[PATCH 0/3] x86, nmi: Fixes

[PATCH 0/3] x86, nmi: Fixes

[Don Zickus]

The patch series started with fixes for kmemcheck but slowly involved
the fixing hpwdt.  Hopefully everything is ok for now.

Don Zickus (2):
  watchdog, hpwdt: Remove priority option for NMI callback
  x86, nmi: Add new NMI queues to deal with IO_CHK and SERR

Li Zhong (1):
  x86,nmi: Fix page faults by nmiaction if kmemcheck is enabled

 arch/x86/include/asm/nmi.h |   22 ++++++++++-
 arch/x86/kernel/nmi.c      |   83 +++++++++++++-------------------------------
 drivers/watchdog/hpwdt.c   |   46 +++++++++++++------------
 3 files changed, 68 insertions(+), 83 deletions(-)

-- 
1.7.7.6

[PATCH 1/3] watchdog, hpwdt: Remove priority option for NMI callback

[Don Zickus]

The NMI_UNKNOWN bucket only allows for one function to register to it.
The reason for that is because only functions which can not determine
if the NMI belongs to them or not should register and would like to
assume/swallow any NMI they see.

As a result it doesn't make sense to let more than one function like this
register.  In fact, letting a second function fail allows us to know that
more than one function is going to swallow NMIs on the current system.
This is better than silently being ignored.

Therefore hpwdt's priority mechanism doesn't make sense any more.  They
will be always first on the NMI_UNKNOWN queue, if they register.

Removing this parameter cleans up the code and simplifies things for the
next patch which changes how nmis are registered.

Cc: Thomas Mingarelli <thomas.mingarelli@hp.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Don Zickus <dzickus@redhat.com>
---
 drivers/watchdog/hpwdt.c |   19 ++++---------------
 1 files changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index 3c166d3..deee02c8 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -145,7 +145,6 @@ struct cmn_registers {
 
 static unsigned int hpwdt_nmi_decoding;
 static unsigned int allow_kdump;
-static unsigned int priority;		/* hpwdt at end of die_notify list */
 static unsigned int is_icru;
 static DEFINE_SPINLOCK(rom_lock);
 static void *cru_rom_addr;
@@ -730,13 +729,9 @@ static int __devinit hpwdt_init_nmi_decoding(struct pci_dev *dev)
 	}
 
 	/*
-	 * If the priority is set to 1, then we will be put first on the
-	 * die notify list to handle a critical NMI. The default is to
-	 * be last so other users of the NMI signal can function.
+	 * Only one function can register for NMI_UNKNOWN
 	 */
-	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout,
-					(priority) ? NMI_FLAG_FIRST : 0,
-					"hpwdt");
+	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout, 0, "hpwdt");
 	if (retval != 0) {
 		dev_warn(&dev->dev,
 			"Unable to register a die notifier (err=%d).\n",
@@ -747,10 +742,8 @@ static int __devinit hpwdt_init_nmi_decoding(struct pci_dev *dev)
 
 	dev_info(&dev->dev,
 			"HP Watchdog Timer Driver: NMI decoding initialized"
-			", allow kernel dump: %s (default = 0/OFF)"
-			", priority: %s (default = 0/LAST).\n",
-			(allow_kdump == 0) ? "OFF" : "ON",
-			(priority == 0) ? "LAST" : "FIRST");
+			", allow kernel dump: %s (default = 0/OFF)\n",
+			(allow_kdump == 0) ? "OFF" : "ON");
 	return 0;
 }
 
@@ -888,10 +881,6 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 #ifdef CONFIG_HPWDT_NMI_DECODING
 module_param(allow_kdump, int, 0);
 MODULE_PARM_DESC(allow_kdump, "Start a kernel dump after NMI occurs");
-
-module_param(priority, int, 0);
-MODULE_PARM_DESC(priority, "The hpwdt driver handles NMIs first or last"
-		" (default = 0/Last)\n");
 #endif /* !CONFIG_HPWDT_NMI_DECODING */
 
 module_init(hpwdt_init);
-- 
1.7.7.6

[PATCH 2/3] x86, nmi: Add new NMI queues to deal with IO_CHK and SERR

[Don Zickus]

In discussions with Thomas Mingarelli about hpwdt, he explained to me some
issues they were some when using their virtual NMI button to test the
hpwdt driver.

It turns out the virtual NMI button used on HP's machines do no send
unknown NMIs but instead send IO_CHK NMIs.  The way the kernel code
is written, the hpwdt driver can not register itself against that type
of NMI and therefore can not successfully capture system information
before panic'ing.

To solve this I created two new NMI queues to allow driver to register
against the IO_CHK and SERR NMIs.  Or in the hpwdt all three (if you
include unknown NMIs too).

The change is straightforward and just mimics what the unknown NMI does.

Reported-and-tested-by: Thomas Mingarelli <thomas.mingarelli@hp.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
---
 arch/x86/include/asm/nmi.h |    2 ++
 arch/x86/kernel/nmi.c      |   18 ++++++++++++++++++
 drivers/watchdog/hpwdt.c   |   27 ++++++++++++++++++++-------
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index fd3f9f1..07162df 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -27,6 +27,8 @@ void arch_trigger_all_cpu_backtrace(void);
 enum {
 	NMI_LOCAL=0,
 	NMI_UNKNOWN,
+	NMI_SERR,
+	NMI_IO_CHECK,
 	NMI_MAX
 };
 
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 47acaf3..ac9c1b7 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -54,6 +54,14 @@ static struct nmi_desc nmi_desc[NMI_MAX] =
 		.lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[1].lock),
 		.head = LIST_HEAD_INIT(nmi_desc[1].head),
 	},
+	{
+		.lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[2].lock),
+		.head = LIST_HEAD_INIT(nmi_desc[2].head),
+	},
+	{
+		.lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[3].lock),
+		.head = LIST_HEAD_INIT(nmi_desc[3].head),
+	},
 
 };
 
@@ -120,6 +128,8 @@ static int __setup_nmi(unsigned int type, struct nmiaction *action)
 	 * to manage expectations
 	 */
 	WARN_ON_ONCE(type == NMI_UNKNOWN && !list_empty(&desc->head));
+	WARN_ON_ONCE(type == NMI_SERR && !list_empty(&desc->head));
+	WARN_ON_ONCE(type == NMI_IO_CHECK && !list_empty(&desc->head));
 
 	/*
 	 * some handlers need to be executed first otherwise a fake
@@ -212,6 +222,10 @@ EXPORT_SYMBOL_GPL(unregister_nmi_handler);
 static notrace __kprobes void
 pci_serr_error(unsigned char reason, struct pt_regs *regs)
 {
+	/* check to see if anyone registered against these types of errors */
+	if (nmi_handle(NMI_SERR, regs, false))
+		return;
+
 	pr_emerg("NMI: PCI system error (SERR) for reason %02x on CPU %d.\n",
 		 reason, smp_processor_id());
 
@@ -241,6 +255,10 @@ io_check_error(unsigned char reason, struct pt_regs *regs)
 {
 	unsigned long i;
 
+	/* check to see if anyone registered against these types of errors */
+	if (nmi_handle(NMI_IO_CHECK, regs, false))
+		return;
+
 	pr_emerg(
 	"NMI: IOCK error (debug interrupt?) for reason %02x on CPU %d.\n",
 		 reason, smp_processor_id());
diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index deee02c8..e974c07 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -732,19 +732,32 @@ static int __devinit hpwdt_init_nmi_decoding(struct pci_dev *dev)
 	 * Only one function can register for NMI_UNKNOWN
 	 */
 	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout, 0, "hpwdt");
-	if (retval != 0) {
-		dev_warn(&dev->dev,
-			"Unable to register a die notifier (err=%d).\n",
-			retval);
-		if (cru_rom_addr)
-			iounmap(cru_rom_addr);
-	}
+	if (retval)
+		goto error;
+	retval = register_nmi_handler(NMI_SERR, hpwdt_pretimeout, 0, "hpwdt");
+	if (retval)
+		goto error1;
+	retval = register_nmi_handler(NMI_IO_CHECK, hpwdt_pretimeout, 0, "hpwdt");
+	if (retval)
+		goto error2;
 
 	dev_info(&dev->dev,
 			"HP Watchdog Timer Driver: NMI decoding initialized"
 			", allow kernel dump: %s (default = 0/OFF)\n",
 			(allow_kdump == 0) ? "OFF" : "ON");
 	return 0;
+
+error2:
+	unregister_nmi_handler(NMI_SERR, "hpwdt");
+error1:
+	unregister_nmi_handler(NMI_UNKNOWN, "hpwdt");
+error:
+	dev_warn(&dev->dev,
+		"Unable to register a die notifier (err=%d).\n",
+		retval);
+	if (cru_rom_addr)
+		iounmap(cru_rom_addr);
+	return retval;
 }
 
 static void hpwdt_exit_nmi_decoding(void)
-- 
1.7.7.6

[PATCH 3/3] x86,nmi: Fix page faults by nmiaction if kmemcheck is enabled

[Don Zickus]

From: Li Zhong <zhong@linux.vnet.ibm.com>

This patch tries to fix the problem of page fault exception caused by
accessing nmiaction structure in nmi if kmemcheck is enabled.

If kmemcheck is enabled, the memory allocated through slab are in pages
that are marked non-present, so that some checks could be done in the
page fault handling code ( e.g. whether the memory is read before
written to ).
As nmiaction is allocated in this way, so it resides in a non-present
page. Then there is a page fault while the nmi code accessing the
nmiaction structure, which would then cause a warning by
WARN_ON_ONCE(in_nmi()) in kmemcheck_fault(), called by do_page_fault().

v2: as Peter suggested, changed the nmiaction to use static storage.

v3: as Peter suggested, use macro to shorten the codes. Also keep the
original usage of register_nmi_handler, so users of this call doesn't
need change.

[simplified wrappers -dcz]

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
---
 arch/x86/include/asm/nmi.h |   20 ++++++++++++-
 arch/x86/kernel/nmi.c      |   65 ++++---------------------------------------
 2 files changed, 24 insertions(+), 61 deletions(-)

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index 07162df..730abfe 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -37,8 +37,24 @@ enum {
 
 typedef int (*nmi_handler_t)(unsigned int, struct pt_regs *);
 
-int register_nmi_handler(unsigned int, nmi_handler_t, unsigned long,
-			 const char *);
+struct nmiaction {
+	struct list_head list;
+	nmi_handler_t handler;
+	unsigned int flags;
+	const char *name;
+};
+
+#define register_nmi_handler(t, fn, fg, n)		\
+({							\
+	static struct nmiaction fn##_na = {		\
+		.handler = (fn),			\
+		.name = (n),				\
+		.flags = (fg),				\
+	};						\
+	__register_nmi_handler((t), &fn##_na);	\
+})
+
+int __register_nmi_handler(unsigned int, struct nmiaction *);
 
 void unregister_nmi_handler(unsigned int, const char *);
 
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index ac9c1b7..585be4b 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -31,14 +31,6 @@
 #include <asm/nmi.h>
 #include <asm/x86_init.h>
 
-#define NMI_MAX_NAMELEN	16
-struct nmiaction {
-	struct list_head list;
-	nmi_handler_t handler;
-	unsigned int flags;
-	char *name;
-};
-
 struct nmi_desc {
 	spinlock_t lock;
 	struct list_head head;
@@ -115,11 +107,14 @@ static int notrace __kprobes nmi_handle(unsigned int type, struct pt_regs *regs,
 	return handled;
 }
 
-static int __setup_nmi(unsigned int type, struct nmiaction *action)
+int __register_nmi_handler(unsigned int type, struct nmiaction *action)
 {
 	struct nmi_desc *desc = nmi_to_desc(type);
 	unsigned long flags;
 
+	if (!action->handler)
+		return -EINVAL;
+
 	spin_lock_irqsave(&desc->lock, flags);
 
 	/*
@@ -143,8 +138,9 @@ static int __setup_nmi(unsigned int type, struct nmiaction *action)
 	spin_unlock_irqrestore(&desc->lock, flags);
 	return 0;
 }
+EXPORT_SYMBOL(__register_nmi_handler);
 
-static struct nmiaction *__free_nmi(unsigned int type, const char *name)
+void unregister_nmi_handler(unsigned int type, const char *name)
 {
 	struct nmi_desc *desc = nmi_to_desc(type);
 	struct nmiaction *n;
@@ -167,56 +163,7 @@ static struct nmiaction *__free_nmi(unsigned int type, const char *name)
 
 	spin_unlock_irqrestore(&desc->lock, flags);
 	synchronize_rcu();
-	return (n);
 }
-
-int register_nmi_handler(unsigned int type, nmi_handler_t handler,
-			unsigned long nmiflags, const char *devname)
-{
-	struct nmiaction *action;
-	int retval = -ENOMEM;
-
-	if (!handler)
-		return -EINVAL;
-
-	action = kzalloc(sizeof(struct nmiaction), GFP_KERNEL);
-	if (!action)
-		goto fail_action;
-
-	action->handler = handler;
-	action->flags = nmiflags;
-	action->name = kstrndup(devname, NMI_MAX_NAMELEN, GFP_KERNEL);
-	if (!action->name)
-		goto fail_action_name;
-
-	retval = __setup_nmi(type, action);
-
-	if (retval)
-		goto fail_setup_nmi;
-
-	return retval;
-
-fail_setup_nmi:
-	kfree(action->name);
-fail_action_name:
-	kfree(action);
-fail_action:	
-
-	return retval;
-}
-EXPORT_SYMBOL_GPL(register_nmi_handler);
-
-void unregister_nmi_handler(unsigned int type, const char *name)
-{
-	struct nmiaction *a;
-
-	a = __free_nmi(type, name);
-	if (a) {
-		kfree(a->name);
-		kfree(a);
-	}
-}
-
 EXPORT_SYMBOL_GPL(unregister_nmi_handler);
 
 static notrace __kprobes void
-- 
1.7.7.6

RE: [PATCH 0/3] x86, nmi: Fixes

[Seiji Aguchi]

I tested this patch by making kernel panic with NMI switch and confirmed that it works well.
This patch solves an issue I found in 3.3.0-rc5 because kzalloc in register_nmi_handler() is removed.

https://lkml.org/lkml/2012/3/2/356

Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Don Zickus
> Sent: Thursday, March 29, 2012 4:11 PM
> To: x86@kernel.org
> Cc: LKML; Peter Zijlstra; thomas.mingarelli@hp.com; Don Zickus
> Subject: [PATCH 0/3] x86, nmi: Fixes
> 
> The patch series started with fixes for kmemcheck but slowly involved the fixing hpwdt.  Hopefully everything is ok for now.
> 
> Don Zickus (2):
>   watchdog, hpwdt: Remove priority option for NMI callback
>   x86, nmi: Add new NMI queues to deal with IO_CHK and SERR
> 
> Li Zhong (1):
>   x86,nmi: Fix page faults by nmiaction if kmemcheck is enabled
> 
>  arch/x86/include/asm/nmi.h |   22 ++++++++++-
>  arch/x86/kernel/nmi.c      |   83 +++++++++++++-------------------------------
>  drivers/watchdog/hpwdt.c   |   46 +++++++++++++------------
>  3 files changed, 68 insertions(+), 83 deletions(-)
> 
> --
> 1.7.7.6
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More
> majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

[tip:core/locking] watchdog, hpwdt: Remove priority option for NMI callback

[tip-bot for Don Zickus]

Commit-ID:  09ee10143658cd021d879ead61ead72a196302b6
Gitweb:     http://git.kernel.org/tip/09ee10143658cd021d879ead61ead72a196302b6
Author:     Don Zickus <dzickus@redhat.com>
AuthorDate: Thu, 29 Mar 2012 16:11:15 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 25 Apr 2012 12:43:33 +0200

watchdog, hpwdt: Remove priority option for NMI callback

The NMI_UNKNOWN bucket only allows for one function to register
to it. The reason for that is because only functions which can
not determine if the NMI belongs to them or not should register
and would like to assume/swallow any NMI they see.

As a result it doesn't make sense to let more than one function
like this register.  In fact, letting a second function fail
allows us to know that more than one function is going to
swallow NMIs on the current system. This is better than silently
being ignored.

Therefore hpwdt's priority mechanism doesn't make sense any
more.  They will be always first on the NMI_UNKNOWN queue, if
they register.

Removing this parameter cleans up the code and simplifies things
for the next patch which changes how nmis are registered.

Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Thomas Mingarelli <thomas.mingarelli@hp.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1333051877-15755-2-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 drivers/watchdog/hpwdt.c |   19 ++++---------------
 1 files changed, 4 insertions(+), 15 deletions(-)

diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index cbc7cee..4000b80 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -147,7 +147,6 @@ struct cmn_registers {
 
 static unsigned int hpwdt_nmi_decoding;
 static unsigned int allow_kdump;
-static unsigned int priority;		/* hpwdt at end of die_notify list */
 static unsigned int is_icru;
 static DEFINE_SPINLOCK(rom_lock);
 static void *cru_rom_addr;
@@ -723,13 +722,9 @@ static int __devinit hpwdt_init_nmi_decoding(struct pci_dev *dev)
 	}
 
 	/*
-	 * If the priority is set to 1, then we will be put first on the
-	 * die notify list to handle a critical NMI. The default is to
-	 * be last so other users of the NMI signal can function.
+	 * Only one function can register for NMI_UNKNOWN
 	 */
-	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout,
-					(priority) ? NMI_FLAG_FIRST : 0,
-					"hpwdt");
+	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout, 0, "hpwdt");
 	if (retval != 0) {
 		dev_warn(&dev->dev,
 			"Unable to register a die notifier (err=%d).\n",
@@ -740,10 +735,8 @@ static int __devinit hpwdt_init_nmi_decoding(struct pci_dev *dev)
 
 	dev_info(&dev->dev,
 			"HP Watchdog Timer Driver: NMI decoding initialized"
-			", allow kernel dump: %s (default = 0/OFF)"
-			", priority: %s (default = 0/LAST).\n",
-			(allow_kdump == 0) ? "OFF" : "ON",
-			(priority == 0) ? "LAST" : "FIRST");
+			", allow kernel dump: %s (default = 0/OFF)\n",
+			(allow_kdump == 0) ? "OFF" : "ON");
 	return 0;
 }
 
@@ -881,10 +874,6 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 #ifdef CONFIG_HPWDT_NMI_DECODING
 module_param(allow_kdump, int, 0);
 MODULE_PARM_DESC(allow_kdump, "Start a kernel dump after NMI occurs");
-
-module_param(priority, int, 0);
-MODULE_PARM_DESC(priority, "The hpwdt driver handles NMIs first or last"
-		" (default = 0/Last)\n");
 #endif /* !CONFIG_HPWDT_NMI_DECODING */
 
 module_init(hpwdt_init);

[tip:core/locking] x86/nmi: Add new NMI queues to deal with IO_CHK and SERR

[tip-bot for Don Zickus]

Commit-ID:  553222f3e81f18da31b2552e18dc519715198590
Gitweb:     http://git.kernel.org/tip/553222f3e81f18da31b2552e18dc519715198590
Author:     Don Zickus <dzickus@redhat.com>
AuthorDate: Thu, 29 Mar 2012 16:11:16 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 25 Apr 2012 12:43:34 +0200

x86/nmi: Add new NMI queues to deal with IO_CHK and SERR

In discussions with Thomas Mingarelli about hpwdt, he explained
to me some issues they were some when using their virtual NMI
button to test the hpwdt driver.

It turns out the virtual NMI button used on HP's machines do no
send unknown NMIs but instead send IO_CHK NMIs.  The way the
kernel code is written, the hpwdt driver can not register itself
against that type of NMI and therefore can not successfully
capture system information before panic'ing.

To solve this I created two new NMI queues to allow driver to
register against the IO_CHK and SERR NMIs.  Or in the hpwdt all
three (if you include unknown NMIs too).

The change is straightforward and just mimics what the unknown
NMI does.

Reported-and-tested-by: Thomas Mingarelli <thomas.mingarelli@hp.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1333051877-15755-3-git-send-email-dzickus@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/nmi.h |    2 ++
 arch/x86/kernel/nmi.c      |   18 ++++++++++++++++++
 drivers/watchdog/hpwdt.c   |   27 ++++++++++++++++++++-------
 3 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index fd3f9f1..07162df 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -27,6 +27,8 @@ void arch_trigger_all_cpu_backtrace(void);
 enum {
 	NMI_LOCAL=0,
 	NMI_UNKNOWN,
+	NMI_SERR,
+	NMI_IO_CHECK,
 	NMI_MAX
 };
 
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 47acaf3..ac9c1b7 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -54,6 +54,14 @@ static struct nmi_desc nmi_desc[NMI_MAX] =
 		.lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[1].lock),
 		.head = LIST_HEAD_INIT(nmi_desc[1].head),
 	},
+	{
+		.lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[2].lock),
+		.head = LIST_HEAD_INIT(nmi_desc[2].head),
+	},
+	{
+		.lock = __SPIN_LOCK_UNLOCKED(&nmi_desc[3].lock),
+		.head = LIST_HEAD_INIT(nmi_desc[3].head),
+	},
 
 };
 
@@ -120,6 +128,8 @@ static int __setup_nmi(unsigned int type, struct nmiaction *action)
 	 * to manage expectations
 	 */
 	WARN_ON_ONCE(type == NMI_UNKNOWN && !list_empty(&desc->head));
+	WARN_ON_ONCE(type == NMI_SERR && !list_empty(&desc->head));
+	WARN_ON_ONCE(type == NMI_IO_CHECK && !list_empty(&desc->head));
 
 	/*
 	 * some handlers need to be executed first otherwise a fake
@@ -212,6 +222,10 @@ EXPORT_SYMBOL_GPL(unregister_nmi_handler);
 static notrace __kprobes void
 pci_serr_error(unsigned char reason, struct pt_regs *regs)
 {
+	/* check to see if anyone registered against these types of errors */
+	if (nmi_handle(NMI_SERR, regs, false))
+		return;
+
 	pr_emerg("NMI: PCI system error (SERR) for reason %02x on CPU %d.\n",
 		 reason, smp_processor_id());
 
@@ -241,6 +255,10 @@ io_check_error(unsigned char reason, struct pt_regs *regs)
 {
 	unsigned long i;
 
+	/* check to see if anyone registered against these types of errors */
+	if (nmi_handle(NMI_IO_CHECK, regs, false))
+		return;
+
 	pr_emerg(
 	"NMI: IOCK error (debug interrupt?) for reason %02x on CPU %d.\n",
 		 reason, smp_processor_id());
diff --git a/drivers/watchdog/hpwdt.c b/drivers/watchdog/hpwdt.c
index 4000b80..6e414b5 100644
--- a/drivers/watchdog/hpwdt.c
+++ b/drivers/watchdog/hpwdt.c
@@ -725,19 +725,32 @@ static int __devinit hpwdt_init_nmi_decoding(struct pci_dev *dev)
 	 * Only one function can register for NMI_UNKNOWN
 	 */
 	retval = register_nmi_handler(NMI_UNKNOWN, hpwdt_pretimeout, 0, "hpwdt");
-	if (retval != 0) {
-		dev_warn(&dev->dev,
-			"Unable to register a die notifier (err=%d).\n",
-			retval);
-		if (cru_rom_addr)
-			iounmap(cru_rom_addr);
-	}
+	if (retval)
+		goto error;
+	retval = register_nmi_handler(NMI_SERR, hpwdt_pretimeout, 0, "hpwdt");
+	if (retval)
+		goto error1;
+	retval = register_nmi_handler(NMI_IO_CHECK, hpwdt_pretimeout, 0, "hpwdt");
+	if (retval)
+		goto error2;
 
 	dev_info(&dev->dev,
 			"HP Watchdog Timer Driver: NMI decoding initialized"
 			", allow kernel dump: %s (default = 0/OFF)\n",
 			(allow_kdump == 0) ? "OFF" : "ON");
 	return 0;
+
+error2:
+	unregister_nmi_handler(NMI_SERR, "hpwdt");
+error1:
+	unregister_nmi_handler(NMI_UNKNOWN, "hpwdt");
+error:
+	dev_warn(&dev->dev,
+		"Unable to register a die notifier (err=%d).\n",
+		retval);
+	if (cru_rom_addr)
+		iounmap(cru_rom_addr);
+	return retval;
 }
 
 static void hpwdt_exit_nmi_decoding(void)

[tip:core/locking] x86/nmi: Fix page faults by nmiaction if kmemcheck is enabled

[tip-bot for Li Zhong]

Commit-ID:  72b3fb24713755cf9740b403e95aa67ceedf3509
Gitweb:     http://git.kernel.org/tip/72b3fb24713755cf9740b403e95aa67ceedf3509
Author:     Li Zhong <zhong@linux.vnet.ibm.com>
AuthorDate: Thu, 29 Mar 2012 16:11:17 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 25 Apr 2012 12:44:06 +0200

x86/nmi: Fix page faults by nmiaction if kmemcheck is enabled

This patch tries to fix the problem of page fault exception
caused by accessing nmiaction structure in nmi if kmemcheck
is enabled.

If kmemcheck is enabled, the memory allocated through slab are
in pages that are marked non-present, so that some checks could
be done in the page fault handling code ( e.g. whether the
memory is read before written to ).

As nmiaction is allocated in this way, so it resides in a
non-present page. Then there is a page fault while the nmi code
accessing the nmiaction structure, which would then cause a
warning by WARN_ON_ONCE(in_nmi()) in kmemcheck_fault(), called
by do_page_fault().

This significantly simplifies the code as well, as the whole
dynamic allocation dance goes away.

v2: as Peter suggested, changed the nmiaction to use static
    storage.

v3: as Peter suggested, use macro to shorten the codes. Also
    keep the original usage of register_nmi_handler, so users of
    this call doesn't need change.

Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Fixes: https://lkml.org/lkml/2012/3/2/356
Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
[ simplified the wrappers ]
Signed-off-by: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: thomas.mingarelli@hp.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1333051877-15755-4-git-send-email-dzickus@redhat.com
[ tidied the patch a bit ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/nmi.h |   20 ++++++++++++-
 arch/x86/kernel/nmi.c      |   65 ++++---------------------------------------
 2 files changed, 24 insertions(+), 61 deletions(-)

diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h
index 07162df..a1a836c 100644
--- a/arch/x86/include/asm/nmi.h
+++ b/arch/x86/include/asm/nmi.h
@@ -37,8 +37,24 @@ enum {
 
 typedef int (*nmi_handler_t)(unsigned int, struct pt_regs *);
 
-int register_nmi_handler(unsigned int, nmi_handler_t, unsigned long,
-			 const char *);
+struct nmiaction {
+	struct list_head	list;
+	nmi_handler_t		handler;
+	unsigned int		flags;
+	const char		*name;
+};
+
+#define register_nmi_handler(t, fn, fg, n)		\
+({							\
+	static struct nmiaction fn##_na = {		\
+		.handler = (fn),			\
+		.name = (n),				\
+		.flags = (fg),				\
+	};						\
+	__register_nmi_handler((t), &fn##_na);	\
+})
+
+int __register_nmi_handler(unsigned int, struct nmiaction *);
 
 void unregister_nmi_handler(unsigned int, const char *);
 
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index ac9c1b7..585be4b 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -31,14 +31,6 @@
 #include <asm/nmi.h>
 #include <asm/x86_init.h>
 
-#define NMI_MAX_NAMELEN	16
-struct nmiaction {
-	struct list_head list;
-	nmi_handler_t handler;
-	unsigned int flags;
-	char *name;
-};
-
 struct nmi_desc {
 	spinlock_t lock;
 	struct list_head head;
@@ -115,11 +107,14 @@ static int notrace __kprobes nmi_handle(unsigned int type, struct pt_regs *regs,
 	return handled;
 }
 
-static int __setup_nmi(unsigned int type, struct nmiaction *action)
+int __register_nmi_handler(unsigned int type, struct nmiaction *action)
 {
 	struct nmi_desc *desc = nmi_to_desc(type);
 	unsigned long flags;
 
+	if (!action->handler)
+		return -EINVAL;
+
 	spin_lock_irqsave(&desc->lock, flags);
 
 	/*
@@ -143,8 +138,9 @@ static int __setup_nmi(unsigned int type, struct nmiaction *action)
 	spin_unlock_irqrestore(&desc->lock, flags);
 	return 0;
 }
+EXPORT_SYMBOL(__register_nmi_handler);
 
-static struct nmiaction *__free_nmi(unsigned int type, const char *name)
+void unregister_nmi_handler(unsigned int type, const char *name)
 {
 	struct nmi_desc *desc = nmi_to_desc(type);
 	struct nmiaction *n;
@@ -167,56 +163,7 @@ static struct nmiaction *__free_nmi(unsigned int type, const char *name)
 
 	spin_unlock_irqrestore(&desc->lock, flags);
 	synchronize_rcu();
-	return (n);
 }
-
-int register_nmi_handler(unsigned int type, nmi_handler_t handler,
-			unsigned long nmiflags, const char *devname)
-{
-	struct nmiaction *action;
-	int retval = -ENOMEM;
-
-	if (!handler)
-		return -EINVAL;
-
-	action = kzalloc(sizeof(struct nmiaction), GFP_KERNEL);
-	if (!action)
-		goto fail_action;
-
-	action->handler = handler;
-	action->flags = nmiflags;
-	action->name = kstrndup(devname, NMI_MAX_NAMELEN, GFP_KERNEL);
-	if (!action->name)
-		goto fail_action_name;
-
-	retval = __setup_nmi(type, action);
-
-	if (retval)
-		goto fail_setup_nmi;
-
-	return retval;
-
-fail_setup_nmi:
-	kfree(action->name);
-fail_action_name:
-	kfree(action);
-fail_action:	
-
-	return retval;
-}
-EXPORT_SYMBOL_GPL(register_nmi_handler);
-
-void unregister_nmi_handler(unsigned int type, const char *name)
-{
-	struct nmiaction *a;
-
-	a = __free_nmi(type, name);
-	if (a) {
-		kfree(a->name);
-		kfree(a);
-	}
-}
-
 EXPORT_SYMBOL_GPL(unregister_nmi_handler);
 
 static notrace __kprobes void

Re: [tip:core/locking] watchdog, hpwdt: Remove priority option for NMI callback

[Wim Van Sebroeck]

Hi All,

> Commit-ID:  09ee10143658cd021d879ead61ead72a196302b6
> Gitweb:     http://git.kernel.org/tip/09ee10143658cd021d879ead61ead72a196302b6
> Author:     Don Zickus <dzickus@redhat.com>
> AuthorDate: Thu, 29 Mar 2012 16:11:15 -0400
> Committer:  Ingo Molnar <mingo@kernel.org>
> CommitDate: Wed, 25 Apr 2012 12:43:33 +0200
> 
> watchdog, hpwdt: Remove priority option for NMI callback
> 
> The NMI_UNKNOWN bucket only allows for one function to register
> to it. The reason for that is because only functions which can
> not determine if the NMI belongs to them or not should register
> and would like to assume/swallow any NMI they see.
> 
> As a result it doesn't make sense to let more than one function
> like this register.  In fact, letting a second function fail
> allows us to know that more than one function is going to
> swallow NMIs on the current system. This is better than silently
> being ignored.
> 
> Therefore hpwdt's priority mechanism doesn't make sense any
> more.  They will be always first on the NMI_UNKNOWN queue, if
> they register.
> 
> Removing this parameter cleans up the code and simplifies things
> for the next patch which changes how nmis are registered.
> 
> Signed-off-by: Don Zickus <dzickus@redhat.com>
> Cc: Thomas Mingarelli <thomas.mingarelli@hp.com>
> Cc: Wim Van Sebroeck <wim@iguana.be>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Link: http://lkml.kernel.org/r/1333051877-15755-2-git-send-email-dzickus@redhat.com
> Signed-off-by: Ingo Molnar <mingo@kernel.org>

This is the feedback I have from Tom which he discussed with Don:
> I don't like this patch because the Virtual NMI button doesn't come through the pretimeout routine. It is taken by the
system as an IOCK NMI error and no log messages in our IML.
> Our BIOS is not able to source the NMI.

And since then it became quiet. Imho: this needs more discussion...

Kind regards,
Wim.

Re: [tip:core/locking] watchdog, hpwdt: Remove priority option for NMI callback

[Don Zickus]

On Thu, Apr 26, 2012 at 09:13:39AM +0200, Wim Van Sebroeck wrote:
> > 
> > Therefore hpwdt's priority mechanism doesn't make sense any
> > more.  They will be always first on the NMI_UNKNOWN queue, if
> > they register.
> > 
> > Removing this parameter cleans up the code and simplifies things
> > for the next patch which changes how nmis are registered.
> > 
> > Signed-off-by: Don Zickus <dzickus@redhat.com>
> > Cc: Thomas Mingarelli <thomas.mingarelli@hp.com>
> > Cc: Wim Van Sebroeck <wim@iguana.be>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Linus Torvalds <torvalds@linux-foundation.org>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Link: http://lkml.kernel.org/r/1333051877-15755-2-git-send-email-dzickus@redhat.com
> > Signed-off-by: Ingo Molnar <mingo@kernel.org>
> 
> This is the feedback I have from Tom which he discussed with Don:
> > I don't like this patch because the Virtual NMI button doesn't come through the pretimeout routine. It is taken by the
> system as an IOCK NMI error and no log messages in our IML.
> > Our BIOS is not able to source the NMI.
> 
> And since then it became quiet. Imho: this needs more discussion...

Tom and I discussed this offline.  The result was patch 2 of this series.
The problem he had, had nothing to do with this patch (which was just a
cleanup really).  Tom tested the second patch and was happy with the
results.

If there is any other issues, I am assuming Tom would have let me know a
while ago.  But I believe all his issues are addressed.  Tom?

Cheers,
Don

RE: [tip:core/locking] watchdog, hpwdt: Remove priority option for NMI callback

[Mingarelli, Thomas]

Wim:


Don is correct. We did have a separate discussion about this after I denied the original patch. It is all good now.

And thanks for cutting in the port 0x72 patch.

Thanks,
Tom 

-----Original Message-----
From: Don Zickus [mailto:dzickus@redhat.com] 
Sent: Thursday, April 26, 2012 7:27 AM
To: Wim Van Sebroeck
Cc: mingo@kernel.org; hpa@zytor.com; linux-kernel@vger.kernel.org; torvalds@linux-foundation.org; peterz@infradead.org; Mingarelli, Thomas; akpm@linux-foundation.org; tglx@linutronix.de; linux-tip-commits@vger.kernel.org
Subject: Re: [tip:core/locking] watchdog, hpwdt: Remove priority option for NMI callback

On Thu, Apr 26, 2012 at 09:13:39AM +0200, Wim Van Sebroeck wrote:
> > 
> > Therefore hpwdt's priority mechanism doesn't make sense any
> > more.  They will be always first on the NMI_UNKNOWN queue, if
> > they register.
> > 
> > Removing this parameter cleans up the code and simplifies things
> > for the next patch which changes how nmis are registered.
> > 
> > Signed-off-by: Don Zickus <dzickus@redhat.com>
> > Cc: Thomas Mingarelli <thomas.mingarelli@hp.com>
> > Cc: Wim Van Sebroeck <wim@iguana.be>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Linus Torvalds <torvalds@linux-foundation.org>
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Link: http://lkml.kernel.org/r/1333051877-15755-2-git-send-email-dzickus@redhat.com
> > Signed-off-by: Ingo Molnar <mingo@kernel.org>
> 
> This is the feedback I have from Tom which he discussed with Don:
> > I don't like this patch because the Virtual NMI button doesn't come through the pretimeout routine. It is taken by the
> system as an IOCK NMI error and no log messages in our IML.
> > Our BIOS is not able to source the NMI.
> 
> And since then it became quiet. Imho: this needs more discussion...

Tom and I discussed this offline.  The result was patch 2 of this series.
The problem he had, had nothing to do with this patch (which was just a
cleanup really).  Tom tested the second patch and was happy with the
results.

If there is any other issues, I am assuming Tom would have let me know a
while ago.  But I believe all his issues are addressed.  Tom?

Cheers,
Don

Re: [tip:core/locking] watchdog, hpwdt: Remove priority option for NMI callback

[Wim Van Sebroeck]

Hi All,

> Wim:
> 
> 
> Don is correct. We did have a separate discussion about this after I denied the original patch. It is all good now.
> 
> And thanks for cutting in the port 0x72 patch.
> 
> Thanks,
> Tom 

Then this is also OK for me.
You can add an Acked-by me :-).

Kind regards,
Wim.