1 files changed, 15 insertions, 97 deletions

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index d54cffdc7cac..4cc541051994 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -37,10 +37,12 @@
 #include <linux/mm.h>
 #include <linux/smp.h>
 #include <linux/io.h>
+#include <linux/hardirq.h>
+#include <linux/atomic.h>
+
 #include <asm/stacktrace.h>
 #include <asm/processor.h>
 #include <asm/debugreg.h>
-#include <linux/atomic.h>
 #include <asm/text-patching.h>
 #include <asm/ftrace.h>
 #include <asm/traps.h>
@@ -82,78 +84,6 @@ static inline void cond_local_irq_disable(struct pt_regs *regs)
 		local_irq_disable();
 }
 
-/*
- * In IST context, we explicitly disable preemption.  This serves two
- * purposes: it makes it much less likely that we would accidentally
- * schedule in IST context and it will force a warning if we somehow
- * manage to schedule by accident.
- */
-void ist_enter(struct pt_regs *regs)
-{
-	if (user_mode(regs)) {
-		RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
-	} else {
-		/*
-		 * We might have interrupted pretty much anything.  In
-		 * fact, if we're a machine check, we can even interrupt
-		 * NMI processing.  We don't want in_nmi() to return true,
-		 * but we need to notify RCU.
-		 */
-		rcu_nmi_enter();
-	}
-
-	preempt_disable();
-
-	/* This code is a bit fragile.  Test it. */
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "ist_enter didn't work");
-}
-NOKPROBE_SYMBOL(ist_enter);
-
-void ist_exit(struct pt_regs *regs)
-{
-	preempt_enable_no_resched();
-
-	if (!user_mode(regs))
-		rcu_nmi_exit();
-}
-
-/**
- * ist_begin_non_atomic() - begin a non-atomic section in an IST exception
- * @regs:	regs passed to the IST exception handler
- *
- * IST exception handlers normally cannot schedule.  As a special
- * exception, if the exception interrupted userspace code (i.e.
- * user_mode(regs) would return true) and the exception was not
- * a double fault, it can be safe to schedule.  ist_begin_non_atomic()
- * begins a non-atomic section within an ist_enter()/ist_exit() region.
- * Callers are responsible for enabling interrupts themselves inside
- * the non-atomic section, and callers must call ist_end_non_atomic()
- * before ist_exit().
- */
-void ist_begin_non_atomic(struct pt_regs *regs)
-{
-	BUG_ON(!user_mode(regs));
-
-	/*
-	 * Sanity check: we need to be on the normal thread stack.  This
-	 * will catch asm bugs and any attempt to use ist_preempt_enable
-	 * from double_fault.
-	 */
-	BUG_ON(!on_thread_stack());
-
-	preempt_enable_no_resched();
-}
-
-/**
- * ist_end_non_atomic() - begin a non-atomic section in an IST exception
- *
- * Ends a non-atomic section started with ist_begin_non_atomic().
- */
-void ist_end_non_atomic(void)
-{
-	preempt_disable();
-}
-
 int is_valid_bugaddr(unsigned long addr)
 {
 	unsigned short ud;
@@ -326,7 +256,6 @@ __visible void __noreturn handle_stack_overflow(const char *message,
 }
 #endif
 
-#if defined(CONFIG_X86_64) || defined(CONFIG_DOUBLEFAULT)
 /*
  * Runs on an IST stack for x86_64 and on a special task stack for x86_32.
  *
@@ -363,7 +292,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
 	 * The net result is that our #GP handler will think that we
 	 * entered from usermode with the bad user context.
 	 *
-	 * No need for ist_enter here because we don't use RCU.
+	 * No need for nmi_enter() here because we don't use RCU.
 	 */
 	if (((long)regs->sp >> P4D_SHIFT) == ESPFIX_PGD_ENTRY &&
 		regs->cs == __KERNEL_CS &&
@@ -398,7 +327,7 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
 	}
 #endif
 
-	ist_enter(regs);
+	nmi_enter();
 	notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
 
 	tsk->thread.error_code = error_code;
@@ -450,7 +379,6 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign
 	die("double fault", regs, error_code);
 	panic("Machine halted.");
 }
-#endif
 
 dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
 {
@@ -592,19 +520,13 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 		return;
 
 	/*
-	 * 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 even if we came from a
-	 * preemptible kernel context.  That's okay.
+	 * Unlike any other non-IST entry, we can be called from pretty much
+	 * any location in the kernel through kprobes -- text_poke() will most
+	 * likely be handled by poke_int3_handler() above. This means this
+	 * handler is effectively NMI-like.
 	 */
-	if (!user_mode(regs)) {
-		rcu_nmi_enter();
-		preempt_disable();
-	}
-	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
+	if (!user_mode(regs))
+		nmi_enter();
 
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 	if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
@@ -626,10 +548,8 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
 	cond_local_irq_disable(regs);
 
 exit:
-	if (!user_mode(regs)) {
-		preempt_enable_no_resched();
-		rcu_nmi_exit();
-	}
+	if (!user_mode(regs))
+		nmi_exit();
 }
 NOKPROBE_SYMBOL(do_int3);
 
@@ -733,7 +653,7 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
 	unsigned long dr6;
 	int si_code;
 
-	ist_enter(regs);
+	nmi_enter();
 
 	get_debugreg(dr6, 6);
 	/*
@@ -826,7 +746,7 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
 	debug_stack_usage_dec();
 
 exit:
-	ist_exit(regs);
+	nmi_exit();
 }
 NOKPROBE_SYMBOL(do_debug);
 
@@ -983,7 +903,5 @@ void __init trap_init(void)
 
 	idt_setup_ist_traps();
 
-	x86_init.irqs.trap_init();
-
 	idt_setup_debugidt_traps();
 }