diff options
| author | Borislav Petkov (AMD) <bp@alien8.de> | 2023-05-15 17:07:26 +0300 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-05-17 13:14:21 +0300 |
| commit | f220125b999b2c9694149c6bda2798d8096f47ed (patch) | |
| tree | 7cee09cfdcadf0a27866192d98be136f3a388130 /arch | |
| parent | 7583e8fbdc49a4dbd916d14863cf1deeddb982f9 (diff) | |
| download | linux-f220125b999b2c9694149c6bda2798d8096f47ed.tar.xz | |
x86/retbleed: Add __x86_return_thunk alignment checks
Add a linker assertion and compute the 0xcc padding dynamically so that
__x86_return_thunk is always cacheline-aligned. Leave the SYM_START()
macro in as the untraining doesn't need ENDBR annotations anyway.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Link: https://lore.kernel.org/r/20230515140726.28689-1-bp@alien8.de
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/vmlinux.lds.S | 4 | ||||
| -rw-r--r-- | arch/x86/lib/retpoline.S | 2 |
2 files changed, 5 insertions, 1 deletions
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 25f155205770..03c885d3640f 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -508,4 +508,8 @@ INIT_PER_CPU(irq_stack_backing_store); "fixed_percpu_data is not at start of per-cpu area"); #endif +#ifdef CONFIG_RETHUNK +. = ASSERT((__x86_return_thunk & 0x3f) == 0, "__x86_return_thunk not cacheline-aligned"); +#endif + #endif /* CONFIG_X86_64 */ diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index b3b1e376dce8..3fd066d42ec0 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -143,7 +143,7 @@ SYM_CODE_END(__x86_indirect_jump_thunk_array) * from re-poisioning the BTB prediction. */ .align 64 - .skip 63, 0xcc + .skip 64 - (__x86_return_thunk - zen_untrain_ret), 0xcc SYM_START(zen_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE) ANNOTATE_NOENDBR /* |