linux-kernel - [PATCH 4.9 35/38] Revert "x86/entry/64: Add missing irqflags tracing to native_load_gs

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Date:   Mon,  4 Dec 2017 17:00:15 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bpetkov@...e.de>,
        Brian Gerst <brgerst@...il.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.9 35/38] Revert "x86/entry/64: Add missing irqflags tracing to native_load_gs_index()"

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

This reverts commit 0d794d0d018f23fb09c50f6ae26868bd6ae343d6 which is
commit 0d794d0d018f23fb09c50f6ae26868bd6ae343d6 upstream.

Andy writes:

	I think the thing to do is to revert the patch from -stable.
	The bug it fixes is very minor, and the regression is that it
	made a pre-existing bug in some nearly-undebuggable core resume
	code much easier to hit.  I don't feel comfortable with a
	backport of the latter fix until it has a good long soak in
	Linus' tree.

Reported-by: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bpetkov@...e.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/entry/entry_64.S | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index be9df513141e..e7b0e7ff4c58 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -54,19 +54,15 @@ ENTRY(native_usergs_sysret64)
 ENDPROC(native_usergs_sysret64)
 #endif /* CONFIG_PARAVIRT */
 
-.macro TRACE_IRQS_FLAGS flags:req
+.macro TRACE_IRQS_IRETQ
 #ifdef CONFIG_TRACE_IRQFLAGS
-	bt	$9, \flags		/* interrupts off? */
+	bt	$9, EFLAGS(%rsp)		/* interrupts off? */
 	jnc	1f
 	TRACE_IRQS_ON
 1:
 #endif
 .endm
 
-.macro TRACE_IRQS_IRETQ
-	TRACE_IRQS_FLAGS EFLAGS(%rsp)
-.endm
-
 /*
  * When dynamic function tracer is enabled it will add a breakpoint
  * to all locations that it is about to modify, sync CPUs, update
@@ -872,13 +868,11 @@ idtentry simd_coprocessor_error		do_simd_coprocessor_error	has_error_code=0
 ENTRY(native_load_gs_index)
 	pushfq
 	DISABLE_INTERRUPTS(CLBR_ANY & ~CLBR_RDI)
-	TRACE_IRQS_OFF
 	SWAPGS
 .Lgs_change:
 	movl	%edi, %gs
 2:	ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
 	SWAPGS
-	TRACE_IRQS_FLAGS (%rsp)
 	popfq
 	ret
 END(native_load_gs_index)
-- 
2.15.1