[PATCH 2/2] riscv: kexec_file: Support loading Image binary file
Song Shuai
songshuaishuai at tinylab.org
Sun Oct 15 22:19:42 PDT 2023
在 2023/10/11 18:48, Emil Renner Berthing 写道:
> Song Shuai wrote:
>>
>>
>> 在 2023/9/14 16:37, Emil Renner Berthing 写道:
>>> Song Shuai wrote:
>>>> This patch creates image_kexec_ops to load Image binary file
>>>> for kexec_file_load() syscall.
>>>>
>>>> Signed-off-by: Song Shuai <songshuaishuai at tinylab.org>
>>>> ---
>>>> arch/riscv/include/asm/image.h | 2 +
>>>> arch/riscv/include/asm/kexec.h | 1 +
>>>> arch/riscv/kernel/Makefile | 2 +-
>>>> arch/riscv/kernel/kexec_image.c | 97 ++++++++++++++++++++++++++
>>>> arch/riscv/kernel/machine_kexec_file.c | 1 +
>>>> 5 files changed, 102 insertions(+), 1 deletion(-)
>>>> create mode 100644 arch/riscv/kernel/kexec_image.c
>>>>
>>>> diff --git a/arch/riscv/include/asm/image.h b/arch/riscv/include/asm/image.h
>>>> index e0b319af3681..8927a6ea1127 100644
>>>> --- a/arch/riscv/include/asm/image.h
>>>> +++ b/arch/riscv/include/asm/image.h
>>>> @@ -30,6 +30,8 @@
>>>> RISCV_HEADER_VERSION_MINOR)
>>>>
>>>> #ifndef __ASSEMBLY__
>>>> +#define riscv_image_flag_field(flags, field)\
>>>> + (((flags) >> field##_SHIFT) & field##_MASK)
>>>
>>> Hi Song,
>>>
>>> This macro is almost FIELD_GET from linux/bitfield.h ..
>>>
>>>> /**
>>>> * struct riscv_image_header - riscv kernel image header
>>>> * @code0: Executable code
>>>> diff --git a/arch/riscv/include/asm/kexec.h b/arch/riscv/include/asm/kexec.h
>>>> index 518825fe4160..b9ee8346cc8c 100644
>>>> --- a/arch/riscv/include/asm/kexec.h
>>>> +++ b/arch/riscv/include/asm/kexec.h
>>>> @@ -56,6 +56,7 @@ extern riscv_kexec_method riscv_kexec_norelocate;
>>>>
>>>> #ifdef CONFIG_KEXEC_FILE
>>>> extern const struct kexec_file_ops elf_kexec_ops;
>>>> +extern const struct kexec_file_ops image_kexec_ops;
>>>>
>>>> struct purgatory_info;
>>>> int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
>>>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
>>>> index 1c62c639e875..9ecba3231a36 100644
>>>> --- a/arch/riscv/kernel/Makefile
>>>> +++ b/arch/riscv/kernel/Makefile
>>>> @@ -86,7 +86,7 @@ endif
>>>> obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
>>>> obj-$(CONFIG_KGDB) += kgdb.o
>>>> obj-$(CONFIG_KEXEC_CORE) += kexec_relocate.o crash_save_regs.o machine_kexec.o
>>>> -obj-$(CONFIG_KEXEC_FILE) += kexec_elf.o machine_kexec_file.o
>>>> +obj-$(CONFIG_KEXEC_FILE) += kexec_elf.o kexec_image.o machine_kexec_file.o
>>>> obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
>>>> obj-$(CONFIG_CRASH_CORE) += crash_core.o
>>>>
>>>> diff --git a/arch/riscv/kernel/kexec_image.c b/arch/riscv/kernel/kexec_image.c
>>>> new file mode 100644
>>>> index 000000000000..b6aa7f59bd53
>>>> --- /dev/null
>>>> +++ b/arch/riscv/kernel/kexec_image.c
>>>> @@ -0,0 +1,97 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * RISC-V Kexec image loader
>>>> + *
>>>> + */
>>>> +
>>>> +#define pr_fmt(fmt) "kexec_file(Image): " fmt
>>>> +
>>>> +#include <linux/err.h>
>>>> +#include <linux/errno.h>
>>>> +#include <linux/kernel.h>
>>>> +#include <linux/kexec.h>
>>>> +#include <linux/pe.h>
>>>> +#include <linux/string.h>
>>>> +#include <asm/byteorder.h>
>>>> +#include <asm/image.h>
>>>> +
>>>> +static int image_probe(const char *kernel_buf, unsigned long kernel_len)
>>>> +{
>>>> + const struct riscv_image_header *h =
>>>> + (const struct riscv_image_header *)(kernel_buf);
>>>> +
>>>> + if (!h || (kernel_len < sizeof(*h)))
>>>> + return -EINVAL;
>>>> +
>>>> + /* According to Documentation/riscv/boot-image-header.rst,
>>>> + * use "magic2" field to check when version >= 0.2.
>>>> + */
>>>> +
>>>> + if (h->version >= RISCV_HEADER_VERSION &&
>>>> + memcmp(&h->magic2, RISCV_IMAGE_MAGIC2, sizeof(h->magic2)))
>>>> + return -EINVAL;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static void *image_load(struct kimage *image,
>>>> + char *kernel, unsigned long kernel_len,
>>>> + char *initrd, unsigned long initrd_len,
>>>> + char *cmdline, unsigned long cmdline_len)
>>>> +{
>>>> + struct riscv_image_header *h;
>>>> + u64 flags;
>>>> + bool be_image, be_kernel;
>>>> + struct kexec_buf kbuf;
>>>> + int ret;
>>>> +
>>>> + /* Check Image header */
>>>> + h = (struct riscv_image_header *)kernel;
>>>> + if (!h->image_size) {
>>>> + ret = -EINVAL;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + /* Check endianness */
>>>> + flags = le64_to_cpu(h->flags);
>>>> + be_image = riscv_image_flag_field(flags, RISCV_IMAGE_FLAG_BE);
>>>
>>> ..but here you're just testing a single bit, so since be_image is a bool it
>>> could just be
>>> be_image = flags & RISCV_IMAGE_FLAG_BE_MASK;
>>>
>>> /Emil
>> Hi Emil,
>>
>> Sorry for the delayed response,
>>
>> The `flags` field currently only has bit-0 to indicate the kenrel
>> endianness, your comment looks good in this case.
>>
>> While considering the future extension of the `flags` feild, the
>> riscv_image_flag_field() is neccessiry to make callers to require the
>> bits they want.
>
> Right, but please don't invent your own FIELD_GET then.
Hi Emil,
I tried to use FIELD_PREP/FIELD_GET to set/get the RISCV_IMAGE_FLAG_BE,
but using FIELD_PREP to define the __HEAD_FLAGS (used in head.S) emitted
AS build error and the final .s file looked like:
883 .dword _end - _start
884 .dword (({ ({ do { } while (0); do { } while (0); do { } while
(0); do { } while (0); do { } while (0); }); ((typeof((((1)) <<
(0))))(0) << (__builtin_ffsll((((1)) << (0))) - 1)) & ((((1)) << (0))); }))
IIUC the FIELD_PREP can't work well in this asm context, and using
FILED_GET without FIELD_PREP paired looks not good to me.
The original riscv/*/image.h and the riscv_image_flag_filed() of this
patch just do what arm64 does, so I still like to keep them.
I also found that Patch1 has a build issue due to my previous uncareful
cherry-picking,
V2 will be sent to fix it if you're ok this patch without bitfield armed.
I would like to listen to your advice.
>
>>
>> So I prefer to keep this snippet.
>>>
>>>> + be_kernel = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
>>>> + if (be_image != be_kernel) {
>>>> + ret = -EINVAL;
>>>> + goto out;
>>>> + }
>>>> +
>>>> + /* Load the kernel image */
>>>> + kbuf.image = image;
>>>> + kbuf.buf_min = 0;
>>>> + kbuf.buf_max = ULONG_MAX;
>>>> + kbuf.top_down = false;
>>>> +
>>>> + kbuf.buffer = kernel;
>>>> + kbuf.bufsz = kernel_len;
>>>> + kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
>>>> + kbuf.memsz = le64_to_cpu(h->image_size);
>>>> + kbuf.buf_align = le64_to_cpu(h->text_offset);
>>>> +
>>>> + ret = kexec_add_buffer(&kbuf);
>>>> + if (ret) {
>>>> + pr_err("Error add kernel image ret=%d\n", ret);
>>>> + goto out;
>>>> + }
>>>> +
>>>> + image->start = kbuf.mem;
>>>> +
>>>> + pr_info("Loaded kernel at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
>>>> + kbuf.mem, kbuf.bufsz, kbuf.memsz);
>>>> +
>>>> + ret = load_extra_segments(image, kbuf.mem, kbuf.memsz,
>>>> + initrd, initrd_len, cmdline, cmdline_len);
>>>> +
>>>> +out:
>>>> + return ret ? ERR_PTR(ret) : NULL;
>>>> +}
>>>> +
>>>> +const struct kexec_file_ops image_kexec_ops = {
>>>> + .probe = image_probe,
>>>> + .load = image_load,
>>>> +};
>>>> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
>>>> index aedb8c16a283..5dc700834f1e 100644
>>>> --- a/arch/riscv/kernel/machine_kexec_file.c
>>>> +++ b/arch/riscv/kernel/machine_kexec_file.c
>>>> @@ -17,6 +17,7 @@
>>>>
>>>> const struct kexec_file_ops * const kexec_file_loaders[] = {
>>>> &elf_kexec_ops,
>>>> + &image_kexec_ops,
>>>> NULL
>>>> };
>>>>
>>>> --
>>>> 2.20.1
>>>>
>>>>
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>>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
>>>
>>
>> --
>> Thanks
>> Song Shuai
>>
>>
>> _______________________________________________
>> linux-riscv mailing list
>> linux-riscv at lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/linux-riscv
>
--
Thanks
Song Shuai
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