On 17/08/23 20:18, Athira Rajeev wrote: > Update "struct dso" to include new member "text_end". > This new field will represent the offset for end of text > section for a dso. This value is derived as: > sh_size (Size of section in byes) + sh_offset (Section file > offst) of the elf header for text. > > To resolve the address from a sample, perf looks at the > DSO maps. In case of address from a kernel module, there > were some address found to be not resolved. This was > observed while running perf test for "Object code reading". > Though the ip falls beteen the start address of the loaded > module (perf map->start ) and end address ( perf map->end), > it was unresolved. > > Example: > > Reading object code for memory address: 0xc008000007f0142c > File is: /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko > On file address is: 0x1114cc > Objdump command is: objdump -z -d --start-address=0x11142c > --stop-address=0x1114ac /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko > objdump read too few bytes: 128 > test child finished with -1 > > Here, module is loaded at: > # cat /proc/modules | grep xfs > xfs 2228224 3 - Live 0xc008000007d00000 > > From objdump for xfs module, text section is: > text 0010f7bc 0000000000000000 0000000000000000 000000a0 2**4 > > Here the offset for 0xc008000007f0142c ie 0x112074 falls out > .text section which is up to 0x10f7bc. > > In this case for module, the address 0xc008000007e11fd4 is pointing > to stub instructions. This address range represents the module stubs > which is allocated on module load and hence is not part of DSO offset. > > To identify such address, which falls out of text > section and within module end, added the new field "text_end" to > "struct dso". > > Reported-by: Disha Goel <[email protected]> > Signed-off-by: Athira Rajeev <[email protected]> > --- > Changelog: > v1 -> v2: > Changed commit message to explain need for "text_end" > > tools/perf/util/dso.h | 1 + > tools/perf/util/symbol-elf.c | 4 +++- > 2 files changed, 4 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h > index b41c9782c754..70fe0fe69bef 100644 > --- a/tools/perf/util/dso.h > +++ b/tools/perf/util/dso.h > @@ -181,6 +181,7 @@ struct dso { > u8 rel; > struct build_id bid; > u64 text_offset; > + u64 text_end; > const char *short_name; > const char *long_name; > u16 long_name_len; > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c > index 8bd466d1c2bd..252d26a59e64 100644 > --- a/tools/perf/util/symbol-elf.c > +++ b/tools/perf/util/symbol-elf.c > @@ -1512,8 +1512,10 @@ dso__load_sym_internal(struct dso *dso, struct map > *map, struct symsrc *syms_ss, > } > > if (elf_section_by_name(runtime_ss->elf, &runtime_ss->ehdr, &tshdr, > - ".text", NULL)) > + ".text", NULL)) { > dso->text_offset = tshdr.sh_addr - tshdr.sh_offset; > + dso->text_end = tshdr.sh_offset + tshdr.sh_size; > + } > > if (runtime_ss->opdsec) > opddata = elf_rawdata(runtime_ss->opdsec, NULL);
Should probably amend dso__load_bfd_symbols() also
