// SPDX-License-Identifier: GPL-2.0-only
/*
* Architecture specific (PPC64) functions for kexec based crash dumps.
*
* Copyright (C) 2005, IBM Corp.
*
* Created by: Haren Myneni
*/
#include <linux/kernel.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/kexec.h>
#include <linux/export.h>
#include <linux/crash_dump.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/types.h>
#include <linux/libfdt.h>
#include <linux/memory.h>
#include <asm/processor.h>
#include <asm/machdep.h>
#include <asm/kexec.h>
#include <asm/smp.h>
#include <asm/setjmp.h>
#include <asm/debug.h>
#include <asm/interrupt.h>
#include <asm/kexec_ranges.h>
/*
* The primary CPU waits a while for all secondary CPUs to enter. This is to
* avoid sending an IPI if the secondary CPUs are entering
* crash_kexec_secondary on their own (eg via a system reset).
*
* The secondary timeout has to be longer than the primary. Both timeouts are
* in milliseconds.
*/
#define PRIMARY_TIMEOUT 500
#define SECONDARY_TIMEOUT 1000
#define IPI_TIMEOUT 10000
#define REAL_MODE_TIMEOUT 10000
static int time_to_dump;
/*
* In case of system reset, secondary CPUs enter crash_kexec_secondary with out
* having to send an IPI explicitly. So, indicate if the crash is via
* system reset to avoid sending another IPI.
*/
static int is_via_system_reset;
/*
* crash_wake_offline should be set to 1 by platforms that intend to wake
* up offline cpus prior to jumping to a kdump kernel. Currently powernv
* sets it to 1, since we want to avoid things from happening when an
* offline CPU wakes up due to something like an HMI (malfunction error),
* which propagates to all threads.
*/
int crash_wake_offline;
#define CRASH_HANDLER_MAX 3
/* List of shutdown handles */
static crash_shutdown_t crash_shutdown_handles[CRASH_HANDLER_MAX];
static DEFINE_SPINLOCK(crash_handlers_lock);
static unsigned long crash_shutdown_buf[JMP_BUF_LEN];
static int crash_shutdown_cpu = -1;
static int handle_fault(struct pt_regs *regs)
{
if (crash_shutdown_cpu == smp_processor_id())
longjmp(crash_shutdown_buf, 1);
return 0;
}
#ifdef CONFIG_SMP
static atomic_t cpus_in_crash;
void crash_ipi_callback(struct pt_regs *regs)
{
static cpumask_t cpus_state_saved = CPU_MASK_NONE;
int cpu = smp_processor_id();
hard_irq_disable();
if (!cpumask_test_cpu(cpu, &cpus_state_saved)) {
crash_save_cpu(regs, cpu);
cpumask_set_cpu(cpu, &cpus_state_saved);
}
atomic_inc(&cpus_in_crash);
smp_mb__after_atomic();
/*
* Starting the kdump boot.
* This barrier is needed to make sure that all CPUs are stopped.
*/
while (!time_to_dump)
cpu_relax();
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(1, 1);
#ifdef CONFIG_PPC64
kexec_smp_wait();
#else
for (;;); /* FIXME */
#endif
/* NOTREACHED */
}
static void crash_kexec_prepare_cpus(void)
{
unsigned int msecs;
volatile unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
volatile int tries = 0;
int (*old_handler)(struct pt_regs *regs);
printk(KERN_EMERG "Sending IPI to other CPUs\n");
if (crash_wake_offline)
ncpus = num_present_cpus() - 1;
/*
* If we came in via system reset, secondaries enter via crash_kexec_secondary().
* So, wait a while for the secondary CPUs to enter for that case.
* Else, send IPI to all other CPUs.
*/
if (is_via_system_reset)
mdelay(PRIMARY_TIMEOUT);
else
crash_send_ipi(crash_ipi_callback);
smp_wmb();
again:
/*
* FIXME: Until we will have the way to stop other CPUs reliably,
* the crash CPU will send an IPI and wait for other CPUs to
* respond.
*/
msecs = IPI_TIMEOUT;
while ((atomic_read(&cpus_in_crash) < ncpus) && (--msecs > 0))
mdelay(1);
/* Would it be better to replace the trap vector here? */
if (atomic_read(&cpus_in_crash) >= ncpus) {
printk(KERN_EMERG "IPI complete\n");
return;
}
printk(KERN_EMERG "ERROR: %d cpu(s) not responding\n",
ncpus - atomic_read(&cpus_in_crash));
/*
* If we have a panic timeout set then we can't wait indefinitely
* for someone to activate system reset. We also give up on the
* second time through if system reset fail to work.
*/
if ((panic_timeout > 0) || (tries > 0))
return;
/*
* A system reset will cause all CPUs to take an 0x100 exception.
* The primary CPU returns here via setjmp, and the secondary
* CPUs reexecute the crash_kexec_secondary path.
*/
old_handler = __debugger;
__debugger = handle_fault;
crash_shutdown_cpu = smp_processor_id();
if (setjmp(crash_shutdown_buf) == 0) {
printk(KERN_EMERG "Activate system reset (dumprestart) "
"to stop other cpu(s)\n");
/*
* A system reset will force all CPUs to execute the
* crash code again. We need to reset cpus_in_crash so we
* wait for everyone to do this.
*/
atomic_set(&cpus_in_crash, 0);
smp_mb();
while (atomic_read(&cpus_in_crash) < ncpus)
cpu_relax();
}
crash_shutdown_cpu = -1;
__debugger = old_handler;
tries++;
goto again;
}
/*
* This function will be called by secondary cpus.
*/
void crash_kexec_secondary(struct pt_regs *regs)
{
unsigned long flags;
int msecs = SECONDARY_TIMEOUT;
local_irq_save(flags);
/* Wait for the primary crash CPU to signal its progress */
while (crashing_cpu < 0) {
if (--msecs < 0) {
/* No response, kdump image may not have been loaded */
local_irq_restore(flags);
return;
}
mdelay(1);
}
crash_ipi_callback(regs);
}
#else /* ! CONFIG_SMP */
static void crash_kexec_prepare_cpus(void)
{
/*
* move the secondaries to us so that we can copy
* the new kernel 0-0x100 safely
*
* do this if kexec in setup.c ?
*/
#ifdef CONFIG_PPC64
smp_release_cpus();
#else
/* FIXME */
#endif
}
void crash_kexec_secondary(struct pt_regs *regs)
{
}
#endif /* CONFIG_SMP */
/* wait for all the CPUs to hit real mode but timeout if they don't come in */
#if defined(CONFIG_SMP) && defined(CONFIG_PPC64)
noinstr static void __maybe_unused crash_kexec_wait_realmode(int cpu)
{
unsigned int msecs;
int i;
msecs = REAL_MODE_TIMEOUT;
for (i=0; i < nr_cpu_ids && msecs > 0; i++) {
if (i == cpu)
continue;
while (paca_ptrs[i]->kexec_state < KEXEC_STATE_REAL_MODE) {
barrier();
if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
break;
msecs--;
mdelay(1);
}
}
mb();
}
#else
static inline void crash_kexec_wait_realmode(int cpu) {}
#endif /* CONFIG_SMP && CONFIG_PPC64 */
void crash_kexec_prepare(void)
{
/* Avoid hardlocking with irresponsive CPU holding logbuf_lock */
printk_deferred_enter();
/*
* This function is only called after the system
* has panicked or is otherwise in a critical state.
* The minimum amount of code to allow a kexec'd kernel
* to run successfully needs to happen here.
*
* In practice this means stopping other cpus in
* an SMP system.
* The kernel is broken so disable interrupts.
*/
hard_irq_disable();
/*
* Make a note of crashing cpu. Will be used in machine_kexec
* such that another IPI will not be sent.
*/
crashing_cpu = smp_processor_id();
crash_kexec_prepare_cpus();
}
/*
* Register a function to be called on shutdown. Only use this if you
* can't reset your device in the second kernel.
*/
int crash_shutdown_register(crash_shutdown_t handler)
{
unsigned int i, rc;
spin_lock(&crash_handlers_lock);
for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
if (!crash_shutdown_handles[i]) {
/* Insert handle at first empty entry */
crash_shutdown_handles[i] = handler;
rc = 0;
break;
}
if (i == CRASH_HANDLER_MAX) {
printk(KERN_ERR "Crash shutdown handles full, "
"not registered.\n");
rc = 1;
}
spin_unlock(&crash_handlers_lock);
return rc;
}
EXPORT_SYMBOL(crash_shutdown_register);
int crash_shutdown_unregister(crash_shutdown_t handler)
{
unsigned int i, rc;
spin_lock(&crash_handlers_lock);
for (i = 0 ; i < CRASH_HANDLER_MAX; i++)
if (crash_shutdown_handles[i] == handler)
break;
if (i == CRASH_HANDLER_MAX) {
printk(KERN_ERR "Crash shutdown handle not found\n");
rc = 1;
} else {
/* Shift handles down */
for (; i < (CRASH_HANDLER_MAX - 1); i++)
crash_shutdown_handles[i] =
crash_shutdown_handles[i+1];
/*
* Reset last entry to NULL now that it has been shifted down,
* this will allow new handles to be added here.
*/
crash_shutdown_handles[i] = NULL;
rc = 0;
}
spin_unlock(&crash_handlers_lock);
return rc;
}
EXPORT_SYMBOL(crash_shutdown_unregister);
void default_machine_crash_shutdown(struct pt_regs *regs)
{
volatile unsigned int i;
int (*old_handler)(struct pt_regs *regs);
if (TRAP(regs) == INTERRUPT_SYSTEM_RESET)
is_via_system_reset = 1;
crash_smp_send_stop();
crash_save_cpu(regs, crashing_cpu);
time_to_dump = 1;
crash_kexec_wait_realmode(crashing_cpu);
machine_kexec_mask_interrupts();
/*
* Call registered shutdown routines safely. Swap out
* __debugger_fault_handler, and replace on exit.
*/
old_handler = __debugger_fault_handler;
__debugger_fault_handler = handle_fault;
crash_shutdown_cpu = smp_processor_id();
for (i = 0; i < CRASH_HANDLER_MAX && crash_shutdown_handles[i]; i++) {
if (setjmp(crash_shutdown_buf) == 0) {
/*
* Insert syncs and delay to ensure
* instructions in the dangerous region don't
* leak away from this protected region.
*/
asm volatile("sync; isync");
/* dangerous region */
crash_shutdown_handles[i]();
asm volatile("sync; isync");
}
}
crash_shutdown_cpu = -1;
__debugger_fault_handler = old_handler;
if (ppc_md.kexec_cpu_down)
ppc_md.kexec_cpu_down(1, 0);
}
#ifdef CONFIG_CRASH_HOTPLUG
#undef pr_fmt
#define pr_fmt(fmt) "crash hp: " fmt
/*
* Advertise preferred elfcorehdr size to userspace via
* /sys/kernel/crash_elfcorehdr_size sysfs interface.
*/
unsigned int arch_crash_get_elfcorehdr_size(void)
{
unsigned long phdr_cnt;
/* A program header for possible CPUs + vmcoreinfo */
phdr_cnt = num_possible_cpus() + 1;
if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
phdr_cnt += CONFIG_CRASH_MAX_MEMORY_RANGES;
return sizeof(struct elfhdr) + (phdr_cnt * sizeof(Elf64_Phdr));
}
/**
* update_crash_elfcorehdr() - Recreate the elfcorehdr and replace it with old
* elfcorehdr in the kexec segment array.
* @image: the active struct kimage
* @mn: struct memory_notify data handler
*/
static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *mn)
{
int ret;
struct crash_mem *cmem = NULL;
struct kexec_segment *ksegment;
void *ptr, *mem, *elfbuf = NULL;
unsigned long elfsz, memsz, base_addr, size;
ksegment = &image->segment[image->elfcorehdr_index];
mem = (void *) ksegment->mem;
memsz = ksegment->memsz;
ret = get_crash_memory_ranges(&cmem);
if (ret) {
pr_err("Failed to get crash mem range\n");
return;
}
/*
* The hot unplugged memory is part of crash memory ranges,
* remove it here.
*/
if (image->hp_action == KEXEC_CRASH_HP_REMOVE_MEMORY) {
base_addr = PFN_PHYS(mn->start_pfn);
size = mn->nr_pages * PAGE_SIZE;
ret = remove_mem_range(&cmem, base_addr, size);
if (ret) {
pr_err("Failed to remove hot-unplugged memory from crash memory ranges\n");
goto out;
}
}
ret = crash_prepare_elf64_headers(cmem, false, &elfbuf, &elfsz);
if (ret) {
pr_err("Failed to prepare elf header\n");
goto out;
}
/*
* It is unlikely that kernel hit this because elfcorehdr kexec
* segment (memsz) is built with addition space to accommodate growing
* number of crash memory ranges while loading the kdump kernel. It is
* Just to avoid any unforeseen case.
*/
if (elfsz > memsz) {
pr_err("Updated crash elfcorehdr elfsz %lu > memsz %lu", elfsz, memsz);
goto out;
}
ptr = __va(mem);
if (ptr) {
/* Temporarily invalidate the crash image while it is replaced */
xchg(&kexec_crash_image, NULL);
/* Replace the old elfcorehdr with newly prepared elfcorehdr */
memcpy((void *)ptr, elfbuf, elfsz);
/* The crash image is now valid once again */
xchg(&kexec_crash_image, image);
}
out:
kvfree(cmem);
kvfree(elfbuf);
}
/**
* get_fdt_index - Loop through the kexec segment array and find
* the index of the FDT segment.
* @image: a pointer to kexec_crash_image
*
* Returns the index of FDT segment in the kexec segment array
* if found; otherwise -1.
*/
static int get_fdt_index(struct kimage *image)
{
void *ptr;
unsigned long mem;
int i, fdt_index = -1;
/* Find the FDT segment index in kexec segment array. */
for (i = 0; i < image->nr_segments; i++) {
mem = image->segment[i].mem;
ptr = __va(mem);
if (ptr && fdt_magic(ptr) == FDT_MAGIC) {
fdt_index = i;
break;
}
}
return fdt_index;
}
/**
* update_crash_fdt - updates the cpus node of the crash FDT.
*
* @image: a pointer to kexec_crash_image
*/
static void update_crash_fdt(struct kimage *image)
{
void *fdt;
int fdt_index;
fdt_index = get_fdt_index(image);
if (fdt_index < 0) {
pr_err("Unable to locate FDT segment.\n");
return;
}
fdt = __va((void *)image->segment[fdt_index].mem);
/* Temporarily invalidate the crash image while it is replaced */
xchg(&kexec_crash_image, NULL);
/* update FDT to reflect changes in CPU resources */
if (update_cpus_node(fdt))
pr_err("Failed to update crash FDT");
/* The crash image is now valid once again */
xchg(&kexec_crash_image, image);
}
int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags)
{
#ifdef CONFIG_KEXEC_FILE
if (image->file_mode)
return 1;
#endif
return kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT;
}
/**
* arch_crash_handle_hotplug_event - Handle crash CPU/Memory hotplug events to update the
* necessary kexec segments based on the hotplug event.
* @image: a pointer to kexec_crash_image
* @arg: struct memory_notify handler for memory hotplug case and NULL for CPU hotplug case.
*
* Update the kdump image based on the type of hotplug event, represented by image->hp_action.
* CPU add: Update the FDT segment to include the newly added CPU.
* CPU remove: No action is needed, with the assumption that it's okay to have offline CPUs
* part of the FDT.
* Memory add/remove: No action is taken as this is not yet supported.
*/
void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
{
struct memory_notify *mn;
switch (image->hp_action) {
case KEXEC_CRASH_HP_REMOVE_CPU:
return;
case KEXEC_CRASH_HP_ADD_CPU:
update_crash_fdt(image);
break;
case KEXEC_CRASH_HP_REMOVE_MEMORY:
case KEXEC_CRASH_HP_ADD_MEMORY:
mn = (struct memory_notify *)arg;
update_crash_elfcorehdr(image, mn);
return;
default:
pr_warn_once("Unknown hotplug action\n");
}
}
#endif /* CONFIG_CRASH_HOTPLUG */
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