diff options
Diffstat (limited to 'libiberty/simple-object-elf.c')
| -rw-r--r-- | libiberty/simple-object-elf.c | 70 |
1 files changed, 56 insertions, 14 deletions
diff --git a/libiberty/simple-object-elf.c b/libiberty/simple-object-elf.c index 7eb3df8..b249146 100644 --- a/libiberty/simple-object-elf.c +++ b/libiberty/simple-object-elf.c @@ -1,5 +1,5 @@ /* simple-object-elf.c -- routines to manipulate ELF object files. - Copyright (C) 2010-2017 Free Software Foundation, Inc. + Copyright (C) 2010-2018 Free Software Foundation, Inc. Written by Ian Lance Taylor, Google. This program is free software; you can redistribute it and/or modify it @@ -196,6 +196,7 @@ typedef struct { /* Values for sh_flags field. */ +#define SHF_EXECINSTR 0x00000004 /* Executable section. */ #define SHF_EXCLUDE 0x80000000 /* Link editor is to exclude this section from executable and shared library that it builds @@ -235,8 +236,10 @@ typedef struct #define STB_LOCAL 0 /* Local symbol */ #define STB_GLOBAL 1 /* Global symbol */ +#define STB_WEAK 2 /* Weak global */ #define STV_DEFAULT 0 /* Visibility is specified by binding type */ +#define STV_HIDDEN 2 /* Can only be seen inside currect component */ /* Functions to fetch and store different ELF types, depending on the endianness and size. */ @@ -1085,8 +1088,10 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj, off_t shstroff; unsigned char *names; unsigned int i; + int changed; int *pfnret; const char **pfnname; + unsigned first_shndx = 0; shdr_size = (ei_class == ELFCLASS32 ? sizeof (Elf32_External_Shdr) @@ -1154,11 +1159,13 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj, ret = (*pfn) (&name); pfnret[i - 1] = ret == 1 ? 0 : -1; pfnname[i - 1] = name; + if (first_shndx == 0 + && pfnret[i - 1] == 0) + first_shndx = i; } /* Mark sections as preserved that are required by to be preserved sections. */ - int changed; do { changed = 0; @@ -1324,6 +1331,15 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj, sobj->offset + stroff, (unsigned char *)strings, strsz, &errmsg, err); + /* Find gnu_lto_ in strings. */ + char *gnu_lto = strings; + while ((gnu_lto = memchr (gnu_lto, 'g', + strings + strsz - gnu_lto))) + if (strncmp (gnu_lto, "gnu_lto_v1", + strings + strsz - gnu_lto) == 0) + break; + else + gnu_lto++; for (ent = buf; ent < buf + length; ent += entsize) { unsigned st_shndx = ELF_FETCH_FIELD (type_functions, ei_class, @@ -1346,9 +1362,6 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj, and __gnu_lto_slim which otherwise cause endless LTO plugin invocation. */ if (st_shndx == SHN_COMMON) - /* Setting st_name to "" seems to work to purge - COMMON symbols (in addition to setting their - size to zero). */ discard = 1; /* We also need to remove symbols refering to sections we'll eventually remove as with fat LTO objects @@ -1364,18 +1377,36 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj, { /* Make discarded symbols undefined and unnamed in case it is local. */ - if (ELF_ST_BIND (*st_info) == STB_LOCAL) - ELF_SET_FIELD (type_functions, ei_class, Sym, - ent, st_name, Elf_Word, 0); + int bind = ELF_ST_BIND (*st_info); + int other = STV_DEFAULT; + if (bind == STB_LOCAL) + { + /* Make discarded local symbols unnamed and + defined in the first prevailing section. */ + ELF_SET_FIELD (type_functions, ei_class, Sym, + ent, st_name, Elf_Word, 0); + ELF_SET_FIELD (type_functions, ei_class, Sym, + ent, st_shndx, Elf_Half, first_shndx); + } + else + { + /* Make discarded global symbols hidden weak + undefined and sharing the gnu_lto_ name. */ + bind = STB_WEAK; + other = STV_HIDDEN; + if (gnu_lto) + ELF_SET_FIELD (type_functions, ei_class, Sym, + ent, st_name, Elf_Word, + gnu_lto - strings); + ELF_SET_FIELD (type_functions, ei_class, Sym, + ent, st_shndx, Elf_Half, SHN_UNDEF); + } + *st_other = other; + *st_info = ELF_ST_INFO (bind, STT_NOTYPE); ELF_SET_FIELD (type_functions, ei_class, Sym, ent, st_value, Elf_Addr, 0); ELF_SET_FIELD (type_functions, ei_class, Sym, ent, st_size, Elf_Word, 0); - ELF_SET_FIELD (type_functions, ei_class, Sym, - ent, st_shndx, Elf_Half, SHN_UNDEF); - *st_info = ELF_ST_INFO (ELF_ST_BIND (*st_info), - STT_NOTYPE); - *st_other = STV_DEFAULT; } } XDELETEVEC (strings); @@ -1398,12 +1429,23 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj, link. */ ELF_SET_FIELD (type_functions, ei_class, Shdr, shdr, sh_type, Elf_Word, SHT_NULL); + ELF_SET_FIELD (type_functions, ei_class, Shdr, + shdr, sh_info, Elf_Word, 0); + ELF_SET_FIELD (type_functions, ei_class, Shdr, + shdr, sh_link, Elf_Word, 0); } flags = ELF_FETCH_FIELD (type_functions, ei_class, Shdr, shdr, sh_flags, Elf_Addr); if (ret == 0) - flags &= ~SHF_EXCLUDE; + { + /* The debugobj doesn't contain any code, thus no trampolines. + Even when the original object needs trampolines, debugobj + doesn't. */ + if (strcmp (name, ".note.GNU-stack") == 0) + flags &= ~SHF_EXECINSTR; + flags &= ~SHF_EXCLUDE; + } else if (ret == -1) flags = SHF_EXCLUDE; ELF_SET_FIELD (type_functions, ei_class, Shdr, |