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Subject[PATCH 2/2] x86, NMI: add back unknown_nmi_panic and nmi_watchdog sysctls
Date
Originally adapted from Huang Ying's patch which moved the unknown_nmi_panic
to the traps.c file. Because the old nmi watchdog was deleted before this
change happened, the unknown_nmi_panic sysctl was lost. This re-adds it.

Also, the nmi_watchdog sysctl was re-implemented and its documentation
updated accordingly.

Patch-inspired-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
---
Documentation/kernel-parameters.txt | 10 +---------
arch/x86/kernel/apic/hw_nmi.c | 3 ---
arch/x86/kernel/traps.c | 16 +++++++++++-----
kernel/sysctl.c | 16 ++++++++++++++++
kernel/sysctl_binary.c | 1 -
kernel/watchdog.c | 2 ++
6 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index cdd2a6e..5e55e46 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1579,20 +1579,12 @@ and is between 256 and 4096 characters. It is defined in the file

nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Format: [panic,][num]
- Valid num: 0,1,2
+ Valid num: 0
0 - turn nmi_watchdog off
- 1 - use the IO-APIC timer for the NMI watchdog
- 2 - use the local APIC for the NMI watchdog using
- a performance counter. Note: This will use one
- performance counter and the local APIC's performance
- vector.
When panic is specified, panic when an NMI watchdog
timeout occurs.
This is useful when you use a panic=... timeout and
need the box quickly up again.
- Instead of 1 and 2 it is possible to use the following
- symbolic names: lapic and ioapic
- Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic

netpoll.carrier_timeout=
[NET] Specifies amount of time (in seconds) that
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index d13081e..a86840c 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -100,6 +100,3 @@ static int __init register_trigger_all_cpu_backtrace(void)
}
early_initcall(register_trigger_all_cpu_backtrace);
#endif
-
-/* STUB calls to mimic old nmi_watchdog behaviour */
-int unknown_nmi_panic;
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index f02c179..bb6f041 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -83,6 +83,8 @@ EXPORT_SYMBOL_GPL(used_vectors);

static int ignore_nmis;

+int unknown_nmi_panic;
+
static inline void conditional_sti(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
@@ -300,6 +302,13 @@ gp_in_kernel:
die("general protection fault", regs, error_code);
}

+static int __init setup_unknown_nmi_panic(char *str)
+{
+ unknown_nmi_panic = 1;
+ return 1;
+}
+__setup("unknown_nmi_panic", setup_unknown_nmi_panic);
+
static notrace __kprobes void
mem_parity_error(unsigned char reason, struct pt_regs *regs)
{
@@ -371,7 +380,7 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
reason, smp_processor_id());

printk(KERN_EMERG "Do you have a strange power saving mode enabled?\n");
- if (panic_on_unrecovered_nmi)
+ if (unknown_nmi_panic || panic_on_unrecovered_nmi)
panic("NMI: Not continuing");

printk(KERN_EMERG "Dazed and confused, but trying to continue\n");
@@ -397,11 +406,8 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT)
== NOTIFY_STOP)
return;
-
- unknown_nmi_error(reason, regs);
-#else
- unknown_nmi_error(reason, regs);
#endif
+ unknown_nmi_error(reason, regs);

return;
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index d91b07d..140344d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -733,6 +733,22 @@ static struct ctl_table kern_table[] = {
.extra1 = &zero,
.extra2 = &one,
},
+ {
+ .procname = "nmi_watchdog",
+ .data = &watchdog_enabled,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = proc_dowatchdog_enabled,
+ },
+#endif
+#if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86)
+ {
+ .procname = "unknown_nmi_panic",
+ .data = &unknown_nmi_panic,
+ .maxlen = sizeof (int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
#endif
#if defined(CONFIG_X86)
{
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 1357c57..4b2545a 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -136,7 +136,6 @@ static const struct bin_table bin_kern_table[] = {
{ CTL_INT, KERN_IA64_UNALIGNED, "ignore-unaligned-usertrap" },
{ CTL_INT, KERN_COMPAT_LOG, "compat-log" },
{ CTL_INT, KERN_MAX_LOCK_DEPTH, "max_lock_depth" },
- { CTL_INT, KERN_NMI_WATCHDOG, "nmi_watchdog" },
{ CTL_INT, KERN_PANIC_ON_NMI, "panic_on_unrecovered_nmi" },
{}
};
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index fd77b69..e0f44dc 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -57,6 +57,8 @@ static int __init hardlockup_panic_setup(char *str)
{
if (!strncmp(str, "panic", 5))
hardlockup_panic = 1;
+ else if (!strncmp(str, "0", 1))
+ no_watchdog = 1;
return 1;
}
__setup("nmi_watchdog=", hardlockup_panic_setup);
--
1.7.3.2


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