[U-Boot,34/48] efi: Add support for loading U-Boot through an EFI stub

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

Hi Simon,

On Wed, Jul 22, 2015 at 11:49 PM, Simon Glass <sjg@chromium.org> wrote:
> 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';                              \
> +) > $@
> +

Please check another approach @ http://patchwork.ozlabs.org/patch/499458/

> +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))

Please change to use cmd_xxx to avoid putting compiler message to the console.

> +
> +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");

Please remove the "\n\t"

> +       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().
> + */

reset_cpu() in the EFI_STUB case does not return back to EFI.

> +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);

Why do we need call exit_boot_services() twice? Please add a comment on this.

> +               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;
> +}
> --

Regards,
Bin