linux-kernel - [tip:x86/mm] x86/fault: Don't set thread.cr2, etc before OOPSing

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Message-ID: <tip-1ad33f5aec20f53785dbad44c6fb3b204aefd921@git.kernel.org>
Date:   Tue, 20 Nov 2018 00:17:58 -0800
From:   tip-bot for Andy Lutomirski <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mingo@...nel.org, dave.hansen@...ux.intel.com, luto@...nel.org,
        brgerst@...il.com, bp@...en8.de, yu-cheng.yu@...el.com,
        riel@...riel.com, peterz@...radead.org,
        linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        dvlasenk@...hat.com, tglx@...utronix.de, hpa@...or.com,
        luto@...capital.net
Subject: [tip:x86/mm] x86/fault: Don't set thread.cr2, etc before OOPSing

Commit-ID:  1ad33f5aec20f53785dbad44c6fb3b204aefd921
Gitweb:     https://git.kernel.org/tip/1ad33f5aec20f53785dbad44c6fb3b204aefd921
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Mon, 19 Nov 2018 14:45:32 -0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 20 Nov 2018 08:44:30 +0100

x86/fault: Don't set thread.cr2, etc before OOPSing

The fault handling code sets the cr2, trap_nr, and error_code fields
in thread_struct before OOPSing.  No one reads those fields during
an OOPS, so remove the code to set them.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@...el.com>
Link: http://lkml.kernel.org/r/d418022aa0fad9cb40467aa7acaf4e95be50ee96.1542667307.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/mm/fault.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index b5ec1ca2f4a0..b898a38093a3 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -621,10 +621,6 @@ pgtable_bad(struct pt_regs *regs, unsigned long error_code,
 	       tsk->comm, address);
 	dump_pagetable(address);
 
-	tsk->thread.cr2		= address;
-	tsk->thread.trap_nr	= X86_TRAP_PF;
-	tsk->thread.error_code	= error_code;
-
 	if (__die("Bad pagetable", regs, error_code))
 		sig = 0;
 
@@ -753,10 +749,6 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 	if (task_stack_end_corrupted(tsk))
 		printk(KERN_EMERG "Thread overran stack, or stack corrupted\n");
 
-	tsk->thread.cr2		= address;
-	tsk->thread.trap_nr	= X86_TRAP_PF;
-	tsk->thread.error_code	= error_code;
-
 	sig = SIGKILL;
 	if (__die("Oops", regs, error_code))
 		sig = 0;