Workaround to adjust .text symbols from ET_EXEC images correctly.
This is not a complete fix, but addresses the common case and does not create additional assumptions beyond those which perf already makes. ELF images with a weird link map may still be processed incorrectly (as at present) -- that will require a separate fix.
The workaround allows correct symbol offsets to be generated for ET_EXEC executables on systems with separated debug info (where section sh_offset fields from the debug image may bear no relation to the layout of the executable image).
The cover note accompanying this patch contains a more detailed explanation.
Signed-off-by: Dave Martin dave.martin@linaro.org --- tools/perf/util/symbol.c | 10 +++++++++- 1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 3b8c005..3930398 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -1135,7 +1135,15 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name, "sh_addr: %#Lx sh_offset: %#Lx\n", __func__, (u64)sym.st_value, (u64)shdr.sh_addr, (u64)shdr.sh_offset); - sym.st_value -= shdr.sh_addr - shdr.sh_offset; + /* Assumptions: + * a) shdr.sh_addr - shdr.sh_offset == + * map->start - map->pgoff + * b) map->pgoff == 0 + * These are true iff we are looking at a function + * symbol in the main executable segment _and_ + * the main executable segment starts at the start of + * the ELF image (normally true). */ + sym.st_value -= map->start; } /* * We need to figure out if the object was created from C++ sources