b24413180f560 (Greg Kroah-Hartman 2017-11-01 15:07:57 +0100 1) // SPDX-License-Identifier: GPL-2.0
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 2) /*
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 3) * NMI backtrace support
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 4) *
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 5) * Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King,
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 6) * with the following header:
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 7) *
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 8) * HW NMI watchdog support
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 9) *
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 10) * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 11) *
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 12) * Arch specific calls to support NMI watchdog
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 13) *
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 14) * Bits copied from original nmi.c file
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 15) */
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 16) #include <linux/cpumask.h>
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 17) #include <linux/delay.h>
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 18) #include <linux/kprobes.h>
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 19) #include <linux/nmi.h>
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 20) #include <linux/cpu.h>
b17b01533b719 (Ingo Molnar 2017-02-08 18:51:35 +0100 21) #include <linux/sched/debug.h>
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 22)
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 23) #ifdef arch_trigger_cpumask_backtrace
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 24) /* For reliability, we're prepared to waste bits here. */
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 25) static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 26)
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 27) /* "in progress" flag of arch_trigger_cpumask_backtrace */
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 28) static unsigned long backtrace_flag;
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 29)
0768330d46435 (Daniel Thompson 2015-09-22 17:12:10 +0100 30) /*
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 31) * When raise() is called it will be passed a pointer to the
0768330d46435 (Daniel Thompson 2015-09-22 17:12:10 +0100 32) * backtrace_mask. Architectures that call nmi_cpu_backtrace()
0768330d46435 (Daniel Thompson 2015-09-22 17:12:10 +0100 33) * directly from their raise() functions may rely on the mask
0768330d46435 (Daniel Thompson 2015-09-22 17:12:10 +0100 34) * they are passed being updated as a side effect of this call.
0768330d46435 (Daniel Thompson 2015-09-22 17:12:10 +0100 35) */
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 36) void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 37) bool exclude_self,
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 38) void (*raise)(cpumask_t *mask))
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 39) {
42a0bb3f71383 (Petr Mladek 2016-05-20 17:00:33 -0700 40) int i, this_cpu = get_cpu();
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 41)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 42) if (test_and_set_bit(0, &backtrace_flag)) {
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 43) /*
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 44) * If there is already a trigger_all_cpu_backtrace() in progress
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 45) * (backtrace_flag == 1), don't output double cpu dump infos.
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 46) */
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 47) put_cpu();
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 48) return;
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 49) }
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 50)
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 51) cpumask_copy(to_cpumask(backtrace_mask), mask);
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 52) if (exclude_self)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 53) cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 54)
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 55) /*
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 56) * Don't try to send an NMI to this cpu; it may work on some
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 57) * architectures, but on others it may not, and we'll get
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 58) * information at least as useful just by doing a dump_stack() here.
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 59) * Note that nmi_cpu_backtrace(NULL) will clear the cpu bit.
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 60) */
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 61) if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask)))
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 62) nmi_cpu_backtrace(NULL);
6776648952782 (Chris Metcalf 2016-10-07 17:02:49 -0700 63)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 64) if (!cpumask_empty(to_cpumask(backtrace_mask))) {
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 65) pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n",
9a01c3ed5cdb3 (Chris Metcalf 2016-10-07 17:02:45 -0700 66) this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask));
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 67) raise(to_cpumask(backtrace_mask));
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 68) }
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 69)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 70) /* Wait for up to 10 seconds for all CPUs to do the backtrace */
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 71) for (i = 0; i < 10 * 1000; i++) {
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 72) if (cpumask_empty(to_cpumask(backtrace_mask)))
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 73) break;
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 74) mdelay(1);
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 75) touch_softlockup_watchdog();
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 76) }
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 77)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 78) /*
42a0bb3f71383 (Petr Mladek 2016-05-20 17:00:33 -0700 79) * Force flush any remote buffers that might be stuck in IRQ context
42a0bb3f71383 (Petr Mladek 2016-05-20 17:00:33 -0700 80) * and therefore could not run their irq_work.
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 81) */
f92bac3b141b8 (Sergey Senozhatsky 2016-12-27 23:16:05 +0900 82) printk_safe_flush();
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 83)
42a0bb3f71383 (Petr Mladek 2016-05-20 17:00:33 -0700 84) clear_bit_unlock(0, &backtrace_flag);
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 85) put_cpu();
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 86) }
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 87)
160c7ba34605d (Paul E. McKenney 2020-07-08 16:25:43 -0700 88) // Dump stacks even for idle CPUs.
160c7ba34605d (Paul E. McKenney 2020-07-08 16:25:43 -0700 89) static bool backtrace_idle;
160c7ba34605d (Paul E. McKenney 2020-07-08 16:25:43 -0700 90) module_param(backtrace_idle, bool, 0644);
160c7ba34605d (Paul E. McKenney 2020-07-08 16:25:43 -0700 91)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 92) bool nmi_cpu_backtrace(struct pt_regs *regs)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 93) {
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 94) int cpu = smp_processor_id();
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 95)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 96) if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
160c7ba34605d (Paul E. McKenney 2020-07-08 16:25:43 -0700 97) if (!READ_ONCE(backtrace_idle) && regs && cpu_in_idle(instruction_pointer(regs))) {
2f9b7e08cb27d (Liu, Changcheng 2017-11-17 15:28:20 -0800 98) pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n",
2f9b7e08cb27d (Liu, Changcheng 2017-11-17 15:28:20 -0800 99) cpu, (void *)instruction_pointer(regs));
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 100) } else {
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 101) pr_warn("NMI backtrace for cpu %d\n", cpu);
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 102) if (regs)
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 103) show_regs(regs);
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 104) else
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 105) dump_stack();
6727ad9e206cc (Chris Metcalf 2016-10-07 17:02:55 -0700 106) }
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 107) cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 108) return true;
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 109) }
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 110)
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 111) return false;
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 112) }
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 113) NOKPROBE_SYMBOL(nmi_cpu_backtrace);
b2c0b2cbb282f (Russell King 2014-09-03 23:57:13 +0100 114) #endif
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