Commit e49d722f authored Dec 04, 2017 by Greg Kroah-Hartman

Revert "x86/entry/64: Add missing irqflags tracing to native_load_gs_index()"



This reverts commit f9a64e23 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@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 88e1bb2a

arch/x86/entry/entry_64.S

+2 −8

Original line number	Diff line number	Diff line
		@@ -51,19 +51,15 @@ ENTRY(native_usergs_sysret64)
		END(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
		@@ -927,13 +923,11 @@ ENTRY(native_load_gs_index)
		FRAME_BEGIN
		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
		FRAME_END
		ret