diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2023-07-29 00:28:43 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-07-29 14:15:19 +0200 |
| commit | 238ec850b95a02dcdff3edc86781aa913549282f (patch) | |
| tree | 0fa80998fd217be07aa85987a22c60883d0e0821 /arch | |
| parent | x86/srso: Add IBPB on VMEXIT (diff) | |
| download | linux-238ec850b95a02dcdff3edc86781aa913549282f.tar.xz linux-238ec850b95a02dcdff3edc86781aa913549282f.zip | |
x86/srso: Fix return thunks in generated code
Set X86_FEATURE_RETHUNK when enabling the SRSO mitigation so that
generated code (e.g., ftrace, static call, eBPF) generates "jmp
__x86_return_thunk" instead of RET.
[ bp: Add a comment. ]
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/alternative.c | 4 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 6 |
2 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 920a8ca7a8f8..2dcf3a06af09 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -707,9 +707,7 @@ static int patch_return(void *addr, struct insn *insn, u8 *bytes) int i = 0; /* Patch the custom return thunks... */ - if (cpu_feature_enabled(X86_FEATURE_RETHUNK) || - cpu_feature_enabled(X86_FEATURE_SRSO) || - cpu_feature_enabled(X86_FEATURE_SRSO_ALIAS)) { + if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) { i = JMP32_INSN_SIZE; __text_gen_insn(bytes, JMP32_INSN_OPCODE, addr, x86_return_thunk, i); } else { diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index d4109eb5eb2e..7314a6bdc862 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2297,6 +2297,12 @@ static void __init srso_select_mitigation(void) case SRSO_CMD_SAFE_RET: if (IS_ENABLED(CONFIG_CPU_SRSO)) { + /* + * Enable the return thunk for generated code + * like ftrace, static_call, etc. + */ + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + if (boot_cpu_data.x86 == 0x19) setup_force_cpu_cap(X86_FEATURE_SRSO_ALIAS); else |