Messages in this thread | | | Subject | Re: [PATCH 1/3] LoongArch: Add kexec support | From | Jinyang He <> | Date | Tue, 30 Aug 2022 12:07:48 +0800 |
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On 08/30/2022 11:42 AM, Huacai Chen wrote:
> On Tue, Aug 30, 2022 at 11:26 AM Youling Tang <tangyouling@loongson.cn> wrote: >> Hi, Jinyang >> >> On 08/30/2022 09:53 AM, Jinyang He wrote: >>> Hi, Youling, >>> >>> >>> On 08/29/2022 12:37 PM, Youling Tang wrote: >>>> Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to >>>> the >>>> LoongArch architecture that add support for the kexec re-boot mechanis >>>> (CONFIG_KEXEC) on LoongArch platforms. >>>> >>>> Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in >>>> PE format. >>>> >>>> I tested this on LoongArch 3A5000 machine and works as expected, >>>> >>>> $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline >>>> $ sudo kexec -e >>>> >>>> Signed-off-by: Youling Tang <tangyouling@loongson.cn> >>>> --- >>>> arch/loongarch/Kconfig | 11 ++ >>>> arch/loongarch/include/asm/kexec.h | 58 ++++++++ >>>> arch/loongarch/kernel/Makefile | 2 + >>>> arch/loongarch/kernel/head.S | 7 +- >>>> arch/loongarch/kernel/machine_kexec.c | 178 ++++++++++++++++++++++++ >>>> arch/loongarch/kernel/relocate_kernel.S | 125 +++++++++++++++++ >>>> 6 files changed, 380 insertions(+), 1 deletion(-) >>>> create mode 100644 arch/loongarch/include/asm/kexec.h >>>> create mode 100644 arch/loongarch/kernel/machine_kexec.c >>>> create mode 100644 arch/loongarch/kernel/relocate_kernel.S >>>> >>>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig >>>> index 45364cffc793..903c82fa958d 100644 >>>> --- a/arch/loongarch/Kconfig >>>> +++ b/arch/loongarch/Kconfig >>>> @@ -409,6 +409,17 @@ config FORCE_MAX_ZONEORDER >>>> The page size is not necessarily 4KB. Keep this in mind >>>> when choosing a value for this option. >>>> +config KEXEC >>>> + bool "Kexec system call" >>>> + select KEXEC_CORE >>>> + help >>>> + kexec is a system call that implements the ability to shutdown >>>> your >>>> + current kernel, and to start another kernel. It is like a reboot >>>> + but it is independent of the system firmware. And like a reboot >>>> + you can start any kernel with it, not just Linux. >>>> + >>>> + The name comes from the similarity to the exec system call. >>>> + >>>> config SECCOMP >>>> bool "Enable seccomp to safely compute untrusted bytecode" >>>> depends on PROC_FS >>>> diff --git a/arch/loongarch/include/asm/kexec.h >>>> b/arch/loongarch/include/asm/kexec.h >>>> new file mode 100644 >>>> index 000000000000..5c9e7b5eccb8 >>>> --- /dev/null >>>> +++ b/arch/loongarch/include/asm/kexec.h >>>> @@ -0,0 +1,58 @@ >>>> +/* SPDX-License-Identifier: GPL-2.0 */ >>>> +/* >>>> + * kexec.h for kexec >>>> + * >>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited >>>> + */ >>>> + >>>> +#ifndef _ASM_KEXEC_H >>>> +#define _ASM_KEXEC_H >>>> + >>>> +#include <asm/stacktrace.h> >>>> +#include <asm/page.h> >>>> + >>>> +/* Maximum physical address we can use pages from */ >>>> +#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL) >>>> +/* Maximum address we can reach in physical address mode */ >>>> +#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL) >>>> + /* Maximum address we can use for the control code buffer */ >>>> +#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL) >>>> + >>>> +/* Reserve a page for the control code buffer */ >>>> +#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE >>>> + >>>> +/* The native architecture */ >>>> +#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH >>>> + >>>> +static inline void crash_setup_regs(struct pt_regs *newregs, >>>> + struct pt_regs *oldregs) >>>> +{ >>>> + if (oldregs) >>>> + memcpy(newregs, oldregs, sizeof(*newregs)); >>>> + else >>>> + prepare_frametrace(newregs); >>>> +} >>>> + >>>> +#define ARCH_HAS_KIMAGE_ARCH >>>> + >>>> +struct kimage_arch { >>>> + unsigned long boot_flag; >>>> + unsigned long fdt_addr; >>>> +}; >>>> + >>>> +typedef void (*do_kexec_t)(unsigned long boot_flag, >>>> + unsigned long fdt_addr, >>>> + unsigned long first_ind_entry, >>>> + unsigned long jump_addr); >>>> + >>>> +struct kimage; >>>> +extern const unsigned char relocate_new_kernel[]; >>>> +extern const size_t relocate_new_kernel_size; >>>> + >>>> +#ifdef CONFIG_SMP >>>> +extern atomic_t kexec_ready_to_reboot; >>>> +extern const unsigned char kexec_smp_wait[]; >>>> +extern void kexec_reboot(void); >>>> +#endif >>>> + >>>> +#endif /* !_ASM_KEXEC_H */ >>>> diff --git a/arch/loongarch/kernel/Makefile >>>> b/arch/loongarch/kernel/Makefile >>>> index a213e994db68..20b64ac3f128 100644 >>>> --- a/arch/loongarch/kernel/Makefile >>>> +++ b/arch/loongarch/kernel/Makefile >>>> @@ -17,6 +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-$(CONFIG_PROC_FS) += proc.o >>>> obj-$(CONFIG_SMP) += smp.o >>>> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S >>>> index 01bac62a6442..22bdf4928325 100644 >>>> --- a/arch/loongarch/kernel/head.S >>>> +++ b/arch/loongarch/kernel/head.S >>>> @@ -20,7 +20,12 @@ >>>> _head: >>>> .word MZ_MAGIC /* "MZ", MS-DOS header */ >>>> - .org 0x3c /* 0x04 ~ 0x3b reserved */ >>>> + .org 0x8 >>>> + .quad 0 /* Image load offset from start of RAM */ >>>> + .dword _end - _text /* Effective size of kernel image */ >>>> + .quad 0 >>>> + .dword kernel_entry /* Kernel entry point */ >>>> + .org 0x3c /* 0x28 ~ 0x3b reserved */ >>>> .long pe_header - _head /* Offset to the PE header */ >>>> pe_header: >>>> diff --git a/arch/loongarch/kernel/machine_kexec.c >>>> b/arch/loongarch/kernel/machine_kexec.c >>>> new file mode 100644 >>>> index 000000000000..4ffcd4cd9c8c >>>> --- /dev/null >>>> +++ b/arch/loongarch/kernel/machine_kexec.c >>>> @@ -0,0 +1,178 @@ >>>> +// SPDX-License-Identifier: GPL-2.0-only >>>> +/* >>>> + * machine_kexec.c for kexec >>>> + * >>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited >>>> + */ >>>> +#include <linux/compiler.h> >>>> +#include <linux/cpu.h> >>>> +#include <linux/kexec.h> >>>> +#include <linux/mm.h> >>>> +#include <linux/delay.h> >>>> +#include <linux/libfdt.h> >>>> +#include <linux/of_fdt.h> >>>> + >>>> +#include <asm/bootinfo.h> >>>> +#include <asm/cacheflush.h> >>>> +#include <asm/page.h> >>>> + >>>> +/* 0x100000 ~ 0x200000 is safe */ >>>> +#define KEXEC_CTRL_CODE TO_CACHE(0x100000UL) >>>> +#define KEXEC_BLOB_ADDR TO_CACHE(0x108000UL) >>>> + >>>> +static unsigned long reboot_code_buffer; >>>> +#ifdef CONFIG_SMP >>>> +void (*relocated_kexec_smp_wait)(void *); >>>> +atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0); >>>> +#endif >>>> + >>>> +static unsigned long jump_addr; >>>> +static unsigned long first_ind_entry; >>>> +static unsigned long boot_flag; >>>> +static unsigned long fdt_addr; >>>> + >>>> +static void kexec_image_info(const struct kimage *kimage) >>>> +{ >>>> + unsigned long i; >>>> + >>>> + pr_debug("kexec kimage info:\n"); >>>> + pr_debug("\ttype: %d\n", kimage->type); >>>> + pr_debug("\tstart: %lx\n", kimage->start); >>>> + pr_debug("\thead: %lx\n", kimage->head); >>>> + pr_debug("\tnr_segments: %lu\n", kimage->nr_segments); >>>> + >>>> + for (i = 0; i < kimage->nr_segments; i++) { >>>> + pr_debug("\t segment[%lu]: %016lx - %016lx", i, >>>> + kimage->segment[i].mem, >>>> + kimage->segment[i].mem + kimage->segment[i].memsz); >>>> + pr_debug("\t\t0x%lx bytes, %lu pages\n", >>>> + (unsigned long)kimage->segment[i].memsz, >>>> + (unsigned long)kimage->segment[i].memsz / PAGE_SIZE); >>>> + } >>>> +} >>>> + >>>> +int machine_kexec_prepare(struct kimage *kimage) >>>> +{ >>>> + int i; >>>> + void *dtb = (void *)KEXEC_BLOB_ADDR; >>>> + >>>> + kexec_image_info(kimage); >>>> + >>>> + /* Find the Flattened Device Tree */ >>>> + for (i = 0; i < kimage->nr_segments; i++) { >>>> + if (!fdt_check_header(kimage->segment[i].buf)) { >>>> + memcpy(dtb, kimage->segment[i].buf, SZ_64K); >>>> + kimage->arch.boot_flag = fw_arg0; >>>> + kimage->arch.fdt_addr = (unsigned long) dtb; >>>> + break; >>>> + } >>>> + continue; >>>> + } >>>> + >>>> + /* kexec need a safe page to save reboot_code_buffer */ >>>> + kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE); >>>> + >>>> + reboot_code_buffer = >>>> + (unsigned long)page_address(kimage->control_code_page); >>>> + memcpy((void *)reboot_code_buffer, relocate_new_kernel, >>>> + relocate_new_kernel_size); >>> It copys same content to KEXEC_CTRL_CODE each time, could we do this at >>> boot time? >> I think it's possible to have the copy action happen at boot-time or >> during the prepare phase. (RISCV in prepare, MIPS in boot-time) >> >>> BTW, our system always keep the low-2MB no used, on mips-loongson or >>> LoongArch. Is that necessary on LoongArch? We cannot use parameter >>> 'mem=YYM' normally but 'mem=YYM@2M' is ok. And the low-2MB is not >>> in virtual memory management, although we can get it in kernel. >> For existing kernels, the low 2M has been reserved by >> memblock_reserve(PHYS_OFFSET, 0x200000), maybe it is acceptable to keep >> the low 2M behavior. >> >> Yes, we need to use "mem=YM@2M" if the low 2M is reserved. >> >>> In kexec/kdump process, we can follows kimage_alloc_control_pages(). >>> When the boot cpu copy complete the second-kernels, all cpus can jump >>> to a kernel-entry-trampoline which is in kernel image. Then we don't >>> worry about the code can be destroyed. The kernel-entry-trampoline >>> get its cpuid, keep non-boot cpus do as kexec_smp_wait and let boot >>> cpu go kernel-entry. In this way we can drop the low-2MB IMO. >> It is also feasible to dynamically allocate control pages, but it is >> easier to use a low 2M approach. What do you think, Huacai? > I prefer to use the low 2MB. > > Huacai Low 2MB also is ok for me, like a trick. And should it free control_code_page here?
>>>> + >>>> + /* All secondary cpus now may jump to kexec_smp_wait cycle */ >>>> + relocated_kexec_smp_wait = reboot_code_buffer + >>>> + (void *)(kexec_smp_wait - relocate_new_kernel); >>>> + >>>> + return 0; >>>> +} >>>> + >>>> +void machine_kexec_cleanup(struct kimage *kimage) >>>> +{ >>>> +} >>>> + >>>> +#ifdef CONFIG_SMP >>>> +void kexec_reboot(void) >>>> +{ >>>> + do_kexec_t do_kexec = NULL; >>>> + >>>> + /* All secondary cpus go to kexec_smp_wait */ >>>> + if (smp_processor_id() > 0) { >>>> + relocated_kexec_smp_wait(NULL); >>>> + unreachable(); >>>> + } >>>> + >>>> + do_kexec = (void *)reboot_code_buffer; >>>> + do_kexec(boot_flag, fdt_addr, first_ind_entry, jump_addr); >>>> + >>>> + unreachable(); >>>> +} >>>> + >>>> +static void kexec_shutdown_secondary(void *) >>>> +{ >>>> + local_irq_disable(); >>>> + while (!atomic_read(&kexec_ready_to_reboot)) >>>> + cpu_relax(); >>>> + >>>> + kexec_reboot(); >>>> +} >>>> + >>>> +void machine_crash_shutdown(struct pt_regs *regs) >>>> +{ >>>> +} >>>> +#endif >>>> + >>>> +void machine_shutdown(void) >>>> +{ >>>> + smp_call_function(kexec_shutdown_secondary, NULL, 0); >>>> +} >>>> + >>>> +void machine_kexec(struct kimage *image) >>>> +{ >>>> + unsigned long entry; >>>> + unsigned long *ptr; >>>> + struct kimage_arch *internal = &image->arch; >>>> + >>>> + boot_flag = internal->boot_flag; >>>> + fdt_addr = internal->fdt_addr; >>>> + >>>> + jump_addr = (unsigned long)phys_to_virt(image->start); >>>> + >>>> + first_ind_entry = (unsigned long)phys_to_virt(image->head & >>>> PAGE_MASK); >>>> + >>>> + /* >>>> + * The generic kexec code builds a page list with physical >>>> + * addresses. they are directly accessible through XKPRANGE >>>> + * hence the phys_to_virt() call. >>>> + */ >>>> + for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); >>>> + ptr = (entry & IND_INDIRECTION) ? >>>> + phys_to_virt(entry & PAGE_MASK) : ptr + 1) { >>>> + if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION || >>>> + *ptr & IND_DESTINATION) >>>> + *ptr = (unsigned long) phys_to_virt(*ptr); >>>> + } >>>> + >>>> + /* Mark offline before disabling local irq. */ >>>> + set_cpu_online(smp_processor_id(), false); >>>> + >>>> + /* we do not want to be bothered. */ >>>> + local_irq_disable(); >>>> + >>>> + pr_notice("Will call new kernel at %lx\n", jump_addr); >>>> + pr_notice("FDT image at %lx\n", fdt_addr); >>>> + pr_notice("Bye ...\n"); >>>> + >>>> + /* Make reboot code buffer available to the boot CPU. */ >>>> + flush_cache_all(); >>>> + >>>> + atomic_set(&kexec_ready_to_reboot, 1); >>>> + >>>> + /* >>>> + * We know we were online, and there will be no incoming IPIs at >>>> + * this point. >>>> + */ >>>> + set_cpu_online(smp_processor_id(), true); >>>> + >>>> + /* Ensure remote CPUs observe that we're online before rebooting. */ >>>> + smp_mb__after_atomic(); >>>> + >>>> + kexec_reboot(); >>>> +} >>>> diff --git a/arch/loongarch/kernel/relocate_kernel.S >>>> b/arch/loongarch/kernel/relocate_kernel.S >>>> new file mode 100644 >>>> index 000000000000..d1f242f74ea8 >>>> --- /dev/null >>>> +++ b/arch/loongarch/kernel/relocate_kernel.S >>>> @@ -0,0 +1,125 @@ >>>> +/* SPDX-License-Identifier: GPL-2.0 */ >>>> +/* >>>> + * relocate_kernel.S for kexec >>>> + * >>>> + * Copyright (C) 2022 Loongson Technology Corporation Limited >>>> + */ >>>> + >>>> +#include <linux/kexec.h> >>>> + >>>> +#include <asm/asm.h> >>>> +#include <asm/asmmacro.h> >>>> +#include <asm/regdef.h> >>>> +#include <asm/loongarch.h> >>>> +#include <asm/stackframe.h> >>>> +#include <asm/addrspace.h> >>>> + >>>> +#define IPI_REG_BASE 0x1fe01000 >>>> + >>>> +SYM_CODE_START(relocate_new_kernel) >>>> + /* >>>> + * s0: Boot flag passed to the new kernel >>>> + * s1: Virt address of the FDT image >>>> + * s2: Pointer to the current entry >>>> + * s3: Virt address to jump to after relocation >>>> + */ >>>> + move s0, a0 >>>> + move s1, a1 >>>> + move s2, a2 >>>> + move s3, a3 >>>> + >>>> +process_entry: >>>> + PTR_L s4, s2, 0 >>>> + PTR_ADDI s2, s2, SZREG >>>> + >>>> + /* destination page */ >>>> + andi s5, s4, IND_DESTINATION >>>> + beqz s5, 1f >>>> + li.w t0, ~0x1 >>>> + and s6, s4, t0 /* store destination addr in s6 */ >>>> + b process_entry >>>> + >>>> +1: >>>> + /* indirection page, update s2 */ >>>> + andi s5, s4, IND_INDIRECTION >>>> + beqz s5, 1f >>>> + li.w t0, ~0x2 >>>> + and s2, s4, t0 >>>> + b process_entry >>>> + >>>> +1: >>>> + /* done page */ >>>> + andi s5, s4, IND_DONE >>>> + beqz s5, 1f >>>> + b done >>>> +1: >>>> + /* source page */ >>>> + andi s5, s4, IND_SOURCE >>>> + beqz s5, process_entry >>>> + li.w t0, ~0x8 >>>> + and s4, s4, t0 >>>> + li.w s8, (1 << _PAGE_SHIFT) / SZREG >>>> + >>>> +copy_word: >>>> + /* copy page word by word */ >>>> + REG_L s7, s4, 0 >>>> + REG_S s7, s6, 0 >>>> + PTR_ADDI s6, s6, SZREG >>>> + PTR_ADDI s4, s4, SZREG >>>> + LONG_ADDI s8, s8, -1 >>>> + beqz s8, process_entry >>>> + b copy_word >>>> + b process_entry >>>> + >>>> +done: >>>> + dbar 0 >>> ibar, too? >> Will add ibar 0. >> >>>> + >>>> + move a0, s0 >>>> + move a1, s1 >>>> + /* jump to the new kernel */ >>>> + jr s3 >>>> +SYM_CODE_END(relocate_new_kernel) >>>> + >>>> +#ifdef CONFIG_SMP >>>> +/* >>>> + * Other CPUs should wait until code is relocated and >>>> + * then start at entry (?) point. >>>> + */ >>>> +SYM_CODE_START(kexec_smp_wait) >>>> + li.d t0, IPI_REG_BASE >>>> + li.d t1, UNCACHE_BASE >>>> + or t0, t0, t1 >>>> + >>>> + /* >>>> + * s1:initfn >>>> + * t0:base t1:cpuid t2:node t3:core t4:count >>>> + */ >>>> + csrrd t1, LOONGARCH_CSR_CPUID >>>> + andi t1, t1, CSR_CPUID_COREID >>>> + andi t3, t1, 0x3 >>>> + slli.w t3, t3, 8 /* get core id */ >>>> + or t0, t0, t3 >>>> + andi t2, t1, 0x3c >>>> + slli.d t2, t2, 42 /* get node id */ >>>> + or t0, t0, t2 >>>> + >>>> +1: li.w t4, 0x100 /* wait for init loop */ >>>> +2: addi.w t4, t4, -1 /* limit mailbox access */ >>>> + bnez t4, 2b >>>> + ld.w s1, t0, 0x20 /* check PC as an indicator */ >>> Can we do this with iocsr*? >> OK, I will consider the implementation in the iocsr way. >> >> Thanks, >> Youling >>> Thanks, >>> Jinyang >>>> + beqz s1, 1b >>>> + ld.d s1, t0, 0x20 /* get PC via mailbox */ >>>> + ld.d sp, t0, 0x28 /* get SP via mailbox */ >>>> + ld.d tp, t0, 0x30 /* get TP via mailbox */ >>>> + >>>> + li.d t0, CACHE_BASE >>>> + or s1, s1, t0 >>>> + jr s1 /* jump to initial PC */ >>>> +SYM_CODE_END(kexec_smp_wait) >>>> +#endif >>>> + >>>> +relocate_new_kernel_end: >>>> + >>>> +SYM_DATA_START(relocate_new_kernel_size) >>>> + PTR relocate_new_kernel_end - relocate_new_kernel >>>> +SYM_DATA_END(relocate_new_kernel_size)
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