From ef47cc01cb4abcd760d8ac66b9361d6ade4d0846 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 26 Mar 2021 16:12:07 +0100 Subject: [PATCH] objtool: Add elf_create_reloc() helper We have 4 instances of adding a relocation. Create a common helper to avoid growing even more. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Signed-off-by: Ingo Molnar Reviewed-by: Miroslav Benes Link: https://lkml.kernel.org/r/20210326151259.817438847@infradead.org --- tools/objtool/check.c | 78 ++++++-------------------- tools/objtool/elf.c | 86 +++++++++++++++++++---------- tools/objtool/include/objtool/elf.h | 10 +++- tools/objtool/orc_gen.c | 30 ++-------- 4 files changed, 85 insertions(+), 119 deletions(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 1d0415b3391a..61fe29ae4cd4 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -433,8 +433,7 @@ reachable: static int create_static_call_sections(struct objtool_file *file) { - struct section *sec, *reloc_sec; - struct reloc *reloc; + struct section *sec; struct static_call_site *site; struct instruction *insn; struct symbol *key_sym; @@ -460,8 +459,7 @@ static int create_static_call_sections(struct objtool_file *file) if (!sec) return -1; - reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA); - if (!reloc_sec) + if (!elf_create_reloc_section(file->elf, sec, SHT_RELA)) return -1; idx = 0; @@ -471,25 +469,11 @@ static int create_static_call_sections(struct objtool_file *file) memset(site, 0, sizeof(struct static_call_site)); /* populate reloc for 'addr' */ - reloc = malloc(sizeof(*reloc)); - - if (!reloc) { - perror("malloc"); - return -1; - } - memset(reloc, 0, sizeof(*reloc)); - - insn_to_reloc_sym_addend(insn->sec, insn->offset, reloc); - if (!reloc->sym) { - WARN_FUNC("static call tramp: missing containing symbol", - insn->sec, insn->offset); + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(struct static_call_site), + R_X86_64_PC32, + insn->sec, insn->offset)) return -1; - } - - reloc->type = R_X86_64_PC32; - reloc->offset = idx * sizeof(struct static_call_site); - reloc->sec = reloc_sec; - elf_add_reloc(file->elf, reloc); /* find key symbol */ key_name = strdup(insn->call_dest->name); @@ -526,18 +510,11 @@ static int create_static_call_sections(struct objtool_file *file) free(key_name); /* populate reloc for 'key' */ - reloc = malloc(sizeof(*reloc)); - if (!reloc) { - perror("malloc"); + if (elf_add_reloc(file->elf, sec, + idx * sizeof(struct static_call_site) + 4, + R_X86_64_PC32, key_sym, + is_sibling_call(insn) * STATIC_CALL_SITE_TAIL)) return -1; - } - memset(reloc, 0, sizeof(*reloc)); - reloc->sym = key_sym; - reloc->addend = is_sibling_call(insn) ? STATIC_CALL_SITE_TAIL : 0; - reloc->type = R_X86_64_PC32; - reloc->offset = idx * sizeof(struct static_call_site) + 4; - reloc->sec = reloc_sec; - elf_add_reloc(file->elf, reloc); idx++; } @@ -547,8 +524,7 @@ static int create_static_call_sections(struct objtool_file *file) static int create_mcount_loc_sections(struct objtool_file *file) { - struct section *sec, *reloc_sec; - struct reloc *reloc; + struct section *sec; unsigned long *loc; struct instruction *insn; int idx; @@ -571,8 +547,7 @@ static int create_mcount_loc_sections(struct objtool_file *file) if (!sec) return -1; - reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA); - if (!reloc_sec) + if (!elf_create_reloc_section(file->elf, sec, SHT_RELA)) return -1; idx = 0; @@ -581,32 +556,11 @@ static int create_mcount_loc_sections(struct objtool_file *file) loc = (unsigned long *)sec->data->d_buf + idx; memset(loc, 0, sizeof(unsigned long)); - reloc = malloc(sizeof(*reloc)); - if (!reloc) { - perror("malloc"); + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(unsigned long), + R_X86_64_64, + insn->sec, insn->offset)) return -1; - } - memset(reloc, 0, sizeof(*reloc)); - - if (insn->sec->sym) { - reloc->sym = insn->sec->sym; - reloc->addend = insn->offset; - } else { - reloc->sym = find_symbol_containing(insn->sec, insn->offset); - - if (!reloc->sym) { - WARN("missing symbol for insn at offset 0x%lx\n", - insn->offset); - return -1; - } - - reloc->addend = insn->offset - reloc->sym->offset; - } - - reloc->type = R_X86_64_64; - reloc->offset = idx * sizeof(unsigned long); - reloc->sec = reloc_sec; - elf_add_reloc(file->elf, reloc); idx++; } diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 374813eafa52..0ab52ac3f861 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -211,32 +211,6 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns return find_reloc_by_dest_range(elf, sec, offset, 1); } -void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset, - struct reloc *reloc) -{ - if (sec->sym) { - reloc->sym = sec->sym; - reloc->addend = offset; - return; - } - - /* - * The Clang assembler strips section symbols, so we have to reference - * the function symbol instead: - */ - reloc->sym = find_symbol_containing(sec, offset); - if (!reloc->sym) { - /* - * Hack alert. This happens when we need to reference the NOP - * pad insn immediately after the function. - */ - reloc->sym = find_symbol_containing(sec, offset - 1); - } - - if (reloc->sym) - reloc->addend = offset - reloc->sym->offset; -} - static int read_sections(struct elf *elf) { Elf_Scn *s = NULL; @@ -473,14 +447,66 @@ err: return -1; } -void elf_add_reloc(struct elf *elf, struct reloc *reloc) +int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset, + unsigned int type, struct symbol *sym, int addend) { - struct section *sec = reloc->sec; + struct reloc *reloc; + + reloc = malloc(sizeof(*reloc)); + if (!reloc) { + perror("malloc"); + return -1; + } + memset(reloc, 0, sizeof(*reloc)); - list_add_tail(&reloc->list, &sec->reloc_list); + reloc->sec = sec->reloc; + reloc->offset = offset; + reloc->type = type; + reloc->sym = sym; + reloc->addend = addend; + + list_add_tail(&reloc->list, &sec->reloc->reloc_list); elf_hash_add(elf->reloc_hash, &reloc->hash, reloc_hash(reloc)); - sec->changed = true; + sec->reloc->changed = true; + + return 0; +} + +int elf_add_reloc_to_insn(struct elf *elf, struct section *sec, + unsigned long offset, unsigned int type, + struct section *insn_sec, unsigned long insn_off) +{ + struct symbol *sym; + int addend; + + if (insn_sec->sym) { + sym = insn_sec->sym; + addend = insn_off; + + } else { + /* + * The Clang assembler strips section symbols, so we have to + * reference the function symbol instead: + */ + sym = find_symbol_containing(insn_sec, insn_off); + if (!sym) { + /* + * Hack alert. This happens when we need to reference + * the NOP pad insn immediately after the function. + */ + sym = find_symbol_containing(insn_sec, insn_off - 1); + } + + if (!sym) { + WARN("can't find symbol containing %s+0x%lx", insn_sec->name, insn_off); + return -1; + } + + addend = insn_off - sym->offset; + } + + return elf_add_reloc(elf, sec, offset, type, sym, addend); } static int read_rel_reloc(struct section *sec, int i, struct reloc *reloc, unsigned int *symndx) diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index fc576edacfc4..825ad326201d 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -123,7 +123,13 @@ static inline u32 reloc_hash(struct reloc *reloc) struct elf *elf_open_read(const char *name, int flags); struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr); struct section *elf_create_reloc_section(struct elf *elf, struct section *base, int reltype); -void elf_add_reloc(struct elf *elf, struct reloc *reloc); + +int elf_add_reloc(struct elf *elf, struct section *sec, unsigned long offset, + unsigned int type, struct symbol *sym, int addend); +int elf_add_reloc_to_insn(struct elf *elf, struct section *sec, + unsigned long offset, unsigned int type, + struct section *insn_sec, unsigned long insn_off); + int elf_write_insn(struct elf *elf, struct section *sec, unsigned long offset, unsigned int len, const char *insn); @@ -140,8 +146,6 @@ struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, uns struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec, unsigned long offset, unsigned int len); struct symbol *find_func_containing(struct section *sec, unsigned long offset); -void insn_to_reloc_sym_addend(struct section *sec, unsigned long offset, - struct reloc *reloc); #define for_each_sec(file, sec) \ list_for_each_entry(sec, &file->elf->sections, list) diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c index f5347089550e..1b57be6508f4 100644 --- a/tools/objtool/orc_gen.c +++ b/tools/objtool/orc_gen.c @@ -82,12 +82,11 @@ static int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi) } static int write_orc_entry(struct elf *elf, struct section *orc_sec, - struct section *ip_rsec, unsigned int idx, + struct section *ip_sec, unsigned int idx, struct section *insn_sec, unsigned long insn_off, struct orc_entry *o) { struct orc_entry *orc; - struct reloc *reloc; /* populate ORC data */ orc = (struct orc_entry *)orc_sec->data->d_buf + idx; @@ -96,25 +95,9 @@ static int write_orc_entry(struct elf *elf, struct section *orc_sec, orc->bp_offset = bswap_if_needed(orc->bp_offset); /* populate reloc for ip */ - reloc = malloc(sizeof(*reloc)); - if (!reloc) { - perror("malloc"); + if (elf_add_reloc_to_insn(elf, ip_sec, idx * sizeof(int), R_X86_64_PC32, + insn_sec, insn_off)) return -1; - } - memset(reloc, 0, sizeof(*reloc)); - - insn_to_reloc_sym_addend(insn_sec, insn_off, reloc); - if (!reloc->sym) { - WARN("missing symbol for insn at offset 0x%lx", - insn_off); - return -1; - } - - reloc->type = R_X86_64_PC32; - reloc->offset = idx * sizeof(int); - reloc->sec = ip_rsec; - - elf_add_reloc(elf, reloc); return 0; } @@ -153,7 +136,7 @@ static unsigned long alt_group_len(struct alt_group *alt_group) int orc_create(struct objtool_file *file) { - struct section *sec, *ip_rsec, *orc_sec; + struct section *sec, *orc_sec; unsigned int nr = 0, idx = 0; struct orc_list_entry *entry; struct list_head orc_list; @@ -242,13 +225,12 @@ int orc_create(struct objtool_file *file) sec = elf_create_section(file->elf, ".orc_unwind_ip", 0, sizeof(int), nr); if (!sec) return -1; - ip_rsec = elf_create_reloc_section(file->elf, sec, SHT_RELA); - if (!ip_rsec) + if (!elf_create_reloc_section(file->elf, sec, SHT_RELA)) return -1; /* Write ORC entries to sections: */ list_for_each_entry(entry, &orc_list, list) { - if (write_orc_entry(file->elf, orc_sec, ip_rsec, idx++, + if (write_orc_entry(file->elf, orc_sec, sec, idx++, entry->insn_sec, entry->insn_off, &entry->orc)) return -1; -- 2.20.1