From: Andy Lutomirski <luto@kernel.org>
Date: Mon, 19 Nov 2018 22:45:32 +0000 (-0800)
Subject: x86/fault: Don't set thread.cr2, etc before OOPSing
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=1ad33f5aec20f53785dbad44c6fb3b204aefd921;p=openwrt%2Fstaging%2Fblogic.git

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@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/d418022aa0fad9cb40467aa7acaf4e95be50ee96.1542667307.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

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;