Messages in this thread |  | | Date | Mon, 16 Dec 2013 09:55:50 +0200 | From | Adrian Hunter <> | Subject | Re: [PATCH v0 07/71] perf tools: Record whether a dso is 64-bit |
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On 16/12/13 05:16, David Ahern wrote: > On 12/11/13, 5:36 AM, Alexander Shishkin wrote: >> diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c >> index a0c7c59..80817ec 100644 >> --- a/tools/perf/util/dso.c >> +++ b/tools/perf/util/dso.c >> @@ -446,6 +446,7 @@ struct dso *dso__new(const char *name) >> dso->cache = RB_ROOT; >> dso->symtab_type = DSO_BINARY_TYPE__NOT_FOUND; >> dso->data_type = DSO_BINARY_TYPE__NOT_FOUND; >> + dso->is_64_bit = (sizeof(void *) == 8); >> dso->loaded = 0; >> dso->rel = 0; >> dso->sorted_by_name = 0; >> diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h >> index 384f2d9..62680e1 100644 >> --- a/tools/perf/util/dso.h >> +++ b/tools/perf/util/dso.h >> @@ -91,6 +91,7 @@ struct dso { >> u8 annotate_warned:1; >> u8 sname_alloc:1; >> u8 lname_alloc:1; >> + u8 is_64_bit:1; >> u8 sorted_by_name; >> u8 loaded; >> u8 rel; >> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c >> index eed0b96..a0fc81b 100644 >> --- a/tools/perf/util/symbol-elf.c >> +++ b/tools/perf/util/symbol-elf.c >> @@ -595,6 +595,8 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, >> const char *name, >> goto out_elf_end; >> } >> >> + ss->is_64_bit = (gelf_getclass(elf) == ELFCLASS64); >> + >> ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab", >> NULL); >> if (ss->symshdr.sh_type != SHT_SYMTAB) >> @@ -694,6 +696,7 @@ int dso__load_sym(struct dso *dso, struct map *map, >> bool remap_kernel = false, adjust_kernel_syms = false; >> >> dso->symtab_type = syms_ss->type; >> + dso->is_64_bit = syms_ss->is_64_bit; >> dso->rel = syms_ss->ehdr.e_type == ET_REL; >> >> /* >> diff --git a/tools/perf/util/symbol-minimal.c >> b/tools/perf/util/symbol-minimal.c >> index ac7070a..b9d1119 100644 >> --- a/tools/perf/util/symbol-minimal.c >> +++ b/tools/perf/util/symbol-minimal.c >> @@ -1,3 +1,4 @@ >> +#include "util.h" >> #include "symbol.h" >> >> #include <stdio.h> >> @@ -287,6 +288,23 @@ int dso__synthesize_plt_symbols(struct dso *dso >> __maybe_unused, >> return 0; >> } >> >> +static int fd__is_64_bit(int fd) >> +{ >> + u8 e_ident[EI_NIDENT]; >> + >> + if (lseek(fd, 0, SEEK_SET)) >> + return -1; >> + >> + if (readn(fd, e_ident, sizeof(e_ident)) != sizeof(e_ident)) >> + return -1; >> + >> + if (memcmp(e_ident, ELFMAG, SELFMAG) || >> + e_ident[EI_VERSION] != EV_CURRENT) >> + return -1; >> + >> + return e_ident[EI_CLASS] == ELFCLASS64; >> +} >> + >> int dso__load_sym(struct dso *dso, struct map *map __maybe_unused, >> struct symsrc *ss, >> struct symsrc *runtime_ss __maybe_unused, >> @@ -294,6 +312,11 @@ int dso__load_sym(struct dso *dso, struct map *map >> __maybe_unused, >> int kmodule __maybe_unused) >> { >> unsigned char *build_id[BUILD_ID_SIZE]; >> + int ret; >> + >> + ret = fd__is_64_bit(ss->fd); >> + if (ret >= 0) >> + dso->is_64_bit = ret; >> >> if (filename__read_build_id(ss->name, build_id, BUILD_ID_SIZE) > 0) { >> dso__set_build_id(dso, build_id); > > > Here's what is wrong with this API: you are determining DSO bitness at > symbol load time, not when the DSO is created and added to the maps. > > As I pointed out in a prior comment you are initializing dso->is_64_bit to > perf's bitness when the dso object is created (dso__new) but the value is > not correctly set until dso__load time. Some tools (perf-trace) never load > symbols, so that value is always wrong in the sense that its value has no > correlation to the dso object.
That is a very good point. I think Arnaldo has previously noted that symbol loading needs to be split from dso (map) loading. I don't have the time to do that right now.
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