Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 asm updates from Thomas Gleixner:
 "The lowlevel and ASM code updates for x86:

   - Make stack trace unwinding more reliable

   - ASM instruction updates for better code generation

   - Various cleanups"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/entry/64: Add two more instruction suffixes
  x86/asm/64: Use 32-bit XOR to zero registers
  x86/build/vdso: Simplify 'cmd_vdso2c'
  x86/build/vdso: Remove unused vdso-syms.lds
  x86/stacktrace: Enable HAVE_RELIABLE_STACKTRACE for the ORC unwinder
  x86/unwind/orc: Detect the end of the stack
  x86/stacktrace: Do not fail for ORC with regs on stack
  x86/stacktrace: Clarify the reliable success paths
  x86/stacktrace: Remove STACKTRACE_DUMP_ONCE
  x86/stacktrace: Do not unwind after user regs
  x86/asm: Use CC_SET/CC_OUT in percpu_cmpxchg8b_double() to micro-optimize code generation

arch/x86/entry/entry_64.S

@@ -92,7 +92,7 @@ END(native_usergs_sysret64)
 .endm
 
 .macro TRACE_IRQS_IRETQ_DEBUG
-	bt	$9, EFLAGS(%rsp)		/* interrupts off? */
+	btl	$9, EFLAGS(%rsp)		/* interrupts off? */
 	jnc	1f
 	TRACE_IRQS_ON_DEBUG
 1:
@@ -408,6 +408,7 @@ ENTRY(ret_from_fork)
 
 1:
 	/* kernel thread */
+	UNWIND_HINT_EMPTY
 	movq	%r12, %rdi
 	CALL_NOSPEC %rbx
 	/*
@@ -701,7 +702,7 @@ retint_kernel:
 #ifdef CONFIG_PREEMPT
 	/* Interrupts are off */
 	/* Check if we need preemption */
-	bt	$9, EFLAGS(%rsp)		/* were interrupts off? */
+	btl	$9, EFLAGS(%rsp)		/* were interrupts off? */
 	jnc	1f
 0:	cmpl	$0, PER_CPU_VAR(__preempt_count)
 	jnz	1f