When -fpatchable-relocation-entry is used, gcc places nops on the
prologue of each compiled function and creates a section named
__patchable_function_entries which holds relocation entries for the
positions in which the nops were placed. As is, gcc creates this
section without the proper section flags, causing crashes in the
compiled program during its load.
Given the above, fix the problem by creating the section with the
SECTION_WRITE and SECTION_RELRO flags.
The problem was noticed while compiling glibc with
-fpatchable-function-entry compiler flag. After applying the patch,
this issue was solved.
This was also tested on x86-64 arch without visible problems under
the gcc standard tests.
2019-04-10 Joao Moreira <jmore...@suse.de>
* targhooks.c (default_print_patchable_function_entry): Emit
__patchable_function_entries section with writable flags to allow
relocation resolution.
Signed-off-by: Joao Moreira <jmore...@suse.de>
---
gcc/targhooks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index 318f7e9784a..e6f54ddf41b 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -1814,7 +1814,7 @@ default_print_patchable_function_entry (FILE *file,
ASM_GENERATE_INTERNAL_LABEL (buf, "LPFE", patch_area_number);
switch_to_section (get_section ("__patchable_function_entries",
- 0, NULL));
+ SECTION_WRITE | SECTION_RELRO, NULL));
fputs (asm_op, file);
assemble_name_raw (file, buf);
fputc ('\n', file);
--
2.16.4
