linux-kernel - Re: [PATCH] efi/loongarch: Reintroduce efi_relocate

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Message-ID: <CAAhV-H6xAKQ94T5=+iVASwi8F=7+G_ptSGVVBOw4L1fCR+EQOw@mail.gmail.com>
Date:   Wed, 1 Mar 2023 17:30:14 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Youling Tang <tangyouling@...ngson.cn>
Cc:     Huacai Chen <chenhuacai@...ngson.cn>,
        Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org,
        loongarch@...ts.linux.dev, Xuefeng Li <lixuefeng@...ngson.cn>,
        Xuerui Wang <kernel@...0n.name>, linux-kernel@...r.kernel.org,
        loongson-kernel@...ts.loongnix.cn
Subject: Re: [PATCH] efi/loongarch: Reintroduce efi_relocate_kernel() to
 relocate kernel

Hi, Youling,

On Wed, Mar 1, 2023 at 5:21 PM Youling Tang <tangyouling@...ngson.cn> wrote:
>
> Hi, Huacai
>
> On 03/01/2023 04:55 PM, Huacai Chen wrote:
> > Since Linux-6.3, LoongArch supports PIE kernel now, so let's reintroduce
> > efi_relocate_kernel() to relocate the core kernel.
>
> If we strongly rely on the PIE feature after the modification, we need
> to modify it as follows,
There is no strong rely, efi_relocate_kernel() can also handle the
non-PIE kernel.

Huacai
>
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -137,6 +137,7 @@ config LOONGARCH
>          select PCI_MSI_ARCH_FALLBACKS
>          select PCI_QUIRKS
>          select PERF_USE_VMALLOC
> +       select RELOCATABLE
>          select RTC_LIB
>          select SMP
>          select SPARSE_IRQ
>
> or:
>
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -360,6 +360,7 @@ config EFI_STUB
>          default y
>          depends on EFI
>          select EFI_GENERIC_STUB
> +       select RELOCATABLE
>          help
>
> Youling.
>
> >
> > Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
> > ---
> >  drivers/firmware/efi/libstub/loongarch-stub.c | 24 ++++++-------------
> >  1 file changed, 7 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/firmware/efi/libstub/loongarch-stub.c b/drivers/firmware/efi/libstub/loongarch-stub.c
> > index eee7ed43cdfb..72c71ae201f0 100644
> > --- a/drivers/firmware/efi/libstub/loongarch-stub.c
> > +++ b/drivers/firmware/efi/libstub/loongarch-stub.c
> > @@ -21,26 +21,16 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
> >                                efi_loaded_image_t *image,
> >                                efi_handle_t image_handle)
> >  {
> > -     int nr_pages = round_up(kernel_asize, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
> > -     efi_physical_addr_t kernel_addr = EFI_KIMG_PREFERRED_ADDRESS;
> >       efi_status_t status;
> > +     unsigned long kernel_addr = 0;
> >
> > -     /*
> > -      * Allocate space for the kernel image at the preferred offset. This is
> > -      * the only location in memory from where we can execute the image, so
> > -      * no point in falling back to another allocation.
> > -      */
> > -     status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> > -                          EFI_LOADER_DATA, nr_pages, &kernel_addr);
> > -     if (status != EFI_SUCCESS)
> > -             return status;
> > -
> > -     *image_addr = EFI_KIMG_PREFERRED_ADDRESS;
> > -     *image_size = kernel_asize;
> > +     kernel_addr = (unsigned long)&kernel_offset - kernel_offset;
> > +
> > +     status = efi_relocate_kernel(&kernel_addr, kernel_fsize, kernel_asize,
> > +                  EFI_KIMG_PREFERRED_ADDRESS, efi_get_kimg_min_align(), 0x0);
> >
> > -     memcpy((void *)EFI_KIMG_PREFERRED_ADDRESS,
> > -            (void *)&kernel_offset - kernel_offset,
> > -            kernel_fsize);
> > +     *image_addr = kernel_addr;
> > +     *image_size = kernel_asize;
> >
> >       return status;
> >  }
> >
>