On Tue, Mar 10, 2020 at 12:39 PM Atish Patra <atishp@xxxxxxxxxxxxxx> wrote: > > On Thu, Feb 27, 2020 at 10:57 PM Ard Biesheuvel <ardb@xxxxxxxxxx> wrote: > > > > On Fri, 28 Feb 2020 at 02:05, Atish Patra <Atish.Patra@xxxxxxx> wrote: > > > > > > On Thu, 2020-02-27 at 20:59 +0100, Ard Biesheuvel wrote: > > > > On Thu, 27 Feb 2020 at 20:53, Atish Patra <Atish.Patra@xxxxxxx> > > > > wrote: > > > > > On Wed, 2020-02-26 at 08:28 +0100, Ard Biesheuvel wrote: > > > > > > On Wed, 26 Feb 2020 at 02:10, Atish Patra <atish.patra@xxxxxxx> > > > > > > wrote: > > > > > > > Add a RISC-V architecture specific stub code that actually > > > > > > > copies > > > > > > > the > > > > > > > actual kernel image to a valid address and jump to it after > > > > > > > boot > > > > > > > services > > > > > > > are terminated. Enable UEFI related kernel configs as well for > > > > > > > RISC-V. > > > > > > > > > > > > > > Signed-off-by: Atish Patra <atish.patra@xxxxxxx> > > > > > > > --- > > > > > > > arch/riscv/Kconfig | 20 ++++ > > > > > > > arch/riscv/Makefile | 1 + > > > > > > > arch/riscv/configs/defconfig | 1 + > > > > > > > drivers/firmware/efi/libstub/Makefile | 8 ++ > > > > > > > drivers/firmware/efi/libstub/riscv-stub.c | 135 > > > > > > > ++++++++++++++++++++++ > > > > > > > 5 files changed, 165 insertions(+) > > > > > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c > > > > > > > > > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > > > > > index 42c122170cfd..68b1d565e51d 100644 > > > > > > > --- a/arch/riscv/Kconfig > > > > > > > +++ b/arch/riscv/Kconfig > > > > > > > @@ -372,10 +372,30 @@ config CMDLINE_FORCE > > > > > > > > > > > > > > endchoice > > > > > > > > > > > > > > +config EFI_STUB > > > > > > > + bool > > > > > > > + > > > > > > > +config EFI > > > > > > > + bool "UEFI runtime support" > > > > > > > + depends on OF > > > > > > > + select LIBFDT > > > > > > > + select UCS2_STRING > > > > > > > + select EFI_PARAMS_FROM_FDT > > > > > > > + select EFI_STUB > > > > > > > + select EFI_GENERIC_ARCH_STUB > > > > > > > + default y > > > > > > > + help > > > > > > > + This option provides support for runtime services > > > > > > > provided > > > > > > > + by UEFI firmware (such as non-volatile variables, > > > > > > > realtime > > > > > > > + clock, and platform reset). A UEFI stub is also > > > > > > > provided > > > > > > > to > > > > > > > + allow the kernel to be booted as an EFI application. > > > > > > > This > > > > > > > + is only useful on systems that have UEFI firmware. > > > > > > > + > > > > > > > endmenu > > > > > > > > > > > > > > menu "Power management options" > > > > > > > > > > > > > > source "kernel/power/Kconfig" > > > > > > > +source "drivers/firmware/Kconfig" > > > > > > > > > > > > > > endmenu > > > > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > > > > > > > index b9009a2fbaf5..0afaa89ba9ad 100644 > > > > > > > --- a/arch/riscv/Makefile > > > > > > > +++ b/arch/riscv/Makefile > > > > > > > @@ -78,6 +78,7 @@ head-y := arch/riscv/kernel/head.o > > > > > > > core-y += arch/riscv/ > > > > > > > > > > > > > > libs-y += arch/riscv/lib/ > > > > > > > +core-$(CONFIG_EFI_STUB) += > > > > > > > $(objtree)/drivers/firmware/efi/libstub/lib.a > > > > > > > > > > > > > > PHONY += vdso_install > > > > > > > vdso_install: > > > > > > > diff --git a/arch/riscv/configs/defconfig > > > > > > > b/arch/riscv/configs/defconfig > > > > > > > index e2ff95cb3390..0a5d3578f51e 100644 > > > > > > > --- a/arch/riscv/configs/defconfig > > > > > > > +++ b/arch/riscv/configs/defconfig > > > > > > > @@ -125,3 +125,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y > > > > > > > # CONFIG_FTRACE is not set > > > > > > > # CONFIG_RUNTIME_TESTING_MENU is not set > > > > > > > CONFIG_MEMTEST=y > > > > > > > +CONFIG_EFI=y > > > > > > > diff --git a/drivers/firmware/efi/libstub/Makefile > > > > > > > b/drivers/firmware/efi/libstub/Makefile > > > > > > > index 2c5b76787126..38facb61745b 100644 > > > > > > > --- a/drivers/firmware/efi/libstub/Makefile > > > > > > > +++ b/drivers/firmware/efi/libstub/Makefile > > > > > > > @@ -21,6 +21,8 @@ cflags-$(CONFIG_ARM64) := > > > > > > > $(subst > > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > > cflags-$(CONFIG_ARM) := $(subst > > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > > -fno-builtin -fpic \ > > > > > > > $(call cc-option,-mno- > > > > > > > single- > > > > > > > pic-base) > > > > > > > +cflags-$(CONFIG_RISCV) := $(subst > > > > > > > $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \ > > > > > > > + -fpic > > > > > > > > > > > > > > cflags-$(CONFIG_EFI_GENERIC_ARCH_STUB) += > > > > > > > -I$(srctree)/scripts/dtc/libfdt > > > > > > > > > > > > > > @@ -55,6 +57,7 @@ lib- > > > > > > > $(CONFIG_EFI_GENERIC_ARCH_STUB) += > > > > > > > efi-stub.o fdt.o string.o \ > > > > > > > lib-$(CONFIG_ARM) += arm32-stub.o > > > > > > > lib-$(CONFIG_ARM64) += arm64-stub.o > > > > > > > lib-$(CONFIG_X86) += x86-stub.o > > > > > > > +lib-$(CONFIG_RISCV) += riscv-stub.o > > > > > > > CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > > > > > > CFLAGS_arm64-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET) > > > > > > > > > > > > > > @@ -79,6 +82,11 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += -- > > > > > > > prefix-alloc-sections=.init \ > > > > > > > --prefix-symbols=__efistub_ > > > > > > > STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS > > > > > > > > > > > > > > +STUBCOPY_FLAGS-$(CONFIG_RISCV) += --prefix-alloc- > > > > > > > sections=.init \ > > > > > > > + --prefix-symbols=__efistub_ > > > > > > > +STUBCOPY_RELOC-$(CONFIG_RISCV) := R_RISCV_HI20 > > > > > > > + > > > > > > > + > > > > > > > $(obj)/%.stub.o: $(obj)/%.o FORCE > > > > > > > $(call if_changed,stubcopy) > > > > > > > > > > > > > > diff --git a/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > > b/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > > new file mode 100644 > > > > > > > index 000000000000..3935b29ea93a > > > > > > > --- /dev/null > > > > > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c > > > > > > > @@ -0,0 +1,135 @@ > > > > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > > > > +/* > > > > > > > + * Copyright (C) 2013, 2014 Linaro Ltd; <roy.franz@xxxxxxxxxx > > > > > > > > > > > > > > > + * Copyright (C) 2020 Western Digital Corporation or its > > > > > > > affiliates. > > > > > > > + * > > > > > > > + * This file implements the EFI boot stub for the RISC-V > > > > > > > kernel. > > > > > > > + * Adapted from ARM64 version at > > > > > > > drivers/firmware/efi/libstub/arm64-stub.c. > > > > > > > + */ > > > > > > > + > > > > > > > +#include <linux/efi.h> > > > > > > > +#include <linux/libfdt.h> > > > > > > > +#include <linux/libfdt_env.h> > > > > > > > +#include <asm/efi.h> > > > > > > > +#include <asm/sections.h> > > > > > > > + > > > > > > > +#include "efistub.h" > > > > > > > +/* > > > > > > > + * RISCV requires the kernel image to placed TEXT_OFFSET bytes > > > > > > > beyond a 2 MB > > > > > > > + * aligned base for 64 bit and 4MB for 32 bit. > > > > > > > + */ > > > > > > > +#if IS_ENABLED(CONFIG_64BIT) > > > > > > > > > > > > You can use #ifdef here > > > > > > > > > > > > > > > > ok. > > > > > > > > > > > > +#define MIN_KIMG_ALIGN SZ_2M > > > > > > > +#else > > > > > > > +#define MIN_KIMG_ALIGN SZ_4M > > > > > > > +#endif > > > > > > > +/* > > > > > > > + * TEXT_OFFSET ensures that we don't overwrite the firmware > > > > > > > that > > > > > > > probably sits > > > > > > > + * at the beginning of the DRAM. > > > > > > > + */ > > > > > > > > > > > > Ugh. Really? On an EFI system, that memory should be reserved in > > > > > > some > > > > > > way, we shouldn't be able to stomp on it like that. > > > > > > > > > > > > > > > > Currently, we reserve the initial 128KB for run time firmware(only > > > > > openSBI for now, EDK2 later) by using PMP (physical memory > > > > > protection). > > > > > Any acess to that region from supervisor mode (i.e. U-Boot) will > > > > > result > > > > > in a fault. > > > > > > > > > > Is it mandatory for UEFI to reserve the beginning of the DRAM ? > > > > > > > > > > > > > It is mandatory to describe which memory is usable and which memory > > > > is > > > > reserved. If this memory is not usable, you either describe it as > > > > reserved, or not describe it at all. Describing it as usable memory, > > > > allocating it for the kernel but with a hidden agreement that it is > > > > reserved is highly likely to cause problems down the road. > > > > > > > > > > I completely agree with you on this. We have been talking to have a > > > booting guide and memory map document for RISC-V Linux to document all > > > the idiosyncries of RISC-V. But that has not happend until now. > > > Once, the ordered booting patches are merged, I will try to take a stab > > > at it. > > > > > > Other than that, do we need to describe it somewhere in U-boot wrt to > > > UEFI so that it doesn't allocate memory from that region ? > > > > > > > It is an idiosyncrasy that the firmware should hide from the OS. > > > > What if GRUB comes along and attempts to allocate that memory? Do we > > also have to teach it that the first 128 KB memory of free memory are > > magic and should not be touched? > > > > So the answer is to mark it as reserved. This way, no UEFI tools, > > bootloaders etc will ever try to use it. > > Sounds good to me. We are currently discussing the best approach to > provide reserved memory > information to U-Boot/EDK2. The idea is to U-Boot/EDK2 may have to > update the DT with > reserved-memory node so that Linux is aware of the reservation as well. The discussion is happening on Github at: https://github.com/riscv/riscv-sbi-doc/pull/37 Feel free to share your views in above mentioned Github link. Regards, Anup
