[PATCH RFC/RFT 0/3] efi/libstub: arm32: Remove dependency on dram_base

[Atish Patra]

On Wed, Sep 9, 2020 at 2:44 PM Atish Patra <atishp at atishpatra.org> wrote:
>
> On Wed, Sep 9, 2020 at 1:52 PM Palmer Dabbelt <palmer at dabbelt.com> wrote:
> >
> > On Wed, 09 Sep 2020 08:16:20 PDT (-0700), ardb at kernel.org wrote:
> > > Maxim reports boot failures on platforms that describe reserved memory
> > > regions in DT that are disjoint from system DRAM, and which are converted
> > > to EfiReservedMemory regions by the EFI subsystem in u-boot.
> > >
> > > As it turns out, the whole notion of discovering the base of DRAM is
> > > problematic, and it would be better to simply rely on the EFI memory
> > > allocation routines instead, and derive the FDT and initrd allocation
> > > limits from the actual placement of the kernel (which is what defines
> > > the start of the linear region anyway)
> > >
> > > Finally, we should be able to get rid of get_dram_base() entirely.
> > > However, as RISC-V only just started using it, we will need to address
> > > that at a later time.
> >
> > Looks like we're using dram_base to derive two argumets to
> > efi_relocate_kernel(): the preferred load address and the minimum load address.
> > I don't see any reason why we can't use the same PAGE_OFFSET-like logic that
> > x86 uses for the minimum load address, but I don't think we have any mechanism
> > like "struct boot_params" so we'd need to come up with something.
> >
>
> As discussed in the other thread
> (https://www.spinics.net/lists/linux-efi/msg20262.html),
> we don't need to do anything special. efi_relocate_kernel can just
> take preferred address as 0
> so that efi_bs_alloc will fail and efi_low_alloc_above will be used to
> allocate 2MB/4MB aligned address as per requirement.
>
> I don't think the other changes in this series will cause any issue
> for RISC-V. I will test it and update anyways.
>
> > > Cc: Maxim Uvarov <maxim.uvarov at linaro.org>
> > > Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
> > > Cc: Atish Patra <atish.patra at wdc.com>
> > > Cc: Palmer Dabbelt <palmer at dabbelt.com>
> > > Cc: Jens Wiklander <jens.wiklander at linaro.org>
> > > Cc: Francois Ozog <francois.ozog at linaro.org>
> > > Cc: Etienne CARRIERE <etienne.carriere at st.com>
> > > Cc: Takahiro Akashi <takahiro.akashi at linaro.org>
> > > Cc: Patrice CHOTARD <patrice.chotard at st.com>
> > > Cc: Sumit Garg <sumit.garg at linaro.org>
> > > Cc: Grant Likely <Grant.Likely at arm.com>
> > > Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> > > Cc: Christophe Priouzeau <christophe.priouzeau at linaro.org>
> > > Cc: Rouven Czerwinski <r.czerwinski at pengutronix.de>
> > > Cc: Patrick DELAUNAY <patrick.delaunay at st.com>
> > >
> > > Ard Biesheuvel (3):
> > >   efi/libstub: Export efi_low_alloc_above() to other units
> > >   efi/libstub: Use low allocation for the uncompressed kernel
> > >   efi/libstub: base FDT and initrd placement on image address not DRAM
> > >     base
> > >
> > >  arch/arm/include/asm/efi.h                |   6 +-
> > >  arch/arm64/include/asm/efi.h              |   2 +-
> > >  drivers/firmware/efi/libstub/arm32-stub.c | 177 ++++----------------
> > >  drivers/firmware/efi/libstub/efi-stub.c   |   2 +-
> > >  drivers/firmware/efi/libstub/efistub.h    |   3 +
> > >  drivers/firmware/efi/libstub/relocate.c   |   4 +-
> > >  6 files changed, 47 insertions(+), 147 deletions(-)
>

I verified the above patches along with the following RISC-V specific changes.

diff --git a/arch/riscv/include/asm/efi.h b/arch/riscv/include/asm/efi.h
index 93c305a638f4..dd6ceea9d548 100644
--- a/arch/riscv/include/asm/efi.h
+++ b/arch/riscv/include/asm/efi.h
@@ -37,7 +37,7 @@ static inline unsigned long
efi_get_max_fdt_addr(unsigned long dram_base)
 static inline unsigned long efi_get_max_initrd_addr(unsigned long dram_base,
                                                    unsigned long image_addr)
 {
-       return dram_base + SZ_256M;
+       return image_addr + SZ_256M;
 }

--- a/drivers/firmware/efi/libstub/riscv-stub.c
+++ b/drivers/firmware/efi/libstub/riscv-stub.c
@@ -100,7 +100,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
         */
        preferred_addr = round_up(dram_base, MIN_KIMG_ALIGN) + MIN_KIMG_ALIGN;
        status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
-                                    preferred_addr, MIN_KIMG_ALIGN, dram_base);
+                                    0, MIN_KIMG_ALIGN, 0);

FWIW: Tested-by: Atish Patra <atish.patra at wdc.com>
>
>
> --
> Regards,
> Atish

Do

-- 
Regards,
Atish