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.pa...@wdc.com> Link: https://lore.kernel.org/r/20200421033336.9663-4-atish.pa...@wdc.com [ardb: - move hartid fetch into check_platform_features() - use image_size not reserve_size - select ISA_C ] Signed-off-by: Ard Biesheuvel <a...@kernel.org> --- arch/riscv/Kconfig | 22 +++++ arch/riscv/Makefile | 1 + arch/riscv/configs/defconfig | 1 + arch/riscv/include/asm/efi.h | 36 +++++++ drivers/firmware/efi/Kconfig | 3 +- drivers/firmware/efi/libstub/Makefile | 10 ++ drivers/firmware/efi/libstub/riscv-stub.c | 110 ++++++++++++++++++++++ 7 files changed, 182 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 e6c1c98a53fb..a6569c268565 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -390,6 +390,26 @@ 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 + select RISCV_ISA_C + 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 config BUILTIN_DTB @@ -402,3 +422,5 @@ menu "Power management options" source "kernel/power/Kconfig" endmenu + +source "drivers/firmware/Kconfig" diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index fb6e37db836d..10df59f28add 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/ +libs-$(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..86da231909bb --- /dev/null +++ b/arch/riscv/include/asm/efi.h @@ -0,0 +1,36 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2020 Western Digital Corporation or its affiliates. + */ +#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> + +/* 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 alloc_screen_info(x...) (&screen_info) + +static inline void free_screen_info(struct screen_info *si) +{ +} + +static inline void efifb_setup_from_dmi(struct screen_info *si, const char *opt) +{ +} + +#endif /* _ASM_EFI_H */ diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index 3939699e62fe..a29fbd6e657e 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 @@ -128,6 +128,7 @@ config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER bool "Enable the command line initrd loader" if !X86 depends on EFI_STUB && (EFI_GENERIC_STUB || X86) default y + depends on !RISCV help Select this config option to add support for the initrd= command line parameter, allowing an initrd that resides on the same volume diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 75daaf20374e..d1564ffcf82f 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 @@ -63,6 +65,7 @@ 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=$(TEXT_OFFSET) @@ -106,6 +109,13 @@ STUBCOPY_FLAGS-$(CONFIG_ARM64) += --prefix-alloc-sections=.init \ --prefix-symbols=__efistub_ STUBCOPY_RELOC-$(CONFIG_ARM64) := R_AARCH64_ABS +# For RISC-V, we don't need anything special other than arm64. Keep all the +# symbols in .init section and make sure that no absolute symbols references +# doesn't exist. +STUBCOPY_FLAGS-$(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..77c3fd6f820e --- /dev/null +++ b/drivers/firmware/efi/libstub/riscv-stub.c @@ -0,0 +1,110 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020 Western Digital Corporation or its affiliates. + */ + +#include <linux/efi.h> +#include <linux/libfdt.h> + +#include <asm/efi.h> +#include <asm/sections.h> + +#include "efistub.h" + +/* + * RISC-V requires the kernel image to placed 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 + +typedef void __noreturn (*jump_kernel_func)(unsigned int, unsigned long); + +static u32 hartid; + +static u32 get_boot_hartid_from_fdt(void) +{ + const void *fdt; + int chosen_node, len; + const fdt32_t *prop; + + fdt = get_efi_config_table(DEVICE_TREE_GUID); + if (!fdt) + return U32_MAX; + + chosen_node = fdt_path_offset(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); +} + +efi_status_t check_platform_features(void) +{ + hartid = get_boot_hartid_from_fdt(); + if (hartid == U32_MAX) { + efi_err("/chosen/boot-hartid missing or invalid!\n"); + return EFI_UNSUPPORTED; + } + return EFI_SUCCESS; +} + +void __noreturn efi_enter_kernel(unsigned long entrypoint, unsigned long fdt, + unsigned long fdt_size) +{ + unsigned long stext_offset = _start_kernel - _start; + unsigned long kernel_entry = entrypoint + stext_offset; + jump_kernel_func jump_kernel = (jump_kernel_func)kernel_entry; + + /* + * Jump to real kernel here with following constraints. + * 1. MMU should be disabled. + * 2. a0 should contain hartid + * 3. a1 should DT address + */ + 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) +{ + unsigned long kernel_size = 0; + unsigned long preferred_addr; + efi_status_t status; + + kernel_size = _edata - _start; + *image_addr = (unsigned long)_start; + *image_size = kernel_size + (_end - _edata); + + /* + * RISC-V kernel maps PAGE_OFFSET virtual address to the same physical + * address where kernel is booted. That's why kernel should boot from + * as low as possible to avoid wastage of memory. Currently, dram_base + * is occupied by the firmware. So the preferred address for kernel to + * boot is next aligned address. If preferred address is not available, + * relocate_kernel will fall back to efi_low_alloc_above to allocate + * lowest possible memory region as long as the address and size meets + * the alignment constraints. + */ + 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); + + if (status != EFI_SUCCESS) { + efi_err("Failed to relocate kernel\n"); + *image_size = 0; + } + return status; +} -- 2.24.0
