diff options
| author | Fangrui Song <maskray@google.com> | 2021-08-22 16:29:16 -0700 |
|---|---|---|
| committer | Fangrui Song <maskray@google.com> | 2021-08-22 16:29:16 -0700 |
| commit | 5544862ebedb02e75b6b333c2d44ad9eb51ea36e (patch) | |
| tree | b0232a628501d4028e0469ed1152df837d086a8d /elf/dl-reloc-static-pie.c | |
| parent | bca0f5cbc9257c13322b99e55235c4f21ba0bd82 (diff) | |
| download | glibc-maskray/nesting.tar.gz | |
elf: Avoid nested functions in the loader (aarch64, x86-64) [BZ #27220]maskray/nesting
dynamic-link.h is included more than once in some elf/ files (rtld.c,
dl-conflict.c, dl-reloc.c, dl-reloc-static-pie.c) and uses GCC nested
functions. This harms readability and the nested functions usage
is the biggest obstacle prevents CC=clang (which doesn't support the
feature).
To un-nest elf_machine_rela, the key idea is to pass the variable in
the containing scope as an extra argument.
Stan Shebs implemented this in the google/grte/v5-2.27/master branch.
This patch squashes and cleans up the commits.
This patch just fixes aarch64 and x86-64: they use the `#ifndef NESTING`
branch to avoid nested functions. The `#ifdef NESTING` branch is used by
all other ports whose dl-machine.h files haven't been migrated.
For the time being, there is some duplicated code. `#ifdef NESTING`
dispatches can be removed in the future when all arches are migrated.
I can fix powerpc64, riscv, and other arches subsequently.
Migrating all ports at once is just too risky. Also, appreciate help
from arch maintainers.
Tested on {aarch64,x86_64}-linux-gnu (!NESTING) and
powerpc64le-linux-gnu (NESTING).
Diffstat (limited to 'elf/dl-reloc-static-pie.c')
| -rw-r--r-- | elf/dl-reloc-static-pie.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/elf/dl-reloc-static-pie.c b/elf/dl-reloc-static-pie.c index d5bd2f31e9..0ab4613021 100644 --- a/elf/dl-reloc-static-pie.c +++ b/elf/dl-reloc-static-pie.c @@ -23,6 +23,13 @@ #include <ldsodefs.h> #include "dynamic-link.h" +#ifndef NESTING +# define STATIC_PIE_BOOTSTRAP +# define BOOTSTRAP_MAP (main_map) +# define RESOLVE_MAP(sym, version, flags) BOOTSTRAP_MAP +# include "dynamic-link.h" +#endif /* n NESTING */ + /* Relocate static executable with PIE. */ void @@ -30,10 +37,12 @@ _dl_relocate_static_pie (void) { struct link_map *main_map = _dl_get_dl_main_map (); +#ifdef NESTING # define STATIC_PIE_BOOTSTRAP # define BOOTSTRAP_MAP (main_map) # define RESOLVE_MAP(sym, version, flags) BOOTSTRAP_MAP # include "dynamic-link.h" +#endif /* NESTING */ /* Figure out the run-time load address of static PIE. */ main_map->l_addr = elf_machine_load_address (); @@ -48,7 +57,11 @@ _dl_relocate_static_pie (void) /* Relocate ourselves so we can do normal function calls and data access using the global offset table. */ - ELF_DYNAMIC_RELOCATE (main_map, 0, 0, 0); + ELF_DYNAMIC_RELOCATE (main_map, 0, 0, 0 +#ifndef NESTING + , main_map +#endif + ); main_map->l_relocated = 1; /* Initialize _r_debug. */ |