_SYMBOL_HANDLING
    +int probe_function_filter(struct map *map __maybe_unused, struct symbol *sym)
    {
    if ((sym->binding == STB_GLOBAL || sym->binding == STB_LOCAL) &&
    strcmp(looking_function_name, sym->name) == 0) {
    @@ -2223,6 +2222,7 @@ static int probe_function_filter(struct map *map __maybe_unused,
    }
    return 1;
    }
    +#endif /* HAVE_ARCH_SYMBOL_HANDLING */

    #define strdup_or_goto(str, label) \
    ({ char *__p = strdup(str); if (!__p) goto label; __p; })
    diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
    index e01e994..8564451 100644
    --- a/tools/perf/util/probe-event.h
    +++ b/tools/perf/util/probe-event.h
    @@ -7,6 +7,8 @@
    #include "strfilter.h"

    extern bool probe_event_dry_run;
    +extern char *looking_function_name;
    +extern int num_matched_functions;

    /* kprobe-tracer and uprobe-tracer tracing point */
    struct probe_trace_point {
    @@ -136,6 +138,9 @@ extern int show_available_vars(struct perf_probe_event *pevs, int npevs,
    extern int show_available_funcs(const char *module, struct strfilter *filter,
    bool user);

    +extern int probe_function_filter(struct map *map __maybe_unused,
    + struct symbol *sym);
    +
    /* Maximum index number of event-name postfix */
    #define MAX_EVENT_INDEX 1024

    --
    2.1.3


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