iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86/srso: Fix return thunks in generated code

Browse Source 
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>
This commit is contained in:
Josh Poimboeuf 2023-07-28 17:28:43 -05:00 committed by Borislav Petkov (AMD)
parent d893832d0e
commit 238ec850b9
2 changed files with 7 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/kernel/alternative.c
View File

@ -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 {

6
arch/x86/kernel/cpu/bugs.c
View File

@ -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