On 2025/8/20 13:56, Youling Tang wrote:
From: Youling Tang <tangyoul...@kylinos.cn>
This patch creates kexec_elf_ops to load ELF binary file
for kexec_file_load() syscall.
Signed-off-by: Youling Tang <tangyoul...@kylinos.cn>
---
arch/loongarch/Kconfig | 1 +
arch/loongarch/include/asm/kexec.h | 1 +
arch/loongarch/kernel/Makefile | 2 +-
arch/loongarch/kernel/kexec_elf.c | 105 +++++++++++++++++++++
arch/loongarch/kernel/machine_kexec_file.c | 1 +
5 files changed, 109 insertions(+), 1 deletion(-)
create mode 100644 arch/loongarch/kernel/kexec_elf.c
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 490dc6eed749..bf2664ed7ce3 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -632,6 +632,7 @@ config ARCH_SELECTS_KEXEC_FILE
def_bool y
depends on KEXEC_FILE
select HAVE_IMA_KEXEC if IMA
+ select KEXEC_ELF
select RELOCATABLE
config ARCH_SUPPORTS_CRASH_DUMP
diff --git a/arch/loongarch/include/asm/kexec.h
b/arch/loongarch/include/asm/kexec.h
index 34799db933fb..fecfb3015abc 100644
--- a/arch/loongarch/include/asm/kexec.h
+++ b/arch/loongarch/include/asm/kexec.h
@@ -43,6 +43,7 @@ struct kimage_arch {
#ifdef CONFIG_KEXEC_FILE
extern const struct kexec_file_ops kexec_efi_ops;
+extern const struct kexec_file_ops kexec_elf_ops;
int arch_kimage_file_post_load_cleanup(struct kimage *image);
#define arch_kimage_file_post_load_cleanup arch_kimage_file_post_load_cleanup
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index dd6183f353e6..001924877772 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -62,7 +62,7 @@ obj-$(CONFIG_MAGIC_SYSRQ) += sysrq.o
obj-$(CONFIG_RELOCATABLE) += relocate.o
obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o relocate_kernel.o
-obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o kexec_efi.o
+obj-$(CONFIG_KEXEC_FILE) += machine_kexec_file.o kexec_efi.o kexec_elf.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o
diff --git a/arch/loongarch/kernel/kexec_elf.c
b/arch/loongarch/kernel/kexec_elf.c
new file mode 100644
index 000000000000..d41ee5fd7cef
--- /dev/null
+++ b/arch/loongarch/kernel/kexec_elf.c
@@ -0,0 +1,105 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Load ELF vmlinux file for the kexec_file_load syscall.
+ *
+ * Author: Youling Tang <tangyoul...@kylinos.cn>
+ * Copyright (C) 2025 KylinSoft Corporation.
+ */
+
+#define pr_fmt(fmt) "kexec_file(ELF): " fmt
+
+#include <linux/elf.h>
+#include <linux/kexec.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/memblock.h>
+#include <asm/image.h>
+#include <asm/setup.h>
+
+static int loongarch_kexec_elf_load(struct kimage *image, struct elfhdr *ehdr,
+ struct kexec_elf_info *elf_info,
+ struct kexec_buf *kbuf,
+ unsigned long *text_offset)
+{
+ int ret = -1;
+ size_t i;
+
+ /* Read in the PT_LOAD segments. */
+ for (i = 0; i < ehdr->e_phnum; i++) {
+ size_t size;
+ const struct elf_phdr *phdr;
+ struct loongarch_image_header *header;
+
+ phdr = &elf_info->proghdrs[i];
+ if (phdr->p_type != PT_LOAD)
+ continue;
+
+ size = phdr->p_filesz;
+ if (size > phdr->p_memsz)
+ size = phdr->p_memsz;
+
+ kbuf->buffer = (void *)elf_info->buffer + phdr->p_offset;
+ kbuf->bufsz = size;
+ kbuf->buf_align = phdr->p_align;
+ header = (struct loongarch_image_header *)kbuf->buffer;
+ *text_offset = le64_to_cpu(header->text_offset);
+ kbuf->buf_min = *text_offset;
+ kbuf->memsz = le64_to_cpu(header->image_size);
Elf kernel resolution should not be used to struct loongarch_image_header,
members of the content contained in the inner world of CONFIG_EFI_STUB in
the arch/loongarch/kernel/head.S, should use the content inside the elf
header information, The kexec-tools tool should also be fixed.
However, there is certain content in the elf header information, and the
general kexec_elf_load() function cannot be used. Special processing of
kbuf->memsz and kbuf->memsz is required.
$ readelf -l vmlinux
...
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000010000 0x9000000000200000 0x9000000000200000
0x0000000002747a00 0x000000000287a0d8 RWE 0x10000
NOTE 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 R 0x8
phdr->p_paddr should have been a physical address, but it is a virtual
address on the current LoongArch. This will cause kexec_file to fail
when loading the kernel and need to be converted to a physical address.
Another patch is working to fix this issue[1].
From the above MemSiz, it can be seen that 0x287a0d8 has not been aligned.
Although kexec_add_buffer() will perform PAGE_SIZE alignment on kbuf->memsz,
there is still a stampeding in the loaded kernel space and initrd space.
The initrd resolution failed when starting the second kernel.
It can be known from the link script vmlinux.lds.S that,
BSS_SECTION(0, SZ_64K, 8)
. = ALIGN(PECOFF_SEGMENT_ALIGN);
It needs to be aligned according to the SZ_64K size, so that after
alignment,
its size is consistent with _kernel_asize
(loongarch_image_header->image_size).
The following modifications will be used in the next version to fix it，
--- a/arch/loongarch/kernel/kexec_elf.c
+++ b/arch/loongarch/kernel/kexec_elf.c
@@ -28,7 +28,6 @@ static int loongarch_kexec_elf_load(struct kimage
*image, struct elfhdr *ehdr,
for (i = 0; i < ehdr->e_phnum; i++) {
size_t size;
const struct elf_phdr *phdr;
- struct loongarch_image_header *header;
phdr = &elf_info->proghdrs[i];
if (phdr->p_type != PT_LOAD)
@@ -41,10 +40,9 @@ static int loongarch_kexec_elf_load(struct kimage
*image, struct elfhdr *ehdr,
kbuf->buffer = (void *)elf_info->buffer + phdr->p_offset;
kbuf->bufsz = size;
kbuf->buf_align = phdr->p_align;
- header = (struct loongarch_image_header *)kbuf->buffer;
- *text_offset = le64_to_cpu(header->text_offset);
- kbuf->buf_min = *text_offset;
- kbuf->memsz = le64_to_cpu(header->image_size);
+ *text_offset = __pa(phdr->p_paddr);
+ kbuf->buf_min = _*text_offset;
+ kbuf->memsz = ALIGN(phdr->p_memsz, SZ_64K);
kbuf->mem = KEXEC_BUF_MEM_UNKNOWN;
[1]:
https://lore.kernel.org/loongarch/00651f3a-6649-4c69-b365-352c8d323...@flygoat.com/T/#t
Thanks,
Youling.
+ kbuf->mem = KEXEC_BUF_MEM_UNKNOWN;
+ ret = kexec_add_buffer(kbuf);
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+static void *elf_kexec_load(struct kimage *image, char *kernel_buf,
+ unsigned long kernel_len, char *initrd,
+ unsigned long initrd_len, char *cmdline,
+ unsigned long cmdline_len)
+{
+ int ret;
+ unsigned long text_offset = 0, kernel_segment_number;
+ struct elfhdr ehdr;
+ struct kexec_elf_info elf_info;
+ struct kexec_segment *kernel_segment;
+ struct kexec_buf kbuf;
+
+ ret = kexec_build_elf_info(kernel_buf, kernel_len, &ehdr, &elf_info);
+ if (ret)
+ return ERR_PTR(ret);
+
+ /* Load the kernel */
+ kbuf.image = image;
+ kbuf.buf_max = ULONG_MAX;
+ kbuf.top_down = false;
+
+ kernel_segment_number = image->nr_segments;
+
+ ret = loongarch_kexec_elf_load(image, &ehdr, &elf_info, &kbuf,
&text_offset);
+ if (ret)
+ goto out;
+
+ /* Load additional data */
+ kernel_segment = &image->segment[kernel_segment_number];
+ ret = load_other_segments(image, kernel_segment->mem,
kernel_segment->memsz,
+ initrd, initrd_len, cmdline, cmdline_len);
+ if (ret)
+ goto out;
+
+ /* Make sure the second kernel jumps to the correct "kernel_entry". */
+ image->start = kernel_segment->mem + __pa(ehdr.e_entry) - text_offset;
+
+ kexec_dprintk("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+ kernel_segment->mem, kbuf.bufsz, kernel_segment->memsz);
+
+out:
+ kexec_free_elf_info(&elf_info);
+ return ret ? ERR_PTR(ret) : NULL;
+}
+
+const struct kexec_file_ops kexec_elf_ops = {
+ .probe = kexec_elf_probe,
+ .load = elf_kexec_load,
+};
diff --git a/arch/loongarch/kernel/machine_kexec_file.c
b/arch/loongarch/kernel/machine_kexec_file.c
index a713acf32db8..dc6e37457559 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -22,6 +22,7 @@
const struct kexec_file_ops * const kexec_file_loaders[] = {
&kexec_efi_ops,
+ &kexec_elf_ops,
NULL
};
