From: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
To: mricon@kernel.org
Subject: [PATCH v5 16/21] objtool: Disable CFI warnings
Date: Thu, 01 Sep 2022 15:29:01 -0400 [thread overview]
Message-ID: <20220901-kcfi_support-v5-16-be2007d8da63@linuxfoundation.org> (raw)
In-Reply-To: <20220901-kcfi_support-v5-0-be2007d8da63@linuxfoundation.org>
From: Sami Tolvanen <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>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
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)
--
b4 0.10.0-dev-03aea
next prev parent reply other threads:[~2022-09-01 19:29 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-01 19:28 [PATCH v5 00/21] KCFI support Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 01/21] treewide: Filter out CC_FLAGS_CFI Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 02/21] scripts/kallsyms: Ignore __kcfi_typeid_ Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 03/21] cfi: Remove CONFIG_CFI_CLANG_SHADOW Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 04/21] cfi: Drop __CFI_ADDRESSABLE Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 05/21] cfi: Switch to -fsanitize=kcfi Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 06/21] cfi: Add type helper macros Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 07/21] lkdtm: Emit an indirect call for CFI tests Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 08/21] psci: Fix the function type for psci_initcall_t Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 09/21] arm64: Add types to indirect called assembly functions Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 10/21] arm64: Add CFI error handling Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 11/21] arm64: Drop unneeded __nocfi attributes Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 12/21] init: Drop __nocfi from __init Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 13/21] treewide: Drop function_nocfi Konstantin Ryabitsev
2022-09-01 19:28 ` [PATCH v5 14/21] treewide: Drop WARN_ON_FUNCTION_MISMATCH Konstantin Ryabitsev
2022-09-01 19:29 ` [PATCH v5 15/21] treewide: Drop __cficanonical Konstantin Ryabitsev
2022-09-01 19:29 ` Konstantin Ryabitsev [this message]
2022-09-01 19:29 ` [PATCH v5 17/21] kallsyms: Drop CONFIG_CFI_CLANG workarounds Konstantin Ryabitsev
2022-09-01 19:29 ` [PATCH v5 18/21] x86/tools/relocs: Ignore __kcfi_typeid_ relocations Konstantin Ryabitsev
2022-09-01 19:29 ` [PATCH v5 19/21] x86: Add types to indirectly called assembly functions Konstantin Ryabitsev
2022-09-01 19:29 ` [PATCH v5 20/21] x86/purgatory: Disable CFI Konstantin Ryabitsev
2022-09-01 19:29 ` [PATCH v5 21/21] x86: Add support for CONFIG_CFI_CLANG Konstantin Ryabitsev
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