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Message-ID: <ee8da2cb-eb00-b7d1-968b-62c552e7ac74@loongson.cn>
Date: Mon, 5 Sep 2022 21:07:27 +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 09:01 PM, Huacai Chen wrote:
> Hi, Youling,
>
> On Mon, Sep 5, 2022 at 3:45 PM Youling Tang <tangyouling@...ngson.cn> wrote:
>>
>> 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.
> Then 0x9000000090000000 is not suitable, but I think 512M is enough?
> If so, let's use 0x90000000a0000000.
I'm not sure if it's enough for the server machine?
I will change to 0x90000000a0000000.
Youling.
>
> Huacai
>
> Huacai
>>
>> # 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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