2 files changed, 58 insertions, 35 deletions

diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 01e7ca8c7661..076739863d24 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -7,13 +7,11 @@
  */
 
 /*
- * 'Traps.c' handles hardware traps and faults after we have saved some
- * state in 'asm.s'.
+ * Handle hardware traps and faults.
  */
 #include <linux/interrupt.h>
 #include <linux/kallsyms.h>
 #include <linux/spinlock.h>
-#include <linux/highmem.h>
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
 #include <linux/utsname.h>
@@ -32,6 +30,8 @@
 #include <linux/bug.h>
 #include <linux/nmi.h>
 #include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/io.h>
 
 #ifdef CONFIG_EISA
 #include <linux/ioport.h>
@@ -46,22 +46,26 @@
 #include <linux/edac.h>
 #endif
 
-#include <asm/processor-flags.h>
-#include <asm/arch_hooks.h>
 #include <asm/stacktrace.h>
 #include <asm/processor.h>
+#include <asm/kmemcheck.h>
 #include <asm/debugreg.h>
 #include <asm/atomic.h>
 #include <asm/system.h>
 #include <asm/unwind.h>
+#include <asm/traps.h>
 #include <asm/desc.h>
 #include <asm/i387.h>
+
+#include <mach_traps.h>
+
+#include <asm/processor-flags.h>
+#include <asm/arch_hooks.h>
 #include <asm/nmi.h>
 #include <asm/smp.h>
 #include <asm/io.h>
 #include <asm/traps.h>
 
-#include "mach_traps.h"
 #include "cpu/mcheck/mce.h"
 
 DECLARE_BITMAP(used_vectors, NR_VECTORS);
@@ -340,7 +344,8 @@ io_check_error(unsigned char reason, struct pt_regs *regs)
 static notrace __kprobes void
 unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
 {
-        if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) == NOTIFY_STOP)
+        if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) ==
+                        NOTIFY_STOP)
                 return;
 #ifdef CONFIG_MCA
         /*
@@ -446,13 +451,9 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
 dotraplinkage notrace __kprobes void
 do_nmi(struct pt_regs *regs, long error_code)
 {
-        int cpu;
-
         nmi_enter();
 
-        cpu = smp_processor_id();
-
-        ++nmi_count(cpu);
+        { int cpu; cpu = smp_processor_id(); ++nmi_count(cpu); }
 
         if (!ignore_nmis)
                 default_do_nmi(regs);
@@ -472,6 +473,7 @@ void restart_nmi(void)
         acpi_nmi_enable();
 }
 
+/* May run on IST stack. */
 dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
 {
 #ifdef CONFIG_KPROBES
@@ -510,6 +512,8 @@ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
  * about restoring all the debug state, and ptrace doesn't have to
  * find every occurrence of the TF bit that could be saved away even
  * by user code)
+ *
+ * May run on IST stack.
  */
 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 {
diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 71c2629997b3..22fe62a24edb 100644
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -7,10 +7,8 @@
  */
 
 /*
- * 'Traps.c' handles hardware traps and faults after we have saved some
- * state in 'entry.S'.
+ * Handle hardware traps and faults.
  */
-#include <linux/moduleparam.h>
 #include <linux/interrupt.h>
 #include <linux/kallsyms.h>
 #include <linux/spinlock.h>
@@ -41,18 +39,21 @@
 
 #include <asm/stacktrace.h>
 #include <asm/processor.h>
+#include <asm/kmemcheck.h>
 #include <asm/debugreg.h>
 #include <asm/atomic.h>
 #include <asm/system.h>
 #include <asm/unwind.h>
+#include <asm/traps.h>
 #include <asm/desc.h>
 #include <asm/i387.h>
+
+#include <mach_traps.h>
+
 #include <asm/pgalloc.h>
 #include <asm/proto.h>
 #include <asm/pda.h>
-#include <asm/traps.h>
 
-#include <mach_traps.h>
 
 static int ignore_nmis;
 
@@ -73,8 +74,6 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
 {
         if (regs->flags & X86_EFLAGS_IF)
                 local_irq_disable();
-        /* Make sure to not schedule here because we could be running
-           on an exception stack. */
         dec_preempt_count();
 }
 
@@ -228,9 +227,12 @@ gp_in_kernel:
 static notrace __kprobes void
 mem_parity_error(unsigned char reason, struct pt_regs *regs)
 {
-        printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x.\n",
-                reason);
-        printk(KERN_EMERG "You have some hardware problem, likely on the PCI bus.\n");
+        printk(KERN_EMERG
+                "Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
+                        reason, smp_processor_id());
+
+        printk(KERN_EMERG
+                "You have some hardware problem, likely on the PCI bus.\n");
 
 #if defined(CONFIG_EDAC)
         if (edac_handler_set()) {
@@ -275,19 +277,18 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
         if (notify_die(DIE_NMIUNKNOWN, "nmi", regs, reason, 2, SIGINT) ==
                         NOTIFY_STOP)
                 return;
-        printk(KERN_EMERG "Uhhuh. NMI received for unknown reason %02x.\n",
-                reason);
-        printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
+        printk(KERN_EMERG
+                "Uhhuh. NMI received for unknown reason %02x on CPU %d.\n",
+                        reason, smp_processor_id());
 
+        printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
         if (panic_on_unrecovered_nmi)
                 panic("NMI: Not continuing");
 
         printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
 }
 
-/* Runs on IST stack. This code must keep interrupts off all the time.
-   Nested NMIs are prevented by the CPU. */
-asmlinkage notrace __kprobes void default_do_nmi(struct pt_regs *regs)
+static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
 {
         unsigned char reason = 0;
         int cpu;
@@ -348,7 +349,7 @@ void restart_nmi(void)
         acpi_nmi_enable();
 }
 
-/* runs on IST stack. */
+/* May run on IST stack. */
 dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code)
 {
         if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP)
@@ -381,7 +382,30 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
         return regs;
 }
 
-/* runs on IST stack. */
+/*
+ * Our handling of the processor debug registers is non-trivial.
+ * We do not clear them on entry and exit from the kernel. Therefore
+ * it is possible to get a watchpoint trap here from inside the kernel.
+ * However, the code in ./ptrace.c has ensured that the user can
+ * only set watchpoints on userspace addresses. Therefore the in-kernel
+ * watchpoint trap can only occur in code which is reading/writing
+ * from user space. Such code must not hold kernel locks (since it
+ * can equally take a page fault), therefore it is safe to call
+ * force_sig_info even though that claims and releases locks.
+ *
+ * Code in ./signal.c ensures that the debug control register
+ * is restored before we deliver any signal, and therefore that
+ * user code runs with the correct debug control register even though
+ * we clear it here.
+ *
+ * Being careful here means that we don't have to be as careful in a
+ * lot of more complicated places (task switching can be a bit lazy
+ * about restoring all the debug state, and ptrace doesn't have to
+ * find every occurrence of the TF bit that could be saved away even
+ * by user code)
+ *
+ * May run on IST stack.
+ */
 dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 {
         struct task_struct *tsk = current;
@@ -525,11 +549,6 @@ dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
         math_error((void __user *)regs->ip);
 }
 
-asmlinkage void bad_intr(void)
-{
-        printk("bad interrupt");
-}
-
 static void simd_math_error(void __user *ip)
 {
         struct task_struct *task;