On Wed, 15 Apr 2020 at 02:11, Atish Patra <Atish.Patra@xxxxxxx> wrote: > > On Tue, 2020-04-14 at 09:41 +0200, Ard Biesheuvel wrote: > > On Mon, 13 Apr 2020 at 23:29, 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 + > > > arch/riscv/include/asm/efi.h | 45 ++++++++ > > > drivers/firmware/efi/Kconfig | 2 +- > > > drivers/firmware/efi/libstub/Makefile | 8 ++ > > > drivers/firmware/efi/libstub/riscv-stub.c | 131 > > > ++++++++++++++++++++++ > > > 7 files changed, 207 insertions(+), 1 deletion(-) > > > create mode 100644 arch/riscv/include/asm/efi.h > > > create mode 100644 drivers/firmware/efi/libstub/riscv-stub.c > > > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > > index f39e326a7a42..eb4f41c8f3ce 100644 > > > --- a/arch/riscv/Kconfig > > > +++ b/arch/riscv/Kconfig > > > @@ -379,10 +379,30 @@ 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_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 fb6e37db836d..079435804d6d 100644 > > > --- a/arch/riscv/Makefile > > > +++ b/arch/riscv/Makefile > > > @@ -80,6 +80,7 @@ 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 4da4886246a4..ae69e12d306a 100644 > > > --- a/arch/riscv/configs/defconfig > > > +++ b/arch/riscv/configs/defconfig > > > @@ -129,3 +129,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y > > > # CONFIG_RUNTIME_TESTING_MENU is not set > > > CONFIG_MEMTEST=y > > > # CONFIG_SYSFS_SYSCALL is not set > > > +CONFIG_EFI=y > > > diff --git a/arch/riscv/include/asm/efi.h > > > b/arch/riscv/include/asm/efi.h > > > new file mode 100644 > > > index 000000000000..ba0a6d35cc15 > > > --- /dev/null > > > +++ b/arch/riscv/include/asm/efi.h > > > @@ -0,0 +1,45 @@ > > > +/* SPDX-License-Identifier: GPL-2.0 */ > > > +/* > > > + * Copyright (C) 2020 Western Digital Corporation or its > > > affiliates. > > > + * Based on arch/arm64/include/asm/efi.h > > > + */ > > > +#ifndef _ASM_EFI_H > > > +#define _ASM_EFI_H > > > + > > > +#include <asm/io.h> > > > +#include <asm/mmu_context.h> > > > +#include <asm/ptrace.h> > > > +#include <asm/tlbflush.h> > > > + > > > +#define VA_BITS_MIN 39 > > > + > > > +/* on RISC-V, the FDT may be located anywhere in system RAM */ > > > +static inline unsigned long efi_get_max_fdt_addr(unsigned long > > > dram_base) > > > +{ > > > + return ULONG_MAX; > > > +} > > > + > > > +/* Load initrd at enough distance from DRAM start */ > > > +static inline unsigned long efi_get_max_initrd_addr(unsigned long > > > dram_base, > > > + unsigned long > > > image_addr) > > > +{ > > > + return dram_base + SZ_256M; > > > +} > > > + > > > +#define efi_bs_call(func, ...) efi_system_table()->boottime- > > > >func(__VA_ARGS__) > > > +#define efi_rt_call(func, ...) efi_system_table()->runtime- > > > >func(__VA_ARGS__) > > > +#define efi_is_native() (true) > > > + > > > +#define efi_table_attr(inst, attr) (inst->attr) > > > + > > > +#define efi_call_proto(inst, func, ...) inst->func(inst, > > > ##__VA_ARGS__) > > > + > > > +#define alloc_screen_info(x...) (&screen_info) > > > +extern char stext_offset[]; > > > + > > > +static inline void free_screen_info(struct screen_info *si) > > > +{ > > > +} > > > +#define EFI_ALLOC_ALIGN SZ_64K > > > + > > > +#endif /* _ASM_EFI_H */ > > > diff --git a/drivers/firmware/efi/Kconfig > > > b/drivers/firmware/efi/Kconfig > > > index 2a2b2b96a1dc..fcdc789d3f87 100644 > > > --- a/drivers/firmware/efi/Kconfig > > > +++ b/drivers/firmware/efi/Kconfig > > > @@ -111,7 +111,7 @@ config EFI_GENERIC_STUB > > > > > > config EFI_ARMSTUB_DTB_LOADER > > > bool "Enable the DTB loader" > > > - depends on EFI_GENERIC_STUB > > > + depends on EFI_GENERIC_STUB && !RISCV > > > default y > > > help > > > Select this config option to add support for the dtb= > > > command > > > diff --git a/drivers/firmware/efi/libstub/Makefile > > > b/drivers/firmware/efi/libstub/Makefile > > > index d590504541f6..b1db3a793c43 100644 > > > --- a/drivers/firmware/efi/libstub/Makefile > > > +++ b/drivers/firmware/efi/libstub/Makefile > > > @@ -22,6 +22,8 @@ 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-$(CONFIG_EFI_GENERIC_STUB) += > > > -I$(srctree)/scripts/dtc/libfdt > > > > > > @@ -56,6 +58,7 @@ lib-$(CONFIG_EFI_GENERIC_STUB) += > > > efi-stub.o fdt.o string.o \ > > > lib-$(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=$(TEXT_OFFSET) > > > > > > @@ -80,6 +83,11 @@ STUBCOPY_FLAGS-$(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..acb69eae187a > > > --- /dev/null > > > +++ b/drivers/firmware/efi/libstub/riscv-stub.c > > > @@ -0,0 +1,131 @@ > > > +// 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. > > > + */ > > > +#ifdef CONFIG_64BIT > > > +#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. > > > + */ > > > +#define TEXT_OFFSET MIN_KIMG_ALIGN > > > + > > > > Again, this is not the right approach. If there are any allocations > > in > > memory that EFI cannot touch, you have to mark them as reserved in > > the > > EFI memory map. Otherwise, anything running in the EFI context (GRUB, > > systemd-boot, shim, etc) could step on it, not just the kernel. > > > > Correct. That's why I added the U-Boot series which takes care of > modifying the DT to add the reserved memory regions. With those > changes, any memory marked reserved by the firmware will be marked > reserved in the EFI memory map. The proper kernel will > also never map those memory regions if "nomap" is set. > OK, good to know. > To be honest, I forgot to remove the TEXT_OFFSET in this series. I > have removed it in the next version. > OK. > > > +typedef __attribute__((noreturn)) void > > > (*jump_kernel_func)(unsigned int, > > > + unsigned > > > long); > > > +efi_status_t check_platform_features(void) > > > +{ > > > + return EFI_SUCCESS; > > > +} > > > + > > > +static u32 get_boot_hartid_from_fdt(unsigned long fdt) > > > +{ > > > + int chosen_node, len; > > > + const fdt32_t *prop; > > > + > > > + chosen_node = fdt_path_offset((void *)fdt, "/chosen"); > > > + if (chosen_node < 0) > > > + return U32_MAX; > > > + prop = fdt_getprop((void *)fdt, chosen_node, "boot-hartid", > > > &len); > > > + if (!prop || len != sizeof(u32)) > > > + return U32_MAX; > > > + > > > + return fdt32_to_cpu(*prop); > > > +} > > > + > > > +/* > > > + * Jump to real kernel here with following constraints. > > > + * 1. MMU should be disabled. > > > + * 2. a0 should contain hartid > > > + * 3. a1 should DT address > > > + */ > > > +void __noreturn efi_enter_kernel(unsigned long entrypoint, > > > unsigned long fdt, > > > + unsigned long fdt_size) > > > +{ > > > + unsigned long kernel_entry = entrypoint + (unsigned > > > long)stext_offset; > > > + jump_kernel_func jump_kernel = (void (*)(unsigned int, > > > unsigned long))kernel_entry; > > > + u32 hartid = get_boot_hartid_from_fdt(fdt); > > > + > > > + if (hartid == U32_MAX) > > > + /* We can not use panic or BUG at this point */ > > > + __asm__ __volatile__ ("ebreak"); > > > + /* Disable MMU */ > > > + csr_write(CSR_SATP, 0); > > > + jump_kernel(hartid, fdt); > > > +} > > > + > > > +efi_status_t handle_kernel_image(unsigned long *image_addr, > > > + unsigned long *image_size, > > > + unsigned long *reserve_addr, > > > + unsigned long *reserve_size, > > > + unsigned long dram_base, > > > + efi_loaded_image_t *image) > > > +{ > > > + efi_status_t status; > > > + unsigned long kernel_size, kernel_memsize = 0; > > > + unsigned long preferred_offset; > > > + > > > + /* > > > + * The preferred offset of the kernel Image is TEXT_OFFSET > > > bytes beyond > > > + * a KIMG_ALIGN aligned base. > > > > MIN_KIMG_ALIGN > > > > > + */ > > > + preferred_offset = round_up(dram_base, MIN_KIMG_ALIGN) + > > > TEXT_OFFSET; > > > + > > > + kernel_size = _edata - _start; > > > + kernel_memsize = kernel_size + (_end - _edata); > > > + > > > + /* > > > + * Try a straight allocation at the preferred offset. It > > > will also > > > + * ensure that, on platforms where the [dram_base, > > > dram_base + TEXT_OFFSET) > > > + * interval is partially occupied by the firmware we can > > > still place > > > + * the kernel at the address 'dram_base + TEXT_OFFSET'. If > > > the straight > > > + * allocation fails, efi_low_alloc tries allocate memory > > > from the lowest > > > + * available LOADER_DATA mapped memory as long as address > > > and size meet > > > + * the alignment constraints. > > > + */ > > > + if (*image_addr == preferred_offset) > > > + return EFI_SUCCESS; > > > + > > > + *image_addr = *reserve_addr = preferred_offset; > > > + *reserve_size = round_up(kernel_memsize, EFI_ALLOC_ALIGN); > > > + > > > + status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS, > > > + EFI_LOADER_DATA, > > > + *reserve_size / EFI_PAGE_SIZE, > > > + (efi_physical_addr_t > > > *)reserve_addr); > > > + > > > + if (status != EFI_SUCCESS) { > > > + pr_efi("straight allocation failed do a low > > > alloc\n"); > > > + *reserve_size = kernel_memsize + TEXT_OFFSET; > > > + status = efi_low_alloc(*reserve_size, > > > MIN_KIMG_ALIGN, > > > + reserve_addr); > > > + > > > > So, instead of the above, could we simply allocate kernel_memsize > > bytes using efi_allocate_pages(), with the max address set to > > 'round_up(dram_base, MIN_KIMG_ALIGN) + kernel_memsize + TEXT_OFFSET - > > 1'? This should work in the majority of cases, and not trample on the > > TEXT_OFFSET bytes at the start, regardless of whether they are > > reserved or not. > > > > As per my understanding, efi_allocate_pages aligns as per > EFI_ALLOC_ALIGN. But the kernel needs to be placed at a memory aligned > to MIN_KIMG_ALIGN. That's why efi_allocate_pages may not work. > It will work if you do the round_up() afterwards. But efi_allocate_pages_aligned() essentially does the same thing, so if that works for you, it is preferred. > > In the future, I imagine you may want to relax the requirements > > regarding the physical placement of the kernel, in which case you can > > start falling back to a suitably aligned allocation anywhere in > > memory. > > > > > > > > > + if (status != EFI_SUCCESS) { > > > + pr_efi_err("Failed to relocate kernel\n"); > > > + *reserve_size = 0; > > > + return status; > > > + } > > > + *image_addr = *reserve_addr + TEXT_OFFSET; > > > + } > > > + memcpy((void *)*image_addr, image->image_base, > > > kernel_size); > > > + > > > + return EFI_SUCCESS; > > > +} > > > -- > > > 2.24.0 > > > > > Actually, we don't have any kernel placement restriction other than > 2MB/4MB alignment. > (considering that firmware now marks all the reserved memory in DT). > > Can we just use efi_allocate_pages_aligned similar to arm64 ? It seems > to work during my testing. But I wanted to make sure that I didn't > misunderstand anything. > Yes, that is the preferred approach.