From: George Guo <[email protected]> Enable Kexec Handover (KHO) on LoongArch64 for FDT-based systems.
- Kconfig: select ARCH_SUPPORTS_KEXEC_HANDOVER for CONFIG_64BIT - kexec.h: add fdt/fdt_mem fields to kimage_arch to hold the KHO FDT kexec segment virtual and physical addresses - machine_kexec_file.c: add kho_load_fdt() which copies the running kernel's FDT (initial_boot_params), appends linux,kho-fdt and linux,kho-scratch properties to /chosen, and loads the result as a kexec segment; called from load_other_segments(). Returns -EINVAL when initial_boot_params is NULL (ACPI-only boot) since that path requires separate handling. - machine_kexec.c: before jumping to the new kernel, update the DEVICE_TREE_GUID entry in the EFI config table to point to the KHO FDT segment so the second kernel finds it via efi_fdt_pointer() and early_init_dt_check_kho() calls kho_populate() Co-developed-by: Kexin Liu <[email protected]> Signed-off-by: Kexin Liu <[email protected]> Signed-off-by: George Guo <[email protected]> --- arch/loongarch/Kconfig | 3 + arch/loongarch/include/asm/kexec.h | 4 + arch/loongarch/kernel/machine_kexec.c | 27 +++++ arch/loongarch/kernel/machine_kexec_file.c | 118 +++++++++++++++++++++ 4 files changed, 152 insertions(+) diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 606597da46b8..d494418545f5 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -684,6 +684,9 @@ config ARCH_SUPPORTS_KEXEC config ARCH_SUPPORTS_KEXEC_FILE def_bool 64BIT +config ARCH_SUPPORTS_KEXEC_HANDOVER + def_bool 64BIT + config ARCH_SELECTS_KEXEC_FILE def_bool 64BIT depends on KEXEC_FILE diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h index 209fa43222e1..adf54bfcdd49 100644 --- a/arch/loongarch/include/asm/kexec.h +++ b/arch/loongarch/include/asm/kexec.h @@ -39,6 +39,10 @@ struct kimage_arch { unsigned long efi_boot; unsigned long cmdline_ptr; unsigned long systable_ptr; +#ifdef CONFIG_KEXEC_HANDOVER + void *fdt; /* virtual address of KHO FDT segment buffer */ + unsigned long fdt_mem; /* physical address of KHO FDT segment */ +#endif }; #ifdef CONFIG_KEXEC_FILE diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c index ad27fef098f1..98529c71d001 100644 --- a/arch/loongarch/kernel/machine_kexec.c +++ b/arch/loongarch/kernel/machine_kexec.c @@ -6,6 +6,7 @@ */ #include <linux/compiler.h> #include <linux/cpu.h> +#include <linux/efi.h> #include <linux/kexec.h> #include <linux/crash_dump.h> #include <linux/delay.h> @@ -289,6 +290,32 @@ void machine_kexec(struct kimage *image) pr_notice("We will call new kernel at 0x%lx\n", start_addr); pr_notice("Bye ...\n"); +#ifdef CONFIG_KEXEC_HANDOVER + /* + * Point the EFI FDTPTR config table entry at the modified FDT so the + * second kernel picks up the linux,kho-fdt and linux,kho-scratch + * properties via early_init_dt_check_kho(). + */ + if (internal->fdt_mem) { + /* + * FDT-based system: DEVICE_TREE_GUID already exists in the EFI + * config table; just update its pointer to our KHO FDT. + */ + efi_system_table_t *st = + (efi_system_table_t *)TO_CACHE(systable_ptr); + efi_config_table_t *ct = + (efi_config_table_t *)TO_CACHE((unsigned long)st->tables); + unsigned long i; + + for (i = 0; i < st->nr_tables; i++) { + if (!efi_guidcmp(ct[i].guid, DEVICE_TREE_GUID)) { + ct[i].table = (void *)internal->fdt_mem; + break; + } + } + } +#endif + /* Make reboot code buffer available to the boot CPU. */ flush_cache_all(); diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c index 5584b798ba46..bf1e8c1c7e70 100644 --- a/arch/loongarch/kernel/machine_kexec_file.c +++ b/arch/loongarch/kernel/machine_kexec_file.c @@ -13,7 +13,9 @@ #include <linux/ioport.h> #include <linux/kernel.h> #include <linux/kexec.h> +#include <linux/libfdt.h> #include <linux/memblock.h> +#include <linux/of_fdt.h> #include <linux/slab.h> #include <linux/string.h> #include <linux/types.h> @@ -32,6 +34,11 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image) image->elf_headers = NULL; image->elf_headers_sz = 0; +#ifdef CONFIG_KEXEC_HANDOVER + kvfree(image->arch.fdt); + image->arch.fdt = NULL; +#endif + return kexec_image_post_load_cleanup_default(image); } @@ -55,6 +62,111 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl *cmdline_tmplen += initrd_strlen; } +#ifdef CONFIG_KEXEC_HANDOVER +/* + * Add KHO metadata to an FDT /chosen node and load the FDT as a kexec + * segment. The second kernel reads linux,kho-fdt and linux,kho-scratch + * from /chosen via early_init_dt_check_kho() and calls kho_populate(). + * + */ +static int kho_load_fdt(struct kimage *image) +{ + void *fdt; + int ret, chosen_node; + size_t fdt_size; + struct kexec_buf kbuf = { + .image = image, + .buf_min = 0, + .buf_max = ULONG_MAX, + .top_down = true, + }; + + if (!image->kho.fdt || !image->kho.scratch) + return 0; + + if (initial_boot_params) { + /* + * FDT boot: copy the running kernel's FDT and append KHO + * properties to /chosen. + */ + + /* + * Only two KHO properties are added to /chosen (linux,kho-fdt + * and linux,kho-scratch), so SZ_1K of extra space is + * sufficient. + */ + fdt_size = fdt_totalsize(initial_boot_params) + SZ_1K; + fdt = kvmalloc(fdt_size, GFP_KERNEL); + if (!fdt) + return -ENOMEM; + + ret = fdt_open_into(initial_boot_params, fdt, fdt_size); + if (ret < 0) { + pr_err("Failed to open FDT: %d\n", ret); + goto out_free; + } + + chosen_node = fdt_path_offset(fdt, "/chosen"); + if (chosen_node == -FDT_ERR_NOTFOUND) { + pr_debug("No /chosen node in FDT, creating one\n"); + chosen_node = fdt_add_subnode(fdt, + fdt_path_offset(fdt, "/"), + "chosen"); + } + if (chosen_node < 0) { + ret = chosen_node; + goto out_free; + } + + /* Remove stale KHO properties left by a previous kexec load */ + fdt_delprop(fdt, chosen_node, "linux,kho-fdt"); + fdt_delprop(fdt, chosen_node, "linux,kho-scratch"); + + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, + "linux,kho-fdt", + image->kho.fdt, PAGE_SIZE); + if (ret) + goto out_free; + + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, + "linux,kho-scratch", + image->kho.scratch->mem, + image->kho.scratch->bufsz); + if (ret) + goto out_free; + + /* + * Shrink totalsize to the actual data size so the kexec segment + * allocated by kexec_add_buffer() covers only the packed FDT data. + * The slack added above for property insertion is part of the + * kvmalloc'd buffer, which is freed by kimage_file_post_load_cleanup() + * once the kexec image has been loaded. + */ + fdt_pack(fdt); + + kbuf.buffer = fdt; + kbuf.bufsz = fdt_totalsize(fdt); + kbuf.memsz = kbuf.bufsz; + kbuf.buf_align = PAGE_SIZE; + kbuf.mem = KEXEC_BUF_MEM_UNKNOWN; + + ret = kexec_add_buffer(&kbuf); + if (ret) + goto out_free; + + image->arch.fdt = fdt; + image->arch.fdt_mem = kbuf.mem; + return 0; + } else { + return -EINVAL; + } + +out_free: + kvfree(fdt); + return ret; +} +#endif + #ifdef CONFIG_CRASH_DUMP static int prepare_elf_headers(void **addr, unsigned long *sz) @@ -230,6 +342,12 @@ int load_other_segments(struct kimage *image, cmdline = modified_cmdline; image->arch.cmdline_ptr = (unsigned long)cmdline; +#ifdef CONFIG_KEXEC_HANDOVER + ret = kho_load_fdt(image); + if (ret) + goto out_err; +#endif + return 0; out_err: -- 2.25.1
