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author | Fangrui Song <maskray@google.com> | 2021-10-07 11:55:02 -0700 |
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committer | Fangrui Song <maskray@google.com> | 2021-10-07 11:55:02 -0700 |
commit | 490e6c62aa31a8aa5c4a059f6e646ede121edf0a (patch) | |
tree | 40bedb62d8b555792f91c82127b0f599da90ef39 /elf/dl-conflict.c | |
parent | 349b0441dab375099b1d7f6909c1742286a67da9 (diff) | |
download | glibc-490e6c62aa31a8aa5c4a059f6e646ede121edf0a.tar.gz glibc-490e6c62aa31a8aa5c4a059f6e646ede121edf0a.tar.xz glibc-490e6c62aa31a8aa5c4a059f6e646ede121edf0a.zip |
elf: Avoid nested functions in the loader [BZ #27220]
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 Clang build (Clang doesn't support GCC nested functions). The key idea for unnesting is to add extra parameters (struct link_map *and struct r_scope_elm *[]) to RESOLVE_MAP, ELF_MACHINE_BEFORE_RTLD_RELOC, ELF_DYNAMIC_RELOCATE, elf_machine_rel[a], elf_machine_lazy_rel, and elf_machine_runtime_setup. (This is inspired by Stan Shebs' ppc64/x86-64 implementation in the google/grte/v5-2.27/master which uses mixed extra parameters and static variables.) Future simplification: * If mips elf_machine_runtime_setup no longer needs RESOLVE_GOTSYM, elf_machine_runtime_setup can drop the `scope` parameter. * If TLSDESC no longer need to be in elf_machine_lazy_rel, elf_machine_lazy_rel can drop the `scope` parameter. Tested on aarch64, i386, x86-64, powerpc64le, powerpc64, powerpc32, sparc64, sparcv9, s390x, s390, hppa, ia64, armhf, alpha, and mips64. In addition, tested build-many-glibcs.py with {arc,csky,microblaze,nios2}-linux-gnu and riscv64-linux-gnu-rv64imafdc-lp64d. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diffstat (limited to 'elf/dl-conflict.c')
-rw-r--r-- | elf/dl-conflict.c | 39 |
1 files changed, 21 insertions, 18 deletions
diff --git a/elf/dl-conflict.c b/elf/dl-conflict.c index 64fa5793d2..b58929cc5d 100644 --- a/elf/dl-conflict.c +++ b/elf/dl-conflict.c @@ -26,20 +26,12 @@ #include <sys/types.h> #include "dynamic-link.h" -void -_dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict, - ElfW(Rela) *conflictend) -{ -#if ! ELF_MACHINE_NO_RELA - if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_RELOC)) - _dl_debug_printf ("\nconflict processing: %s\n", DSO_FILENAME (l->l_name)); - - { - /* Do the conflict relocation of the object and library GOT and other - data. */ +/* Used at loading time solely for prelink executable. It is not called + concurrently so it is be safe to defined as static. */ +static struct link_map *resolve_conflict_map __attribute__ ((__unused__)); /* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code. */ -#define RESOLVE_MAP(ref, version, flags) (*ref = NULL, NULL) +#define RESOLVE_MAP(map, scope, ref, version, flags) (*ref = NULL, NULL) #define RESOLVE(ref, version, flags) (*ref = NULL, 0) #define RESOLVE_CONFLICT_FIND_MAP(map, r_offset) \ do { \ @@ -50,12 +42,23 @@ _dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict, (map) = resolve_conflict_map; \ } while (0) +#include "dynamic-link.h" + +void +_dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict, + ElfW(Rela) *conflictend) +{ +#if ! ELF_MACHINE_NO_RELA + if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_RELOC)) + _dl_debug_printf ("\nconflict processing: %s\n", DSO_FILENAME (l->l_name)); + + { + /* Do the conflict relocation of the object and library GOT and other + data. */ + /* Prelinking makes no sense for anything but the main namespace. */ assert (l->l_ns == LM_ID_BASE); - struct link_map *resolve_conflict_map __attribute__ ((__unused__)) - = GL(dl_ns)[LM_ID_BASE]._ns_loaded; - -#include "dynamic-link.h" + resolve_conflict_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded; /* Override these, defined in dynamic-link.h. */ #undef CHECK_STATIC_TLS @@ -66,8 +69,8 @@ _dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict, GL(dl_num_cache_relocations) += conflictend - conflict; for (; conflict < conflictend; ++conflict) - elf_machine_rela (l, conflict, NULL, NULL, (void *) conflict->r_offset, - 0); + elf_machine_rela (l, NULL, conflict, NULL, NULL, + (void *) conflict->r_offset, 0); } #endif } |