linux-kernel - [patch V2 09/20] x86/extable: Remove EX_TYPE

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Message-ID: <20210907195004.269330688@linutronix.de>
Date:   Tue,  7 Sep 2021 21:56:26 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Tony Luck <tony.luck@...el.com>,
        Song Liu <songliubraving@...com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Peter Ziljstra <peterz@...radead.org>
Subject: [patch V2 09/20] 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 not longer trick the MCE code
to assume that #MC is handled correctly for ENCLS.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V2: New patch
---
 arch/x86/kernel/cpu/mce/severity.c |    1 -
 1 file changed, 1 deletion(-)

--- 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,
 			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;