From 60fbb3e49abe8421b677d5eee32fe7fb27b05e3b Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Tue, 31 Jan 2023 15:16:22 +0200 Subject: [PATCH] perf symbols: Allow for .plt without header A static executable can have a .plt due to the presence of IFUNCs. In that case the .plt does not have a header. Check for whether there is a header by comparing the number of entries to the number of relocation entries. Reviewed-by: Namhyung Kim Signed-off-by: Adrian Hunter Cc: Ian Rogers Cc: Jiri Olsa Link: https://lore.kernel.org/r/20230131131625.6964-7-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol-elf.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index a002fc0..8f78020 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -489,6 +489,7 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) Elf *elf; int nr = 0, err = -1; struct rel_info ri = { .is_rela = false }; + bool lazy_plt; elf = ss->elf; ehdr = ss->ehdr; @@ -523,8 +524,10 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) plt_sym->end = plt_sym->start + shdr_plt.sh_size; /* Use .plt.sec offset */ plt_offset = plt_sec_shdr.sh_offset; + lazy_plt = false; } else { - plt_offset = shdr_plt.sh_offset + plt_header_size; + plt_offset = shdr_plt.sh_offset; + lazy_plt = true; } scn_dynsym = ss->dynsym; @@ -577,6 +580,17 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss) ri.is_rela = shdr_rel_plt.sh_type == SHT_RELA; + if (lazy_plt) { + /* + * Assume a .plt with the same number of entries as the number + * of relocation entries is not lazy and does not have a header. + */ + if (ri.nr_entries * plt_entry_size == shdr_plt.sh_size) + dso__delete_symbol(dso, plt_sym); + else + plt_offset += plt_header_size; + } + /* * x86 doesn't insert IFUNC relocations in .plt order, so sort to get * back in order. -- 2.7.4