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From:   Emil Renner Berthing <emil.renner.berthing@canonical.com>
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References: <20230914020044.1397356-1-songshuaishuai@tinylab.org>
 <20230914020044.1397356-3-songshuaishuai@tinylab.org> <CAJM55Z8D3yJREg0+UtecW3wpgrGKxZYP73Pvbi2oaQfsZf4Gfw@mail.gmail.com>
 <22EFF2C197DC5C5A+f82966f5-90cf-09a5-214e-4b0e87bc6064@tinylab.org>
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Date:   Wed, 11 Oct 2023 03:48:35 -0700
Message-ID: <CAJM55Z8OebLJHg3mxk7y7Dw0z=JLgi4j17tQPf4-Mdd0BCQbaw@mail.gmail.com>
Subject: Re: [PATCH 2/2] riscv: kexec_file: Support loading Image binary file
To:     Song Shuai <songshuaishuai@tinylab.org>,
        Emil Renner Berthing <emil.renner.berthing@canonical.com>,
        paul.walmsley@sifive.com, palmer@dabbelt.com,
        aou@eecs.berkeley.edu, lihuafei1@huawei.com,
        conor.dooley@microchip.com, liaochang1@huawei.com,
        ajones@ventanamicro.com, alexghiti@rivosinc.com, evan@rivosinc.com,
        sunilvl@ventanamicro.com, xianting.tian@linux.alibaba.com,
        samitolvanen@google.com, masahiroy@kernel.org,
        apatel@ventanamicro.com, jszhang@kernel.org, duwe@suse.de,
        eric.devolder@oracle.com
Cc:     linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
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Song Shuai wrote:
>
>
> =E5=9C=A8 2023/9/14 16:37, Emil Renner Berthing =E5=86=99=E9=81=93:
> > 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@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/i=
mage.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/k=
exec.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-$(CONFIG_HOTPLUG_CPU)	+=3D cpu-hotplug.o
> >>   obj-$(CONFIG_KGDB)		+=3D kgdb.o
> >>   obj-$(CONFIG_KEXEC_CORE)	+=3D kexec_relocate.o crash_save_regs.o mac=
hine_kexec.o
> >> -obj-$(CONFIG_KEXEC_FILE)	+=3D kexec_elf.o machine_kexec_file.o
> >> +obj-$(CONFIG_KEXEC_FILE)	+=3D kexec_elf.o kexec_image.o machine_kexec=
_file.o
> >>   obj-$(CONFIG_CRASH_DUMP)	+=3D crash_dump.o
> >>   obj-$(CONFIG_CRASH_CORE)	+=3D 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_l=
en)
> >> +{
> >> +	const struct riscv_image_header *h =3D
> >> +		(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 >=3D 0.2.
> >> +	 */
> >> +
> >> +	if (h->version >=3D 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 =3D (struct riscv_image_header *)kernel;
> >> +	if (!h->image_size) {
> >> +		ret =3D -EINVAL;
> >> +		goto out;
> >> +	}
> >> +
> >> +	/* Check endianness */
> >> +	flags =3D le64_to_cpu(h->flags);
> >> +	be_image =3D riscv_image_flag_field(flags, RISCV_IMAGE_FLAG_BE);
> >
> > ..but here you're just testing a single bit, so since be_image is a boo=
l it
> > could just be
> > 	be_image =3D 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.

>
> So I prefer to keep this snippet.
> >
> >> +	be_kernel =3D IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
> >> +	if (be_image !=3D be_kernel) {
> >> +		ret =3D -EINVAL;
> >> +		goto out;
> >> +	}
> >> +
> >> +	/* Load the kernel image */
> >> +	kbuf.image =3D image;
> >> +	kbuf.buf_min =3D 0;
> >> +	kbuf.buf_max =3D ULONG_MAX;
> >> +	kbuf.top_down =3D false;
> >> +
> >> +	kbuf.buffer =3D kernel;
> >> +	kbuf.bufsz =3D kernel_len;
> >> +	kbuf.mem =3D KEXEC_BUF_MEM_UNKNOWN;
> >> +	kbuf.memsz =3D le64_to_cpu(h->image_size);
> >> +	kbuf.buf_align =3D le64_to_cpu(h->text_offset);
> >> +
> >> +	ret =3D kexec_add_buffer(&kbuf);
> >> +	if (ret) {
> >> +		pr_err("Error add kernel image ret=3D%d\n", ret);
> >> +		goto out;
> >> +	}
> >> +
> >> +	image->start =3D kbuf.mem;
> >> +
> >> +	pr_info("Loaded kernel at 0x%lx bufsz=3D0x%lx memsz=3D0x%lx\n",
> >> +				kbuf.mem, kbuf.bufsz, kbuf.memsz);
> >> +
> >> +	ret =3D 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 =3D {
> >> +	.probe =3D image_probe,
> >> +	.load =3D image_load,
> >> +};
> >> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kerne=
l/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[] =3D {
> >>   	&elf_kexec_ops,
> >> +	&image_kexec_ops,
> >>   	NULL
> >>   };
> >>
> >> --
> >> 2.20.1
> >>
> >>
> >> _______________________________________________
> >> linux-riscv mailing list
> >> linux-riscv@lists.infradead.org
> >> http://lists.infradead.org/mailman/listinfo/linux-riscv
> >
>
> --
> Thanks
> Song Shuai
>
>
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