| Message ID | 20220616080739.3736718-1-maskray@google.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86-64: Handle fewer relocation types for RTLD_BOOTSTRAP | expand |
On Thu, Jun 16, 2022 at 1:07 AM Fangrui Song <maskray@google.com> wrote: > > The RTLD_BOOTSTRAP branch is used to relocate ld.so itself. It only > needs to handle RELATIVE, GLOB_DAT, and JUMP_SLOT. RELATIVE has been > handled (by _ELF_DYNAMIC_DO_RELOC due to DT_RELACOUNT, or RELR), so the > switch statement only needs to handle GLOB_DAT and JUMP_SLOT. > > We can drop these `#if[n]def RTLD_BOOTSTRAP` and add a large > `# ifndef RTLD_BOOTSTRAP` instead. > --- > sysdeps/x86_64/dl-machine.h | 32 ++++++-------------------------- > 1 file changed, 6 insertions(+), 26 deletions(-) > > diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h > index 06c9a932b0..34766325ae 100644 > --- a/sysdeps/x86_64/dl-machine.h > +++ b/sysdeps/x86_64/dl-machine.h > @@ -298,6 +298,11 @@ and creates an unsatisfiable circular dependency.\n", > > switch (r_type) > { > + case R_X86_64_GLOB_DAT: > + case R_X86_64_JUMP_SLOT: > + *reloc_addr = value; > + break; > + > # ifndef RTLD_BOOTSTRAP > # ifdef __ILP32__ > case R_X86_64_SIZE64: > @@ -314,29 +319,14 @@ and creates an unsatisfiable circular dependency.\n", > value = sym->st_size; > *reloc_addr = value + reloc->r_addend; > break; > -# endif > - > - case R_X86_64_GLOB_DAT: > - case R_X86_64_JUMP_SLOT: > - *reloc_addr = value; > - break; > > case R_X86_64_DTPMOD64: > -# ifdef RTLD_BOOTSTRAP > - /* During startup the dynamic linker is always the module > - with index 1. > - XXX If this relocation is necessary move before RESOLVE > - call. */ > - *reloc_addr = 1; > -# else > /* Get the information from the link map returned by the > resolve function. */ > if (sym_map != NULL) > *reloc_addr = sym_map->l_tls_modid; > -# endif > break; > case R_X86_64_DTPOFF64: > -# ifndef RTLD_BOOTSTRAP > /* During relocation all TLS symbols are defined and used. > Therefore the offset is already correct. */ > if (sym != NULL) > @@ -353,23 +343,19 @@ and creates an unsatisfiable circular dependency.\n", > *reloc_addr = value; > # endif > } > -# endif > break; > case R_X86_64_TLSDESC: > { > struct tlsdesc volatile *td = > (struct tlsdesc volatile *)reloc_addr; > > -# ifndef RTLD_BOOTSTRAP > if (! sym) > { > td->arg = (void*)reloc->r_addend; > td->entry = _dl_tlsdesc_undefweak; > } > else > -# endif > { > -# ifndef RTLD_BOOTSTRAP > # ifndef SHARED > CHECK_STATIC_TLS (map, sym_map); > # else > @@ -381,7 +367,6 @@ and creates an unsatisfiable circular dependency.\n", > } > else > # endif > -# endif > { > td->arg = (void*)(sym->st_value - sym_map->l_tls_offset > + reloc->r_addend); > @@ -392,13 +377,9 @@ and creates an unsatisfiable circular dependency.\n", > } > case R_X86_64_TPOFF64: > /* The offset is negative, forward from the thread pointer. */ > -# ifndef RTLD_BOOTSTRAP > if (sym != NULL) > -# endif > { > -# ifndef RTLD_BOOTSTRAP > CHECK_STATIC_TLS (map, sym_map); > -# endif > /* We know the offset of the object the symbol is contained in. > It is a negative value which will be added to the > thread pointer. */ > @@ -416,7 +397,6 @@ and creates an unsatisfiable circular dependency.\n", > } > break; > > -# ifndef RTLD_BOOTSTRAP > case R_X86_64_64: > /* value + r_addend may be > 0xffffffff and R_X86_64_64 > relocation updates the whole 64-bit entry. */ > @@ -481,7 +461,7 @@ and creates an unsatisfiable circular dependency.\n", > default: > _dl_reloc_bad_type (map, r_type, 0); > break; > -# endif > +# endif /* !RTLD_BOOTSTRAP */ > } > } > } > -- > 2.36.1.476.g0c4daa206d-goog > LGTM. Thanks.
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index 06c9a932b0..34766325ae 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -298,6 +298,11 @@ and creates an unsatisfiable circular dependency.\n", switch (r_type) { + case R_X86_64_GLOB_DAT: + case R_X86_64_JUMP_SLOT: + *reloc_addr = value; + break; + # ifndef RTLD_BOOTSTRAP # ifdef __ILP32__ case R_X86_64_SIZE64: @@ -314,29 +319,14 @@ and creates an unsatisfiable circular dependency.\n", value = sym->st_size; *reloc_addr = value + reloc->r_addend; break; -# endif - - case R_X86_64_GLOB_DAT: - case R_X86_64_JUMP_SLOT: - *reloc_addr = value; - break; case R_X86_64_DTPMOD64: -# ifdef RTLD_BOOTSTRAP - /* During startup the dynamic linker is always the module - with index 1. - XXX If this relocation is necessary move before RESOLVE - call. */ - *reloc_addr = 1; -# else /* Get the information from the link map returned by the resolve function. */ if (sym_map != NULL) *reloc_addr = sym_map->l_tls_modid; -# endif break; case R_X86_64_DTPOFF64: -# ifndef RTLD_BOOTSTRAP /* During relocation all TLS symbols are defined and used. Therefore the offset is already correct. */ if (sym != NULL) @@ -353,23 +343,19 @@ and creates an unsatisfiable circular dependency.\n", *reloc_addr = value; # endif } -# endif break; case R_X86_64_TLSDESC: { struct tlsdesc volatile *td = (struct tlsdesc volatile *)reloc_addr; -# ifndef RTLD_BOOTSTRAP if (! sym) { td->arg = (void*)reloc->r_addend; td->entry = _dl_tlsdesc_undefweak; } else -# endif { -# ifndef RTLD_BOOTSTRAP # ifndef SHARED CHECK_STATIC_TLS (map, sym_map); # else @@ -381,7 +367,6 @@ and creates an unsatisfiable circular dependency.\n", } else # endif -# endif { td->arg = (void*)(sym->st_value - sym_map->l_tls_offset + reloc->r_addend); @@ -392,13 +377,9 @@ and creates an unsatisfiable circular dependency.\n", } case R_X86_64_TPOFF64: /* The offset is negative, forward from the thread pointer. */ -# ifndef RTLD_BOOTSTRAP if (sym != NULL) -# endif { -# ifndef RTLD_BOOTSTRAP CHECK_STATIC_TLS (map, sym_map); -# endif /* We know the offset of the object the symbol is contained in. It is a negative value which will be added to the thread pointer. */ @@ -416,7 +397,6 @@ and creates an unsatisfiable circular dependency.\n", } break; -# ifndef RTLD_BOOTSTRAP case R_X86_64_64: /* value + r_addend may be > 0xffffffff and R_X86_64_64 relocation updates the whole 64-bit entry. */ @@ -481,7 +461,7 @@ and creates an unsatisfiable circular dependency.\n", default: _dl_reloc_bad_type (map, r_type, 0); break; -# endif +# endif /* !RTLD_BOOTSTRAP */ } } }