From 753da4179d08b625d8df72e97724e22749969fd3 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Mon, 18 Apr 2022 09:50:43 -0700 Subject: objtool: Remove --lto and --vmlinux in favor of --link The '--lto' option is a confusing way of telling objtool to do stack validation despite it being a linked object. It's no longer needed now that an explicit '--stackval' option exists. The '--vmlinux' option is also redundant. Remove both options in favor of a straightforward '--link' option which identifies a linked object. Also, implicitly set '--link' with a warning if the user forgets to do so and we can tell that it's a linked object. This makes it easier for manual vmlinux runs. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Link: https://lkml.kernel.org/r/dcd3ceffd15a54822c6183e5766d21ad06082b45.1650300597.git.jpoimboe@redhat.com --- scripts/Makefile.build | 4 +++- scripts/link-vmlinux.sh | 8 +++---- tools/objtool/builtin-check.c | 39 ++++++++++++++++++++++++++++---- tools/objtool/check.c | 40 ++++++++++++--------------------- tools/objtool/elf.c | 3 +++ tools/objtool/include/objtool/builtin.h | 3 +-- tools/objtool/include/objtool/elf.h | 12 +++++++++- 7 files changed, 70 insertions(+), 39 deletions(-) diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 6c206a1bab97..ac8167227bc0 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -229,7 +229,7 @@ objtool := $(objtree)/tools/objtool/objtool objtool_args = \ $(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \ $(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \ - $(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \ + $(if $(CONFIG_X86_KERNEL_IBT), --ibt) \ $(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \ $(if $(CONFIG_UNWINDER_ORC), --orc) \ $(if $(CONFIG_RETPOLINE), --retpoline) \ @@ -237,6 +237,7 @@ objtool_args = \ $(if $(CONFIG_STACK_VALIDATION), --stackval) \ $(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \ $(if $(CONFIG_X86_SMAP), --uaccess) \ + $(if $(linked-object), --link) \ $(if $(part-of-module), --module) \ $(if $(CONFIG_GCOV_KERNEL), --no-unreachable) @@ -306,6 +307,7 @@ quiet_cmd_cc_prelink_modules = LD [M] $@ # modules into native code $(obj)/%.prelink.o: objtool-enabled = y $(obj)/%.prelink.o: part-of-module := y +$(obj)/%.prelink.o: linked-object := y $(obj)/%.prelink.o: $(obj)/%.o FORCE $(call if_changed,cc_prelink_modules) diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index fce4f41816cd..eb9324f07f3d 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -114,8 +114,8 @@ objtool_link() if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then - # Don't perform vmlinux validation unless explicitly requested, - # but run objtool on vmlinux.o now that we have an object file. + # For LTO and IBT, objtool doesn't run on individual + # translation units. Run everything on vmlinux instead. if is_enabled CONFIG_HAVE_JUMP_LABEL_HACK; then objtoolopt="${objtoolopt} --hacks=jump_label" @@ -156,8 +156,6 @@ objtool_link() if is_enabled CONFIG_X86_SMAP; then objtoolopt="${objtoolopt} --uaccess" fi - - objtoolopt="${objtoolopt} --lto" fi if is_enabled CONFIG_NOINSTR_VALIDATION; then @@ -170,7 +168,7 @@ objtool_link() objtoolopt="${objtoolopt} --no-unreachable" fi - objtoolopt="${objtoolopt} --vmlinux" + objtoolopt="${objtoolopt} --link" info OBJTOOL ${1} tools/objtool/objtool ${objtoolopt} ${1} diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c index 1803a63147e4..f4c3a5091737 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -9,6 +9,11 @@ #include #include +#define ERROR(format, ...) \ + fprintf(stderr, \ + "error: objtool: " format "\n", \ + ##__VA_ARGS__) + struct opts opts; static const char * const check_usage[] = { @@ -73,12 +78,11 @@ const struct option check_options[] = { OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"), OPT_BOOLEAN(0, "backup", &opts.backup, "create .orig files before modification"), OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"), - OPT_BOOLEAN(0, "lto", &opts.lto, "whole-archive like runs"), + OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"), OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"), OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"), OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"), OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"), - OPT_BOOLEAN(0, "vmlinux", &opts.vmlinux, "vmlinux.o validation"), OPT_END(), }; @@ -124,7 +128,7 @@ static bool opts_valid(void) opts.static_call || opts.uaccess) { if (opts.dump_orc) { - fprintf(stderr, "--dump can't be combined with other options\n"); + ERROR("--dump can't be combined with other options"); return false; } @@ -134,10 +138,34 @@ static bool opts_valid(void) if (opts.dump_orc) return true; - fprintf(stderr, "At least one command required\n"); + ERROR("At least one command required"); return false; } +static bool link_opts_valid(struct objtool_file *file) +{ + if (opts.link) + return true; + + if (has_multiple_files(file->elf)) { + ERROR("Linked object detected, forcing --link"); + opts.link = true; + return true; + } + + if (opts.noinstr) { + ERROR("--noinstr requires --link"); + return false; + } + + if (opts.ibt) { + ERROR("--ibt requires --link"); + return false; + } + + return true; +} + int objtool_run(int argc, const char **argv) { const char *objname; @@ -157,6 +185,9 @@ int objtool_run(int argc, const char **argv) if (!file) return 1; + if (!link_opts_valid(file)) + return 1; + ret = check(file); if (ret) return ret; diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 30b24dce48b5..2063f9fea1a2 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -263,7 +263,8 @@ static void init_cfi_state(struct cfi_state *cfi) cfi->drap_offset = -1; } -static void init_insn_state(struct insn_state *state, struct section *sec) +static void init_insn_state(struct objtool_file *file, struct insn_state *state, + struct section *sec) { memset(state, 0, sizeof(*state)); init_cfi_state(&state->cfi); @@ -273,7 +274,7 @@ static void init_insn_state(struct insn_state *state, struct section *sec) * not correctly determine insn->call_dest->sec (external symbols do * not have a section). */ - if (opts.vmlinux && opts.noinstr && sec) + if (opts.link && opts.noinstr && sec) state->noinstr = sec->noinstr; } @@ -3405,7 +3406,7 @@ static int validate_unwind_hints(struct objtool_file *file, struct section *sec) if (!file->hints) return 0; - init_insn_state(&state, sec); + init_insn_state(file, &state, sec); if (sec) { insn = find_insn(file, sec, 0); @@ -3491,14 +3492,14 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio return true; /* - * Whole archive runs might encounder dead code from weak symbols. + * Whole archive runs might encounter dead code from weak symbols. * This is where the linker will have dropped the weak symbol in * favour of a regular symbol, but leaves the code in place. * * In this case we'll find a piece of code (whole function) that is not * covered by a !section symbol. Ignore them. */ - if (!insn->func && opts.lto) { + if (opts.link && !insn->func) { int size = find_symbol_hole_containing(insn->sec, insn->offset); unsigned long end = insn->offset + size; @@ -3620,7 +3621,7 @@ static int validate_section(struct objtool_file *file, struct section *sec) if (func->type != STT_FUNC) continue; - init_insn_state(&state, sec); + init_insn_state(file, &state, sec); set_func_state(&state.cfi); warnings += validate_symbol(file, sec, func, &state); @@ -3629,7 +3630,7 @@ static int validate_section(struct objtool_file *file, struct section *sec) return warnings; } -static int validate_vmlinux_functions(struct objtool_file *file) +static int validate_noinstr_sections(struct objtool_file *file) { struct section *sec; int warnings = 0; @@ -3890,16 +3891,6 @@ int check(struct objtool_file *file) { int ret, warnings = 0; - if (opts.lto && !(opts.vmlinux || opts.module)) { - fprintf(stderr, "--lto requires: --vmlinux or --module\n"); - return 1; - } - - if (opts.ibt && !opts.lto) { - fprintf(stderr, "--ibt requires: --lto\n"); - return 1; - } - arch_initial_func_cfi_state(&initial_func_cfi); init_cfi_state(&init_cfi); init_cfi_state(&func_cfi); @@ -3920,15 +3911,6 @@ int check(struct objtool_file *file) if (list_empty(&file->insn_list)) goto out; - if (opts.vmlinux && !opts.lto) { - ret = validate_vmlinux_functions(file); - if (ret < 0) - goto out; - - warnings += ret; - goto out; - } - if (opts.retpoline) { ret = validate_retpoline(file); if (ret < 0) @@ -3953,6 +3935,12 @@ int check(struct objtool_file *file) goto out; warnings += ret; } + + } else if (opts.noinstr) { + ret = validate_noinstr_sections(file); + if (ret < 0) + goto out; + warnings += ret; } if (opts.ibt) { diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c index 0f6fa372e10e..583a3ec987b5 100644 --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -377,6 +377,9 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym) sym->type = GELF_ST_TYPE(sym->sym.st_info); sym->bind = GELF_ST_BIND(sym->sym.st_info); + if (sym->type == STT_FILE) + elf->num_files++; + sym->offset = sym->sym.st_value; sym->len = sym->sym.st_size; diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h index f3a1a754b5c4..280ea18b7f2b 100644 --- a/tools/objtool/include/objtool/builtin.h +++ b/tools/objtool/include/objtool/builtin.h @@ -28,12 +28,11 @@ struct opts { bool backtrace; bool backup; bool dryrun; - bool lto; + bool link; bool module; bool no_unreachable; bool sec_address; bool stats; - bool vmlinux; }; extern struct opts opts; diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 9b36802ed86f..de0cb2f313ba 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -86,7 +86,7 @@ struct elf { int fd; bool changed; char *name; - unsigned int text_size; + unsigned int text_size, num_files; struct list_head sections; int symbol_bits; @@ -131,6 +131,16 @@ static inline u32 reloc_hash(struct reloc *reloc) return sec_offset_hash(reloc->sec, reloc->offset); } +/* + * Try to see if it's a whole archive (vmlinux.o or module). + * + * Note this will miss the case where a module only has one source file. + */ +static inline bool has_multiple_files(struct elf *elf) +{ + return elf->num_files > 1; +} + 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); -- cgit v1.2.3-58-ga151