diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
index 707adc6549d82335a20bdf18d18b697fa1fe9eab..3cf525ec762dcc2a68eedbfcf379d83f622b7f44 100644
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -1,6 +1,7 @@
#ifndef _ASM_X86_TRAPS_H
#define _ASM_X86_TRAPS_H
+#include <linux/context_tracking_state.h>
#include <linux/kprobes.h>
#include <asm/debugreg.h>
@@ -110,6 +111,9 @@ asmlinkage void smp_thermal_interrupt(void);
asmlinkage void mce_threshold_interrupt(void);
#endif
+extern enum ctx_state ist_enter(struct pt_regs *regs);
+extern void ist_exit(struct pt_regs *regs, enum ctx_state prev_state);
+
/* Interrupts/Exceptions */
enum {
X86_TRAP_DE = 0, /* 0, Divide-by-zero */
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index d2c611699cd9d2d49bfd1cee5b79c7fedf87ef71..800d423f1e920b33b0dceca0bf939004937d5740 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -43,6 +43,7 @@
#include <linux/export.h>
#include <asm/processor.h>
+#include <asm/traps.h>
#include <asm/mce.h>
#include <asm/msr.h>
@@ -1063,6 +1064,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
{
struct mca_config *cfg = &mca_cfg;
struct mce m, *final;
+ enum ctx_state prev_state;
int i;
int worst = 0;
int severity;
@@ -1085,6 +1087,8 @@ void do_machine_check(struct pt_regs *regs, long error_code)
DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
char *msg = "Unknown";
+ prev_state = ist_enter(regs);
+
this_cpu_inc(mce_exception_count);
if (!cfg->banks)
@@ -1216,6 +1220,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
mce_wrmsrl(MSR_IA32_MCG_STATUS, 0);
out:
sync_core();
+ ist_exit(regs, prev_state);
}
EXPORT_SYMBOL_GPL(do_machine_check);
diff --git a/arch/x86/kernel/cpu/mcheck/p5.c b/arch/x86/kernel/cpu/mcheck/p5.c
index a3042989398c1cdb7d33da49bf7dea1887e00aa5..ec2663a708e40d2e3fa03b36fa7587c860a1871b 100644
--- a/arch/x86/kernel/cpu/mcheck/p5.c
+++ b/arch/x86/kernel/cpu/mcheck/p5.c
@@ -8,6 +8,7 @@
#include <linux/smp.h>
#include <asm/processor.h>
+#include <asm/traps.h>
#include <asm/mce.h>
#include <asm/msr.h>
@@ -17,8 +18,11 @@ int mce_p5_enabled __read_mostly;
/* Machine check handler for Pentium class Intel CPUs: */
static void pentium_machine_check(struct pt_regs *regs, long error_code)
{
+ enum ctx_state prev_state;
u32 loaddr, hi, lotype;
+ prev_state = ist_enter(regs);
+
rdmsr(MSR_IA32_P5_MC_ADDR, loaddr, hi);
rdmsr(MSR_IA32_P5_MC_TYPE, lotype, hi);
@@ -33,6 +37,8 @@ static void pentium_machine_check(struct pt_regs *regs, long error_code)
}
add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
+
+ ist_exit(regs, prev_state);
}
/* Set up machine check reporting for processors with Intel style MCE: */
diff --git a/arch/x86/kernel/cpu/mcheck/winchip.c b/arch/x86/kernel/cpu/mcheck/winchip.c
index 7dc5564d0cdf57c0e7ca8c181f87f3ebb6f6ceb2..bd5d46a32210a15deb8895c37e67e5e0dea9d7c5 100644
--- a/arch/x86/kernel/cpu/mcheck/winchip.c
+++ b/arch/x86/kernel/cpu/mcheck/winchip.c
@@ -7,14 +7,19 @@
#include <linux/types.h>
#include <asm/processor.h>
+#include <asm/traps.h>
#include <asm/mce.h>
#include <asm/msr.h>
/* Machine check handler for WinChip C6: */
static void winchip_machine_check(struct pt_regs *regs, long error_code)
{
+ enum ctx_state prev_state = ist_enter(regs);
+
printk(KERN_EMERG "CPU0: Machine Check Exception.\n");
add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);
+
+ ist_exit(regs, prev_state);
}
/* Set up machine check reporting on the Winchip C6 series */
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 28f3e5ffc55ddce45e19570fed420c090acfdb6f..b3a9d24dba25cc1c8b276ce3cffb2c8cd83e9fe5 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -108,6 +108,39 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
preempt_count_dec();
}
+enum ctx_state ist_enter(struct pt_regs *regs)
+{
+ /*
+ * We are atomic because we're on the IST stack (or we're on x86_32,
+ * in which case we still shouldn't schedule.
+ */
+ preempt_count_add(HARDIRQ_OFFSET);
+
+ if (user_mode_vm(regs)) {
+ /* Other than that, we're just an exception. */
+ return exception_enter();
+ } 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();
+ return IN_KERNEL; /* the value is irrelevant. */
+ }
+}
+
+void ist_exit(struct pt_regs *regs, enum ctx_state prev_state)
+{
+ preempt_count_sub(HARDIRQ_OFFSET);
+
+ if (user_mode_vm(regs))
+ return exception_exit(prev_state);
+ else
+ rcu_nmi_exit();
+}
+
static nokprobe_inline int
do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
struct pt_regs *regs, long error_code)
@@ -251,6 +284,8 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
* end up promoting it to a doublefault. In that case, modify
* the stack to make it look like we just entered the #GP
* handler from user space, similar to bad_iret.
+ *
+ * No need for ist_enter here because we don't use RCU.
*/
if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY &&
regs->cs == __KERNEL_CS &&
@@ -263,12 +298,12 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
normal_regs->orig_ax = 0; /* Missing (lost) #GP error code */
regs->ip = (unsigned long)general_protection;
regs->sp = (unsigned long)&normal_regs->orig_ax;
+
return;
}
#endif
- exception_enter();
- /* Return not checked because double check cannot be ignored */
+ ist_enter(regs); /* Discard prev_state because we won't return. */
notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
tsk->thread.error_code = error_code;
@@ -434,7 +469,7 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
if (poke_int3_handler(regs))
return;
- prev_state = exception_enter();
+ prev_state = ist_enter(regs);
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
@@ -460,7 +495,7 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code)
preempt_conditional_cli(regs);
debug_stack_usage_dec();
exit:
- exception_exit(prev_state);
+ ist_exit(regs, prev_state);
}
NOKPROBE_SYMBOL(do_int3);
@@ -541,7 +576,7 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
unsigned long dr6;
int si_code;
- prev_state = exception_enter();
+ prev_state = ist_enter(regs);
get_debugreg(dr6, 6);
@@ -616,7 +651,7 @@ dotraplinkage void do_debug(struct pt_regs *regs, long error_code)
debug_stack_usage_dec();
exit:
- exception_exit(prev_state);
+ ist_exit(regs, prev_state);
}
NOKPROBE_SYMBOL(do_debug);