Re: [PATCH 5/8] perf tools: Promote proper messages for cross-platform unwind

[Jiri Olsa <jolsa@redhat.com>]

On Fri, May 06, 2016 at 08:59:11AM +0000, He Kuang wrote:
> Currently, perf script uses host unwind methods to parse perf.data
> callchain info regardless of the target architecture. So we get wrong
> result and no promotion when unwinding callchains of x86(32bit) on
> x86(64bit) machine.
> 
> This patch shows proper error messages when we do remote unwind
> x86(32bit) on other machines.
> 
> Same thing for other platforms will be added in next patches.
> 
> Signed-off-by: He Kuang <hekuang@huawei.com>
> ---
>  tools/perf/config/Makefile   |  6 ++++++
>  tools/perf/util/symbol-elf.c | 16 +++++++++++++++
>  tools/perf/util/symbol.c     | 49 ++++++++++++++++++++++++++++++++++++++++++++
>  tools/perf/util/symbol.h     |  2 ++
>  tools/perf/util/thread.c     | 31 ++++++++++++++++++++++++++++
>  5 files changed, 104 insertions(+)
> 
> diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
> index 1e46277..a86b864 100644
> --- a/tools/perf/config/Makefile
> +++ b/tools/perf/config/Makefile
> @@ -345,6 +345,12 @@ ifeq ($(ARCH),powerpc)
>  endif
>  
>  ifndef NO_LIBUNWIND
> +  ifeq ($(feature-libunwind-x86), 1)
> +    LIBUNWIND_LIBS += -lunwind-x86
> +    $(call detected,CONFIG_LIBUNWIND_X86)
> +    CFLAGS += -DHAVE_LIBUNWIND_X86_SUPPORT
> +  endif
> +
>    ifneq ($(feature-libunwind), 1)
>      msg := $(warning No libunwind found. Please install libunwind-dev[el] >= 1.1 and/or set LIBUNWIND_DIR);
>      NO_LIBUNWIND := 1
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index 3f9d679..9f290b9 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -636,6 +636,22 @@ bool __weak elf__needs_adjust_symbols(GElf_Ehdr ehdr)
>  	return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL;
>  }
>  
> +int elf_is_64_bit(char *name)
> +{
> +	Elf *elf;
> +	int fd;
> +
> +	fd = open(name, O_RDONLY);
> +	if (fd < 0)
> +		return -1;
> +
> +	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
> +	if (elf == NULL)
> +		return -1;
> +
> +	return (gelf_getclass(elf) == ELFCLASS64);
> +}
> +
>  int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
>  		 enum dso_binary_type type)
>  {
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index 93f348f..c33aa5a 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -1395,6 +1395,55 @@ static bool dso__is_compatible_symtab_type(struct dso *dso, bool kmod,
>  	}
>  }
>  
> +int dso_is_64_bit(struct dso *dso, struct map *map)
> +{
> +	char *name;
> +	u_int i;
> +	bool kmod;
> +	char *root_dir = (char *) "";
> +	struct machine *machine;
> +
> +	if (map->groups && map->groups->machine)
> +		machine = map->groups->machine;
> +	else
> +		machine = NULL;
> +
> +	if (machine)
> +		root_dir = machine->root_dir;
> +
> +	name = malloc(PATH_MAX);
> +	if (!name)
> +		return -1;
> +
> +	kmod = dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE ||
> +		dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP ||
> +		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE ||
> +		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;
> +
> +	/*
> +	 * Iterate over candidate debug images.
> +	 * Keep track of "interesting" ones (those which have a symtab, dynsym,
> +	 * and/or opd section) for processing.
> +	 */
> +	for (i = 0; i < DSO_BINARY_TYPE__SYMTAB_CNT; i++) {
> +		enum dso_binary_type symtab_type = binary_type_symtab[i];
> +
> +		if (!dso__is_compatible_symtab_type(dso, kmod, symtab_type))
> +			continue;
> +
> +		if (dso__read_binary_type_filename(dso, symtab_type,
> +						   root_dir, name, PATH_MAX))
> +			continue;
> +
> +		if (!is_regular_file(name))
> +			continue;
> +
> +		return elf_is_64_bit(name);
> +	}
> +
> +	return -1;
> +}
> +
>  int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
>  {
>  	char *name;
> diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
> index 4e6910e..d33fbf4 100644
> --- a/tools/perf/util/symbol.h
> +++ b/tools/perf/util/symbol.h
> @@ -308,6 +308,8 @@ int setup_list(struct strlist **list, const char *list_str,
>  	       const char *list_name);
>  int setup_intlist(struct intlist **list, const char *list_str,
>  		  const char *list_name);
> +int elf_is_64_bit(char *name);
> +int dso_is_64_bit(struct dso *dso, struct map *map);
>  
>  #ifdef HAVE_LIBELF_SUPPORT
>  bool elf__needs_adjust_symbols(GElf_Ehdr ehdr);
> diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
> index dfd00c6..e0cdcf7 100644
> --- a/tools/perf/util/thread.c
> +++ b/tools/perf/util/thread.c
> @@ -184,8 +184,39 @@ size_t thread__fprintf(struct thread *thread, FILE *fp)
>  
>  void thread__insert_map(struct thread *thread, struct map *map)
>  {
> +	char * __maybe_unused arch;
> +	int __maybe_unused is_64_bit;
> +
>  	map_groups__fixup_overlappings(thread->mg, map, stderr);
>  	map_groups__insert(thread->mg, map);
> +
> +#ifdef HAVE_LIBUNWIND_SUPPORT
> +	if (!thread->mg->machine->env)
> +		return;
> +
> +	is_64_bit = dso_is_64_bit(map->dso, map);
> +	if (is_64_bit < 0)
> +		return;
> +
> +	if (thread->addr_space)
> +		pr_debug("Thread map already set, 64bit is %d, dso=%s\n",
> +			 is_64_bit, map->dso->name);
> +
> +	arch = thread->mg->machine->env->arch;
> +
> +	if (!strcmp(arch, "x86_64")
> +		   || !strcmp(arch, "x86")
> +		   || !strcmp(arch, "i686")) {
> +		pr_debug("Thread map is X86, 64bit is %d\n", is_64_bit);
> +		if (!is_64_bit)
> +#ifdef HAVE_LIBUNWIND_X86_SUPPORT
> +			pr_err("target platform=%s is not implemented!\n",
> +			       arch);
> +#else
> +			pr_err("target platform=%s is not supported!\n", arch);
> +#endif
> +	}
> +#endif

could you please move above code under unwind object,
like we do with unwind__prepare_access in thread__new?

also we could unite both names somehome now we have 2 callbacks
to unwind code from generic code

thanks,
jirka