diff options
Diffstat (limited to 'kernel/panic.c')
| -rw-r--r-- | kernel/panic.c | 168 |
1 files changed, 164 insertions, 4 deletions
diff --git a/kernel/panic.c b/kernel/panic.c index 0d52210a9e2b..c78600212b6c 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -42,6 +42,7 @@ #define PANIC_TIMER_STEP 100 #define PANIC_BLINK_SPD 18 +#define PANIC_MSG_BUFSZ 1024 #ifdef CONFIG_SMP /* @@ -74,6 +75,8 @@ EXPORT_SYMBOL_GPL(panic_timeout); unsigned long panic_print; +static int panic_force_cpu = -1; + ATOMIC_NOTIFIER_HEAD(panic_notifier_list); EXPORT_SYMBOL(panic_notifier_list); @@ -131,7 +134,8 @@ static int proc_taint(const struct ctl_table *table, int write, static int sysctl_panic_print_handler(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { - panic_print_deprecated(); + if (write) + panic_print_deprecated(); return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); } @@ -299,6 +303,150 @@ void __weak crash_smp_send_stop(void) } atomic_t panic_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); +atomic_t panic_redirect_cpu = ATOMIC_INIT(PANIC_CPU_INVALID); + +#if defined(CONFIG_SMP) && defined(CONFIG_CRASH_DUMP) +static char *panic_force_buf; + +static int __init panic_force_cpu_setup(char *str) +{ + int cpu; + + if (!str) + return -EINVAL; + + if (kstrtoint(str, 0, &cpu) || cpu < 0 || cpu >= nr_cpu_ids) { + pr_warn("panic_force_cpu: invalid value '%s'\n", str); + return -EINVAL; + } + + panic_force_cpu = cpu; + return 0; +} +early_param("panic_force_cpu", panic_force_cpu_setup); + +static int __init panic_force_cpu_late_init(void) +{ + if (panic_force_cpu < 0) + return 0; + + panic_force_buf = kmalloc(PANIC_MSG_BUFSZ, GFP_KERNEL); + + return 0; +} +late_initcall(panic_force_cpu_late_init); + +static void do_panic_on_target_cpu(void *info) +{ + panic("%s", (char *)info); +} + +/** + * panic_smp_redirect_cpu - Redirect panic to target CPU + * @target_cpu: CPU that should handle the panic + * @msg: formatted panic message + * + * Default implementation uses IPI. Architectures with NMI support + * can override this for more reliable delivery. + * + * Return: 0 on success, negative errno on failure + */ +int __weak panic_smp_redirect_cpu(int target_cpu, void *msg) +{ + static call_single_data_t panic_csd; + + panic_csd.func = do_panic_on_target_cpu; + panic_csd.info = msg; + + return smp_call_function_single_async(target_cpu, &panic_csd); +} + +/** + * panic_try_force_cpu - Redirect panic to a specific CPU for crash kernel + * @fmt: panic message format string + * @args: arguments for format string + * + * Some platforms require panic handling to occur on a specific CPU + * for the crash kernel to function correctly. This function redirects + * panic handling to the CPU specified via the panic_force_cpu= boot parameter. + * + * Returns false if panic should proceed on current CPU. + * Returns true if panic was redirected. + */ +__printf(1, 0) +static bool panic_try_force_cpu(const char *fmt, va_list args) +{ + int this_cpu = raw_smp_processor_id(); + int old_cpu = PANIC_CPU_INVALID; + const char *msg; + + /* Feature not enabled via boot parameter */ + if (panic_force_cpu < 0) + return false; + + /* Already on target CPU - proceed normally */ + if (this_cpu == panic_force_cpu) + return false; + + /* Target CPU is offline, can't redirect */ + if (!cpu_online(panic_force_cpu)) { + pr_warn("panic: target CPU %d is offline, continuing on CPU %d\n", + panic_force_cpu, this_cpu); + return false; + } + + /* Another panic already in progress */ + if (panic_in_progress()) + return false; + + /* + * Only one CPU can do the redirect. Use atomic cmpxchg to ensure + * we don't race with another CPU also trying to redirect. + */ + if (!atomic_try_cmpxchg(&panic_redirect_cpu, &old_cpu, this_cpu)) + return false; + + /* + * Use dynamically allocated buffer if available, otherwise + * fall back to static message for early boot panics or allocation failure. + */ + if (panic_force_buf) { + vsnprintf(panic_force_buf, PANIC_MSG_BUFSZ, fmt, args); + msg = panic_force_buf; + } else { + msg = "Redirected panic (buffer unavailable)"; + } + + console_verbose(); + bust_spinlocks(1); + + pr_emerg("panic: Redirecting from CPU %d to CPU %d for crash kernel.\n", + this_cpu, panic_force_cpu); + + /* Dump original CPU before redirecting */ + if (!test_taint(TAINT_DIE) && + oops_in_progress <= 1 && + IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE)) { + dump_stack(); + } + + if (panic_smp_redirect_cpu(panic_force_cpu, (void *)msg) != 0) { + atomic_set(&panic_redirect_cpu, PANIC_CPU_INVALID); + pr_warn("panic: failed to redirect to CPU %d, continuing on CPU %d\n", + panic_force_cpu, this_cpu); + return false; + } + + /* IPI/NMI sent, this CPU should stop */ + return true; +} +#else +__printf(1, 0) +static inline bool panic_try_force_cpu(const char *fmt, va_list args) +{ + return false; +} +#endif /* CONFIG_SMP && CONFIG_CRASH_DUMP */ bool panic_try_start(void) { @@ -427,7 +575,7 @@ static void panic_other_cpus_shutdown(bool crash_kexec) */ void vpanic(const char *fmt, va_list args) { - static char buf[1024]; + static char buf[PANIC_MSG_BUFSZ]; long i, i_next = 0, len; int state = 0; bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers; @@ -451,6 +599,15 @@ void vpanic(const char *fmt, va_list args) local_irq_disable(); preempt_disable_notrace(); + /* Redirect panic to target CPU if configured via panic_force_cpu=. */ + if (panic_try_force_cpu(fmt, args)) { + /* + * Mark ourselves offline so panic_other_cpus_shutdown() won't wait + * for us on architectures that check num_online_cpus(). + */ + set_cpu_online(smp_processor_id(), false); + panic_smp_self_stop(); + } /* * It's possible to come here directly from a panic-assertion and * not have preempt disabled. Some functions called from here want @@ -483,7 +640,11 @@ void vpanic(const char *fmt, va_list args) /* * Avoid nested stack-dumping if a panic occurs during oops processing */ - if (test_taint(TAINT_DIE) || oops_in_progress > 1) { + if (atomic_read(&panic_redirect_cpu) != PANIC_CPU_INVALID && + panic_force_cpu == raw_smp_processor_id()) { + pr_emerg("panic: Redirected from CPU %d, skipping stack dump.\n", + atomic_read(&panic_redirect_cpu)); + } else if (test_taint(TAINT_DIE) || oops_in_progress > 1) { panic_this_cpu_backtrace_printed = true; } else if (IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE)) { dump_stack(); @@ -1014,7 +1175,6 @@ static int panic_print_set(const char *val, const struct kernel_param *kp) static int panic_print_get(char *val, const struct kernel_param *kp) { - panic_print_deprecated(); return param_get_ulong(val, kp); } |