linux-kernel - [tip: x86/fpu] x86/extable: Remove EX_TYPE

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Message-ID: <163164717172.25758.13914549878374483404.tip-bot2@tip-bot2>
Date:   Tue, 14 Sep 2021 19:19:31 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/fpu] x86/extable: Remove EX_TYPE_FAULT from MCE safe fixups

The following commit has been merged into the x86/fpu branch of tip:

Commit-ID:     0c2e62ba04cd0b7194b380bae4fc35c45bb2e46e
Gitweb:        https://git.kernel.org/tip/0c2e62ba04cd0b7194b380bae4fc35c45bb2e46e
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Wed, 08 Sep 2021 15:29:24 +02:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Mon, 13 Sep 2021 18:23:00 +02:00

x86/extable: Remove EX_TYPE_FAULT from MCE safe fixups

Now that the MC safe copy and FPU have been converted to use the MCE safe
fixup types remove EX_TYPE_FAULT from the list of types which MCE considers
to be safe to be recovered in kernel.

This removes the SGX exception handling of ENCLS from the #MC safe
handling, but according to the SGX wizards the current SGX implementations
cannot survive #MC on ENCLS:

  https://lore.kernel.org/r/YS+upEmTfpZub3s9@google.com

The code relies on the trap number being stored if ENCLS raised an
exception. That's still working, but it does no longer trick the MCE code
into assuming that #MC is handled correctly for ENCLS.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lkml.kernel.org/r/20210908132525.445255957@linutronix.de
---
 arch/x86/kernel/cpu/mce/severity.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
index d9b77a7..f60bbaf 100644
--- a/arch/x86/kernel/cpu/mce/severity.c
+++ b/arch/x86/kernel/cpu/mce/severity.c
@@ -277,7 +277,6 @@ static int error_context(struct mce *m, struct pt_regs *regs)
 			return IN_KERNEL;
 		m->kflags |= MCE_IN_KERNEL_COPYIN;
 		fallthrough;
-	case EX_TYPE_FAULT:
 	case EX_TYPE_FAULT_MCE_SAFE:
 	case EX_TYPE_DEFAULT_MCE_SAFE:
 		m->kflags |= MCE_IN_KERNEL_RECOV;