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Message-ID: <20111110195538.GB22646@phenom.dumpdata.com>
Date: Thu, 10 Nov 2011 14:55:38 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To: Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H. Peter Anvin" <hpa@...or.com>,
Randy Dunlap <rdunlap@...otime.net>, x86@...nel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
yrl.pp-manager.tt@...achi.com
Subject: Re: [RFC PATCH 3/5] x86: add a sysctl parameter to panic on stack
overflow
On Mon, Nov 07, 2011 at 02:53:01PM +0900, Mitsuo Hayasaka wrote:
> This patch adds kernel.panic_on_stackoverflow sysctl parameter,
> which can cause a panic when detecting the stack overflow.
Why would we want to panic?
>
> Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>
> Cc: Randy Dunlap <rdunlap@...otime.net>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> ---
>
> Documentation/sysctl/kernel.txt | 13 +++++++++++++
> arch/x86/kernel/irq_64.c | 2 ++
> include/linux/kernel.h | 1 +
> include/linux/sysctl.h | 1 +
> kernel/sysctl.c | 9 +++++++++
> kernel/sysctl_binary.c | 1 +
> 6 files changed, 27 insertions(+), 0 deletions(-)
>
> diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
> index 704e474..eb8d263 100644
> --- a/Documentation/sysctl/kernel.txt
> +++ b/Documentation/sysctl/kernel.txt
> @@ -48,6 +48,7 @@ show up in /proc/sys/kernel:
> - panic
> - panic_on_oops
> - panic_on_unrecovered_nmi
> +- panic_on_stackoverflow
> - pid_max
> - powersave-nap [ PPC only ]
> - printk
> @@ -385,6 +386,18 @@ Controls the kernel's behaviour when an oops or BUG is encountered.
>
> ==============================================================
>
> +panic_on_stackoverflow:
> +
> +Controls the kernel's behaviour when detecting stack overflow.
> +This file shows up if CONFIG_DEBUG_STACKOVERFLOW is enabled.
> +
> +0: try to continue operation.
> +
> +1: panic immediately.
> +
> +==============================================================
> +
> +
> pid_max:
>
> PID allocation wrap value. When the kernel's next PID value
> diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
> index 530cfd0..d720813 100644
> --- a/arch/x86/kernel/irq_64.c
> +++ b/arch/x86/kernel/irq_64.c
> @@ -20,6 +20,8 @@
> #include <asm/idle.h>
> #include <asm/apic.h>
>
> +int sysctl_panic_on_stackoverflow;
__read_mostly
> +
> DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
> EXPORT_PER_CPU_SYMBOL(irq_stat);
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 8eefcf7..19b3595 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -339,6 +339,7 @@ extern int panic_timeout;
> extern int panic_on_oops;
> extern int panic_on_unrecovered_nmi;
> extern int panic_on_io_nmi;
> +extern int sysctl_panic_on_stackoverflow;
> extern const char *print_tainted(void);
> extern void add_taint(unsigned flag);
> extern int test_taint(unsigned flag);
> diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
> index 9a1ec10..4b9dc3d 100644
> --- a/include/linux/sysctl.h
> +++ b/include/linux/sysctl.h
> @@ -153,6 +153,7 @@ enum
> KERN_MAX_LOCK_DEPTH=74, /* int: rtmutex's maximum lock depth */
> KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */
> KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */
> + KERN_PANIC_ON_STACKOVERFLOW = 77, /* int: panic on stack overflow */
> };
>
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 11d65b5..08a18f9 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -792,6 +792,15 @@ static struct ctl_table kern_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec,
> },
> +#if defined(CONFIG_DEBUG_STACKOVERFLOW)
> + {
> + .procname = "panic_on_stackoverflow",
> + .data = &sysctl_panic_on_stackoverflow,
> + .maxlen = sizeof(int),
> + .mode = 0644,
> + .proc_handler = proc_dointvec,
> + },
> +#endif
> {
> .procname = "bootloader_type",
> .data = &bootloader_type,
> diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
> index 6318b51..24fc654 100644
> --- a/kernel/sysctl_binary.c
> +++ b/kernel/sysctl_binary.c
> @@ -137,6 +137,7 @@ static const struct bin_table bin_kern_table[] = {
> { CTL_INT, KERN_COMPAT_LOG, "compat-log" },
> { CTL_INT, KERN_MAX_LOCK_DEPTH, "max_lock_depth" },
> { CTL_INT, KERN_PANIC_ON_NMI, "panic_on_unrecovered_nmi" },
> + { CTL_INT, KERN_PANIC_ON_STACKOVERFLOW, "panic_on_stackoverflow" },
This shouldn't be wrapped in the #ifdef?
> {}
> };
>
>
> --
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