From nobody Thu Apr 2 14:47:17 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41E5CC6FA82 for ; Fri, 23 Sep 2022 07:45:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230071AbiIWHpN (ORCPT ); Fri, 23 Sep 2022 03:45:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229804AbiIWHpB (ORCPT ); Fri, 23 Sep 2022 03:45:01 -0400 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 579C53DBDA for ; Fri, 23 Sep 2022 00:44:56 -0700 (PDT) Received: from bogon.localdomain (unknown [113.200.148.30]) by localhost.localdomain (Coremail) with SMTP id AQAAf8CxT+DpYy1jsI4gAA--.57695S4; Fri, 23 Sep 2022 15:44:43 +0800 (CST) From: Youling Tang To: Huacai Chen , Ard Biesheuvel , Baoquan He , Eric Biederman Cc: WANG Xuerui , Vivek Goyal , Dave Young , Guo Ren , Jiaxun Yang , kexec@lists.infradead.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org Subject: [PATCH v4 2/3] LoongArch: Add kdump support Date: Fri, 23 Sep 2022 15:44:32 +0800 Message-Id: <1663919073-26849-3-git-send-email-tangyouling@loongson.cn> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1663919073-26849-1-git-send-email-tangyouling@loongson.cn> References: <1663919073-26849-1-git-send-email-tangyouling@loongson.cn> X-CM-TRANSID: AQAAf8CxT+DpYy1jsI4gAA--.57695S4 X-Coremail-Antispam: 1UD129KBjvAXoW3ur4kur15XF1UJr13XF1rtFb_yoW8XF45Go WxtF18tw1rKrW2yrs5CF1jyFW5Kr1qkrsxA39xZa13WF1Syw1UX348Kr9Iy347Jws5Ww4x G34ag3yjva97Xr95n29KB7ZKAUJUUUU8529EdanIXcx71UUUUU7v73VFW2AGmfu7bjvjm3 AaLaJ3UjIYCTnIWjp_UUUOn7k0a2IF6w4kM7kC6x804xWl14x267AKxVWrJVCq3wAFc2x0 x2IEx4CE42xK8VAvwI8IcIk0rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87 I2jVAFwI0_Jryl82xGYIkIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY 1VAKz4vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Xr0_Ar1l84ACjcxK6xIIjxv20x vEc7CjxVAFwI0_Cr0_Gr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv 6xkF7I0E14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c 02F40Ex7xfMcIj6xIIjxv20xvE14v26r1Y6r17McIj6I8E87Iv67AKxVW8JVWxJwAm72CE 4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc2 xSY4AK67AK6r4xMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E 5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtV W8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1I6r4UMIIF0xvE2Ix0cI8IcVCY 1x0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI 0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7I U5LID3UUUUU== X-CM-SenderInfo: 5wdqw5prxox03j6o00pqjv00gofq/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" This patch adds support for kdump. In kdump case the normal 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, such as kexec-tools, is responsible for allocating a separate region for the core's ELF header within the crash kdump kernel memory and filling it in when executing kexec_load(). Then, its location will be advertised to the crash dump kernel via a command line argument "elfcorehdr=3D", and the crash dump kernel will preserve this region for later use with loongarch_reserve_vmcore at boot time. At the same time, the crash kdump kernel is also limited within the "crashkernel" area via a command line argument "mem=3D", so as not to destroy the original kernel dump data. In the crash dump kernel environment, /proc/vmcore is used to access the primary kernel's memory with copy_oldmem_page(). I tested kdump on LoongArch machines (Loongson-3A5000) and it works as expected (suggested crashkernel parameter is "crashkernel=3D512M@2560M"), you may test it by triggering a crash through /proc/sysrq-trigger: $ sudo kexec -p /boot/vmlinux-kdump --reuse-cmdline --append=3D"nr_cpus=3D= 1" # echo c > /proc/sysrq-trigger Signed-off-by: Youling Tang --- arch/loongarch/Kconfig | 22 +++++ arch/loongarch/Makefile | 4 + arch/loongarch/kernel/Makefile | 1 + arch/loongarch/kernel/crash_dump.c | 19 ++++ arch/loongarch/kernel/machine_kexec.c | 98 ++++++++++++++++++- arch/loongarch/kernel/mem.c | 1 + arch/loongarch/kernel/relocate_kernel.S | 6 ++ arch/loongarch/kernel/setup.c | 123 ++++++++++++++++++++++-- arch/loongarch/kernel/traps.c | 4 + 9 files changed, 263 insertions(+), 15 deletions(-) create mode 100644 arch/loongarch/kernel/crash_dump.c diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 4352e9b271aa..b2da0a6f844e 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -430,6 +430,28 @@ config KEXEC =20 The name comes from the similarity to the exec system call. =20 +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 "0x90000000a0000000" + 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=3DYM@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 42352f905858..ea17e692684e 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -69,7 +69,11 @@ endif cflags-y +=3D -ffreestanding cflags-y +=3D $(call cc-option, -mno-check-zero-division) =20 +ifndef CONFIG_PHYSICAL_START load-y =3D 0x9000000000200000 +else +load-y =3D $(CONFIG_PHYSICAL_START) +endif bootvars-y =3D VMLINUX_LOAD_ADDRESS=3D$(load-y) =20 drivers-$(CONFIG_PCI) +=3D arch/loongarch/pci/ diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile index 17554244db54..53581442fa73 100644 --- a/arch/loongarch/kernel/Makefile +++ b/arch/loongarch/kernel/Makefile @@ -18,6 +18,7 @@ obj-$(CONFIG_MODULES) +=3D module.o module-sections.o obj-$(CONFIG_STACKTRACE) +=3D stacktrace.o =20 obj-$(CONFIG_KEXEC) +=3D machine_kexec.o relocate_kernel.o +obj-$(CONFIG_CRASH_DUMP) +=3D crash_dump.o =20 obj-$(CONFIG_PROC_FS) +=3D proc.o =20 diff --git a/arch/loongarch/kernel/crash_dump.c b/arch/loongarch/kernel/cra= sh_dump.c new file mode 100644 index 000000000000..3a3711e57f39 --- /dev/null +++ b/arch/loongarch/kernel/crash_dump.c @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +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 =3D kmap_local_pfn(pfn); + csize =3D 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 348d914d6d85..0ca9118c0a22 100644 --- a/arch/loongarch/kernel/machine_kexec.c +++ b/arch/loongarch/kernel/machine_kexec.c @@ -7,10 +7,15 @@ #include #include #include -#include +#include #include +#include #include +#include #include +#include +#include +#include =20 #include #include @@ -22,6 +27,7 @@ #define KEXEC_STBL_ADDR TO_CACHE(0x110000UL) =20 static unsigned long reboot_code_buffer; +static cpumask_t cpus_in_crash =3D CPU_MASK_NONE; =20 #ifdef CONFIG_SMP static void (*relocated_kexec_smp_wait)(void *); @@ -83,7 +89,7 @@ int machine_kexec_prepare(struct kimage *kimage) return -EINVAL; } =20 - /* 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 =3D virt_to_page((void *)KEXEC_CTRL_CODE); =20 reboot_code_buffer =3D (unsigned long)page_address(kimage->control_code_p= age); @@ -107,7 +113,8 @@ void kexec_reboot(void) =20 /* * 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); =20 @@ -152,7 +159,74 @@ static void kexec_shutdown_secondary(void *) =20 kexec_reboot(); } -#endif + +static void crash_shutdown_secondary(void *passed_regs) +{ + int cpu =3D smp_processor_id(); + struct pt_regs *regs =3D passed_regs; + + /* + * 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 =3D get_irq_regs(); + if (!regs) + regs =3D task_pt_regs(current); + + if (!cpu_online(cpu)) + return; + + /* We won't be sent IPIs any more. */ + set_cpu_online(cpu, false); + + 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(); +} + +void crash_smp_send_stop(void) +{ + unsigned int ncpus; + unsigned long timeout; + static int cpus_stopped; + + /* + * This function can be called twice in panic path, but obviously + * we should execute this only once. + */ + if (cpus_stopped) + return; + + cpus_stopped =3D 1; + + /* Excluding the panic cpu */ + ncpus =3D 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. + */ + timeout =3D MSEC_PER_SEC * 10; + pr_emerg("Sending IPI to other cpus...\n"); + while ((cpumask_weight(&cpus_in_crash) < ncpus) && timeout--) { + mdelay(1); + cpu_relax(); + } +} +#endif /* defined(CONFIG_SMP) */ =20 void machine_shutdown(void) { @@ -170,6 +244,19 @@ void machine_shutdown(void) =20 void machine_crash_shutdown(struct pt_regs *regs) { + int crashing_cpu; + + local_irq_disable(); + + crashing_cpu =3D smp_processor_id(); + crash_save_cpu(regs, crashing_cpu); + +#ifdef CONFIG_SMP + crash_smp_send_stop(); +#endif + cpumask_set_cpu(crashing_cpu, &cpus_in_crash); + + pr_info("Starting crashdump kernel...\n"); } =20 void machine_kexec(struct kimage *image) @@ -184,7 +271,8 @@ void machine_kexec(struct kimage *image) =20 jump_addr =3D (unsigned long)phys_to_virt(image->start); =20 - first_ind_entry =3D (unsigned long)phys_to_virt(image->head & PAGE_MASK); + first_ind_entry =3D (image->type =3D=3D KEXEC_TYPE_DEFAULT) ? + (unsigned long)phys_to_virt(image->head & PAGE_MASK) : 0; =20 /* * The generic kexec code builds a page list with physical diff --git a/arch/loongarch/kernel/mem.c b/arch/loongarch/kernel/mem.c index 7423361b0ebc..0f155e86e2dc 100644 --- a/arch/loongarch/kernel/mem.c +++ b/arch/loongarch/kernel/mem.c @@ -5,6 +5,7 @@ #include #include #include +#include =20 #include #include diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kerne= l/relocate_kernel.S index 6eaa1eb05d8c..c7d663655246 100644 --- a/arch/loongarch/kernel/relocate_kernel.S +++ b/arch/loongarch/kernel/relocate_kernel.S @@ -24,6 +24,12 @@ SYM_CODE_START(relocate_new_kernel) */ move s0, a4 =20 + /* + * In case of a kdump/crash kernel, the indirection page is not + * populated as the kernel is directly copied to a reserved location + */ + beqz s0, done + process_entry: PTR_L s1, s0, 0 PTR_ADDI s0, s0, SZREG diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c index 05af1102fee7..cbb485e2477d 100644 --- a/arch/loongarch/kernel/setup.c +++ b/arch/loongarch/kernel/setup.c @@ -19,6 +19,8 @@ #include #include #include +#include +#include #include #include #include @@ -60,6 +62,8 @@ EXPORT_SYMBOL(cpu_data); struct loongson_board_info b_info; static const char dmi_empty_string[] =3D " "; =20 +static phys_addr_t crashmem_start, crashmem_size; + /* * Setup information * @@ -157,16 +161,6 @@ static int __init early_parse_mem(char *p) return -EINVAL; } =20 - /* - * If a user specifies memory size, we - * blow away any automatically generated - * size. - */ - if (usermem =3D=3D 0) { - usermem =3D 1; - memblock_remove(memblock_start_of_DRAM(), - memblock_end_of_DRAM() - memblock_start_of_DRAM()); - } start =3D 0; size =3D memparse(p, &p); if (*p =3D=3D '@') @@ -176,6 +170,23 @@ static int __init early_parse_mem(char *p) return -EINVAL; } =20 + /* + * If a user specifies memory size, we + * blow away any automatically generated + * size. + */ + if (usermem =3D=3D 0) { + usermem =3D 1; + if (!strstr(boot_command_line, "elfcorehdr")) { + memblock_remove(memblock_start_of_DRAM(), + memblock_end_of_DRAM() - memblock_start_of_DRAM()); + } else { + crashmem_start =3D start; + crashmem_size =3D size; + return 0; + } + } + if (!IS_ENABLED(CONFIG_NUMA)) memblock_add(start, size); else @@ -185,6 +196,93 @@ static int __init early_parse_mem(char *p) } early_param("mem", early_parse_mem); =20 +void __init loongarch_reserve_vmcore(void) +{ + phys_addr_t start, end; + u64 i; + + if (!is_kdump_kernel()) + return; + + if (!elfcorehdr_size) { + for_each_mem_range(i, &start, &end) { + if (elfcorehdr_addr >=3D start && elfcorehdr_addr < end) { + /* + * Reserve from the elf core header to the end of + * the memory segment, that should all be kdump + * reserved memory. + */ + elfcorehdr_size =3D end - elfcorehdr_addr; + break; + } + } + } + + if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) { + pr_warn("elfcorehdr is overlapped\n"); + return; + } + + memblock_reserve(elfcorehdr_addr, elfcorehdr_size); + + pr_info("Reserving %llu KiB of memory at 0x%llx for elfcorehdr\n", + elfcorehdr_size >> 10, elfcorehdr_addr); +} + +/* + * After the kdump operation is performed to enter the capture kernel, the + * memory area used by the previous production kernel should be reserved to + * avoid destroy to the captured data. + */ +static void reserve_oldmem_region(void) +{ + if (!is_kdump_kernel()) + return; + + memblock_cap_memory_range(crashmem_start, crashmem_size); +} + +static void __init loongarch_parse_crashkernel(void) +{ +#ifdef CONFIG_KEXEC + int ret; + unsigned long long start; + unsigned long long total_mem; + unsigned long long crash_size, crash_base; + + total_mem =3D memblock_phys_mem_size(); + ret =3D parse_crashkernel(boot_command_line, total_mem, &crash_size, &cra= sh_base); + if (ret < 0 || crash_size <=3D 0) + return; + + + start =3D memblock_phys_alloc_range(crash_size, 1, crash_base, crash_base= + crash_size); + if (start !=3D crash_base) { + pr_warn("Invalid memory region reserved for crash kernel\n"); + return; + } + + crashk_res.start =3D crash_base; + crashk_res.end =3D crash_base + crash_size - 1; +#endif +} + +static void __init request_crashkernel(struct resource *res) +{ +#ifdef CONFIG_KEXEC + int ret; + + if (crashk_res.start =3D=3D crashk_res.end) + return; + + ret =3D 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) { #ifdef CONFIG_ACPI_TABLE_UPGRADE @@ -227,6 +325,10 @@ static void __init arch_mem_init(char **cmdline_p) =20 check_kernel_sections_mem(); =20 + loongarch_parse_crashkernel(); + loongarch_reserve_vmcore(); + reserve_oldmem_region(); + /* * In order to reduce the possibility of kernel panic when failed to * get IO TLB memory under CONFIG_SWIOTLB, it is better to allocate @@ -288,6 +390,7 @@ static void __init resource_init(void) request_resource(res, &code_resource); request_resource(res, &data_resource); request_resource(res, &bss_resource); + request_crashkernel(res); } } =20 diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c index 950af620e7d0..a692009fee31 100644 --- a/arch/loongarch/kernel/traps.c +++ b/arch/loongarch/kernel/traps.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -246,6 +247,9 @@ void __noreturn die(const char *str, struct pt_regs *re= gs) =20 oops_exit(); =20 + if (regs && kexec_should_crash(current)) + crash_kexec(regs); + if (in_interrupt()) panic("Fatal exception in interrupt"); =20 --=20 2.36.0