It is useful to be able to load U-Boot onto a board even it is it already running EFI. This can allow access to the U-Boot command interface, flexible booting options and easier development.
The easiest way to do this is to build U-Boot as a binary blob and have an EFI stub copy it into RAM. Add support for this feature, targeting 32-bit initially.
Also add a way to detect when U-Boot has been loaded via a stub. This goes in common.h since it needs to be widely available so that we avoid redoing initialisation that should be skipped.
Signed-off-by: Simon Glass sjg@chromium.org ---
Makefile | 32 ++++++ include/common.h | 7 ++ include/efi.h | 4 + lib/efi/Kconfig | 21 ++++ lib/efi/Makefile | 9 ++ lib/efi/efi_stub.c | 293 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 366 insertions(+) create mode 100644 lib/efi/efi_stub.c
diff --git a/Makefile b/Makefile index 91ebc2e..9f863e1 100644 --- a/Makefile +++ b/Makefile @@ -753,6 +753,7 @@ ALL-$(CONFIG_SPL) += $(CONFIG_SPL_TARGET:"%"=%) endif ALL-$(CONFIG_REMAKE_ELF) += u-boot.elf ALL-$(CONFIG_ARCH_EFI) += u-boot.efi +ALL-$(CONFIG_EFI_STUB) += u-boot-payload.efi
ifneq ($(BUILD_ROM),) ALL-$(CONFIG_X86_RESET_VECTOR) += u-boot.rom @@ -1085,6 +1086,37 @@ OBJCOPYFLAGS_u-boot.efi := $(OBJCOPYFLAGS_EFI) u-boot.efi: u-boot FORCE $(call if_changed,zobjcopy)
+# Generate an assembly file to wrap a binary file +quiet_cmd_bin_S = BIN $@ +cmd_bin_S = \ +( \ + echo '.section .u_boot_bin.init.rodata,"a"'; \ + echo '.balign 16'; \ + echo '.global __u_boot_bin_begin'; \ + echo '__u_boot_bin_begin:'; \ + echo '.incbin "$<" '; \ + echo '__u_boot_bin_end:'; \ + echo '.global __u_boot_bin_end'; \ + echo '.balign 16'; \ +) > $@ + +u-boot-dtb.bin.S: u-boot-dtb.bin FORCE + $(call if_changed,bin_S) + +u-boot-payload.lds: $(LDSCRIPT_EFI) FORCE + $(call if_changed_dep,cpp_lds) + +u-boot-payload: u-boot-dtb.bin.o u-boot-payload.lds \ + FORCE + $(LD) $(LDFLAGS_EFI) -o $@ \ + -T u-boot-payload.lds \ + lib/efi/efi.o lib/efi/efi_stub.o u-boot-dtb.bin.o \ + $(addprefix arch/$(ARCH)/lib/,$(EFISTUB)) + +OBJCOPYFLAGS_u-boot-payload.efi := $(OBJCOPYFLAGS_EFI) +u-boot-payload.efi: u-boot-payload FORCE + $(call if_changed,zobjcopy) + u-boot-img.bin: spl/u-boot-spl.bin u-boot.img FORCE $(call if_changed,cat)
diff --git a/include/common.h b/include/common.h index 8f4b2ec..406fb33 100644 --- a/include/common.h +++ b/include/common.h @@ -1010,6 +1010,13 @@ int cpu_release(int nr, int argc, char * const argv[]); #define DEFINE_CACHE_ALIGN_BUFFER(type, name, size) \ DEFINE_ALIGN_BUFFER(type, name, size, ARCH_DMA_MINALIGN)
+/* Avoid using CONFIG_EFI_STUB directly as we may boot from other loaders */ +#ifdef CONFIG_EFI_STUB +#define ll_boot_init() false +#else +#define ll_boot_init() true +#endif + /* Pull in stuff for the build system */ #ifdef DO_DEPS_ONLY # include <environment.h> diff --git a/include/efi.h b/include/efi.h index 66ef6c3..edc8cd9 100644 --- a/include/efi.h +++ b/include/efi.h @@ -268,11 +268,15 @@ struct efi_priv { /* Base address of the EFI image */ extern char ImageBase[];
+/* Start and end of U-Boot image (for payload) */ +extern char __u_boot_bin_begin[], __u_boot_bin_end[]; + /** * efi_get_sys_table() - Get access to the main EFI system table * * @return pointer to EFI system table */ + struct efi_system_table *efi_get_sys_table(void);
/** diff --git a/lib/efi/Kconfig b/lib/efi/Kconfig index 2b3dbd4..f1a8873 100644 --- a/lib/efi/Kconfig +++ b/lib/efi/Kconfig @@ -20,6 +20,11 @@ config ARCH_EFI command problem and memory and I/O functions. Use 'reset' to return to EFI.
+config EFI_STUB + bool "Support running as an EFI payload" + +endchoice + config EFI_RAM_SIZE hex "Amount of EFI RAM for U-Boot" depends on ARCH_EFI @@ -30,4 +35,20 @@ config EFI_RAM_SIZE other smaller amounts) and it can never be increased after that. It is used as the RAM size in withU-Boot.
+choice + prompt "EFI 32/64-bit selection" + depends on EFI_STUB + help + EFI does not support mixing 32-bit and 64-bit modes. This is a + significant problem because it means that you must build a stub with + the correct type for EFI to load it correctly. If you are using + 32-bit EFI, select 32-bit here, else select 64-bit. Failure to do + this may produce no error message - it just won't start! + +config EFI_STUB_32BIT + bool "Produce a stub for running with 32-bit EFI" + +config EFI_STUB_64BIT + bool "Produce a stub for running with 64-bit EFI" + endchoice diff --git a/lib/efi/Makefile b/lib/efi/Makefile index 137d2f9..ba2824e 100644 --- a/lib/efi/Makefile +++ b/lib/efi/Makefile @@ -5,3 +5,12 @@ #
obj-$(CONFIG_ARCH_EFI) += efi_app.o efi.o + +CFLAGS_REMOVE_efi_stub.o := -mregparm=3 \ + $(if $(CONFIG_EFI_STUB_64BIT),-march=i386 -m32) +CFLAGS_efi_stub.o := -fpic -fshort-wchar +CFLAGS_REMOVE_efi.o := -mregparm=3 \ + $(if $(CONFIG_EFI_STUB_64BIT),-march=i386 -m32) +CFLAGS_efi.o := -fpic -fshort-wchar + +extra-$(CONFIG_EFI_STUB) += efi_stub.o efi.o diff --git a/lib/efi/efi_stub.c b/lib/efi/efi_stub.c new file mode 100644 index 0000000..e3b7cdb --- /dev/null +++ b/lib/efi/efi_stub.c @@ -0,0 +1,293 @@ +/* + * Copyright (c) 2015 Google, Inc + * + * SPDX-License-Identifier: GPL-2.0+ + * + * EFI information obtained here: + * http://wiki.phoenix.com/wiki/index.php/EFI_BOOT_SERVICES + * + * Loads a payload (U-Boot) within the EFI environment. This is built as a + * 32-bit EFI application. + */ + +#include <common.h> +#include <debug_uart.h> +#include <efi.h> +#include <efi_api.h> +#include <errno.h> +#include <ns16550.h> +#include <asm/cpu.h> +#include <asm/io.h> +#include <linux/err.h> +#include <linux/types.h> + +DECLARE_GLOBAL_DATA_PTR; + +#ifndef CONFIG_X86 +/* + * Problem areas: + * - putc() uses the ns16550 address directly and assumed I/O access. Many + * platforms will use memory access + * get_codeseg32() is only meaningful on x86 + */ +#error "This file needs to be ported for use on architectures" +#endif + +static struct efi_priv *global_priv; +static bool use_uart; + +struct __packed desctab_info { + uint16_t limit; + uint64_t addr; + uint16_t pad; +}; + +/* + * EFI uses Unicode and we don't. The easiest way to get a sensible output + * function is to use the U-Boot debug UART. We use EFI's console output + * function where available, and assume the built-in UART after that. We rely + * on EFI to set up the UART for us and just bring in the functions here. + * This last bit is a bit icky, but it's only for debugging anyway. We could + * build in ns16550.c with some effort, but this is a payload loader after + * all. + * + * Note: We avoid using printf() so we don't need to bring in lib/vsprintf.c. + * That would require some refactoring since we already build this for U-Boot. + * Building an EFI shared library version would have to be a separate stem. + * That might push us to using the SPL framework to build this stub. However + * that would involve a round of EFI-specific changes in SPL. Worth + * considering if we start needing more U-Boot functionality. Note that we + * could then move get_codeseg32() to arch/x86/cpu/cpu.c. + */ +void debug_uart_init(void) +{ +} + +void putc(const char ch) +{ + if (use_uart) { + NS16550_t com_port = (NS16550_t)0x3f8; + + while ((inb((ulong)&com_port->lsr) & UART_LSR_THRE) == 0) + ; + outb(ch, (ulong)&com_port->thr); + } else { + efi_putc(global_priv, ch); + } + if (ch == '\n') + putc('\r'); +} + +void puts(const char *str) +{ + while (*str) + putc(*str++); +} + +static void _debug_uart_putc(int ch) +{ + putc(ch); +} + +DEBUG_UART_FUNCS + +void *memcpy(void *dest, const void *src, size_t size) +{ + unsigned char *dptr = dest; + const unsigned char *ptr = src; + const unsigned char *end = src + size; + + while (ptr < end) + *dptr++ = *ptr++; + + return dest; +} + +void *memset(void *inptr, int ch, size_t size) +{ + char *ptr = inptr; + char *end = ptr + size; + + while (ptr < end) + *ptr++ = ch; + + return ptr; +} + +static void jump_to_uboot(ulong cs32, ulong addr, ulong info) +{ + typedef void (*func_t)(int bist, int unused, ulong info); + +#ifdef CONFIG_EFI_STUB_32BIT + ((func_t)addr)(bist, 0, info); +#else + /* TODO: Implement this */ +#endif +} + +static void get_gdt(struct desctab_info *info) +{ + asm volatile ("sgdt %0" : : "m"(*info) : "memory"); +} + +static inline unsigned long read_cr3(void) +{ + unsigned long val; + + asm volatile("mov %%cr3,%0\n\t" : "=r" (val) : : "memory"); + return val; +} + +/** + * get_codeseg32() - Find the code segment to use for 32-bit code + * + * U-Boot only works in 32-bit mode at present, so when booting from 64-bit + * EFI we must first change to 32-bit mode. To do this we need to find the + * correct code segment to use (an entry in the Global Descriptor Table). + * + * @return code segment GDT offset, or 0 for 32-bit EFI, -ENOENT if not found + */ +static int get_codeseg32(void) +{ + int cs32 = 0; + + /* TODO(sjg): Implement this for 64-bit mode */ + return cs32; +} + +static int setup_info_table(struct efi_priv *priv, int size) +{ + struct efi_info_hdr *info; + efi_status_t ret; + + /* Get some memory for our info table */ + priv->info_size = size; + info = efi_malloc(priv, priv->info_size, &ret); + if (ret) { + printhex2(ret); + puts(" No memory for info table: "); + return ret; + } + + memset(info, '\0', sizeof(*info)); + info->version = EFI_TABLE_VERSION; + info->hdr_size = sizeof(*info); + priv->info = info; + priv->next_hdr = (char *)info + info->hdr_size; + + return 0; +} + +static void add_entry_addr(struct efi_priv *priv, enum efi_entry_t type, + void *ptr1, int size1, void *ptr2, int size2) +{ + struct efi_entry_hdr *hdr = priv->next_hdr; + + hdr->type = type; + hdr->size = size1 + size2; + hdr->addr = 0; + hdr->link = ALIGN(sizeof(*hdr) + hdr->size, 16); + priv->next_hdr += hdr->link; + memcpy(hdr + 1, ptr1, size1); + memcpy((void *)(hdr + 1) + size1, ptr2, size2); + priv->info->total_size = (ulong)priv->next_hdr - (ulong)priv->info; +} + +/** + * efi_main() - Start an EFI image + * + * This function is called by our EFI start-up code. It handles running + * U-Boot. If it returns, EFI will continue. Another way to get back to EFI + * is via reset_cpu(). + */ +efi_status_t efi_main(efi_handle_t image, struct efi_system_table *sys_table) +{ + struct efi_priv local_priv, *priv = &local_priv; + struct efi_boot_services *boot = sys_table->boottime; + struct efi_mem_desc *desc; + struct efi_entry_memmap map; + ulong key, desc_size, size; + efi_status_t ret; + u32 version; + int cs32; + + ret = efi_init(priv, "Payload", image, sys_table); + if (ret) { + printhex2(ret); puts(" efi_init() failed\n"); + return ret; + } + global_priv = priv; + + cs32 = get_codeseg32(); + if (cs32 < 0) + return EFI_UNSUPPORTED; + + /* Get the memory map so we can switch off EFI */ + size = 0; + ret = boot->get_memory_map(&size, NULL, &key, &desc_size, &version); + if (ret != EFI_BUFFER_TOO_SMALL) { + printhex2(BITS_PER_LONG); + printhex2(ret); + puts(" No memory map\n"); + return ret; + } + size += 1024; /* Since doing a malloc() may change the memory map! */ + desc = efi_malloc(priv, size, &ret); + if (!desc) { + printhex2(ret); + puts(" No memory for memory descriptor: "); + return ret; + } + ret = setup_info_table(priv, size + 128); + if (ret) + return ret; + + ret = boot->get_memory_map(&size, desc, &key, &desc_size, &version); + if (ret) { + printhex2(ret); + puts(" Can't get memory map\n"); + return ret; + } + + ret = boot->exit_boot_services(image, key); + if (ret) { + printhex2(ret); + puts(" Can't exit boot services\n"); + size = sizeof(desc); + ret = boot->get_memory_map(&size, desc, &key, &desc_size, + &version); + if (ret) { + printhex2(ret); + puts(" Can't get memory map\n"); + return ret; + } + ret = boot->exit_boot_services(image, key); + if (ret) { + printhex2(ret); + puts(" Can't exit boot services 2\n"); + return ret; + } + } + + map.version = version; + map.desc_size = desc_size; + add_entry_addr(priv, EFIET_MEMORY_MAP, &map, sizeof(map), desc, size); + add_entry_addr(priv, EFIET_END, NULL, 0, 0, 0); + + /* The EFI UART won't work now, switch to a debug one */ + use_uart = true; + + memcpy((void *)CONFIG_SYS_TEXT_BASE, __u_boot_bin_begin, + (ulong)__u_boot_bin_end - (ulong)__u_boot_bin_begin); + +#ifdef DEBUG + puts("EFI table at "); + printhex8((ulong)priv->info); + puts(" size "); + printhex8(priv->info->total_size); +#endif + putc('\n'); + jump_to_uboot(cs32, CONFIG_SYS_TEXT_BASE, (ulong)priv->info); + + return EFI_LOAD_ERROR; +}