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Message-ID: <20100723125505.GQ7330@redhat.com>
Date: Fri, 23 Jul 2010 08:55:05 -0400
From: Don Zickus <dzickus@...hat.com>
To: Yinghai Lu <yinghai@...nel.org>
Cc: fweisbec@...il.com, peterz@...radead.org, mingo@...e.hu,
linux-kernel@...r.kernel.org
Subject: Re: [RFC] x86: perf swallows all NMIs when registered with a user
On Thu, Jul 22, 2010 at 03:58:21PM -0700, Yinghai Lu wrote:
> cool, with your patch and following patch i can use nmi button now with CONFIG_LOCKUP_DETECTOR defined
>
> [PATCH] x86,nmi: move unknown_nmi_panic to traps.c
>
> So we use it even LOCKUP_DETECTOR is defined.
>
> need Don's patch...
Thanks for the feedback Yinghai!
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
With regards to your patch, I am still a little uncomfortable with it, as
it seems to be redundant with what is used in unknown_nmi_error() and the
panic_on_unrecovered_nmi flag. I agree that keeping the familiar flag
'unknown_nmi_panic' is needed. But I was still wondering if wrapping it
around 'panic_on_unrecovered_nmi' would be simpler and less code.
Cheers,
Don
>
> ---
> arch/x86/include/asm/nmi.h | 8 --------
> arch/x86/kernel/apic/hw_nmi.c | 1 -
> arch/x86/kernel/apic/nmi.c | 27 ---------------------------
> arch/x86/kernel/traps.c | 29 ++++++++++++++++++++++++++++-
> kernel/sysctl.c | 4 +++-
> 5 files changed, 31 insertions(+), 38 deletions(-)
>
> Index: linux-2.6/arch/x86/kernel/apic/nmi.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/apic/nmi.c
> +++ linux-2.6/arch/x86/kernel/apic/nmi.c
> @@ -37,7 +37,6 @@
>
> #include <asm/mach_traps.h>
>
> -int unknown_nmi_panic;
> int nmi_watchdog_enabled;
>
> /* For reliability, we're prepared to waste bits here. */
> @@ -483,23 +482,6 @@ static void disable_ioapic_nmi_watchdog(
> on_each_cpu(stop_apic_nmi_watchdog, NULL, 1);
> }
>
> -static int __init setup_unknown_nmi_panic(char *str)
> -{
> - unknown_nmi_panic = 1;
> - return 1;
> -}
> -__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
> -
> -static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
> -{
> - unsigned char reason = get_nmi_reason();
> - char buf[64];
> -
> - sprintf(buf, "NMI received for unknown reason %02x\n", reason);
> - die_nmi(buf, regs, 1); /* Always panic here */
> - return 0;
> -}
> -
> /*
> * proc handler for /proc/sys/kernel/nmi
> */
> @@ -540,15 +522,6 @@ int proc_nmi_enabled(struct ctl_table *t
>
> #endif /* CONFIG_SYSCTL */
>
> -int do_nmi_callback(struct pt_regs *regs, int cpu)
> -{
> -#ifdef CONFIG_SYSCTL
> - if (unknown_nmi_panic)
> - return unknown_nmi_panic_callback(regs, cpu);
> -#endif
> - return 0;
> -}
> -
> void arch_trigger_all_cpu_backtrace(void)
> {
> int i;
> Index: linux-2.6/arch/x86/kernel/apic/hw_nmi.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/apic/hw_nmi.c
> +++ linux-2.6/arch/x86/kernel/apic/hw_nmi.c
> @@ -100,7 +100,6 @@ void acpi_nmi_disable(void) { return; }
> #endif
> atomic_t nmi_active = ATOMIC_INIT(0); /* oprofile uses this */
> EXPORT_SYMBOL(nmi_active);
> -int unknown_nmi_panic;
> void cpu_nmi_set_wd_enabled(void) { return; }
> void stop_apic_nmi_watchdog(void *unused) { return; }
> void setup_apic_nmi_watchdog(void *unused) { return; }
> Index: linux-2.6/arch/x86/kernel/traps.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/traps.c
> +++ linux-2.6/arch/x86/kernel/traps.c
> @@ -377,6 +377,33 @@ unknown_nmi_error(unsigned char reason,
> printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
> }
>
> +#if defined(CONFIG_SYSCTL) && defined(CONFIG_X86_LOCAL_APIC)
> +int unknown_nmi_panic;
> +static int __init setup_unknown_nmi_panic(char *str)
> +{
> + unknown_nmi_panic = 1;
> + return 1;
> +}
> +__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
> +
> +static int unknown_nmi_panic_callback(struct pt_regs *regs, int cpu)
> +{
> + unsigned char reason = get_nmi_reason();
> + char buf[64];
> +
> + sprintf(buf, "NMI received for unknown reason %02x\n", reason);
> + die_nmi(buf, regs, 1); /* Always panic here */
> + return 0;
> +}
> +
> +static int do_nmi_callback(struct pt_regs *regs, int cpu)
> +{
> + if (unknown_nmi_panic)
> + return unknown_nmi_panic_callback(regs, cpu);
> + return 0;
> +}
> +#endif
> +
> static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
> {
> unsigned char reason = 0;
> @@ -405,8 +432,8 @@ static notrace __kprobes void default_do
> */
> if (nmi_watchdog_tick(regs, reason))
> return;
> - if (!do_nmi_callback(regs, cpu))
> #endif /* !CONFIG_LOCKUP_DETECTOR */
> + if (!do_nmi_callback(regs, cpu))
> unknown_nmi_error(reason, regs);
> #else
> unknown_nmi_error(reason, regs);
> Index: linux-2.6/kernel/sysctl.c
> ===================================================================
> --- linux-2.6.orig/kernel/sysctl.c
> +++ linux-2.6/kernel/sysctl.c
> @@ -741,7 +741,7 @@ static struct ctl_table kern_table[] = {
> .extra2 = &one,
> },
> #endif
> -#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86) && !defined(CONFIG_LOCKUP_DETECTOR)
> +#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
> {
> .procname = "unknown_nmi_panic",
> .data = &unknown_nmi_panic,
> @@ -749,6 +749,8 @@ static struct ctl_table kern_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec,
> },
> +#endif
> +#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86) && !defined(CONFIG_LOCKUP_DETECTOR)
> {
> .procname = "nmi_watchdog",
> .data = &nmi_watchdog_enabled,
> Index: linux-2.6/arch/x86/include/asm/nmi.h
> ===================================================================
> --- linux-2.6.orig/arch/x86/include/asm/nmi.h
> +++ linux-2.6/arch/x86/include/asm/nmi.h
> @@ -7,14 +7,6 @@
>
> #ifdef ARCH_HAS_NMI_WATCHDOG
>
> -/**
> - * do_nmi_callback
> - *
> - * Check to see if a callback exists and execute it. Return 1
> - * if the handler exists and was handled successfully.
> - */
> -int do_nmi_callback(struct pt_regs *regs, int cpu);
> -
> extern void die_nmi(char *str, struct pt_regs *regs, int do_panic);
> extern int check_nmi_watchdog(void);
> #if !defined(CONFIG_LOCKUP_DETECTOR)
>
--
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