6 files changed, 104 insertions, 23 deletions

diff --git a/arch/i386/Kconfig.debug b/arch/i386/Kconfig.debug
index b20ddd04f3d8..b31c0802e1cc 100644
--- a/arch/i386/Kconfig.debug
+++ b/arch/i386/Kconfig.debug
@@ -1,5 +1,9 @@
 menu "Kernel hacking"
 
+config TRACE_IRQFLAGS_SUPPORT
+        bool
+        default y
+
 source "lib/Kconfig.debug"
 
 config EARLY_PRINTK
diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 787190c45fdb..d9a260f2efb4 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -42,6 +42,7 @@
 
 #include <linux/linkage.h>
 #include <asm/thread_info.h>
+#include <asm/irqflags.h>
 #include <asm/errno.h>
 #include <asm/segment.h>
 #include <asm/smp.h>
@@ -76,12 +77,21 @@ NT_MASK		= 0x00004000
 VM_MASK         = 0x00020000
 
 #ifdef CONFIG_PREEMPT
-#define preempt_stop            cli
+#define preempt_stop            cli; TRACE_IRQS_OFF
 #else
 #define preempt_stop
 #define resume_kernel           restore_nocheck
 #endif
 
+.macro TRACE_IRQS_IRET
+#ifdef CONFIG_TRACE_IRQFLAGS
+        testl $IF_MASK,EFLAGS(%esp)     # interrupts off?
+        jz 1f
+        TRACE_IRQS_ON
+1:
+#endif
+.endm
+
 #ifdef CONFIG_VM86
 #define resume_userspace_sig    check_userspace
 #else
@@ -257,6 +267,10 @@ ENTRY(sysenter_entry)
         CFI_REGISTER esp, ebp
         movl TSS_sysenter_esp0(%esp),%esp
 sysenter_past_esp:
+        /*
+         * No need to follow this irqs on/off section: the syscall
+         * disabled irqs and here we enable it straight after entry:
+         */
         sti
         pushl $(__USER_DS)
         CFI_ADJUST_CFA_OFFSET 4
@@ -303,6 +317,7 @@ sysenter_past_esp:
         call *sys_call_table(,%eax,4)
         movl %eax,EAX(%esp)
         cli
+        TRACE_IRQS_OFF
         movl TI_flags(%ebp), %ecx
         testw $_TIF_ALLWORK_MASK, %cx
         jne syscall_exit_work
@@ -310,6 +325,7 @@ sysenter_past_esp:
         movl EIP(%esp), %edx
         movl OLDESP(%esp), %ecx
         xorl %ebp,%ebp
+        TRACE_IRQS_ON
         sti
         sysexit
         CFI_ENDPROC
@@ -339,6 +355,7 @@ syscall_exit:
         cli                             # make sure we don't miss an interrupt
                                         # setting need_resched or sigpending
                                         # between sampling and the iret
+        TRACE_IRQS_OFF
         movl TI_flags(%ebp), %ecx
         testw $_TIF_ALLWORK_MASK, %cx   # current->work
         jne syscall_exit_work
@@ -355,12 +372,15 @@ restore_all:
         CFI_REMEMBER_STATE
         je ldt_ss                       # returning to user-space with LDT SS
 restore_nocheck:
+        TRACE_IRQS_IRET
+restore_nocheck_notrace:
         RESTORE_REGS
         addl $4, %esp
         CFI_ADJUST_CFA_OFFSET -4
 1:      iret
 .section .fixup,"ax"
 iret_exc:
+        TRACE_IRQS_ON
         sti
         pushl $0                        # no error code
         pushl $do_iret_error
@@ -386,11 +406,13 @@ ldt_ss:
         subl $8, %esp           # reserve space for switch16 pointer
         CFI_ADJUST_CFA_OFFSET 8
         cli
+        TRACE_IRQS_OFF
         movl %esp, %eax
         /* Set up the 16bit stack frame with switch32 pointer on top,
          * and a switch16 pointer on top of the current frame. */
         call setup_x86_bogus_stack
         CFI_ADJUST_CFA_OFFSET -8        # frame has moved
+        TRACE_IRQS_IRET
         RESTORE_REGS
         lss 20+4(%esp), %esp    # switch to 16bit stack
 1:      iret
@@ -411,6 +433,7 @@ work_resched:
         cli                             # make sure we don't miss an interrupt
                                         # setting need_resched or sigpending
                                         # between sampling and the iret
+        TRACE_IRQS_OFF
         movl TI_flags(%ebp), %ecx
         andl $_TIF_WORK_MASK, %ecx      # is there any work to be done other
                                         # than syscall tracing?
@@ -462,6 +485,7 @@ syscall_trace_entry:
 syscall_exit_work:
         testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP), %cl
         jz work_pending
+        TRACE_IRQS_ON
         sti                             # could let do_syscall_trace() call
                                         # schedule() instead
         movl %esp, %eax
@@ -535,9 +559,14 @@ ENTRY(irq_entries_start)
 vector=vector+1
 .endr
 
+/*
+ * the CPU automatically disables interrupts when executing an IRQ vector,
+ * so IRQ-flags tracing has to follow that:
+ */
         ALIGN
 common_interrupt:
         SAVE_ALL
+        TRACE_IRQS_OFF
         movl %esp,%eax
         call do_IRQ
         jmp ret_from_intr
@@ -549,9 +578,10 @@ ENTRY(name)				\
         pushl $~(nr);                   \
         CFI_ADJUST_CFA_OFFSET 4;        \
         SAVE_ALL;                       \
+        TRACE_IRQS_OFF                  \
         movl %esp,%eax;                 \
         call smp_/**/name;              \
-        jmp ret_from_intr;      \
+        jmp ret_from_intr;              \
         CFI_ENDPROC
 
 /* The include is where all of the SMP etc. interrupts come from */
@@ -726,7 +756,7 @@ nmi_stack_correct:
         xorl %edx,%edx          # zero error code
         movl %esp,%eax          # pt_regs pointer
         call do_nmi
-        jmp restore_all
+        jmp restore_nocheck_notrace
         CFI_ENDPROC
 
 nmi_stack_fixup:
diff --git a/arch/i386/kernel/irq.c b/arch/i386/kernel/irq.c
index 16b491703967..6cb529f60dcc 100644
--- a/arch/i386/kernel/irq.c
+++ b/arch/i386/kernel/irq.c
@@ -166,7 +166,7 @@ void irq_ctx_init(int cpu)
         irqctx->tinfo.task              = NULL;
         irqctx->tinfo.exec_domain       = NULL;
         irqctx->tinfo.cpu               = cpu;
-        irqctx->tinfo.preempt_count     = SOFTIRQ_OFFSET;
+        irqctx->tinfo.preempt_count     = 0;
         irqctx->tinfo.addr_limit        = MAKE_MM_SEG(0);
 
         softirq_ctx[cpu] = irqctx;
@@ -211,6 +211,10 @@ asmlinkage void do_softirq(void)
                         : "0"(isp)
                         : "memory", "cc", "edx", "ecx", "eax"
                 );
+                /*
+                 * Shouldnt happen, we returned above if in_interrupt():
+                 */
+                WARN_ON_ONCE(softirq_count());
         }
 
         local_irq_restore(flags);
diff --git a/include/asm-i386/irqflags.h b/include/asm-i386/irqflags.h
new file mode 100644
index 000000000000..ca777e894c92
--- /dev/null
+++ b/include/asm-i386/irqflags.h
@@ -0,0 +1,56 @@
+/*
+ * include/asm-i386/irqflags.h
+ *
+ * IRQ flags handling
+ *
+ * This file gets included from lowlevel asm headers too, to provide
+ * wrapped versions of the local_irq_*() APIs, based on the
+ * raw_local_irq_*() macros from the lowlevel headers.
+ */
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+#define raw_local_save_flags(x) do { typecheck(unsigned long,x); __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */); } while (0)
+#define raw_local_irq_restore(x) do { typecheck(unsigned long,x); __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc"); } while (0)
+#define raw_local_irq_disable() __asm__ __volatile__("cli": : :"memory")
+#define raw_local_irq_enable()  __asm__ __volatile__("sti": : :"memory")
+/* used in the idle loop; sti takes one instruction cycle to complete */
+#define raw_safe_halt()         __asm__ __volatile__("sti; hlt": : :"memory")
+/* used when interrupts are already enabled or to shutdown the processor */
+#define halt()                  __asm__ __volatile__("hlt": : :"memory")
+
+#define raw_irqs_disabled_flags(flags)  (!((flags) & (1<<9)))
+
+/* For spinlocks etc */
+#define raw_local_irq_save(x)   __asm__ __volatile__("pushfl ; popl %0 ; cli":"=g" (x): /* no input */ :"memory")
+
+/*
+ * Do the CPU's IRQ-state tracing from assembly code. We call a
+ * C function, so save all the C-clobbered registers:
+ */
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+# define TRACE_IRQS_ON                          \
+        pushl %eax;                             \
+        pushl %ecx;                             \
+        pushl %edx;                             \
+        call trace_hardirqs_on;                 \
+        popl %edx;                              \
+        popl %ecx;                              \
+        popl %eax;
+
+# define TRACE_IRQS_OFF                         \
+        pushl %eax;                             \
+        pushl %ecx;                             \
+        pushl %edx;                             \
+        call trace_hardirqs_off;                \
+        popl %edx;                              \
+        popl %ecx;                              \
+        popl %eax;
+
+#else
+# define TRACE_IRQS_ON
+# define TRACE_IRQS_OFF
+#endif
+
+#endif
diff --git a/include/asm-i386/spinlock.h b/include/asm-i386/spinlock.h
index 04ba30234c48..7e29b51bcaa0 100644
--- a/include/asm-i386/spinlock.h
+++ b/include/asm-i386/spinlock.h
@@ -31,6 +31,11 @@
         "jmp 1b\n" \
         "3:\n\t"
 
+/*
+ * NOTE: there's an irqs-on section here, which normally would have to be
+ * irq-traced, but on CONFIG_TRACE_IRQFLAGS we never use
+ * __raw_spin_lock_string_flags().
+ */
 #define __raw_spin_lock_string_flags \
         "\n1:\t" \
         "lock ; decb %0\n\t" \
diff --git a/include/asm-i386/system.h b/include/asm-i386/system.h
index cab0180567f9..db398d88b1d9 100644
--- a/include/asm-i386/system.h
+++ b/include/asm-i386/system.h
@@ -456,25 +456,7 @@ static inline unsigned long long __cmpxchg64(volatile void *ptr, unsigned long l
 
 #define set_wmb(var, value) do { var = value; wmb(); } while (0)
 
-/* interrupt control.. */
-#define local_save_flags(x)     do { typecheck(unsigned long,x); __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */); } while (0)
-#define local_irq_restore(x)    do { typecheck(unsigned long,x); __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc"); } while (0)
-#define local_irq_disable()     __asm__ __volatile__("cli": : :"memory")
-#define local_irq_enable()      __asm__ __volatile__("sti": : :"memory")
-/* used in the idle loop; sti takes one instruction cycle to complete */
-#define safe_halt()             __asm__ __volatile__("sti; hlt": : :"memory")
-/* used when interrupts are already enabled or to shutdown the processor */
-#define halt()                  __asm__ __volatile__("hlt": : :"memory")
-
-#define irqs_disabled()                 \
-({                                      \
-        unsigned long flags;            \
-        local_save_flags(flags);        \
-        !(flags & (1<<9));              \
-})
-
-/* For spinlocks etc */
-#define local_irq_save(x)       __asm__ __volatile__("pushfl ; popl %0 ; cli":"=g" (x): /* no input */ :"memory")
+#include <linux/irqflags.h>
 
 /*
  * disable hlt during certain critical i/o operations