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

Pull x86 asm changes from Ingo Molnar:
 "There were lots of changes in this development cycle:

   - over 100 separate cleanups, restructuring changes, speedups and
     fixes in the x86 system call, irq, trap and other entry code, part
     of a heroic effort to deobfuscate a decade old spaghetti asm code
     and its C code dependencies (Denys Vlasenko, Andy Lutomirski)

   - alternatives code fixes and enhancements (Borislav Petkov)

   - simplifications and cleanups to the compat code (Brian Gerst)

   - signal handling fixes and new x86 testcases (Andy Lutomirski)

   - various other fixes and cleanups

  By their nature many of these changes are risky - we tried to test
  them well on many different x86 systems (there are no known
  regressions), and they are split up finely to help bisection - but
  there's still a fair bit of residual risk left so caveat emptor"

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (148 commits)
  perf/x86/64: Report regs_user->ax too in get_regs_user()
  perf/x86/64: Simplify regs_user->abi setting code in get_regs_user()
  perf/x86/64: Do report user_regs->cx while we are in syscall, in get_regs_user()
  perf/x86/64: Do not guess user_regs->cs, ss, sp in get_regs_user()
  x86/asm/entry/32: Tidy up JNZ instructions after TESTs
  x86/asm/entry/64: Reduce padding in execve stubs
  x86/asm/entry/64: Remove GET_THREAD_INFO() in ret_from_fork
  x86/asm/entry/64: Simplify jumps in ret_from_fork
  x86/asm/entry/64: Remove a redundant jump
  x86/asm/entry/64: Optimize [v]fork/clone stubs
  x86/asm/entry: Zero EXTRA_REGS for stub32_execve() too
  x86/asm/entry/64: Move stub_x32_execvecloser() to stub_execveat()
  x86/asm/entry/64: Use common code for rt_sigreturn() epilogue
  x86/asm/entry/64: Add forgotten CFI annotation
  x86/asm/entry/irq: Simplify interrupt dispatch table (IDT) layout
  x86/asm/entry/64: Move opportunistic sysret code to syscall code path
  x86, selftests: Add sigreturn selftest
  x86/alternatives: Guard NOPs optimization
  x86/asm/entry: Clear EXTRA_REGS for all executable formats
  x86/signal: Remove pax argument from restore_sigcontext
  ...

3 files changed, 6 insertions, 17 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 5240f563076d..81665c9f2132 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -912,6 +912,7 @@ static void xen_load_sp0(struct tss_struct *tss,
 	mcs = xen_mc_entry(0);
 	MULTI_stack_switch(mcs.mc, __KERNEL_DS, thread->sp0);
 	xen_mc_issue(PARAVIRT_LAZY_CPU);
+	tss->x86_tss.sp0 = thread->sp0;
 }
 
 static void xen_set_iopl_mask(unsigned mask)
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 08e8489c47f1..7413ee3706d0 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -445,15 +445,7 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle)
 {
 	int rc;
 
-	per_cpu(current_task, cpu) = idle;
-#ifdef CONFIG_X86_32
-	irq_ctx_init(cpu);
-#else
-	clear_tsk_thread_flag(idle, TIF_FORK);
-#endif
-	per_cpu(kernel_stack, cpu) =
-		(unsigned long)task_stack_page(idle) -
-		KERNEL_STACK_OFFSET + THREAD_SIZE;
+	common_cpu_up(cpu, idle);
 
 	xen_setup_runstate_info(cpu);
 	xen_setup_timer(cpu);
@@ -468,10 +460,6 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle)
 	if (rc)
 		return rc;
 
-	if (num_online_cpus() == 1)
-		/* Just in case we booted with a single CPU. */
-		alternatives_enable_smp();
-
 	rc = xen_smp_intr_init(cpu);
 	if (rc)
 		return rc;
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index 53adefda4275..985fc3ee0973 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -68,11 +68,11 @@ ENTRY(xen_sysret64)
 	 * We're already on the usermode stack at this point, but
 	 * still with the kernel gs, so we can easily switch back
 	 */
-	movq %rsp, PER_CPU_VAR(old_rsp)
+	movq %rsp, PER_CPU_VAR(rsp_scratch)
 	movq PER_CPU_VAR(kernel_stack), %rsp
 
 	pushq $__USER_DS
-	pushq PER_CPU_VAR(old_rsp)
+	pushq PER_CPU_VAR(rsp_scratch)
 	pushq %r11
 	pushq $__USER_CS
 	pushq %rcx
@@ -87,11 +87,11 @@ ENTRY(xen_sysret32)
 	 * We're already on the usermode stack at this point, but
 	 * still with the kernel gs, so we can easily switch back
 	 */
-	movq %rsp, PER_CPU_VAR(old_rsp)
+	movq %rsp, PER_CPU_VAR(rsp_scratch)
 	movq PER_CPU_VAR(kernel_stack), %rsp
 
 	pushq $__USER32_DS
-	pushq PER_CPU_VAR(old_rsp)
+	pushq PER_CPU_VAR(rsp_scratch)
 	pushq %r11
 	pushq $__USER32_CS
 	pushq %rcx