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| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2023-07-29 01:28:43 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-08-08 21:03:51 +0300 |
| commit | c7f2cd04554259c2474c4f9fa134528bc2826b22 (patch) | |
| tree | 67ad69cf4afe9f1ceab73d4c405c71d8d16bfa56 | |
| parent | c9ae63d773ca182c4ef63fbdd22cdf090d9c1cd7 (diff) | |
| download | linux-c7f2cd04554259c2474c4f9fa134528bc2826b22.tar.xz | |
x86/srso: Fix return thunks in generated code
Upstream commit: 238ec850b95a02dcdff3edc86781aa913549282f
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 f8a6062f6ae3..d1d92897ed6b 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -538,9 +538,7 @@ static int patch_return(void *addr, struct insn *insn, u8 *bytes) { int i = 0; - 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)) return -1; bytes[i++] = RET_INSN_OPCODE; diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index af612778a328..b4ac1f3d41b3 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2415,6 +2415,12 @@ 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 |