LoongArch: Add kexec support
Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the LoongArch architecture, so as to add support for the kexec re-boot mechanism (CONFIG_KEXEC) on LoongArch platforms. Kexec supports loading vmlinux.elf in ELF format and vmlinux.efi in PE format. I tested kexec on LoongArch machines (Loongson-3A5000) and it works as expected: $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline $ sudo kexec -e Signed-off-by: Youling Tang <tangyouling@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Youling Tang
Huacai Chen
parent
2d2c395217
commit
4a03b2ac06
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@ -426,6 +426,17 @@ config ARCH_IOREMAP
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protection support. However, you can enable LoongArch DMW-based
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ioremap() for better performance.
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config KEXEC
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bool "Kexec system call"
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select KEXEC_CORE
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help
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kexec is a system call that implements the ability to shutdown your
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current kernel, and to start another kernel. It is like a reboot
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but it is independent of the system firmware. And like a reboot
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you can start any kernel with it, not just Linux.
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The name comes from the similarity to the exec system call.
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config SECCOMP
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bool "Enable seccomp to safely compute untrusted bytecode"
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depends on PROC_FS
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@ -0,0 +1,60 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* kexec.h for kexec
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*
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* Copyright (C) 2022 Loongson Technology Corporation Limited
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*/
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#ifndef _ASM_KEXEC_H
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#define _ASM_KEXEC_H
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#include <asm/stacktrace.h>
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#include <asm/page.h>
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/* Maximum physical address we can use pages from */
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#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
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/* Maximum address we can reach in physical address mode */
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#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
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/* Maximum address we can use for the control code buffer */
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#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
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/* Reserve a page for the control code buffer */
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#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
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/* The native architecture */
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#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
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static inline void crash_setup_regs(struct pt_regs *newregs,
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struct pt_regs *oldregs)
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{
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if (oldregs)
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memcpy(newregs, oldregs, sizeof(*newregs));
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else
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prepare_frametrace(newregs);
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}
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#define ARCH_HAS_KIMAGE_ARCH
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struct kimage_arch {
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unsigned long efi_boot;
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unsigned long cmdline_ptr;
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unsigned long systable_ptr;
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};
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typedef void (*do_kexec_t)(unsigned long efi_boot,
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unsigned long cmdline_ptr,
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unsigned long systable_ptr,
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unsigned long start_addr,
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unsigned long first_ind_entry);
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struct kimage;
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extern const unsigned char relocate_new_kernel[];
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extern const size_t relocate_new_kernel_size;
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extern void kexec_reboot(void);
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#ifdef CONFIG_SMP
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extern atomic_t kexec_ready_to_reboot;
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extern const unsigned char kexec_smp_wait[];
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#endif
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#endif /* !_ASM_KEXEC_H */
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@ -25,6 +25,8 @@ obj-$(CONFIG_NUMA) += numa.o
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obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o
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obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
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obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
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obj-$(CONFIG_UNWINDER_PROLOGUE) += unwind_prologue.o
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@ -21,7 +21,11 @@
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_head:
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.word MZ_MAGIC /* "MZ", MS-DOS header */
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.org 0x3c /* 0x04 ~ 0x3b reserved */
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.org 0x8
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.dword kernel_entry /* Kernel entry point */
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.dword _end - _text /* Kernel image effective size */
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.quad 0 /* Kernel image load offset from start of RAM */
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.org 0x3c /* 0x20 ~ 0x3b reserved */
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.long pe_header - _head /* Offset to the PE header */
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pe_header:
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@ -0,0 +1,216 @@
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* machine_kexec.c for kexec
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*
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* Copyright (C) 2022 Loongson Technology Corporation Limited
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*/
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#include <linux/compiler.h>
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#include <linux/cpu.h>
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#include <linux/kexec.h>
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#include <linux/mm.h>
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#include <linux/delay.h>
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#include <linux/libfdt.h>
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#include <linux/of_fdt.h>
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#include <asm/bootinfo.h>
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#include <asm/cacheflush.h>
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#include <asm/page.h>
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/* 0x100000 ~ 0x200000 is safe */
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#define KEXEC_CONTROL_CODE TO_CACHE(0x100000UL)
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#define KEXEC_CMDLINE_ADDR TO_CACHE(0x108000UL)
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static unsigned long reboot_code_buffer;
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#ifdef CONFIG_SMP
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static void (*relocated_kexec_smp_wait)(void *);
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atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
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#endif
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static unsigned long efi_boot;
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static unsigned long cmdline_ptr;
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static unsigned long systable_ptr;
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static unsigned long start_addr;
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static unsigned long first_ind_entry;
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static void kexec_image_info(const struct kimage *kimage)
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{
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unsigned long i;
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pr_debug("kexec kimage info:\n");
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pr_debug("\ttype: %d\n", kimage->type);
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pr_debug("\tstart: %lx\n", kimage->start);
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pr_debug("\thead: %lx\n", kimage->head);
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pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
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for (i = 0; i < kimage->nr_segments; i++) {
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pr_debug("\t segment[%lu]: %016lx - %016lx", i,
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kimage->segment[i].mem,
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kimage->segment[i].mem + kimage->segment[i].memsz);
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pr_debug("\t\t0x%lx bytes, %lu pages\n",
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(unsigned long)kimage->segment[i].memsz,
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(unsigned long)kimage->segment[i].memsz / PAGE_SIZE);
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}
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}
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int machine_kexec_prepare(struct kimage *kimage)
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{
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int i;
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char *bootloader = "kexec";
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void *cmdline_ptr = (void *)KEXEC_CMDLINE_ADDR;
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kexec_image_info(kimage);
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kimage->arch.efi_boot = fw_arg0;
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kimage->arch.systable_ptr = fw_arg2;
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/* Find the command line */
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for (i = 0; i < kimage->nr_segments; i++) {
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if (!strncmp(bootloader, (char __user *)kimage->segment[i].buf, strlen(bootloader))) {
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if (!copy_from_user(cmdline_ptr, kimage->segment[i].buf, COMMAND_LINE_SIZE))
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kimage->arch.cmdline_ptr = (unsigned long)cmdline_ptr;
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break;
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}
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}
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if (!kimage->arch.cmdline_ptr) {
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pr_err("Command line not included in the provided image\n");
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return -EINVAL;
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}
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/* kexec need a safe page to save reboot_code_buffer */
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kimage->control_code_page = virt_to_page((void *)KEXEC_CONTROL_CODE);
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reboot_code_buffer = (unsigned long)page_address(kimage->control_code_page);
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memcpy((void *)reboot_code_buffer, relocate_new_kernel, relocate_new_kernel_size);
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#ifdef CONFIG_SMP
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/* All secondary cpus now may jump to kexec_smp_wait cycle */
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relocated_kexec_smp_wait = reboot_code_buffer + (void *)(kexec_smp_wait - relocate_new_kernel);
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#endif
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return 0;
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}
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void machine_kexec_cleanup(struct kimage *kimage)
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{
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}
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void kexec_reboot(void)
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{
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do_kexec_t do_kexec = NULL;
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/*
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* We know we were online, and there will be no incoming IPIs at
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* this point.
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*/
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set_cpu_online(smp_processor_id(), true);
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/* Ensure remote CPUs observe that we're online before rebooting. */
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smp_mb__after_atomic();
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/*
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* Make sure we get correct instructions written by the
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* machine_kexec_prepare() CPU.
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*/
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__asm__ __volatile__ ("\tibar 0\n"::);
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#ifdef CONFIG_SMP
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/* All secondary cpus go to kexec_smp_wait */
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if (smp_processor_id() > 0) {
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relocated_kexec_smp_wait(NULL);
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unreachable();
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}
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#endif
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do_kexec = (void *)reboot_code_buffer;
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do_kexec(efi_boot, cmdline_ptr, systable_ptr, start_addr, first_ind_entry);
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unreachable();
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}
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#ifdef CONFIG_SMP
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static void kexec_shutdown_secondary(void *regs)
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{
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int cpu = smp_processor_id();
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if (!cpu_online(cpu))
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return;
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/* We won't be sent IPIs any more. */
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set_cpu_online(cpu, false);
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local_irq_disable();
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while (!atomic_read(&kexec_ready_to_reboot))
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cpu_relax();
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kexec_reboot();
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}
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#endif
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void machine_shutdown(void)
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{
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int cpu;
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/* All CPUs go to reboot_code_buffer */
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for_each_possible_cpu(cpu)
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if (!cpu_online(cpu))
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cpu_device_up(get_cpu_device(cpu));
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#ifdef CONFIG_SMP
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smp_call_function(kexec_shutdown_secondary, NULL, 0);
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#endif
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}
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void machine_crash_shutdown(struct pt_regs *regs)
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{
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}
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void machine_kexec(struct kimage *image)
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{
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unsigned long entry, *ptr;
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struct kimage_arch *internal = &image->arch;
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efi_boot = internal->efi_boot;
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cmdline_ptr = internal->cmdline_ptr;
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systable_ptr = internal->systable_ptr;
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start_addr = (unsigned long)phys_to_virt(image->start);
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first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
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/*
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* The generic kexec code builds a page list with physical
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* addresses. they are directly accessible through XKPRANGE
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* hence the phys_to_virt() call.
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*/
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for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
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ptr = (entry & IND_INDIRECTION) ?
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phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
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if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
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*ptr & IND_DESTINATION)
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*ptr = (unsigned long) phys_to_virt(*ptr);
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}
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/* Mark offline before disabling local irq. */
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set_cpu_online(smp_processor_id(), false);
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/* We do not want to be bothered. */
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local_irq_disable();
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pr_notice("EFI boot flag 0x%lx\n", efi_boot);
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pr_notice("Command line at 0x%lx\n", cmdline_ptr);
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pr_notice("System table at 0x%lx\n", systable_ptr);
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pr_notice("We will call new kernel at 0x%lx\n", start_addr);
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pr_notice("Bye ...\n");
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/* Make reboot code buffer available to the boot CPU. */
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flush_cache_all();
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#ifdef CONFIG_SMP
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atomic_set(&kexec_ready_to_reboot, 1);
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#endif
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kexec_reboot();
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}
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@ -0,0 +1,106 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* relocate_kernel.S for kexec
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*
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* Copyright (C) 2022 Loongson Technology Corporation Limited
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*/
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#include <linux/kexec.h>
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#include <asm/asm.h>
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#include <asm/asmmacro.h>
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#include <asm/regdef.h>
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#include <asm/loongarch.h>
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#include <asm/stackframe.h>
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#include <asm/addrspace.h>
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SYM_CODE_START(relocate_new_kernel)
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/*
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* a0: EFI boot flag for the new kernel
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* a1: Command line pointer for the new kernel
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* a2: System table pointer for the new kernel
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* a3: Start address to jump to after relocation
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* a4: Pointer to the current indirection page entry
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*/
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move s0, a4
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process_entry:
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PTR_L s1, s0, 0
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PTR_ADDI s0, s0, SZREG
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/* destination page */
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andi s2, s1, IND_DESTINATION
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beqz s2, 1f
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li.w t0, ~0x1
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and s3, s1, t0 /* store destination addr in s3 */
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b process_entry
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1:
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/* indirection page, update s0 */
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andi s2, s1, IND_INDIRECTION
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beqz s2, 1f
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li.w t0, ~0x2
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and s0, s1, t0
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b process_entry
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1:
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/* done page */
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andi s2, s1, IND_DONE
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beqz s2, 1f
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b done
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1:
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/* source page */
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andi s2, s1, IND_SOURCE
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beqz s2, process_entry
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li.w t0, ~0x8
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and s1, s1, t0
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li.w s5, (1 << _PAGE_SHIFT) / SZREG
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copy_word:
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/* copy page word by word */
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REG_L s4, s1, 0
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REG_S s4, s3, 0
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PTR_ADDI s3, s3, SZREG
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PTR_ADDI s1, s1, SZREG
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LONG_ADDI s5, s5, -1
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beqz s5, process_entry
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b copy_word
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b process_entry
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done:
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ibar 0
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dbar 0
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/*
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* Jump to the new kernel,
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* make sure the values of a0, a1, a2 and a3 are not changed.
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*/
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jr a3
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SYM_CODE_END(relocate_new_kernel)
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#ifdef CONFIG_SMP
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/*
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* Other CPUs should wait until code is relocated and
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* then start at the entry point from LOONGARCH_IOCSR_MBUF0.
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*/
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SYM_CODE_START(kexec_smp_wait)
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1: li.w t0, 0x100 /* wait for init loop */
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2: addi.w t0, t0, -1 /* limit mailbox access */
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bnez t0, 2b
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li.w t1, LOONGARCH_IOCSR_MBUF0
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iocsrrd.w s0, t1 /* check PC as an indicator */
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beqz s0, 1b
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iocsrrd.d s0, t1 /* get PC via mailbox */
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li.d t0, CACHE_BASE
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or s0, s0, t0 /* s0 = TO_CACHE(s0) */
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jr s0 /* jump to initial PC */
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SYM_CODE_END(kexec_smp_wait)
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#endif
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relocate_new_kernel_end:
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SYM_DATA_START(relocate_new_kernel_size)
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PTR relocate_new_kernel_end - relocate_new_kernel
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SYM_DATA_END(relocate_new_kernel_size)
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