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Liao Changpalmer-dabbelt
Liao Chang
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palmer-dabbelt
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RISC-V: Add kexec_file support
This patch adds support for kexec_file on RISC-V. I tested it on riscv64 QEMU with busybear-linux and single core along with the OpenSBI firmware fw_jump.bin for generic platform. On SMP system, it depends on CONFIG_{HOTPLUG_CPU, RISCV_SBI} to resume/stop hart through OpenSBI firmware, it also needs a OpenSBI that support the HSM extension. Signed-off-by: Liao Chang <liaochang1@huawei.com> Signed-off-by: Li Zhengyu <lizhengyu3@huawei.com> Link: https://lore.kernel.org/r/20220408100914.150110-4-lizhengyu3@huawei.com [Palmer: Make 64-bit only] Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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‎arch/riscv/Kconfig‎

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@@ -383,6 +383,20 @@ config KEXEC
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The name comes from the similarity to the exec system call.
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config KEXEC_FILE
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bool "kexec file based systmem call"
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select KEXEC_CORE
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select KEXEC_ELF
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select HAVE_IMA_KEXEC if IMA
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depends on 64BIT
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help
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This is new version of kexec system call. This system call is
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file based and takes file descriptors as system call argument
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for kernel and initramfs as opposed to list of segments as
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accepted by previous system call.
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If you don't know what to do here, say Y.
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config CRASH_DUMP
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bool "Build kdump crash kernel"
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help

‎arch/riscv/include/asm/kexec.h‎

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@@ -53,4 +53,8 @@ typedef void (*riscv_kexec_method)(unsigned long first_ind_entry,
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extern riscv_kexec_method riscv_kexec_norelocate;
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#ifdef CONFIG_KEXEC_FILE
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extern const struct kexec_file_ops elf_kexec_ops;
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#endif
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#endif

‎arch/riscv/kernel/Makefile‎

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@@ -64,6 +64,7 @@ endif
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obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
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obj-$(CONFIG_KGDB) += kgdb.o
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obj-$(CONFIG_KEXEC) += kexec_relocate.o crash_save_regs.o machine_kexec.o
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obj-$(CONFIG_KEXEC_FILE) += elf_kexec.o machine_kexec_file.o
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obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
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obj-$(CONFIG_JUMP_LABEL) += jump_label.o

‎arch/riscv/kernel/elf_kexec.c‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,180 @@
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Load ELF vmlinux file for the kexec_file_load syscall.
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*
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* Copyright (C) 2021 Huawei Technologies Co, Ltd.
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*
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* Author: Liao Chang (liaochang1@huawei.com)
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*
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* Based on kexec-tools' kexec-elf-riscv.c, heavily modified
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* for kernel.
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*/
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#define pr_fmt(fmt) "kexec_image: " fmt
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#include <linux/elf.h>
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#include <linux/kexec.h>
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#include <linux/slab.h>
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#include <linux/of.h>
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#include <linux/libfdt.h>
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#include <linux/types.h>
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static int riscv_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
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struct kexec_elf_info *elf_info, unsigned long old_pbase,
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unsigned long new_pbase)
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{
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int i;
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int ret = 0;
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size_t size;
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struct kexec_buf kbuf;
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const struct elf_phdr *phdr;
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kbuf.image = image;
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for (i = 0; i < ehdr->e_phnum; i++) {
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phdr = &elf_info->proghdrs[i];
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if (phdr->p_type != PT_LOAD)
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continue;
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size = phdr->p_filesz;
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if (size > phdr->p_memsz)
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size = phdr->p_memsz;
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kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
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kbuf.bufsz = size;
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kbuf.buf_align = phdr->p_align;
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kbuf.mem = phdr->p_paddr - old_pbase + new_pbase;
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kbuf.memsz = phdr->p_memsz;
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kbuf.top_down = false;
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ret = kexec_add_buffer(&kbuf);
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if (ret)
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break;
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}
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return ret;
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}
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/*
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* Go through the available phsyical memory regions and find one that hold
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* an image of the specified size.
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*/
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static int elf_find_pbase(struct kimage *image, unsigned long kernel_len,
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struct elfhdr *ehdr, struct kexec_elf_info *elf_info,
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unsigned long *old_pbase, unsigned long *new_pbase)
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{
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int i;
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int ret;
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struct kexec_buf kbuf;
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const struct elf_phdr *phdr;
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unsigned long lowest_paddr = ULONG_MAX;
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unsigned long lowest_vaddr = ULONG_MAX;
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for (i = 0; i < ehdr->e_phnum; i++) {
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phdr = &elf_info->proghdrs[i];
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if (phdr->p_type != PT_LOAD)
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continue;
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if (lowest_paddr > phdr->p_paddr)
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lowest_paddr = phdr->p_paddr;
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if (lowest_vaddr > phdr->p_vaddr)
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lowest_vaddr = phdr->p_vaddr;
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}
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kbuf.image = image;
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kbuf.buf_min = lowest_paddr;
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kbuf.buf_max = ULONG_MAX;
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kbuf.buf_align = PAGE_SIZE;
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kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
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kbuf.memsz = ALIGN(kernel_len, PAGE_SIZE);
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kbuf.top_down = false;
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ret = arch_kexec_locate_mem_hole(&kbuf);
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if (!ret) {
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*old_pbase = lowest_paddr;
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*new_pbase = kbuf.mem;
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image->start = ehdr->e_entry - lowest_vaddr + kbuf.mem;
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}
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return ret;
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}
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static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
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unsigned long kernel_len, char *initrd,
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unsigned long initrd_len, char *cmdline,
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unsigned long cmdline_len)
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{
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int ret;
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unsigned long old_kernel_pbase = ULONG_MAX;
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unsigned long new_kernel_pbase = 0UL;
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unsigned long initrd_pbase = 0UL;
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void *fdt;
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struct elfhdr ehdr;
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struct kexec_buf kbuf;
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struct kexec_elf_info elf_info;
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ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
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if (ret)
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return ERR_PTR(ret);
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ret = elf_find_pbase(image, kernel_len, &ehdr, &elf_info,
119+
&old_kernel_pbase, &new_kernel_pbase);
120+
if (ret)
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goto out;
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pr_notice("The entry point of kernel at 0x%lx\n", image->start);
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/* Add the kernel binary to the image */
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ret = riscv_kexec_elf_load(image, &ehdr, &elf_info,
126+
old_kernel_pbase, new_kernel_pbase);
127+
if (ret)
128+
goto out;
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130+
kbuf.image = image;
131+
kbuf.buf_min = new_kernel_pbase + kernel_len;
132+
kbuf.buf_max = ULONG_MAX;
133+
/* Add the initrd to the image */
134+
if (initrd != NULL) {
135+
kbuf.buffer = initrd;
136+
kbuf.bufsz = kbuf.memsz = initrd_len;
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kbuf.buf_align = PAGE_SIZE;
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kbuf.top_down = false;
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kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
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ret = kexec_add_buffer(&kbuf);
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if (ret)
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goto out;
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initrd_pbase = kbuf.mem;
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pr_notice("Loaded initrd at 0x%lx\n", initrd_pbase);
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}
146+
147+
/* Add the DTB to the image */
148+
fdt = of_kexec_alloc_and_setup_fdt(image, initrd_pbase,
149+
initrd_len, cmdline, 0);
150+
if (!fdt) {
151+
pr_err("Error setting up the new device tree.\n");
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ret = -EINVAL;
153+
goto out;
154+
}
155+
156+
fdt_pack(fdt);
157+
kbuf.buffer = fdt;
158+
kbuf.bufsz = kbuf.memsz = fdt_totalsize(fdt);
159+
kbuf.buf_align = PAGE_SIZE;
160+
kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
161+
kbuf.top_down = true;
162+
ret = kexec_add_buffer(&kbuf);
163+
if (ret) {
164+
pr_err("Error add DTB kbuf ret=%d\n", ret);
165+
goto out_free_fdt;
166+
}
167+
pr_notice("Loaded device tree at 0x%lx\n", kbuf.mem);
168+
goto out;
169+
170+
out_free_fdt:
171+
kvfree(fdt);
172+
out:
173+
kexec_free_elf_info(&elf_info);
174+
return ret ? ERR_PTR(ret) : NULL;
175+
}
176+
177+
const struct kexec_file_ops elf_kexec_ops = {
178+
.probe = kexec_elf_probe,
179+
.load = elf_kexec_load,
180+
};

‎arch/riscv/kernel/machine_kexec_file.c‎

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@@ -0,0 +1,14 @@
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// SPDX-License-Identifier: GPL-2.0-only
2+
/*
3+
* kexec_file for riscv, use vmlinux as the dump-capture kernel image.
4+
*
5+
* Copyright (C) 2021 Huawei Technologies Co, Ltd.
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*
7+
* Author: Liao Chang (liaochang1@huawei.com)
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*/
9+
#include <linux/kexec.h>
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11+
const struct kexec_file_ops * const kexec_file_loaders[] = {
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&elf_kexec_ops,
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NULL
14+
};

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