[patch] lock validator: reenable NMIs

From: Ingo Molnar
Date: Thu Jun 22 2006 - 04:25:58 EST

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Subject: lock validator: reenable NMIs
From: Ingo Molnar <mingo@xxxxxxx>

- not touch the irqtrace state in NMI handlers
- re-enable NMIs and oprofile on i386 and x86_64

i have tested this with high-rate (10 KHz per CPU) NMI load on the
kernel, and while previously we'd quickly get the irqtrace state
confused and a lock validator bug message, with this patch applied it's
now working fine.

(note that on x86_64 we only build one variant of the paranoid-exit
codepath if IRQTRACE is disabled - so there should be no difference
in code generated, as long as the validator is disabled)

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
arch/i386/kernel/nmi.c | 10 ---
arch/i386/oprofile/Kconfig | 2
arch/x86_64/kernel/entry.S | 133 ++++++++++++++++++++++++-------------------
arch/x86_64/kernel/nmi.c | 11 ---
arch/x86_64/oprofile/Kconfig | 2
include/linux/hardirq.h | 4 -
kernel/lockdep.c | 16 ++---
7 files changed, 89 insertions(+), 89 deletions(-)

Index: linux/arch/i386/kernel/nmi.c
===================================================================
--- linux.orig/arch/i386/kernel/nmi.c
+++ linux/arch/i386/kernel/nmi.c
@@ -747,16 +747,6 @@ void setup_apic_nmi_watchdog (void *unus
{
struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

-#ifdef CONFIG_LOCKDEP
- /*
- * The NMI watchdog uses spinlocks (notifier chains, etc.),
- * so it's not lockdep-safe:
- */
- nmi_watchdog = NMI_NONE;
- printk("lockdep: disabled NMI watchdog.\n");
-
- return;
-#endif
/* only support LOCAL and IO APICs for now */
if ((nmi_watchdog != NMI_LOCAL_APIC) &&
(nmi_watchdog != NMI_IO_APIC))
Index: linux/arch/i386/oprofile/Kconfig
===================================================================
--- linux.orig/arch/i386/oprofile/Kconfig
+++ linux/arch/i386/oprofile/Kconfig
@@ -7,7 +7,7 @@ config PROFILING

config OPROFILE
tristate "OProfile system profiling (EXPERIMENTAL)"
- depends on PROFILING && !LOCKDEP
+ depends on PROFILING
help
OProfile is a profiling system capable of profiling the
whole system, include the kernel, kernel modules, libraries,
Index: linux/arch/x86_64/kernel/entry.S
===================================================================
--- linux.orig/arch/x86_64/kernel/entry.S
+++ linux/arch/x86_64/kernel/entry.S
@@ -718,7 +718,7 @@ END(spurious_interrupt)

/* error code is on the stack already */
/* handle NMI like exceptions that can happen everywhere */
- .macro paranoidentry sym, ist=0
+ .macro paranoidentry sym, ist=0, irqtrace=1
SAVE_ALL
cld
movl $1,%ebx
@@ -743,9 +743,73 @@ END(spurious_interrupt)
addq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
.endif
cli
+ .if \irqtrace
TRACE_IRQS_OFF
+ .endif
.endm
-
+
+ /*
+ * "Paranoid" exit path from exception stack.
+ * Paranoid because this is used by NMIs and cannot take
+ * any kernel state for granted.
+ * We don't do kernel preemption checks here, because only
+ * NMI should be common and it does not enable IRQs and
+ * cannot get reschedule ticks.
+ *
+ * "trace" is 0 for the NMI handler only, because irq-tracing
+ * is fundamentally NMI-unsafe. (we cannot change the soft and
+ * hard flags at once, atomically)
+ */
+ .macro paranoidexit trace=1
+ /* ebx: no swapgs flag */
+paranoid_exit\trace:
+ testl %ebx,%ebx /* swapgs needed? */
+ jnz paranoid_restore\trace
+ testl $3,CS(%rsp)
+ jnz paranoid_userspace\trace
+paranoid_swapgs\trace:
+ TRACE_IRQS_IRETQ 0
+ swapgs
+paranoid_restore\trace:
+ RESTORE_ALL 8
+ iretq
+paranoid_userspace\trace:
+ GET_THREAD_INFO(%rcx)
+ movl threadinfo_flags(%rcx),%ebx
+ andl $_TIF_WORK_MASK,%ebx
+ jz paranoid_swapgs\trace
+ movq %rsp,%rdi /* &pt_regs */
+ call sync_regs
+ movq %rax,%rsp /* switch stack for scheduling */
+ testl $_TIF_NEED_RESCHED,%ebx
+ jnz paranoid_schedule\trace
+ movl %ebx,%edx /* arg3: thread flags */
+ .if \trace
+ TRACE_IRQS_ON
+ .endif
+ sti
+ xorl %esi,%esi /* arg2: oldset */
+ movq %rsp,%rdi /* arg1: &pt_regs */
+ call do_notify_resume
+ cli
+ .if \trace
+ TRACE_IRQS_OFF
+ .endif
+ jmp paranoid_userspace\trace
+paranoid_schedule\trace:
+ .if \trace
+ TRACE_IRQS_ON
+ .endif
+ sti
+ call schedule
+ cli
+ .if \trace
+ TRACE_IRQS_OFF
+ .endif
+ jmp paranoid_userspace\trace
+ CFI_ENDPROC
+ .endm
+
/*
* Exception entry point. This expects an error code/orig_rax on the stack
* and the exception handler in %rax.
@@ -974,8 +1038,7 @@ KPROBE_ENTRY(debug)
pushq $0
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_debug, DEBUG_STACK
- jmp paranoid_exit
- CFI_ENDPROC
+ paranoidexit
END(debug)
.previous .text

@@ -984,54 +1047,12 @@ KPROBE_ENTRY(nmi)
INTR_FRAME
pushq $-1
CFI_ADJUST_CFA_OFFSET 8
- paranoidentry do_nmi
- /*
- * "Paranoid" exit path from exception stack.
- * Paranoid because this is used by NMIs and cannot take
- * any kernel state for granted.
- * We don't do kernel preemption checks here, because only
- * NMI should be common and it does not enable IRQs and
- * cannot get reschedule ticks.
- */
- /* ebx: no swapgs flag */
-paranoid_exit:
- testl %ebx,%ebx /* swapgs needed? */
- jnz paranoid_restore
- testl $3,CS(%rsp)
- jnz paranoid_userspace
-paranoid_swapgs:
- TRACE_IRQS_IRETQ 0
- swapgs
-paranoid_restore:
- RESTORE_ALL 8
- iretq
-paranoid_userspace:
- GET_THREAD_INFO(%rcx)
- movl threadinfo_flags(%rcx),%ebx
- andl $_TIF_WORK_MASK,%ebx
- jz paranoid_swapgs
- movq %rsp,%rdi /* &pt_regs */
- call sync_regs
- movq %rax,%rsp /* switch stack for scheduling */
- testl $_TIF_NEED_RESCHED,%ebx
- jnz paranoid_schedule
- movl %ebx,%edx /* arg3: thread flags */
- TRACE_IRQS_ON
- sti
- xorl %esi,%esi /* arg2: oldset */
- movq %rsp,%rdi /* arg1: &pt_regs */
- call do_notify_resume
- cli
- TRACE_IRQS_OFF
- jmp paranoid_userspace
-paranoid_schedule:
- TRACE_IRQS_ON
- sti
- call schedule
- cli
- TRACE_IRQS_OFF
- jmp paranoid_userspace
- CFI_ENDPROC
+ paranoidentry do_nmi, 0, 0
+#ifdef CONFIG_TRACE_IRQFLAGS
+ paranoidexit 0
+#else
+ paranoidexit 1
+#endif
END(nmi)
.previous .text

@@ -1040,7 +1061,7 @@ KPROBE_ENTRY(int3)
pushq $0
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_int3, DEBUG_STACK
- jmp paranoid_exit
+ jmp paranoid_exit1
CFI_ENDPROC
END(int3)
.previous .text
@@ -1069,7 +1090,7 @@ END(reserved)
ENTRY(double_fault)
XCPT_FRAME
paranoidentry do_double_fault
- jmp paranoid_exit
+ jmp paranoid_exit1
CFI_ENDPROC
END(double_fault)

@@ -1085,7 +1106,7 @@ END(segment_not_present)
ENTRY(stack_segment)
XCPT_FRAME
paranoidentry do_stack_segment
- jmp paranoid_exit
+ jmp paranoid_exit1
CFI_ENDPROC
END(stack_segment)

@@ -1113,7 +1134,7 @@ ENTRY(machine_check)
pushq $0
CFI_ADJUST_CFA_OFFSET 8
paranoidentry do_machine_check
- jmp paranoid_exit
+ jmp paranoid_exit1
CFI_ENDPROC
END(machine_check)
#endif
Index: linux/arch/x86_64/kernel/nmi.c
===================================================================
--- linux.orig/arch/x86_64/kernel/nmi.c
+++ linux/arch/x86_64/kernel/nmi.c
@@ -674,17 +674,6 @@ void setup_apic_nmi_watchdog(void *unuse
{
struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

-#ifdef CONFIG_LOCKDEP
- /*
- * The NMI watchdog uses spinlocks (notifier chains, etc.),
- * so it's not lockdep-safe:
- */
- nmi_watchdog = NMI_NONE;
- printk("lockdep: disabled NMI watchdog.\n");
-
- return;
-#endif
-
/* only support LOCAL and IO APICs for now */
if ((nmi_watchdog != NMI_LOCAL_APIC) &&
(nmi_watchdog != NMI_IO_APIC))
Index: linux/arch/x86_64/oprofile/Kconfig
===================================================================
--- linux.orig/arch/x86_64/oprofile/Kconfig
+++ linux/arch/x86_64/oprofile/Kconfig
@@ -7,7 +7,7 @@ config PROFILING

config OPROFILE
tristate "OProfile system profiling (EXPERIMENTAL)"
- depends on PROFILING && !LOCKDEP
+ depends on PROFILING
help
OProfile is a profiling system capable of profiling the
whole system, include the kernel, kernel modules, libraries,
Index: linux/include/linux/hardirq.h
===================================================================
--- linux.orig/include/linux/hardirq.h
+++ linux/include/linux/hardirq.h
@@ -122,7 +122,7 @@ static inline void account_system_vtime(
*/
extern void irq_exit(void);

-#define nmi_enter() irq_enter()
-#define nmi_exit() __irq_exit()
+#define nmi_enter() do { lockdep_off(); irq_enter(); } while (0)
+#define nmi_exit() do { __irq_exit(); lockdep_on(); } while (0)

#endif /* LINUX_HARDIRQ_H */
Index: linux/kernel/lockdep.c
===================================================================
--- linux.orig/kernel/lockdep.c
+++ linux/kernel/lockdep.c
@@ -1869,7 +1869,7 @@ void trace_hardirqs_on(void)
struct task_struct *curr = current;
unsigned long ip;

- if (unlikely(!debug_locks))
+ if (unlikely(!debug_locks || current->lockdep_recursion))
return;

if (DEBUG_WARN_ON(unlikely(!early_boot_irqs_enabled)))
@@ -1916,7 +1916,7 @@ void trace_hardirqs_off(void)
{
struct task_struct *curr = current;

- if (unlikely(!debug_locks))
+ if (unlikely(!debug_locks || current->lockdep_recursion))
return;

if (DEBUG_WARN_ON(!irqs_disabled()))
@@ -2488,16 +2488,16 @@ void lock_acquire(struct lockdep_map *lo
{
unsigned long flags;

+ if (unlikely(current->lockdep_recursion))
+ return;
+
raw_local_irq_save(flags);
check_flags(flags);

- if (unlikely(current->lockdep_recursion))
- goto out;
current->lockdep_recursion = 1;
__lock_acquire(lock, subtype, trylock, read, check,
irqs_disabled_flags(flags), ip);
current->lockdep_recursion = 0;
-out:
raw_local_irq_restore(flags);
}

@@ -2507,14 +2507,14 @@ void lock_release(struct lockdep_map *lo
{
unsigned long flags;

+ if (unlikely(current->lockdep_recursion))
+ return;
+
raw_local_irq_save(flags);
check_flags(flags);
- if (unlikely(current->lockdep_recursion))
- goto out;
current->lockdep_recursion = 1;
__lock_release(lock, nested, ip);
current->lockdep_recursion = 0;
-out:
raw_local_irq_restore(flags);
}

-
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Next message: Herbert Xu: "Re: Memory corruption in 8390.c ? (was Re: Possible leaks in network drivers)"
Previous message: David Miller: "Re: Memory corruption in 8390.c ?"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]