diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | Documentation/sysctl/kernel.txt | 14 | ||||
| -rw-r--r-- | arch/x86/Kconfig.debug | 19 | ||||
| -rw-r--r-- | arch/x86/include/asm/smp.h | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/irq_32.c | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/irq_64.c | 35 | ||||
| -rw-r--r-- | arch/x86/kernel/nmi_selftest.c | 180 | ||||
| -rw-r--r-- | arch/x86/kernel/smp.c | 72 | ||||
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 1 | ||||
| -rw-r--r-- | include/linux/kernel.h | 1 | ||||
| -rw-r--r-- | kernel/sysctl.c | 9 |
12 files changed, 337 insertions, 10 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index a8d389d7240..eb93fd0ec73 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1824,6 +1824,10 @@ 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 1f2463671a1..6d8cd8b2c30 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 bf56e179327..aa4158f3ce6 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 73b11bc0ae6..0434c400287 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 8baca3c4871..02b2f05b371 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 72090705a65..40fc86161d9 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 69bca468c47..d04d3ecded6 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 00000000000..0d01a8ea4e1 --- /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@redhat.com> + */ + +#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 16204dc1548..66c74f481ca 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 e38e21754ee..79f636bc44c 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1143,6 +1143,7 @@ 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 f48e8a52854..d0a7a0c7166 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 ae271964385..f487f257e05 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, |