Commit d7071743 authored by Atish Patra's avatar Atish Patra Committed by Palmer Dabbelt

RISC-V: Add EFI stub support.

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: default avatarAtish Patra <atish.patra@wdc.com>
Link: https://lore.kernel.org/r/20200421033336.9663-4-atish.patra@wdc.com
[ardb: - move hartid fetch into check_platform_features()
       - use image_size not reserve_size
       - select ISA_C
       - do not use dram_base]
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent cb7d2dd5
......@@ -401,6 +401,26 @@ 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
......@@ -413,3 +433,5 @@ menu "Power management options"
source "kernel/power/Kconfig"
endmenu
source "drivers/firmware/Kconfig"
......@@ -80,6 +80,7 @@ head-y := arch/riscv/kernel/head.o
core-y += arch/riscv/
libs-y += arch/riscv/lib/
libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
PHONY += vdso_install
vdso_install:
......
......@@ -130,3 +130,4 @@ CONFIG_DEBUG_BLOCK_EXT_DEVT=y
# CONFIG_RUNTIME_TESTING_MENU is not set
CONFIG_MEMTEST=y
# CONFIG_SYSFS_SYSCALL is not set
CONFIG_EFI=y
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 2020 Western Digital Corporation or its affiliates.
*/
#ifndef _ASM_EFI_H
#define _ASM_EFI_H
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/ptrace.h>
#include <asm/tlbflush.h>
/* on RISC-V, the FDT may be located anywhere in system RAM */
static inline unsigned long efi_get_max_fdt_addr(unsigned long image_addr)
{
return ULONG_MAX;
}
/* Load initrd at enough distance from DRAM start */
static inline unsigned long efi_get_max_initrd_addr(unsigned long image_addr)
{
return image_addr + SZ_256M;
}
#define alloc_screen_info(x...) (&screen_info)
static inline void free_screen_info(struct screen_info *si)
{
}
static inline void efifb_setup_from_dmi(struct screen_info *si, const char *opt)
{
}
#endif /* _ASM_EFI_H */
......@@ -111,7 +111,7 @@ config EFI_GENERIC_STUB
config EFI_ARMSTUB_DTB_LOADER
bool "Enable the DTB loader"
depends on EFI_GENERIC_STUB
depends on EFI_GENERIC_STUB && !RISCV
default y
help
Select this config option to add support for the dtb= command
......@@ -128,6 +128,7 @@ config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER
bool "Enable the command line initrd loader" if !X86
depends on EFI_STUB && (EFI_GENERIC_STUB || X86)
default y
depends on !RISCV
help
Select this config option to add support for the initrd= command
line parameter, allowing an initrd that resides on the same volume
......
......@@ -22,6 +22,8 @@ cflags-$(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)
......
// 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,
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 = MIN_KIMG_ALIGN;
status = efi_relocate_kernel(image_addr, kernel_size, *image_size,
preferred_addr, MIN_KIMG_ALIGN, 0x0);
if (status != EFI_SUCCESS) {
efi_err("Failed to relocate kernel\n");
*image_size = 0;
}
return status;
}
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