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linux/tools/objtool
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Josh Poimboeuf b865005970 x86/traps: Make exc_double_fault() consistently noreturn 
[ Upstream commit 8085fcd78c ]

The CONFIG_X86_ESPFIX64 version of exc_double_fault() can return to its
caller, but the !CONFIG_X86_ESPFIX64 version never does.  In the latter
case the compiler and/or objtool may consider it to be implicitly
noreturn.

However, due to the currently inflexible way objtool detects noreturns,
a function's noreturn status needs to be consistent across configs.

The current workaround for this issue is to suppress unreachable
warnings for exc_double_fault()'s callers.  Unfortunately that can
result in ORC coverage gaps and potentially worse issues like inert
static calls and silently disabled CPU mitigations.

Instead, prevent exc_double_fault() from ever being implicitly marked
noreturn by forcing a return behind a never-taken conditional.

Until a more integrated noreturn detection method exists, this is likely
the least objectionable workaround.

Fixes: 55eeab2a8a ("objtool: Ignore exc_double_fault() __noreturn warnings")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/r/d1f4026f8dc35d0de6cc61f2684e0cb6484009d1.1741975349.git.jpoimboe@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-04-10 14:39:12 +02:00
..
arch objtool: Handle frame pointer related instructions 2024-09-17 22:23:09 +08:00
Documentation x86/alternatives, kvm: Fix a couple of CALLs without a frame pointer 2024-07-01 12:41:11 +02:00
include/objtool objtool: Fix C jump table annotations for Clang 2025-03-07 18:25:36 +01:00
.gitignore objtool: Install libsubcmd in build 2023-01-30 16:27:46 -08:00
Build objtool: Install libsubcmd in build 2023-01-30 16:27:46 -08:00
builtin-check.c objtool: Use "action" in error message to be consistent with help 2024-07-02 23:40:24 -07:00
check.c x86/traps: Make exc_double_fault() consistently noreturn 2025-04-10 14:39:12 +02:00
elf.c objtool: Remove max symbol name length limitation 2023-10-05 17:01:28 -07:00
Makefile objtool/LoongArch: Enable orc to be built 2024-03-11 22:23:47 +08:00
noreturns.h objtool: Add bch2_trans_unlocked_error() to bcachefs noreturns 2025-01-02 10:34:21 +01:00
objtool.c objtool: Propagate early errors 2023-10-05 17:01:11 -07:00
orc_dump.c objtool/x86: Separate arch-specific and generic parts 2024-03-11 22:23:47 +08:00
orc_gen.c objtool/x86: Separate arch-specific and generic parts 2024-03-11 22:23:47 +08:00
special.c x86/alternatives: Add nested alternatives macros 2024-06-11 17:13:08 +02:00
sync-check.sh objtool: Add objtool_types.h 2023-03-23 23:18:56 +01:00
weak.c objtool: Ditch subcommands 2022-04-22 12:32:01 +02:00