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Subject[RFC PATCH 3/5] x86: add a sysctl parameter to panic on stack overflow
Date
This patch adds kernel.panic_on_stackoverflow sysctl parameter,
which can cause a panic when detecting the stack overflow.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.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;
+
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" },
{}
};



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