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| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2023-07-28 17:28:43 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-08-08 20:04:52 +0200 |
| commit | b155f54a92b0c8fe62eb5b45d062613626428fc5 (patch) | |
| tree | c87cdc5e3d6288b5cef4f67add893ceded83e076 | |
| parent | b31eb84b6756825ce935ce0390025b2b09b4ecb4 (diff) | |
| download | linux-stable-b155f54a92b0c8fe62eb5b45d062613626428fc5.tar.gz linux-stable-b155f54a92b0c8fe62eb5b45d062613626428fc5.tar.bz2 linux-stable-b155f54a92b0c8fe62eb5b45d062613626428fc5.zip | |
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 d516781e5756..f615e0cb6d93 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -590,9 +590,7 @@ 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)) { if (x86_return_thunk == __x86_return_thunk) return -1; diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 1ba0e1c0650d..9ab38d04f686 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2444,6 +2444,12 @@ 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 |