From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- lib/nmi_backtrace.c | 139 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 139 insertions(+) create mode 100644 lib/nmi_backtrace.c (limited to 'lib/nmi_backtrace.c') diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c new file mode 100644 index 000000000..f39c9eca8 --- /dev/null +++ b/lib/nmi_backtrace.c @@ -0,0 +1,139 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * NMI backtrace support + * + * Gratuitously copied from arch/x86/kernel/apic/hw_nmi.c by Russell King, + * with the following header: + * + * HW NMI watchdog support + * + * started by Don Zickus, Copyright (C) 2010 Red Hat, Inc. + * + * Arch specific calls to support NMI watchdog + * + * Bits copied from original nmi.c file + */ +#include +#include +#include +#include +#include +#include +#include +#include + +#ifdef arch_trigger_cpumask_backtrace +/* For reliability, we're prepared to waste bits here. */ +static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; + +/* "in progress" flag of arch_trigger_cpumask_backtrace */ +static unsigned long backtrace_flag; + +#define NMI_BT_TIMEOUT_SEC 10 + +/* + * When raise() is called it will be passed a pointer to the + * backtrace_mask. Architectures that call nmi_cpu_backtrace() + * directly from their raise() functions may rely on the mask + * they are passed being updated as a side effect of this call. + */ +void nmi_trigger_cpumask_backtrace(const cpumask_t *mask, + int exclude_cpu, + void (*raise)(cpumask_t *mask)) +{ + int i, this_cpu = get_cpu(); + + if (test_and_set_bit(0, &backtrace_flag)) { + /* + * If there is already a trigger_all_cpu_backtrace() in progress + * (backtrace_flag == 1), don't output double cpu dump infos. + */ + put_cpu(); + return; + } + + cpumask_copy(to_cpumask(backtrace_mask), mask); + if (exclude_cpu != -1) + cpumask_clear_cpu(exclude_cpu, to_cpumask(backtrace_mask)); + + /* + * Don't try to send an NMI to this cpu; it may work on some + * architectures, but on others it may not, and we'll get + * information at least as useful just by doing a dump_stack() here. + * Note that nmi_cpu_backtrace(NULL) will clear the cpu bit. + */ + if (cpumask_test_cpu(this_cpu, to_cpumask(backtrace_mask))) + nmi_cpu_backtrace(NULL); + + if (!cpumask_empty(to_cpumask(backtrace_mask))) { + pr_info("Sending NMI from CPU %d to CPUs %*pbl:\n", + this_cpu, nr_cpumask_bits, to_cpumask(backtrace_mask)); + nmi_backtrace_stall_snap(to_cpumask(backtrace_mask)); + raise(to_cpumask(backtrace_mask)); + } + + /* Wait for up to NMI_BT_TIMEOUT_SEC seconds for all CPUs to do the backtrace */ + for (i = 0; i < NMI_BT_TIMEOUT_SEC * 1000; i++) { + if (cpumask_empty(to_cpumask(backtrace_mask))) + break; + mdelay(1); + touch_softlockup_watchdog(); + } + + if (!cpumask_empty(to_cpumask(backtrace_mask))) { + pr_warn("After " __stringify(NMI_BT_TIMEOUT_SEC) " seconds, these CPUS still haven't responded to the NMI: %*pbl\n", + cpumask_pr_args(to_cpumask(backtrace_mask))); + + nmi_backtrace_stall_check(to_cpumask(backtrace_mask)); + } + + /* + * Force flush any remote buffers that might be stuck in IRQ context + * and therefore could not run their irq_work. + */ + printk_trigger_flush(); + + clear_bit_unlock(0, &backtrace_flag); + put_cpu(); +} + +// Dump stacks even for idle CPUs. +static bool backtrace_idle; +module_param(backtrace_idle, bool, 0644); + +bool nmi_cpu_backtrace(struct pt_regs *regs) +{ + int cpu = smp_processor_id(); + unsigned long flags; + + if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { + /* + * Allow nested NMI backtraces while serializing + * against other CPUs. + */ + printk_cpu_sync_get_irqsave(flags); + if (!READ_ONCE(backtrace_idle) && regs && cpu_in_idle(instruction_pointer(regs))) { + pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n", + cpu, (void *)instruction_pointer(regs)); + } else { + pr_warn("NMI backtrace for cpu %d\n", cpu); + if (regs) + show_regs(regs); + else + dump_stack(); + } + printk_cpu_sync_put_irqrestore(flags); + cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); + return true; + } + + return false; +} +NOKPROBE_SYMBOL(nmi_cpu_backtrace); + +void cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) +{ + arch_trigger_cpumask_backtrace(mask, exclude_cpu); +} +EXPORT_SYMBOL_GPL(cpumask_backtrace); +#endif -- cgit v1.3.1