Merge tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 entry code updates from Thomas Gleixner:

 - Convert the 32bit syscalls to be pt_regs based which removes the
   requirement to push all 6 potential arguments onto the stack and
   consolidates the interface with the 64bit variant

 - The first small portion of the exception and syscall related entry
   code consolidation which aims to address the recently discovered
   issues vs. RCU, int3, NMI and some other exceptions which can
   interrupt any context. The bulk of the changes is still work in
   progress and aimed for 5.8.

 - A few lockdep namespace cleanups which have been applied into this
   branch to keep the prerequisites for the ongoing work confined.

* tag 'x86-entry-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (35 commits)
  x86/entry: Fix build error x86 with !CONFIG_POSIX_TIMERS
  lockdep: Rename trace_{hard,soft}{irq_context,irqs_enabled}()
  lockdep: Rename trace_softirqs_{on,off}()
  lockdep: Rename trace_hardirq_{enter,exit}()
  x86/entry: Rename ___preempt_schedule
  x86: Remove unneeded includes
  x86/entry: Drop asmlinkage from syscalls
  x86/entry/32: Enable pt_regs based syscalls
  x86/entry/32: Use IA32-specific wrappers for syscalls taking 64-bit arguments
  x86/entry/32: Rename 32-bit specific syscalls
  x86/entry/32: Clean up syscall_32.tbl
  x86/entry: Remove ABI prefixes from functions in syscall tables
  x86/entry/64: Add __SYSCALL_COMMON()
  x86/entry: Remove syscall qualifier support
  x86/entry/64: Remove ptregs qualifier from syscall table
  x86/entry: Move max syscall number calculation to syscallhdr.sh
  x86/entry/64: Split X32 syscall table into its own file
  x86/entry/64: Move sys_ni_syscall stub to common.c
  x86/entry/64: Use syscall wrappers for x32_rt_sigreturn
  x86/entry: Refactor SYS_NI macros
  ...

1 files changed, 34 insertions, 7 deletions

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 6ef00eb6fbb9..c0bc9df8634d 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -572,14 +572,20 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 		return;
 
 	/*
-	 * Use ist_enter despite the fact that we don't use an IST stack.
-	 * We can be called from a kprobe in non-CONTEXT_KERNEL kernel
-	 * mode or even during context tracking state changes.
+	 * Unlike any other non-IST entry, we can be called from a kprobe in
+	 * non-CONTEXT_KERNEL kernel mode or even during context tracking
+	 * state changes.  Make sure that we wake up RCU even if we're coming
+	 * from kernel code.
 	 *
-	 * This means that we can't schedule.  That's okay.
+	 * This means that we can't schedule even if we came from a
+	 * preemptible kernel context.  That's okay.
 	 */
-	ist_enter(regs);
+	if (!user_mode(regs)) {
+		rcu_nmi_enter();
+		preempt_disable();
+	}
 	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
+
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 	if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 				SIGTRAP) == NOTIFY_STOP)
@@ -600,7 +606,10 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 	cond_local_irq_disable(regs);
 
 exit:
-	ist_exit(regs);
+	if (!user_mode(regs)) {
+		preempt_enable_no_resched();
+		rcu_nmi_exit();
+	}
 }
 NOKPROBE_SYMBOL(do_int3);
 
@@ -862,7 +871,25 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 dotraplinkage void
 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 {
-	cond_local_irq_enable(regs);
+	/*
+	 * This addresses a Pentium Pro Erratum:
+	 *
+	 * PROBLEM: If the APIC subsystem is configured in mixed mode with
+	 * Virtual Wire mode implemented through the local APIC, an
+	 * interrupt vector of 0Fh (Intel reserved encoding) may be
+	 * generated by the local APIC (Int 15).  This vector may be
+	 * generated upon receipt of a spurious interrupt (an interrupt
+	 * which is removed before the system receives the INTA sequence)
+	 * instead of the programmed 8259 spurious interrupt vector.
+	 *
+	 * IMPLICATION: The spurious interrupt vector programmed in the
+	 * 8259 is normally handled by an operating system's spurious
+	 * interrupt handler. However, a vector of 0Fh is unknown to some
+	 * operating systems, which would crash if this erratum occurred.
+	 *
+	 * In theory this could be limited to 32bit, but the handler is not
+	 * hurting and who knows which other CPUs suffer from this.
+	 */
 }
 
 dotraplinkage void