[U-Boot] [PATCH v3 14/28] efi: Add support for loading U-Boot through an EFI stub
Bin Meng
bmeng.cn at gmail.com
Wed Aug 5 09:59:33 CEST 2015
On Wed, Aug 5, 2015 at 2:33 AM, Simon Glass <sjg at chromium.org> wrote:
> It is useful to be able to load U-Boot onto a board even if 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 at chromium.org>
> Improvements to how the payload is built:
> Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> ---
>
> Changes in v3:
> - Fix calling convention to starting U-Boot in the 32-bit stub
> - Rename LDFLAGS_EFI to LDFLAGS_EFI_PAYLOAD and move into this patch
> - Use quiet_cmd_xxx to link the payload
>
> Changes in v2:
> - Add a comment as to why we must call exit_boot_services() twice
> - Drop \n\t at the end of a one-line asm statement
> - Merge in Bin's implementation of adding a U-Boot payload with objcopy
> - Remove comment about reset_cpu() returning to EFI in the stub
> - Rename CONFIG_ARCH_EFI to CONFIG_EFI_APP
>
> Makefile | 24 +++++
> arch/x86/config.mk | 7 ++
> include/common.h | 7 ++
> include/efi.h | 4 +
> lib/efi/Kconfig | 21 ++++
> lib/efi/Makefile | 9 ++
> lib/efi/efi_stub.c | 304 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 7 files changed, 376 insertions(+)
> create mode 100644 lib/efi/efi_stub.c
>
> diff --git a/Makefile b/Makefile
> index 620c18f..752ee0d 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -755,6 +755,7 @@ ALL-$(CONFIG_SPL) += $(CONFIG_SPL_TARGET:"%"=%)
> endif
> ALL-$(CONFIG_REMAKE_ELF) += u-boot.elf
> ALL-$(CONFIG_EFI_APP) += u-boot-app.efi
> +ALL-$(CONFIG_EFI_STUB) += u-boot-payload.efi
>
> ifneq ($(BUILD_ROM),)
> ALL-$(CONFIG_X86_RESET_VECTOR) += u-boot.rom
> @@ -790,6 +791,9 @@ cmd_objcopy = $(OBJCOPY) --gap-fill=0xff $(OBJCOPYFLAGS) \
> quiet_cmd_zobjcopy = OBJCOPY $@
> cmd_zobjcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
>
> +quiet_cmd_efipayload = OBJCOPY $@
> +cmd_efipayload = $(OBJCOPY) -I binary -O $(EFIPAYLOAD_BFDTARGET) -B $(EFIPAYLOAD_BFDARCH) $< $@
> +
> quiet_cmd_mkimage = MKIMAGE $@
> cmd_mkimage = $(objtree)/tools/mkimage $(MKIMAGEFLAGS_$(@F)) -d $< $@ \
> $(if $(KBUILD_VERBOSE:1=), >/dev/null)
> @@ -1087,6 +1091,26 @@ OBJCOPYFLAGS_u-boot-app.efi := $(OBJCOPYFLAGS_EFI)
> u-boot-app.efi: u-boot FORCE
> $(call if_changed,zobjcopy)
>
> +u-boot-dtb.bin.o: u-boot-dtb.bin FORCE
> + $(call if_changed,efipayload)
> +
> +u-boot-payload.lds: $(LDSCRIPT_EFI) FORCE
> + $(call if_changed_dep,cpp_lds)
> +
> +# Rule to link the EFI payload which contains a stub and a U-Boot binary
> +quiet_cmd_u-boot_payload ?= LD $@
> + cmd_u-boot_payload ?= $(LD) $(LDFLAGS_EFI_PAYLOAD) -o $@ \
> + -T u-boot-payload.lds \
> + lib/efi/efi.o lib/efi/efi_stub.o u-boot-dtb.bin.o \
> + $(addprefix arch/$(ARCH)/lib/efi/,$(EFISTUB))
> +
> +u-boot-payload: u-boot-dtb.bin.o u-boot-payload.lds FORCE
> + $(call if_changed,u-boot_payload)
> +
> +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/arch/x86/config.mk b/arch/x86/config.mk
> index e27f84a..334c10b 100644
> --- a/arch/x86/config.mk
> +++ b/arch/x86/config.mk
> @@ -24,6 +24,10 @@ PLATFORM_LDFLAGS += -Bsymbolic -Bsymbolic-functions -m elf_i386
> LDFLAGS_FINAL += --wrap=__divdi3 --wrap=__udivdi3
> LDFLAGS_FINAL += --wrap=__moddi3 --wrap=__umoddi3
>
> +# This is used in the top-level Makefile which does not include
> +# PLATFORM_LDFLAGS
> +LDFLAGS_EFI_PAYLOAD := -Bsymbolic -Bsymbolic-functions -shared --no-undefined
> +
> OBJCOPYFLAGS_EFI := -j .text -j .sdata -j .data -j .dynamic -j .dynsym \
> -j .rel -j .rela -j .reloc
>
> @@ -31,6 +35,9 @@ CFLAGS_NON_EFI := -mregparm=3
> CFLAGS_EFI := -fpic -fshort-wchar
>
> EFIARCH = ia32
> +EFIPAYLOAD_BFDTARGET = elf32-i386
> +
> +EFIPAYLOAD_BFDARCH = i386
>
> LDSCRIPT_EFI := $(srctree)/$(CPUDIR)/efi/elf_$(EFIARCH)_efi.lds
> OBJCOPYFLAGS_EFI += --target=efi-app-$(EFIARCH)
> diff --git a/include/common.h b/include/common.h
> index 4566bd1..fcc9ae7 100644
> --- a/include/common.h
> +++ b/include/common.h
> @@ -1021,6 +1021,13 @@ int cpu_release(int nr, int argc, char * const argv[]);
> offsetof(struct structure, member) == offset, \
> "`struct " #structure "` offset for `" #member "` is not " #offset)
>
> +/* 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 f009701..1470c08 100644
> --- a/include/efi.h
> +++ b/include/efi.h
> @@ -268,11 +268,15 @@ struct efi_priv {
> /* Base address of the EFI image */
> extern char image_base[];
>
> +/* Start and end of U-Boot image (for payload) */
> +extern char _binary_u_boot_dtb_bin_start[], _binary_u_boot_dtb_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 b23ba5b..919e314 100644
> --- a/lib/efi/Kconfig
> +++ b/lib/efi/Kconfig
> @@ -20,6 +20,11 @@ config EFI_APP
> command prompt 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 EFI_APP
> @@ -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 with U-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 5ee344c..4bc67f0 100644
> --- a/lib/efi/Makefile
> +++ b/lib/efi/Makefile
> @@ -5,3 +5,12 @@
> #
>
> obj-$(CONFIG_EFI_APP) += 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..1e46f6e
> --- /dev/null
> +++ b/lib/efi/efi_stub.c
> @@ -0,0 +1,304 @@
> +/*
> + * 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)
> +{
> +#ifdef CONFIG_EFI_STUB_32BIT
> + /*
> + * U-Boot requires these parameters in registers, not on the stack.
> + * See _x86boot_start() for this code.
> + */
> + typedef void (*func_t)(int bist, int unused, ulong info)
> + __attribute__((regparm(3)));
> +
> + ((func_t)addr)(0, 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" : "=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.
> + */
> +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) {
> + /*
> + * Unfortunately it happens that we cannot exit boot services
> + * the first time. But the second time it work. I don't know
> + * why but this seems to be a repeatable problem. To get
> + * around it, just try again.
> + */
> + 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, _binary_u_boot_dtb_bin_start,
> + (ulong)_binary_u_boot_dtb_bin_end -
> + (ulong)_binary_u_boot_dtb_bin_start);
> +
> +#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;
> +}
> --
Reviewed-by: Bin Meng <bmeng.cn at gmail.com>
Tested on QEMU 32-bit and 64-bit
Tested-by: Bin Meng <bmeng.cn at gmail.com>
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