lkml.org 
[lkml]   [2023]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 6/9] perf symbols: Allow for .plt without header
Date
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.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
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 a002fc0bea03..8f7802097c72 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.
--
2.34.1
\
 
 \ /
  Last update: 2023-03-26 23:58    [W:1.384 / U:0.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site