Ard Biesheuvel <ardb@xxxxxxxxxx> 于2023年12月19日周二 17:22写道：
>
> On Tue, 19 Dec 2023 at 10:14, <wangyao@xxxxxxxxxx> wrote:
> >
> > From: Wang Yao <wangyao@xxxxxxxxxx>
> >
> > The use of the 'kernel_offset' variable to position the image file that
> > has been loaded by UEFI or GRUB is unnecessary, because we can directly
> > position the loaded image file through using the image_base field of the
> > efi_loaded_image struct provided by UEFI.
> >
> > Replace kernel_offset with image_base to positon the image file that has
> > been loaded by UEFI or GRUB.
> >
> > Signed-off-by: Wang Yao <wangyao@xxxxxxxxxx>
> > ---
> >
> > v1->v2:
> > Rewrite the commit log include 'why', not just include 'how'.
> >
> > arch/loongarch/include/asm/efi.h | 2 --
> > arch/loongarch/kernel/head.S | 1 -
> > arch/loongarch/kernel/image-vars.h | 1 -
> > arch/loongarch/kernel/vmlinux.lds.S | 1 -
> > drivers/firmware/efi/libstub/loongarch-stub.c | 9 +++++----
> > drivers/firmware/efi/libstub/loongarch-stub.h | 4 ++++
> > drivers/firmware/efi/libstub/loongarch.c | 6 ++++--
> > 7 files changed, 13 insertions(+), 11 deletions(-)
> > create mode 100644 drivers/firmware/efi/libstub/loongarch-stub.h
> >
> > diff --git a/arch/loongarch/include/asm/efi.h b/arch/loongarch/include/asm/efi.h
> > index 91d81f9730ab..eddc8e79b3fa 100644
> > --- a/arch/loongarch/include/asm/efi.h
> > +++ b/arch/loongarch/include/asm/efi.h
> > @@ -32,6 +32,4 @@ static inline unsigned long efi_get_kimg_min_align(void)
> >
> > #define EFI_KIMG_PREFERRED_ADDRESS PHYSADDR(VMLINUX_LOAD_ADDRESS)
> >
> > -unsigned long kernel_entry_address(unsigned long kernel_addr);
> > -
>
> Why are you removing this? Won't that cause missing prototype warnings?
>
> The rest of the patch looks fine to me, but I haven't tested it.
>
Because the efi_loaded_image_t struct is defined in the efistub.h.
> > #endif /* _ASM_LOONGARCH_EFI_H */
> > diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> > index 53b883db0786..0ecab4216392 100644
> > --- a/arch/loongarch/kernel/head.S
> > +++ b/arch/loongarch/kernel/head.S
> > @@ -34,7 +34,6 @@ pe_header:
> >
> > SYM_DATA(kernel_asize, .long _kernel_asize);
> > SYM_DATA(kernel_fsize, .long _kernel_fsize);
> > -SYM_DATA(kernel_offset, .long _kernel_offset);
> >
> > #endif
> >
> > diff --git a/arch/loongarch/kernel/image-vars.h b/arch/loongarch/kernel/image-vars.h
> > index 5087416b9678..41ddcf56d21c 100644
> > --- a/arch/loongarch/kernel/image-vars.h
> > +++ b/arch/loongarch/kernel/image-vars.h
> > @@ -11,7 +11,6 @@ __efistub_strcmp = strcmp;
> > __efistub_kernel_entry = kernel_entry;
> > __efistub_kernel_asize = kernel_asize;
> > __efistub_kernel_fsize = kernel_fsize;
> > -__efistub_kernel_offset = kernel_offset;
> > #if defined(CONFIG_EFI_EARLYCON) || defined(CONFIG_SYSFB)
> > __efistub_screen_info = screen_info;
> > #endif
> > diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
> > index bb2ec86f37a8..a5d0cd2035da 100644
> > --- a/arch/loongarch/kernel/vmlinux.lds.S
> > +++ b/arch/loongarch/kernel/vmlinux.lds.S
> > @@ -143,7 +143,6 @@ SECTIONS
> > _kernel_fsize = _edata - _text;
> > _kernel_vsize = _end - __initdata_begin;
> > _kernel_rsize = _edata - __initdata_begin;
> > - _kernel_offset = kernel_offset - _text;
> > #endif
> >
> > .gptab.sdata : {
> > diff --git a/drivers/firmware/efi/libstub/loongarch-stub.c b/drivers/firmware/efi/libstub/loongarch-stub.c
> > index d6ec5d4b8dbe..736b6aae323d 100644
> > --- a/drivers/firmware/efi/libstub/loongarch-stub.c
> > +++ b/drivers/firmware/efi/libstub/loongarch-stub.c
> > @@ -8,10 +8,10 @@
> > #include <asm/efi.h>
> > #include <asm/addrspace.h>
> > #include "efistub.h"
> > +#include "loongarch-stub.h"
> >
> > extern int kernel_asize;
> > extern int kernel_fsize;
> > -extern int kernel_offset;
> > extern int kernel_entry;
> >
> > efi_status_t handle_kernel_image(unsigned long *image_addr,
> > @@ -24,7 +24,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
> > efi_status_t status;
> > unsigned long kernel_addr = 0;
> >
> > - kernel_addr = (unsigned long)&kernel_offset - kernel_offset;
> > + kernel_addr = (unsigned long)image->image_base;
> >
> > status = efi_relocate_kernel(&kernel_addr, kernel_fsize, kernel_asize,
> > EFI_KIMG_PREFERRED_ADDRESS, efi_get_kimg_min_align(), 0x0);
> > @@ -35,9 +35,10 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
> > return status;
> > }
> >
> > -unsigned long kernel_entry_address(unsigned long kernel_addr)
> > +unsigned long kernel_entry_address(unsigned long kernel_addr,
> > + efi_loaded_image_t *image)
> > {
> > - unsigned long base = (unsigned long)&kernel_offset - kernel_offset;
> > + unsigned long base = (unsigned long)image->image_base;
> >
> > return (unsigned long)&kernel_entry - base + kernel_addr;
> > }
> > diff --git a/drivers/firmware/efi/libstub/loongarch-stub.h b/drivers/firmware/efi/libstub/loongarch-stub.h
> > new file mode 100644
> > index 000000000000..cd015955a015
> > --- /dev/null
> > +++ b/drivers/firmware/efi/libstub/loongarch-stub.h
> > @@ -0,0 +1,4 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +
> > +unsigned long kernel_entry_address(unsigned long kernel_addr,
> > + efi_loaded_image_t *image);
> > diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c
> > index 0e0aa6cda73f..684c9354637c 100644
> > --- a/drivers/firmware/efi/libstub/loongarch.c
> > +++ b/drivers/firmware/efi/libstub/loongarch.c
> > @@ -8,6 +8,7 @@
> > #include <asm/efi.h>
> > #include <asm/addrspace.h>
> > #include "efistub.h"
> > +#include "loongarch-stub.h"
> >
> > typedef void __noreturn (*kernel_entry_t)(bool efi, unsigned long cmdline,
> > unsigned long systab);
> > @@ -37,7 +38,8 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv)
> > return EFI_SUCCESS;
> > }
> >
> > -unsigned long __weak kernel_entry_address(unsigned long kernel_addr)
> > +unsigned long __weak kernel_entry_address(unsigned long kernel_addr,
> > + efi_loaded_image_t *image)
> > {
> > return *(unsigned long *)(kernel_addr + 8) - VMLINUX_LOAD_ADDRESS + kernel_addr;
> > }
> > @@ -73,7 +75,7 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
> > csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
> > csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
> >
> > - real_kernel_entry = (void *)kernel_entry_address(kernel_addr);
> > + real_kernel_entry = (void *)kernel_entry_address(kernel_addr, image);
> >
> > real_kernel_entry(true, (unsigned long)cmdline_ptr,
> > (unsigned long)efi_system_table);
> > --
> > 2.27.0
> >
