[GIT PULL] x86/debug changes for v3.3

From: Ingo Molnar
Date: Thu Jan 05 2012 - 09:50:03 EST

Linus,

Please pull the latest x86-debug-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-debug-for-linus


out-of-topic modifications in x86-debug-for-linus:
--------------------------------------------------
include/linux/kernel.h # 55af779: x86: Panic on detection of stack
kernel/sysctl.c # 55af779: x86: Panic on detection of stack

Thanks,

Ingo

------------------>
Dan Carpenter (1):
x86, NMI: Add to_cpumask() to silence compile warning

Don Zickus (5):
x86, reboot: Use NMI instead of REBOOT_VECTOR to stop cpus
x86, NMI: Add NMI IPI selftest
x86, NMI: Add knob to disable using NMI IPIs to stop cpus
x86, NMI: NMI-selftest should handle the UP case properly
x86, NMI: NMI selftest depends on the local apic

Ingo Molnar (1):
x86: Fix the 32-bit stackoverflow-debug build

Mitsuo Hayasaka (4):
x86: Check stack overflow in detail
x86: Panic on detection of stack overflow
x86: Clean up the range of stack overflow checking
x86: Add stack top margin for stack overflow checking


Documentation/kernel-parameters.txt | 4 +
Documentation/sysctl/kernel.txt | 14 +++
arch/x86/Kconfig.debug | 19 ++++-
arch/x86/include/asm/smp.h | 6 +
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/irq_32.c | 5 +
arch/x86/kernel/irq_64.c | 35 ++++++-
arch/x86/kernel/nmi_selftest.c | 180 +++++++++++++++++++++++++++++++++++
arch/x86/kernel/smp.c | 72 ++++++++++++++-
arch/x86/kernel/smpboot.c | 1 +
include/linux/kernel.h | 1 +
kernel/sysctl.c | 9 ++
12 files changed, 337 insertions(+), 10 deletions(-)
create mode 100644 arch/x86/kernel/nmi_selftest.c

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a0c5c5f..b4339e5 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1796,6 +1796,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).

+ nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
+ shutdown the other cpus. Instead use the REBOOT_VECTOR
+ irq.
+
nopat [X86] Disable PAT (page attribute table extension of
pagetables) support.

diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
index 1f24636..6d8cd8b 100644
--- a/Documentation/sysctl/kernel.txt
+++ b/Documentation/sysctl/kernel.txt
@@ -49,6 +49,7 @@ show up in /proc/sys/kernel:
- panic
- panic_on_oops
- panic_on_unrecovered_nmi
+- panic_on_stackoverflow
- pid_max
- powersave-nap [ PPC only ]
- printk
@@ -393,6 +394,19 @@ Controls the kernel's behaviour when an oops or BUG is encountered.

==============================================================

+panic_on_stackoverflow:
+
+Controls the kernel's behavior when detecting the overflows of
+kernel, IRQ and exception stacks except a user stack.
+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/Kconfig.debug b/arch/x86/Kconfig.debug
index bf56e17..aa4158f 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -63,8 +63,11 @@ config DEBUG_STACKOVERFLOW
bool "Check for stack overflows"
depends on DEBUG_KERNEL
---help---
- This option will cause messages to be printed if free stack space
- drops below a certain limit.
+ Say Y here if you want to check the overflows of kernel, IRQ
+ and exception stacks. This option will cause messages of the
+ stacks in detail when free stack space drops below a certain
+ limit.
+ If in doubt, say "N".

config X86_PTDUMP
bool "Export kernel pagetable layout to userspace via debugfs"
@@ -284,4 +287,16 @@ config DEBUG_STRICT_USER_COPY_CHECKS

If unsure, or if you run an older (pre 4.4) gcc, say N.

+config DEBUG_NMI_SELFTEST
+ bool "NMI Selftest"
+ depends on DEBUG_KERNEL && X86_LOCAL_APIC
+ ---help---
+ Enabling this option turns on a quick NMI selftest to verify
+ that the NMI behaves correctly.
+
+ This might help diagnose strange hangs that rely on NMI to
+ function properly.
+
+ If unsure, say N.
+
endmenu
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 73b11bc..0434c40 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -225,5 +225,11 @@ extern int hard_smp_processor_id(void);

#endif /* CONFIG_X86_LOCAL_APIC */

+#ifdef CONFIG_DEBUG_NMI_SELFTEST
+extern void nmi_selftest(void);
+#else
+#define nmi_selftest() do { } while (0)
+#endif
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_SMP_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8baca3c..02b2f05 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -80,6 +80,7 @@ obj-$(CONFIG_APB_TIMER) += apb_timer.o
obj-$(CONFIG_AMD_NB) += amd_nb.o
obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
+obj-$(CONFIG_DEBUG_NMI_SELFTEST) += nmi_selftest.o

obj-$(CONFIG_KVM_GUEST) += kvm.o
obj-$(CONFIG_KVM_CLOCK) += kvmclock.o
diff --git a/arch/x86/kernel/irq_32.c b/arch/x86/kernel/irq_32.c
index 7209070..40fc861 100644
--- a/arch/x86/kernel/irq_32.c
+++ b/arch/x86/kernel/irq_32.c
@@ -28,6 +28,9 @@ DEFINE_PER_CPU(struct pt_regs *, irq_regs);
EXPORT_PER_CPU_SYMBOL(irq_regs);

#ifdef CONFIG_DEBUG_STACKOVERFLOW
+
+int sysctl_panic_on_stackoverflow __read_mostly;
+
/* Debugging check for stack overflow: is there less than 1KB free? */
static int check_stack_overflow(void)
{
@@ -43,6 +46,8 @@ static void print_stack_overflow(void)
{
printk(KERN_WARNING "low stack detected by irq handler\n");
dump_stack();
+ if (sysctl_panic_on_stackoverflow)
+ panic("low stack detected by irq handler - check messages\n");
}

#else
diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index 69bca46..d04d3ec 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -26,6 +26,8 @@ EXPORT_PER_CPU_SYMBOL(irq_stat);
DEFINE_PER_CPU(struct pt_regs *, irq_regs);
EXPORT_PER_CPU_SYMBOL(irq_regs);

+int sysctl_panic_on_stackoverflow;
+
/*
* Probabilistic stack overflow check:
*
@@ -36,18 +38,39 @@ EXPORT_PER_CPU_SYMBOL(irq_regs);
static inline void stack_overflow_check(struct pt_regs *regs)
{
#ifdef CONFIG_DEBUG_STACKOVERFLOW
+#define STACK_TOP_MARGIN 128
+ struct orig_ist *oist;
+ u64 irq_stack_top, irq_stack_bottom;
+ u64 estack_top, estack_bottom;
u64 curbase = (u64)task_stack_page(current);

if (user_mode_vm(regs))
return;

- WARN_ONCE(regs->sp >= curbase &&
- regs->sp <= curbase + THREAD_SIZE &&
- regs->sp < curbase + sizeof(struct thread_info) +
- sizeof(struct pt_regs) + 128,
+ if (regs->sp >= curbase + sizeof(struct thread_info) +
+ sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
+ regs->sp <= curbase + THREAD_SIZE)
+ return;
+
+ irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack) +
+ STACK_TOP_MARGIN;
+ irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr);
+ if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
+ return;
+
+ oist = &__get_cpu_var(orig_ist);
+ estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ + STACK_TOP_MARGIN;
+ estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];
+ if (regs->sp >= estack_top && regs->sp <= estack_bottom)
+ return;
+
+ WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx)\n",
+ current->comm, curbase, regs->sp,
+ irq_stack_top, irq_stack_bottom,
+ estack_top, estack_bottom);

- "do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
- current->comm, curbase, regs->sp);
+ if (sysctl_panic_on_stackoverflow)
+ panic("low stack detected by irq handler - check messages\n");
#endif
}

diff --git a/arch/x86/kernel/nmi_selftest.c b/arch/x86/kernel/nmi_selftest.c
new file mode 100644
index 0000000..0d01a8e
--- /dev/null
+++ b/arch/x86/kernel/nmi_selftest.c
@@ -0,0 +1,180 @@
+/*
+ * arch/x86/kernel/nmi-selftest.c
+ *
+ * Testsuite for NMI: IPIs
+ *
+ * Started by Don Zickus:
+ * (using lib/locking-selftest.c as a guide)
+ *
+ * Copyright (C) 2011 Red Hat, Inc., Don Zickus <dzickus@xxxxxxxxxx>
+ */
+
+#include <linux/smp.h>
+#include <linux/cpumask.h>
+#include <linux/delay.h>
+
+#include <asm/apic.h>
+#include <asm/nmi.h>
+
+#define SUCCESS 0
+#define FAILURE 1
+#define TIMEOUT 2
+
+static int nmi_fail;
+
+/* check to see if NMI IPIs work on this machine */
+static DECLARE_BITMAP(nmi_ipi_mask, NR_CPUS) __read_mostly;
+
+static int testcase_total;
+static int testcase_successes;
+static int expected_testcase_failures;
+static int unexpected_testcase_failures;
+static int unexpected_testcase_unknowns;
+
+static int nmi_unk_cb(unsigned int val, struct pt_regs *regs)
+{
+ unexpected_testcase_unknowns++;
+ return NMI_HANDLED;
+}
+
+static void init_nmi_testsuite(void)
+{
+ /* trap all the unknown NMIs we may generate */
+ register_nmi_handler(NMI_UNKNOWN, nmi_unk_cb, 0, "nmi_selftest_unk");
+}
+
+static void cleanup_nmi_testsuite(void)
+{
+ unregister_nmi_handler(NMI_UNKNOWN, "nmi_selftest_unk");
+}
+
+static int test_nmi_ipi_callback(unsigned int val, struct pt_regs *regs)
+{
+ int cpu = raw_smp_processor_id();
+
+ if (cpumask_test_and_clear_cpu(cpu, to_cpumask(nmi_ipi_mask)))
+ return NMI_HANDLED;
+
+ return NMI_DONE;
+}
+
+static void test_nmi_ipi(struct cpumask *mask)
+{
+ unsigned long timeout;
+
+ if (register_nmi_handler(NMI_LOCAL, test_nmi_ipi_callback,
+ NMI_FLAG_FIRST, "nmi_selftest")) {
+ nmi_fail = FAILURE;
+ return;
+ }
+
+ /* sync above data before sending NMI */
+ wmb();
+
+ apic->send_IPI_mask(mask, NMI_VECTOR);
+
+ /* Don't wait longer than a second */
+ timeout = USEC_PER_SEC;
+ while (!cpumask_empty(mask) && timeout--)
+ udelay(1);
+
+ /* What happens if we timeout, do we still unregister?? */
+ unregister_nmi_handler(NMI_LOCAL, "nmi_selftest");
+
+ if (!timeout)
+ nmi_fail = TIMEOUT;
+ return;
+}
+
+static void remote_ipi(void)
+{
+ cpumask_copy(to_cpumask(nmi_ipi_mask), cpu_online_mask);
+ cpumask_clear_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
+ if (!cpumask_empty(to_cpumask(nmi_ipi_mask)))
+ test_nmi_ipi(to_cpumask(nmi_ipi_mask));
+}
+
+static void local_ipi(void)
+{
+ cpumask_clear(to_cpumask(nmi_ipi_mask));
+ cpumask_set_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
+ test_nmi_ipi(to_cpumask(nmi_ipi_mask));
+}
+
+static void reset_nmi(void)
+{
+ nmi_fail = 0;
+}
+
+static void dotest(void (*testcase_fn)(void), int expected)
+{
+ testcase_fn();
+ /*
+ * Filter out expected failures:
+ */
+ if (nmi_fail != expected) {
+ unexpected_testcase_failures++;
+
+ if (nmi_fail == FAILURE)
+ printk("FAILED |");
+ else if (nmi_fail == TIMEOUT)
+ printk("TIMEOUT|");
+ else
+ printk("ERROR |");
+ dump_stack();
+ } else {
+ testcase_successes++;
+ printk(" ok |");
+ }
+ testcase_total++;
+
+ reset_nmi();
+}
+
+static inline void print_testname(const char *testname)
+{
+ printk("%12s:", testname);
+}
+
+void nmi_selftest(void)
+{
+ init_nmi_testsuite();
+
+ /*
+ * Run the testsuite:
+ */
+ printk("----------------\n");
+ printk("| NMI testsuite:\n");
+ printk("--------------------\n");
+
+ print_testname("remote IPI");
+ dotest(remote_ipi, SUCCESS);
+ printk("\n");
+ print_testname("local IPI");
+ dotest(local_ipi, SUCCESS);
+ printk("\n");
+
+ cleanup_nmi_testsuite();
+
+ if (unexpected_testcase_failures) {
+ printk("--------------------\n");
+ printk("BUG: %3d unexpected failures (out of %3d) - debugging disabled! |\n",
+ unexpected_testcase_failures, testcase_total);
+ printk("-----------------------------------------------------------------\n");
+ } else if (expected_testcase_failures && testcase_successes) {
+ printk("--------------------\n");
+ printk("%3d out of %3d testcases failed, as expected. |\n",
+ expected_testcase_failures, testcase_total);
+ printk("----------------------------------------------------\n");
+ } else if (expected_testcase_failures && !testcase_successes) {
+ printk("--------------------\n");
+ printk("All %3d testcases failed, as expected. |\n",
+ expected_testcase_failures);
+ printk("----------------------------------------\n");
+ } else {
+ printk("--------------------\n");
+ printk("Good, all %3d testcases passed! |\n",
+ testcase_successes);
+ printk("---------------------------------\n");
+ }
+}
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 16204dc..113acda 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -29,6 +29,7 @@
#include <asm/mmu_context.h>
#include <asm/proto.h>
#include <asm/apic.h>
+#include <asm/nmi.h>
/*
* Some notes on x86 processor bugs affecting SMP operation:
*
@@ -148,6 +149,60 @@ void native_send_call_func_ipi(const struct cpumask *mask)
free_cpumask_var(allbutself);
}

+static atomic_t stopping_cpu = ATOMIC_INIT(-1);
+
+static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
+{
+ /* We are registered on stopping cpu too, avoid spurious NMI */
+ if (raw_smp_processor_id() == atomic_read(&stopping_cpu))
+ return NMI_HANDLED;
+
+ stop_this_cpu(NULL);
+
+ return NMI_HANDLED;
+}
+
+static void native_nmi_stop_other_cpus(int wait)
+{
+ unsigned long flags;
+ unsigned long timeout;
+
+ if (reboot_force)
+ return;
+
+ /*
+ * Use an own vector here because smp_call_function
+ * does lots of things not suitable in a panic situation.
+ */
+ if (num_online_cpus() > 1) {
+ /* did someone beat us here? */
+ if (atomic_cmpxchg(&stopping_cpu, -1, safe_smp_processor_id() != -1))
+ return;
+
+ if (register_nmi_handler(NMI_LOCAL, smp_stop_nmi_callback,
+ NMI_FLAG_FIRST, "smp_stop"))
+ /* Note: we ignore failures here */
+ return;
+
+ /* sync above data before sending NMI */
+ wmb();
+
+ apic->send_IPI_allbutself(NMI_VECTOR);
+
+ /*
+ * Don't wait longer than a second if the caller
+ * didn't ask us to wait.
+ */
+ timeout = USEC_PER_SEC;
+ while (num_online_cpus() > 1 && (wait || timeout--))
+ udelay(1);
+ }
+
+ local_irq_save(flags);
+ disable_local_APIC();
+ local_irq_restore(flags);
+}
+
/*
* this function calls the 'stop' function on all other CPUs in the system.
*/
@@ -160,7 +215,7 @@ asmlinkage void smp_reboot_interrupt(void)
irq_exit();
}

-static void native_stop_other_cpus(int wait)
+static void native_irq_stop_other_cpus(int wait)
{
unsigned long flags;
unsigned long timeout;
@@ -194,6 +249,11 @@ static void native_stop_other_cpus(int wait)
local_irq_restore(flags);
}

+static void native_smp_disable_nmi_ipi(void)
+{
+ smp_ops.stop_other_cpus = native_irq_stop_other_cpus;
+}
+
/*
* Reschedule call back.
*/
@@ -225,12 +285,20 @@ void smp_call_function_single_interrupt(struct pt_regs *regs)
irq_exit();
}

+static int __init nonmi_ipi_setup(char *str)
+{
+ native_smp_disable_nmi_ipi();
+ return 1;
+}
+
+__setup("nonmi_ipi", nonmi_ipi_setup);
+
struct smp_ops smp_ops = {
.smp_prepare_boot_cpu = native_smp_prepare_boot_cpu,
.smp_prepare_cpus = native_smp_prepare_cpus,
.smp_cpus_done = native_smp_cpus_done,

- .stop_other_cpus = native_stop_other_cpus,
+ .stop_other_cpus = native_nmi_stop_other_cpus,
.smp_send_reschedule = native_smp_send_reschedule,

.cpu_up = native_cpu_up,
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9f548cb..1927781 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1142,6 +1142,7 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
{
pr_debug("Boot done.\n");

+ nmi_selftest();
impress_friends();
#ifdef CONFIG_X86_IO_APIC
setup_ioapic_dest();
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index e8b1597..ff83683 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -341,6 +341,7 @@ 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/kernel/sysctl.c b/kernel/sysctl.c
index ae27196..f487f25 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -803,6 +803,15 @@ static struct ctl_table kern_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec,
},
+#ifdef 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,
--
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