Messages in this thread | | | Date | Wed, 17 Apr 2024 10:40:28 +0200 | Subject | Re: [bisected] Kernel v6.9-rc3 fails to boot on a Thinkpad T60 with MITIGATION_RETHUNK=y (regression from v6.8.5) | From | Thorsten Leemhuis <> |
| |
On 17.04.24 10:38, Linux regression tracking (Thorsten Leemhuis) wrote: > On 14.04.24 11:08, Borislav Petkov wrote: >> On Sun, Apr 14, 2024 at 10:36:26AM +0200, Borislav Petkov wrote: >>>> There was an earlier report about this here: >>>> https://lore.kernel.org/all/78e0d19c-b77a-4169-a80f-2eef91f4a1d6@gmail.com/ >>> Am looking at the whole thing. Stay tuned... >> >> Something like this, I guess... >> >> Execution goes off somewhere into the weeds during alternatives patching >> of the return thunk while it tries to warn about it in the alternatives >> code itself and it all ends up in an endless INT3 exceptions due to our >> speculation blockers everywhere... >> >> I could chase it as to why exactly but the warning is there for all >> those mitigations which need a special return thunk and 32-bit doesn't >> need them (and at least the AMD untraining sequences are 64-bit only >> so...). > > Erhard Furtner, did you try if this helps for a kernel with > MITIGATION_RETHUNK=y? Klara Modin, or could you give it a try? > > Without a check this is unlikely to be merged and then more people might > run into problems like you two did.
Ignore that, I only not noticed the discussion continued in the other thread and Klara Modin already provided a tested-by. Sorry for the noise.
Ciao, Thorsten
>> IOW: >> >> diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S >> index e674ccf720b9..391059b2c6fb 100644 >> --- a/arch/x86/lib/retpoline.S >> +++ b/arch/x86/lib/retpoline.S >> @@ -382,8 +382,15 @@ SYM_FUNC_END(call_depth_return_thunk) >> SYM_CODE_START(__x86_return_thunk) >> UNWIND_HINT_FUNC >> ANNOTATE_NOENDBR >> +#if defined(CONFIG_MITIGATION_UNRET_ENTRY) || \ >> + defined(CONFIG_MITIGATION_SRSO) || \ >> + defined(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) >> ALTERNATIVE __stringify(ANNOTATE_UNRET_SAFE; ret), \ >> "jmp warn_thunk_thunk", X86_FEATURE_ALWAYS >> +#else >> + ANNOTATE_UNRET_SAFE >> + ret >> +#endif >> int3 >> SYM_CODE_END(__x86_return_thunk) >> EXPORT_SYMBOL(__x86_return_thunk) >>
| |