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Message-ID: <c4a222a6-2da0-5c9b-fa05-b572e08e1e14@loongson.cn>
Date: Mon, 5 Sep 2022 15:45:18 +0800
From: Youling Tang <tangyouling@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: Baoquan He <bhe@...hat.com>,
Eric Biederman <ebiederm@...ssion.com>,
WANG Xuerui <kernel@...0n.name>,
Vivek Goyal <vgoyal@...hat.com>,
Dave Young <dyoung@...hat.com>, Guo Ren <guoren@...nel.org>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
kexec@...ts.infradead.org, loongarch@...ts.linux.dev,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] LoongArch: Add kdump support
Hi, Huacai
On 09/05/2022 03:32 PM, Huacai Chen wrote:
> Hi, Youling,
>
> On Mon, Sep 5, 2022 at 10:22 AM Youling Tang <tangyouling@...ngson.cn> wrote:
>>
>>
>>
>> On 09/05/2022 10:14 AM, Huacai Chen wrote:
>>> On Mon, Sep 5, 2022 at 10:04 AM Youling Tang <tangyouling@...ngson.cn> wrote:
>>>>
>>>> Hi, Huacai
>>>>
>>>> On 09/05/2022 09:38 AM, Huacai Chen wrote:
>>>>> Hi, Youling,
>>>>>
>>>>> On Mon, Sep 5, 2022 at 8:54 AM Youling Tang <tangyouling@...ngson.cn> wrote:
>>>>>>
>>>>>> Hi, Huacai
>>>>>>
>>>>>> On 09/04/2022 08:21 PM, Huacai Chen wrote:
>>>>>>> Hi, Youling,
>>>>>>>
>>>>>>> I think crash.c can be merged into crash_dump.c
>>>>>>
>>>>>> Most architectures only implement copy_oldmem_page() in crash_dump.c,
>>>>>> I'm not sure if merging crash.c into crash_dump.c will break its
>>>>>> consistency?
>>>>>>
>>>>>> Thanks,
>>>>>> Youling
>>>>> Yes, you are right, crash.c cannot be merged into crash_dump.c, but it
>>>>> can be merged into machine_kexec.c, as arm64 and riscv do.
>>>>
>>>> For arm64, machine_crash_shutdown() is placed in machine_kexec.c, and
>>>> crash_smp_send_stop is placed in smp.c. If crash.c needs to be merged
>>>> into machine_kexec.c, should crash_shutdown_secondary and
>>>> crash_smp_send_stop be placed in smp.c?
>>> I don't want to touch smp.c, all merged into machine_kexec.c seems reasonable.
>>
>> Ok, I'll merge all into machine_kexec.c.
>>
>> Youling.
> Another problem, 0x9000000091000000 for PHYSICAL_START is too tricky.
> If you want to skip the "low memory", maybe we can use
> 0x9000000090000000 or 0x90000000a0000000?
Because there are many holes in our memory layout, if PHYSICAL_START is
set to 0x90000000a0000000, the largest reserved area of the crashkernel
will be 512M, beyond which it will fail.
# cat /proc/iomem
90400000-bfffffff : System RAM
c0020000-f9efffff : System RAM
f6810000-f6813fff : Reserved
The second System RAM starts at 0x90400000, so 0x9000000090000000 will
be too small.
Youling.
>
> Huacai
>>
>>>
>>> Huacai
>>>>
>>>> Youling.
>>>>>
>>>>> Huacai
>>>>>>
>>>>>>>
>>>>>>> Huacai
>>>>>>>
>>>>>>> On Mon, Aug 29, 2022 at 12:37 PM Youling Tang <tangyouling@...ngson.cn> wrote:
>>>>>>>>
>>>>>>>> This patch adds support for kdump, the kernel will reserve a region
>>>>>>>> for the crash kernel and jump there on panic.
>>>>>>>>
>>>>>>>> Arch-specific functions are added to allow for implementing a crash
>>>>>>>> dump file interface, /proc/vmcore, which can be viewed as a ELF file.
>>>>>>>>
>>>>>>>> A user space tool, like kexec-tools, is responsible for allocating a
>>>>>>>> separate region for the core's ELF header within crash kdump kernel
>>>>>>>> memory and filling it in when executing kexec_load().
>>>>>>>>
>>>>>>>> Then, its location will be advertised to crash dump kernel via a new
>>>>>>>> device-tree property, "linux,elfcorehdr", and crash dump kernel preserves
>>>>>>>> the region for later use with fdt_reserve_elfcorehdr() at boot time.
>>>>>>>>
>>>>>>>> At the same time, it will also limit the crash kdump kernel to the
>>>>>>>> crashkernel area via a new device-tree property, "linux, usable-memory-range",
>>>>>>>> so as not to destroy the original kernel dump data.
>>>>>>>>
>>>>>>>> On crash dump kernel, /proc/vmcore will access the primary kernel's memory
>>>>>>>> with copy_oldmem_page().
>>>>>>>>
>>>>>>>> I tested this on LoongArch 3A5000 machine and works as expected (Suggest
>>>>>>>> crashkernel parameter is "crashkernel=512M@...0M"), you may test it by
>>>>>>>> triggering a crash through /proc/sysrq_trigger:
>>>>>>>>
>>>>>>>> $ sudo kexec -p /boot/vmlinux-kdump --reuse-cmdline --append="nr_cpus=1"
>>>>>>>> # echo c > /proc/sysrq_trigger
>>>>>>>>
>>>>>>>> Signed-off-by: Youling Tang <tangyouling@...ngson.cn>
>>>>>>>> ---
>>>>>>>> arch/loongarch/Kconfig | 22 ++++++
>>>>>>>> arch/loongarch/Makefile | 4 +
>>>>>>>> arch/loongarch/kernel/Makefile | 3 +-
>>>>>>>> arch/loongarch/kernel/crash.c | 100 ++++++++++++++++++++++++
>>>>>>>> arch/loongarch/kernel/crash_dump.c | 19 +++++
>>>>>>>> arch/loongarch/kernel/machine_kexec.c | 12 ++-
>>>>>>>> arch/loongarch/kernel/mem.c | 6 ++
>>>>>>>> arch/loongarch/kernel/relocate_kernel.S | 6 ++
>>>>>>>> arch/loongarch/kernel/setup.c | 49 ++++++++++++
>>>>>>>> arch/loongarch/kernel/traps.c | 4 +
>>>>>>>> 10 files changed, 217 insertions(+), 8 deletions(-)
>>>>>>>> create mode 100644 arch/loongarch/kernel/crash.c
>>>>>>>> create mode 100644 arch/loongarch/kernel/crash_dump.c
>>>>>>>>
>>>>>>>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>>>>>>>> index 903c82fa958d..7c1b07a5b5bd 100644
>>>>>>>> --- a/arch/loongarch/Kconfig
>>>>>>>> +++ b/arch/loongarch/Kconfig
>>>>>>>> @@ -420,6 +420,28 @@ config KEXEC
>>>>>>>>
>>>>>>>> The name comes from the similarity to the exec system call.
>>>>>>>>
>>>>>>>> +config CRASH_DUMP
>>>>>>>> + bool "Build kdump crash kernel"
>>>>>>>> + help
>>>>>>>> + Generate crash dump after being started by kexec. This should
>>>>>>>> + be normally only set in special crash dump kernels which are
>>>>>>>> + loaded in the main kernel with kexec-tools into a specially
>>>>>>>> + reserved region and then later executed after a crash by
>>>>>>>> + kdump/kexec.
>>>>>>>> +
>>>>>>>> + For more details see Documentation/admin-guide/kdump/kdump.rst
>>>>>>>> +
>>>>>>>> +config PHYSICAL_START
>>>>>>>> + hex "Physical address where the kernel is loaded"
>>>>>>>> + default "0x9000000091000000" if 64BIT
>>>>>>>> + depends on CRASH_DUMP
>>>>>>>> + help
>>>>>>>> + This gives the XKPRANGE address where the kernel is loaded.
>>>>>>>> + If you plan to use kernel for capturing the crash dump change
>>>>>>>> + this value to start of the reserved region (the "X" value as
>>>>>>>> + specified in the "crashkernel=YM@XM" command line boot parameter
>>>>>>>> + passed to the panic-ed kernel).
>>>>>>>> +
>>>>>>>> config SECCOMP
>>>>>>>> bool "Enable seccomp to safely compute untrusted bytecode"
>>>>>>>> depends on PROC_FS
>>>>>>>> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
>>>>>>>> index 4bc47f47cfd8..7dabd580426d 100644
>>>>>>>> --- a/arch/loongarch/Makefile
>>>>>>>> +++ b/arch/loongarch/Makefile
>>>>>>>> @@ -48,7 +48,11 @@ KBUILD_CFLAGS_MODULE += -fplt -Wa,-mla-global-with-abs,-mla-local-with-abs
>>>>>>>> cflags-y += -ffreestanding
>>>>>>>> cflags-y += $(call cc-option, -mno-check-zero-division)
>>>>>>>>
>>>>>>>> +ifdef CONFIG_PHYSICAL_START
>>>>>>>> +load-y = $(CONFIG_PHYSICAL_START)
>>>>>>>> +else
>>>>>>>> load-y = 0x9000000000200000
>>>>>>>> +endif
>>>>>>>> bootvars-y = VMLINUX_LOAD_ADDRESS=$(load-y)
>>>>>>>>
>>>>>>>> drivers-$(CONFIG_PCI) += arch/loongarch/pci/
>>>>>>>> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
>>>>>>>> index 20b64ac3f128..df5aea129364 100644
>>>>>>>> --- a/arch/loongarch/kernel/Makefile
>>>>>>>> +++ b/arch/loongarch/kernel/Makefile
>>>>>>>> @@ -17,7 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU) += fpu.o
>>>>>>>> obj-$(CONFIG_MODULES) += module.o module-sections.o
>>>>>>>> obj-$(CONFIG_STACKTRACE) += stacktrace.o
>>>>>>>>
>>>>>>>> -obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
>>>>>>>> +obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
>>>>>>>> +obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
>>>>>>>>
>>>>>>>> obj-$(CONFIG_PROC_FS) += proc.o
>>>>>>>>
>>>>>>>> diff --git a/arch/loongarch/kernel/crash.c b/arch/loongarch/kernel/crash.c
>>>>>>>> new file mode 100644
>>>>>>>> index 000000000000..b4f249ec6301
>>>>>>>> --- /dev/null
>>>>>>>> +++ b/arch/loongarch/kernel/crash.c
>>>>>>>> @@ -0,0 +1,100 @@
>>>>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>>>>> +/*
>>>>>>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited
>>>>>>>> + *
>>>>>>>> + * Derived from MIPS
>>>>>>>> + */
>>>>>>>> +#include <linux/kernel.h>
>>>>>>>> +#include <linux/smp.h>
>>>>>>>> +#include <linux/reboot.h>
>>>>>>>> +#include <linux/crash_dump.h>
>>>>>>>> +#include <linux/delay.h>
>>>>>>>> +#include <linux/irq.h>
>>>>>>>> +#include <linux/types.h>
>>>>>>>> +#include <linux/sched.h>
>>>>>>>> +#include <linux/sched/task_stack.h>
>>>>>>>> +#include <asm/cacheflush.h>
>>>>>>>> +#include <asm/kexec.h>
>>>>>>>> +
>>>>>>>> +static cpumask_t cpus_in_crash = CPU_MASK_NONE;
>>>>>>>> +
>>>>>>>> +#ifdef CONFIG_SMP
>>>>>>>> +static void crash_shutdown_secondary(void *passed_regs)
>>>>>>>> +{
>>>>>>>> + struct pt_regs *regs = passed_regs;
>>>>>>>> + int cpu = smp_processor_id();
>>>>>>>> +
>>>>>>>> + /*
>>>>>>>> + * If we are passed registers, use those. Otherwise get the
>>>>>>>> + * regs from the last interrupt, which should be correct, as
>>>>>>>> + * we are in an interrupt. But if the regs are not there,
>>>>>>>> + * pull them from the top of the stack. They are probably
>>>>>>>> + * wrong, but we need something to keep from crashing again.
>>>>>>>> + */
>>>>>>>> + if (!regs)
>>>>>>>> + regs = get_irq_regs();
>>>>>>>> + if (!regs)
>>>>>>>> + regs = task_pt_regs(current);
>>>>>>>> +
>>>>>>>> + local_irq_disable();
>>>>>>>> + if (!cpumask_test_cpu(cpu, &cpus_in_crash))
>>>>>>>> + crash_save_cpu(regs, cpu);
>>>>>>>> + cpumask_set_cpu(cpu, &cpus_in_crash);
>>>>>>>> +
>>>>>>>> + while (!atomic_read(&kexec_ready_to_reboot))
>>>>>>>> + cpu_relax();
>>>>>>>> +
>>>>>>>> + kexec_reboot();
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +/* Override the weak function in kernel/panic.c */
>>>>>>>> +void crash_smp_send_stop(void)
>>>>>>>> +{
>>>>>>>> + static int cpus_stopped;
>>>>>>>> + unsigned long timeout;
>>>>>>>> + unsigned int ncpus;
>>>>>>>> +
>>>>>>>> + /*
>>>>>>>> + * This function can be called twice in panic path, but obviously
>>>>>>>> + * we execute this only once.
>>>>>>>> + */
>>>>>>>> + if (cpus_stopped)
>>>>>>>> + return;
>>>>>>>> +
>>>>>>>> + cpus_stopped = 1;
>>>>>>>> +
>>>>>>>> + /* Excluding the panic cpu */
>>>>>>>> + ncpus = num_online_cpus() - 1;
>>>>>>>> +
>>>>>>>> + smp_call_function(crash_shutdown_secondary, NULL, 0);
>>>>>>>> + smp_wmb();
>>>>>>>> +
>>>>>>>> + /*
>>>>>>>> + * The crash CPU sends an IPI and wait for other CPUs to
>>>>>>>> + * respond. Delay of at least 10 seconds.
>>>>>>>> + */
>>>>>>>> + pr_emerg("Sending IPI to other cpus...\n");
>>>>>>>> + timeout = USEC_PER_SEC * 10;
>>>>>>>> + while ((cpumask_weight(&cpus_in_crash) < ncpus) && timeout--) {
>>>>>>>> + cpu_relax();
>>>>>>>> + udelay(1);
>>>>>>>> + }
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +#endif
>>>>>>>> +
>>>>>>>> +void machine_crash_shutdown(struct pt_regs *regs)
>>>>>>>> +{
>>>>>>>> + int crashing_cpu;
>>>>>>>> +
>>>>>>>> + local_irq_disable();
>>>>>>>> +
>>>>>>>> + crashing_cpu = smp_processor_id();
>>>>>>>> + crash_save_cpu(regs, crashing_cpu);
>>>>>>>> +
>>>>>>>> + /* shutdown non-crashing cpus */
>>>>>>>> + crash_smp_send_stop();
>>>>>>>> + cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
>>>>>>>> +
>>>>>>>> + pr_info("Starting crashdump kernel...\n");
>>>>>>>> +}
>>>>>>>> diff --git a/arch/loongarch/kernel/crash_dump.c b/arch/loongarch/kernel/crash_dump.c
>>>>>>>> new file mode 100644
>>>>>>>> index 000000000000..13e5d2f7870d
>>>>>>>> --- /dev/null
>>>>>>>> +++ b/arch/loongarch/kernel/crash_dump.c
>>>>>>>> @@ -0,0 +1,19 @@
>>>>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>>>>> +#include <linux/highmem.h>
>>>>>>>> +#include <linux/crash_dump.h>
>>>>>>>> +#include <linux/io.h>
>>>>>>>> +
>>>>>>>> +ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
>>>>>>>> + size_t csize, unsigned long offset)
>>>>>>>> +{
>>>>>>>> + void *vaddr;
>>>>>>>> +
>>>>>>>> + if (!csize)
>>>>>>>> + return 0;
>>>>>>>> +
>>>>>>>> + vaddr = kmap_local_pfn(pfn);
>>>>>>>> + csize = copy_to_iter(vaddr + offset, csize, iter);
>>>>>>>> + kunmap_local(vaddr);
>>>>>>>> +
>>>>>>>> + return csize;
>>>>>>>> +}
>>>>>>>> diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
>>>>>>>> index 4ffcd4cd9c8c..f793a3ff09a3 100644
>>>>>>>> --- a/arch/loongarch/kernel/machine_kexec.c
>>>>>>>> +++ b/arch/loongarch/kernel/machine_kexec.c
>>>>>>>> @@ -69,7 +69,7 @@ int machine_kexec_prepare(struct kimage *kimage)
>>>>>>>> continue;
>>>>>>>> }
>>>>>>>>
>>>>>>>> - /* kexec need a safe page to save reboot_code_buffer */
>>>>>>>> + /* kexec/kdump need a safe page to save reboot_code_buffer */
>>>>>>>> kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
>>>>>>>>
>>>>>>>> reboot_code_buffer =
>>>>>>>> @@ -113,10 +113,6 @@ static void kexec_shutdown_secondary(void *)
>>>>>>>>
>>>>>>>> kexec_reboot();
>>>>>>>> }
>>>>>>>> -
>>>>>>>> -void machine_crash_shutdown(struct pt_regs *regs)
>>>>>>>> -{
>>>>>>>> -}
>>>>>>>> #endif
>>>>>>>>
>>>>>>>> void machine_shutdown(void)
>>>>>>>> @@ -135,7 +131,8 @@ void machine_kexec(struct kimage *image)
>>>>>>>>
>>>>>>>> jump_addr = (unsigned long)phys_to_virt(image->start);
>>>>>>>>
>>>>>>>> - first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
>>>>>>>> + if (image->type == KEXEC_TYPE_DEFAULT)
>>>>>>>> + first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
>>>>>>>>
>>>>>>>> /*
>>>>>>>> * The generic kexec code builds a page list with physical
>>>>>>>> @@ -167,7 +164,8 @@ void machine_kexec(struct kimage *image)
>>>>>>>>
>>>>>>>> /*
>>>>>>>> * We know we were online, and there will be no incoming IPIs at
>>>>>>>> - * this point.
>>>>>>>> + * this point. Mark online again before rebooting so that the crash
>>>>>>>> + * analysis tool will see us correctly.
>>>>>>>> */
>>>>>>>> set_cpu_online(smp_processor_id(), true);
>>>>>>>>
>>>>>>>> diff --git a/arch/loongarch/kernel/mem.c b/arch/loongarch/kernel/mem.c
>>>>>>>> index 7423361b0ebc..c6def6ff81c8 100644
>>>>>>>> --- a/arch/loongarch/kernel/mem.c
>>>>>>>> +++ b/arch/loongarch/kernel/mem.c
>>>>>>>> @@ -5,6 +5,7 @@
>>>>>>>> #include <linux/efi.h>
>>>>>>>> #include <linux/initrd.h>
>>>>>>>> #include <linux/memblock.h>
>>>>>>>> +#include <linux/of_fdt.h>
>>>>>>>>
>>>>>>>> #include <asm/bootinfo.h>
>>>>>>>> #include <asm/loongson.h>
>>>>>>>> @@ -61,4 +62,9 @@ void __init memblock_init(void)
>>>>>>>>
>>>>>>>> /* Reserve the initrd */
>>>>>>>> reserve_initrd_mem();
>>>>>>>> +
>>>>>>>> + /* Mainly reserved memory for the elf core head */
>>>>>>>> + early_init_fdt_scan_reserved_mem();
>>>>>>>> + /* Parse linux,usable-memory-range is for crash dump kernel */
>>>>>>>> + early_init_dt_check_for_usable_mem_range();
>>>>>>>> }
>>>>>>>> diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
>>>>>>>> index d1f242f74ea8..4ee5ac4ac2d7 100644
>>>>>>>> --- a/arch/loongarch/kernel/relocate_kernel.S
>>>>>>>> +++ b/arch/loongarch/kernel/relocate_kernel.S
>>>>>>>> @@ -28,6 +28,12 @@ SYM_CODE_START(relocate_new_kernel)
>>>>>>>> move s2, a2
>>>>>>>> move s3, a3
>>>>>>>>
>>>>>>>> + /*
>>>>>>>> + * In case of a kdump/crash kernel, the indirection page is not
>>>>>>>> + * populated as the kernel is directly copied to a reserved location
>>>>>>>> + */
>>>>>>>> + beqz s2, done
>>>>>>>> +
>>>>>>>> process_entry:
>>>>>>>> PTR_L s4, s2, 0
>>>>>>>> PTR_ADDI s2, s2, SZREG
>>>>>>>> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
>>>>>>>> index f938aae3e92c..ea34b77e402f 100644
>>>>>>>> --- a/arch/loongarch/kernel/setup.c
>>>>>>>> +++ b/arch/loongarch/kernel/setup.c
>>>>>>>> @@ -19,6 +19,8 @@
>>>>>>>> #include <linux/memblock.h>
>>>>>>>> #include <linux/initrd.h>
>>>>>>>> #include <linux/ioport.h>
>>>>>>>> +#include <linux/kexec.h>
>>>>>>>> +#include <linux/crash_dump.h>
>>>>>>>> #include <linux/root_dev.h>
>>>>>>>> #include <linux/console.h>
>>>>>>>> #include <linux/pfn.h>
>>>>>>>> @@ -186,6 +188,50 @@ static int __init early_parse_mem(char *p)
>>>>>>>> }
>>>>>>>> early_param("mem", early_parse_mem);
>>>>>>>>
>>>>>>>> +static void __init loongarch_parse_crashkernel(void)
>>>>>>>> +{
>>>>>>>> +#ifdef CONFIG_KEXEC
>>>>>>>> + unsigned long long start;
>>>>>>>> + unsigned long long total_mem;
>>>>>>>> + unsigned long long crash_size, crash_base;
>>>>>>>> + int ret;
>>>>>>>> +
>>>>>>>> + total_mem = memblock_phys_mem_size();
>>>>>>>> + ret = parse_crashkernel(boot_command_line, total_mem,
>>>>>>>> + &crash_size, &crash_base);
>>>>>>>> + if (ret != 0 || crash_size <= 0)
>>>>>>>> + return;
>>>>>>>> +
>>>>>>>> +
>>>>>>>> + start = memblock_phys_alloc_range(crash_size, 1, crash_base,
>>>>>>>> + crash_base + crash_size);
>>>>>>>> + if (start != crash_base) {
>>>>>>>> + pr_warn("Invalid memory region reserved for crash kernel\n");
>>>>>>>> + return;
>>>>>>>> + }
>>>>>>>> +
>>>>>>>> + crashk_res.start = crash_base;
>>>>>>>> + crashk_res.end = crash_base + crash_size - 1;
>>>>>>>> +#endif
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +static void __init request_crashkernel(struct resource *res)
>>>>>>>> +{
>>>>>>>> +#ifdef CONFIG_KEXEC
>>>>>>>> + int ret;
>>>>>>>> +
>>>>>>>> + if (crashk_res.start == crashk_res.end)
>>>>>>>> + return;
>>>>>>>> +
>>>>>>>> + ret = request_resource(res, &crashk_res);
>>>>>>>> + if (!ret)
>>>>>>>> + pr_info("Reserving %ldMB of memory at %ldMB for crashkernel\n",
>>>>>>>> + (unsigned long)((crashk_res.end -
>>>>>>>> + crashk_res.start + 1) >> 20),
>>>>>>>> + (unsigned long)(crashk_res.start >> 20));
>>>>>>>> +#endif
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> void __init platform_init(void)
>>>>>>>> {
>>>>>>>> efi_init();
>>>>>>>> @@ -229,6 +275,8 @@ static void __init arch_mem_init(char **cmdline_p)
>>>>>>>>
>>>>>>>> check_kernel_sections_mem();
>>>>>>>>
>>>>>>>> + loongarch_parse_crashkernel();
>>>>>>>> +
>>>>>>>> /*
>>>>>>>> * In order to reduce the possibility of kernel panic when failed to
>>>>>>>> * get IO TLB memory under CONFIG_SWIOTLB, it is better to allocate
>>>>>>>> @@ -290,6 +338,7 @@ static void __init resource_init(void)
>>>>>>>> request_resource(res, &code_resource);
>>>>>>>> request_resource(res, &data_resource);
>>>>>>>> request_resource(res, &bss_resource);
>>>>>>>> + request_crashkernel(res);
>>>>>>>> }
>>>>>>>> }
>>>>>>>>
>>>>>>>> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
>>>>>>>> index aa1c95aaf595..0e610872f3f4 100644
>>>>>>>> --- a/arch/loongarch/kernel/traps.c
>>>>>>>> +++ b/arch/loongarch/kernel/traps.c
>>>>>>>> @@ -10,6 +10,7 @@
>>>>>>>> #include <linux/entry-common.h>
>>>>>>>> #include <linux/init.h>
>>>>>>>> #include <linux/kernel.h>
>>>>>>>> +#include <linux/kexec.h>
>>>>>>>> #include <linux/module.h>
>>>>>>>> #include <linux/extable.h>
>>>>>>>> #include <linux/mm.h>
>>>>>>>> @@ -246,6 +247,9 @@ void __noreturn die(const char *str, struct pt_regs *regs)
>>>>>>>>
>>>>>>>> oops_exit();
>>>>>>>>
>>>>>>>> + if (regs && kexec_should_crash(current))
>>>>>>>> + crash_kexec(regs);
>>>>>>>> +
>>>>>>>> if (in_interrupt())
>>>>>>>> panic("Fatal exception in interrupt");
>>>>>>>>
>>>>>>>> --
>>>>>>>> 2.36.0
>>>>>>>>
>>>>>>
>>>>
>>
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