diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index d6c2dbf8455ced..32d195f5cb8a0e 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -1133,6 +1133,9 @@ config ARCH_DEFAULT_CRASH_DUMP config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION def_bool CRASH_RESERVE +config ARCH_SUPPORTS_CRASH_HOTPLUG + def_bool y + config COMPAT bool "Kernel support for 32-bit U-mode" default 64BIT diff --git a/arch/riscv/include/asm/kexec.h b/arch/riscv/include/asm/kexec.h index b9ee8346cc8c9a..e218835eb10c22 100644 --- a/arch/riscv/include/asm/kexec.h +++ b/arch/riscv/include/asm/kexec.h @@ -75,4 +75,17 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start, unsigned long cmdline_len); #endif +#ifdef CONFIG_CRASH_HOTPLUG +struct kimage; + +void arch_crash_handle_hotplug_event(struct kimage *image, void *arg); +#define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event + +int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags); +#define arch_crash_hotplug_support arch_crash_hotplug_support + +unsigned int arch_crash_get_elfcorehdr_size(void); +#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size +#endif + #endif diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index ebe1c3588177b4..d0a5d442110fca 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -111,6 +111,7 @@ obj-$(CONFIG_KGDB) += kgdb.o obj-$(CONFIG_KEXEC_CORE) += kexec_relocate.o crash_save_regs.o machine_kexec.o obj-$(CONFIG_KEXEC_FILE) += kexec_elf.o kexec_image.o machine_kexec_file.o obj-$(CONFIG_CRASH_DUMP) += crash_dump.o +obj-$(CONFIG_CRASH_HOTPLUG) += crash.o obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o diff --git a/arch/riscv/kernel/crash.c b/arch/riscv/kernel/crash.c new file mode 100644 index 00000000000000..fe5a4b306aae3f --- /dev/null +++ b/arch/riscv/kernel/crash.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * RISC-V crash hotplug support + * + * Copyright (C) 2025 Bytedance Ltd. + */ + +#include +#include +#include +#include + +#ifdef CONFIG_CRASH_HOTPLUG + +#undef pr_fmt +#define pr_fmt(fmt) "crash hp: " fmt + +int arch_crash_hotplug_support(struct kimage *image, unsigned long kexec_flags) +{ +#ifdef CONFIG_KEXEC_FILE + if (image->file_mode) + return 1; +#endif + /* + * For the kexec_load() syscall path, the user space kexec tool + * needs to indicate that the elfcorehdr segment is excluded from + * SHA verification by setting the appropriate flags. + */ + return (kexec_flags & KEXEC_UPDATE_ELFCOREHDR || + kexec_flags & KEXEC_CRASH_HOTPLUG_SUPPORT); +} + +unsigned int arch_crash_get_elfcorehdr_size(void) +{ + unsigned int sz; + + /* kernel_map, VMCOREINFO and maximum CPUs */ + sz = 2 + CONFIG_NR_CPUS; + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) + sz += CONFIG_CRASH_MAX_MEMORY_RANGES; + sz *= sizeof(Elf64_Phdr); + return sz; +} + +/** + * arch_crash_handle_hotplug_event() - Handle hotplug elfcorehdr changes + * @image: a pointer to kexec_crash_image + * @arg: struct memory_notify handler for memory hotplug case and + * NULL for CPU hotplug case. + * + * Prepare the new elfcorehdr and replace the existing elfcorehdr. + */ +void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) +{ + void *elfbuf = NULL, *old_elfcorehdr; + unsigned long mem, memsz; + unsigned long elfsz = 0; + + /* + * As crash_prepare_elf64_headers() has already described all + * possible CPUs, there is no need to update the elfcorehdr + * for additional CPU changes. + */ + if ((image->file_mode || image->elfcorehdr_updated) && + ((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) || + (image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU))) + return; + + /* + * Create the new elfcorehdr reflecting the changes to CPU and/or + * memory resources. + */ + if (crash_prepare_headers(true, &elfbuf, &elfsz, NULL)) { + pr_err("unable to create new elfcorehdr"); + goto out; + } + + /* + * Obtain address and size of the elfcorehdr segment, and + * check it against the new elfcorehdr buffer. + */ + mem = image->segment[image->elfcorehdr_index].mem; + memsz = image->segment[image->elfcorehdr_index].memsz; + if (elfsz > memsz) { + pr_err("update elfcorehdr elfsz %lu > memsz %lu", + elfsz, memsz); + goto out; + } + + /* + * Copy new elfcorehdr over the old elfcorehdr at destination. + */ + old_elfcorehdr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT)); + if (!old_elfcorehdr) { + pr_err("mapping elfcorehdr segment failed\n"); + goto out; + } + + /* + * Temporarily invalidate the crash image while the + * elfcorehdr is updated. + */ + xchg(&kexec_crash_image, NULL); + memcpy_flushcache(old_elfcorehdr, elfbuf, elfsz); + xchg(&kexec_crash_image, image); + kunmap_local(old_elfcorehdr); + pr_debug("updated elfcorehdr\n"); + +out: + vfree(elfbuf); +} + +#endif /* CONFIG_CRASH_HOTPLUG */