From: Sami Tolvanen <samitolvanen@google.com> To: linux-kernel@vger.kernel.org Cc: Kees Cook <keescook@chromium.org>, Josh Poimboeuf <jpoimboe@redhat.com>, Peter Zijlstra <peterz@infradead.org>, x86@kernel.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Nathan Chancellor <nathan@kernel.org>, Nick Desaulniers <ndesaulniers@google.com>, Joao Moreira <joao@overdrivepizza.com>, Sedat Dilek <sedat.dilek@gmail.com>, Steven Rostedt <rostedt@goodmis.org>, linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen <samitolvanen@google.com> Subject: [PATCH v4 16/21] objtool: Disable CFI warnings Date: Tue, 30 Aug 2022 16:31:24 -0700 [thread overview] Message-ID: <20220830233129.30610-17-samitolvanen@google.com> (raw) In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> The __cfi_ preambles contain a mov instruction that embeds the KCFI type identifier in the following format: ; type preamble __cfi_function: mov <id>, %eax function: ... While the preamble symbols are STT_FUNC and contain valid instructions, they are never executed and always fall through. Skip the warning for them. .kcfi_traps sections point to CFI traps in text sections. Also skip the warning about them referencing !ENDBR instructions. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> --- tools/objtool/check.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e55fdf952a3a..48e18737a2d1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3316,6 +3316,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, next_insn = next_insn_to_validate(file, insn); if (func && insn->func && func != insn->func->pfunc) { + /* Ignore KCFI type preambles, which always fall through */ + if (!strncmp(func->name, "__cfi_", 6)) + return 0; + WARN("%s() falls through to next function %s()", func->name, insn->func->name); return 1; @@ -4113,7 +4117,8 @@ static int validate_ibt(struct objtool_file *file) !strcmp(sec->name, "__bug_table") || !strcmp(sec->name, "__ex_table") || !strcmp(sec->name, "__jump_table") || - !strcmp(sec->name, "__mcount_loc")) + !strcmp(sec->name, "__mcount_loc") || + !strcmp(sec->name, ".kcfi_traps")) continue; list_for_each_entry(reloc, &sec->reloc->reloc_list, list) -- 2.37.2.672.g94769d06f0-goog
WARNING: multiple messages have this Message-ID (diff)
From: Sami Tolvanen <samitolvanen@google.com> To: linux-kernel@vger.kernel.org Cc: Kees Cook <keescook@chromium.org>, Josh Poimboeuf <jpoimboe@redhat.com>, Peter Zijlstra <peterz@infradead.org>, x86@kernel.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Nathan Chancellor <nathan@kernel.org>, Nick Desaulniers <ndesaulniers@google.com>, Joao Moreira <joao@overdrivepizza.com>, Sedat Dilek <sedat.dilek@gmail.com>, Steven Rostedt <rostedt@goodmis.org>, linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, llvm@lists.linux.dev, Sami Tolvanen <samitolvanen@google.com> Subject: [PATCH v4 16/21] objtool: Disable CFI warnings Date: Tue, 30 Aug 2022 16:31:24 -0700 [thread overview] Message-ID: <20220830233129.30610-17-samitolvanen@google.com> (raw) In-Reply-To: <20220830233129.30610-1-samitolvanen@google.com> The __cfi_ preambles contain a mov instruction that embeds the KCFI type identifier in the following format: ; type preamble __cfi_function: mov <id>, %eax function: ... While the preamble symbols are STT_FUNC and contain valid instructions, they are never executed and always fall through. Skip the warning for them. .kcfi_traps sections point to CFI traps in text sections. Also skip the warning about them referencing !ENDBR instructions. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> --- tools/objtool/check.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e55fdf952a3a..48e18737a2d1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3316,6 +3316,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, next_insn = next_insn_to_validate(file, insn); if (func && insn->func && func != insn->func->pfunc) { + /* Ignore KCFI type preambles, which always fall through */ + if (!strncmp(func->name, "__cfi_", 6)) + return 0; + WARN("%s() falls through to next function %s()", func->name, insn->func->name); return 1; @@ -4113,7 +4117,8 @@ static int validate_ibt(struct objtool_file *file) !strcmp(sec->name, "__bug_table") || !strcmp(sec->name, "__ex_table") || !strcmp(sec->name, "__jump_table") || - !strcmp(sec->name, "__mcount_loc")) + !strcmp(sec->name, "__mcount_loc") || + !strcmp(sec->name, ".kcfi_traps")) continue; list_for_each_entry(reloc, &sec->reloc->reloc_list, list) -- 2.37.2.672.g94769d06f0-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-08-30 23:32 UTC|newest] Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-30 23:31 [PATCH v4 00/21] KCFI support Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 01/21] treewide: Filter out CC_FLAGS_CFI Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 02/21] scripts/kallsyms: Ignore __kcfi_typeid_ Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 03/21] cfi: Remove CONFIG_CFI_CLANG_SHADOW Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 04/21] cfi: Drop __CFI_ADDRESSABLE Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 05/21] cfi: Switch to -fsanitize=kcfi Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 06/21] cfi: Add type helper macros Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 07/21] lkdtm: Emit an indirect call for CFI tests Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 08/21] psci: Fix the function type for psci_initcall_t Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-31 18:22 ` Kees Cook 2022-08-31 18:22 ` Kees Cook 2022-08-30 23:31 ` [PATCH v4 09/21] arm64: Add types to indirect called assembly functions Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 10/21] arm64: Add CFI error handling Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 11/21] arm64: Drop unneeded __nocfi attributes Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 12/21] init: Drop __nocfi from __init Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 13/21] treewide: Drop function_nocfi Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 14/21] treewide: Drop WARN_ON_FUNCTION_MISMATCH Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 15/21] treewide: Drop __cficanonical Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen [this message] 2022-08-30 23:31 ` [PATCH v4 16/21] objtool: Disable CFI warnings Sami Tolvanen 2022-08-31 18:23 ` Kees Cook 2022-08-31 18:23 ` Kees Cook 2022-08-30 23:31 ` [PATCH v4 17/21] kallsyms: Drop CONFIG_CFI_CLANG workarounds Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-31 18:23 ` Kees Cook 2022-08-31 18:23 ` Kees Cook 2022-08-30 23:31 ` [PATCH v4 18/21] x86/tools/relocs: Ignore __kcfi_typeid_ relocations Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 19/21] x86: Add types to indirectly called assembly functions Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 20/21] x86/purgatory: Disable CFI Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-30 23:31 ` [PATCH v4 21/21] x86: Add support for CONFIG_CFI_CLANG Sami Tolvanen 2022-08-30 23:31 ` Sami Tolvanen 2022-08-31 18:28 ` Kees Cook 2022-08-31 18:28 ` Kees Cook 2022-08-31 22:04 ` [PATCH v4 00/21] KCFI support Kees Cook 2022-08-31 22:04 ` Kees Cook 2022-09-01 21:19 ` Nathan Chancellor 2022-09-01 21:19 ` Nathan Chancellor 2022-09-02 0:33 ` Sami Tolvanen 2022-09-02 0:33 ` Sami Tolvanen 2022-09-02 7:51 ` Peter Zijlstra 2022-09-02 7:51 ` Peter Zijlstra 2022-09-02 15:39 ` Sami Tolvanen 2022-09-02 15:39 ` Sami Tolvanen
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