diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2024-01-03 19:36:26 +0100 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2024-02-12 11:42:15 +0100 |
| commit | 4461438a8405e800f90e0e40409e5f3d07eed381 (patch) | |
| tree | 1c660616f321919a56e80cac4fd9e0e980065a68 /arch/x86/kernel/cpu/bugs.c | |
| parent | 0911b8c52c4d68c57d02f172daa55a42bce703f0 (diff) | |
x86/retpoline: Ensure default return thunk isn't used at runtime
Make sure the default return thunk is not used after all return
instructions have been patched by the alternatives because the default
return thunk is insufficient when it comes to mitigating Retbleed or
SRSO.
Fix based on an earlier version by David Kaplan <david.kaplan@amd.com>.
[ bp: Fix the compilation error of warn_thunk_thunk being an invisible
symbol, hoist thunk macro into calling.h ]
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Co-developed-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231010171020.462211-4-david.kaplan@amd.com
Link: https://lore.kernel.org/r/20240104132446.GEZZaxnrIgIyat0pqf@fat_crate.local
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index f2775417bda26..a78892b0f8231 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2850,3 +2850,8 @@ ssize_t cpu_show_gds(struct device *dev, struct device_attribute *attr, char *bu return cpu_show_common(dev, attr, buf, X86_BUG_GDS); } #endif + +void __warn_thunk(void) +{ + WARN_ONCE(1, "Unpatched return thunk in use. This should not happen!\n"); +} |