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| author | Borislav Petkov (AMD) <bp@alien8.de> | 2023-05-12 23:12:26 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2023-05-12 17:19:53 -0500 |
| commit | 9a48d604672220545d209e9996c2a1edbb5637f6 (patch) | |
| tree | 8e6235d2df95972cc333f43e406f39f70d6b6f2f /arch | |
| parent | 76c7f8873a7696dbd8f9cd844e30e5c84cbaba1a (diff) | |
| download | lwn-9a48d604672220545d209e9996c2a1edbb5637f6.tar.gz lwn-9a48d604672220545d209e9996c2a1edbb5637f6.zip | |
x86/retbleed: Fix return thunk alignment
SYM_FUNC_START_LOCAL_NOALIGN() adds an endbr leading to this layout
(leaving only the last 2 bytes of the address):
3bff <zen_untrain_ret>:
3bff: f3 0f 1e fa endbr64
3c03: f6 test $0xcc,%bl
3c04 <__x86_return_thunk>:
3c04: c3 ret
3c05: cc int3
3c06: 0f ae e8 lfence
However, "the RET at __x86_return_thunk must be on a 64 byte boundary,
for alignment within the BTB."
Use SYM_START instead.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/lib/retpoline.S | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index 27ef53fab6bd..b3b1e376dce8 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -144,8 +144,8 @@ SYM_CODE_END(__x86_indirect_jump_thunk_array) */ .align 64 .skip 63, 0xcc -SYM_FUNC_START_NOALIGN(zen_untrain_ret); - +SYM_START(zen_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE) + ANNOTATE_NOENDBR /* * As executed from zen_untrain_ret, this is: * |