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

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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@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>
This commit is contained in:
Greg Kroah-Hartman 2017-12-04 12:59:57 +01:00
parent fb541279bb
commit a11ca51bf7
1 changed files with 2 additions and 8 deletions
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10
arch/x86/entry/entry_64.S
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@ -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)