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x86, efi: Handover Protocol

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As things currently stand, traditional EFI boot loaders and the EFI
boot stub are carrying essentially the same initialisation code
required to setup an EFI machine for booting a kernel. There's really
no need to have this code in two places and the hope is that, with
this new protocol, initialisation and booting of the kernel can be
left solely to the kernel's EFI boot stub. The responsibilities of the
boot loader then become,

   o Loading the kernel image from boot media

File system code still needs to be carried by boot loaders for the
scenario where the kernel and initrd files reside on a file system
that the EFI firmware doesn't natively understand, such as ext4, etc.

   o Providing a user interface

Boot loaders still need to display any menus/interfaces, for example
to allow the user to select from a list of kernels.

Bump the boot protocol number because we added the 'handover_offset'
field to indicate the location of the handover protocol entry point.

Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Acked-and-Tested-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1342689828-16815-1-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Matt Fleming 2012-07-19 10:23:48 +01:00 committed by H. Peter Anvin
parent bacef661ac
commit 9ca8f72a92
6 changed files with 186 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
Documentation/x86/boot.txt
View File

@ -54,6 +54,9 @@ Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment
beyond the kernel_alignment added, new init_size and
pref_address fields. Added extended boot loader IDs.
Protocol 2.11: (Kernel 3.6) Added a field for offset of EFI handover
protocol entry point.
**** MEMORY LAYOUT
The traditional memory map for the kernel loader, used for Image or
@ -189,6 +192,7 @@ Offset Proto Name Meaning
of struct setup_data
0258/8 2.10+ pref_address Preferred loading address
0260/4 2.10+ init_size Linear memory required during initialization
0264/4 2.11+ handover_offset Offset of handover entry point
(1) For backwards compatibility, if the setup_sects field contains 0, the
real value is 4.
@ -690,6 +694,16 @@ Offset/size: 0x260/4
else
runtime_start = pref_address
Field name: handover_offset
Type: read
Offset/size: 0x264/4
This field is the offset from the beginning of the kernel image to
the EFI handover protocol entry point. Boot loaders using the EFI
handover protocol to boot the kernel should jump to this offset.
See EFI HANDOVER PROTOCOL below for more details.
**** THE IMAGE CHECKSUM
@ -1010,3 +1024,30 @@ segment; __BOOS_CS must have execute/read permission, and __BOOT_DS
must have read/write permission; CS must be __BOOT_CS and DS, ES, SS
must be __BOOT_DS; interrupt must be disabled; %esi must hold the base
address of the struct boot_params; %ebp, %edi and %ebx must be zero.
**** EFI HANDOVER PROTOCOL
This protocol allows boot loaders to defer initialisation to the EFI
boot stub. The boot loader is required to load the kernel/initrd(s)
from the boot media and jump to the EFI handover protocol entry point
which is hdr->handover_offset bytes from the beginning of
startup_{32,64}.
The function prototype for the handover entry point looks like this,
efi_main(void *handle, efi_system_table_t *table, struct boot_params *bp)
'handle' is the EFI image handle passed to the boot loader by the EFI
firmware, 'table' is the EFI system table - these are the first two
arguments of the "handoff state" as described in section 2.3 of the
UEFI specification. 'bp' is the boot loader-allocated boot params.
The boot loader *must* fill out the following fields in bp,
o hdr.code32_start
o hdr.cmd_line_ptr
o hdr.cmdline_size
o hdr.ramdisk_image (if applicable)
o hdr.ramdisk_size (if applicable)
All other fields should be zero.

200
arch/x86/boot/compressed/eboot.c
View File

@ -729,32 +729,68 @@ fail:
* need to create one ourselves (usually the bootloader would create
* one for us).
*/
static efi_status_t make_boot_params(struct boot_params *boot_params,
efi_loaded_image_t *image,
void *handle)
struct boot_params *make_boot_params(void *handle, efi_system_table_t *_table)
{
struct efi_info *efi = &boot_params->efi_info;
struct apm_bios_info *bi = &boot_params->apm_bios_info;
struct sys_desc_table *sdt = &boot_params->sys_desc_table;
struct e820entry *e820_map = &boot_params->e820_map[0];
struct e820entry *prev = NULL;
struct setup_header *hdr = &boot_params->hdr;
unsigned long size, key, desc_size, _size;
efi_memory_desc_t *mem_map;
void *options = image->load_options;
u32 load_options_size = image->load_options_size / 2; /* ASCII */
struct boot_params *boot_params;
struct sys_desc_table *sdt;
struct apm_bios_info *bi;
struct setup_header *hdr;
struct efi_info *efi;
efi_loaded_image_t *image;
void *options;
u32 load_options_size;
efi_guid_t proto = LOADED_IMAGE_PROTOCOL_GUID;
int options_size = 0;
efi_status_t status;
__u32 desc_version;
unsigned long cmdline;
u8 nr_entries;
u16 *s2;
u8 *s1;
int i;
sys_table = _table;
/* Check if we were booted by the EFI firmware */
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
return NULL;
status = efi_call_phys3(sys_table->boottime->handle_protocol,
handle, &proto, (void *)&image);
if (status != EFI_SUCCESS) {
efi_printk("Failed to get handle for LOADED_IMAGE_PROTOCOL\n");
return NULL;
}
status = low_alloc(0x4000, 1, (unsigned long *)&boot_params);
if (status != EFI_SUCCESS) {
efi_printk("Failed to alloc lowmem for boot params\n");
return NULL;
}
memset(boot_params, 0x0, 0x4000);
hdr = &boot_params->hdr;
efi = &boot_params->efi_info;
bi = &boot_params->apm_bios_info;
sdt = &boot_params->sys_desc_table;
/* Copy the second sector to boot_params */
memcpy(&hdr->jump, image->image_base + 512, 512);
/*
* Fill out some of the header fields ourselves because the
* EFI firmware loader doesn't load the first sector.
*/
hdr->root_flags = 1;
hdr->vid_mode = 0xffff;
hdr->boot_flag = 0xAA55;
hdr->code32_start = (__u64)(unsigned long)image->image_base;
hdr->type_of_loader = 0x21;
/* Convert unicode cmdline to ascii */
options = image->load_options;
load_options_size = image->load_options_size / 2; /* ASCII */
cmdline = 0;
s2 = (u16 *)options;
@ -791,18 +827,36 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
hdr->ramdisk_image = 0;
hdr->ramdisk_size = 0;
status = handle_ramdisks(image, hdr);
if (status != EFI_SUCCESS)
goto free_cmdline;
setup_graphics(boot_params);
/* Clear APM BIOS info */
memset(bi, 0, sizeof(*bi));
memset(sdt, 0, sizeof(*sdt));
memcpy(&efi->efi_loader_signature, EFI_LOADER_SIGNATURE, sizeof(__u32));
status = handle_ramdisks(image, hdr);
if (status != EFI_SUCCESS)
goto fail2;
return boot_params;
fail2:
if (options_size)
low_free(options_size, hdr->cmd_line_ptr);
fail:
low_free(0x4000, (unsigned long)boot_params);
return NULL;
}
static efi_status_t exit_boot(struct boot_params *boot_params,
void *handle)
{
struct efi_info *efi = &boot_params->efi_info;
struct e820entry *e820_map = &boot_params->e820_map[0];
struct e820entry *prev = NULL;
unsigned long size, key, desc_size, _size;
efi_memory_desc_t *mem_map;
efi_status_t status;
__u32 desc_version;
u8 nr_entries;
int i;
size = sizeof(*mem_map) * 32;
@ -811,7 +865,7 @@ again:
_size = size;
status = low_alloc(size, 1, (unsigned long *)&mem_map);
if (status != EFI_SUCCESS)
goto free_cmdline;
return status;
status = efi_call_phys5(sys_table->boottime->get_memory_map, &size,
mem_map, &key, &desc_size, &desc_version);
@ -823,6 +877,7 @@ again:
if (status != EFI_SUCCESS)
goto free_mem_map;
memcpy(&efi->efi_loader_signature, EFI_LOADER_SIGNATURE, sizeof(__u32));
efi->efi_systab = (unsigned long)sys_table;
efi->efi_memdesc_size = desc_size;
efi->efi_memdesc_version = desc_version;
@ -906,61 +961,13 @@ again:
free_mem_map:
low_free(_size, (unsigned long)mem_map);
free_cmdline:
if (options_size)
low_free(options_size, hdr->cmd_line_ptr);
fail:
return status;
}
/*
* On success we return a pointer to a boot_params structure, and NULL
* on failure.
*/
struct boot_params *efi_main(void *handle, efi_system_table_t *_table)
static efi_status_t relocate_kernel(struct setup_header *hdr)
{
struct boot_params *boot_params;
unsigned long start, nr_pages;
struct desc_ptr *gdt, *idt;
efi_loaded_image_t *image;
struct setup_header *hdr;
efi_status_t status;
efi_guid_t proto = LOADED_IMAGE_PROTOCOL_GUID;
struct desc_struct *desc;
sys_table = _table;
/* Check if we were booted by the EFI firmware */
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
goto fail;
status = efi_call_phys3(sys_table->boottime->handle_protocol,
handle, &proto, (void *)&image);
if (status != EFI_SUCCESS) {
efi_printk("Failed to get handle for LOADED_IMAGE_PROTOCOL\n");
goto fail;
}
status = low_alloc(0x4000, 1, (unsigned long *)&boot_params);
if (status != EFI_SUCCESS) {
efi_printk("Failed to alloc lowmem for boot params\n");
goto fail;
}
memset(boot_params, 0x0, 0x4000);
hdr = &boot_params->hdr;
/* Copy the second sector to boot_params */
memcpy(&hdr->jump, image->image_base + 512, 512);
/*
* Fill out some of the header fields ourselves because the
* EFI firmware loader doesn't load the first sector.
*/
hdr->root_flags = 1;
hdr->vid_mode = 0xffff;
hdr->boot_flag = 0xAA55;
/*
* The EFI firmware loader could have placed the kernel image
@ -978,16 +985,40 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table)
if (status != EFI_SUCCESS) {
status = low_alloc(hdr->init_size, hdr->kernel_alignment,
&start);
if (status != EFI_SUCCESS) {
if (status != EFI_SUCCESS)
efi_printk("Failed to alloc mem for kernel\n");
goto fail;
}
}
hdr->code32_start = (__u32)start;
hdr->pref_address = (__u64)(unsigned long)image->image_base;
if (status == EFI_SUCCESS)
memcpy((void *)start, (void *)(unsigned long)hdr->code32_start,
hdr->init_size);
memcpy((void *)start, image->image_base, image->image_size);
hdr->pref_address = hdr->code32_start;
hdr->code32_start = (__u32)start;
return status;
}
/*
* On success we return a pointer to a boot_params structure, and NULL
* on failure.
*/
struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
struct boot_params *boot_params)
{
struct desc_ptr *gdt, *idt;
efi_loaded_image_t *image;
struct setup_header *hdr = &boot_params->hdr;
efi_status_t status;
struct desc_struct *desc;
sys_table = _table;
/* Check if we were booted by the EFI firmware */
if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
goto fail;
setup_graphics(boot_params);
status = efi_call_phys3(sys_table->boottime->allocate_pool,
EFI_LOADER_DATA, sizeof(*gdt),
@ -1015,7 +1046,18 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table)
idt->size = 0;
idt->address = 0;
status = make_boot_params(boot_params, image, handle);
/*
* If the kernel isn't already loaded at the preferred load
* address, relocate it.
*/
if (hdr->pref_address != hdr->code32_start) {
status = relocate_kernel(hdr);
if (status != EFI_SUCCESS)
goto fail;
}
status = exit_boot(boot_params, handle);
if (status != EFI_SUCCESS)
goto fail;

10
arch/x86/boot/compressed/head_32.S
View File

@ -42,6 +42,16 @@ ENTRY(startup_32)
*/
add $0x4, %esp
call make_boot_params
cmpl $0, %eax
je 1f
movl 0x4(%esp), %esi
movl (%esp), %ecx
pushl %eax
pushl %esi
pushl %ecx
.org 0x30,0x90
call efi_main
cmpl $0, %eax
movl %eax, %esi

10
arch/x86/boot/compressed/head_64.S
View File

@ -209,6 +209,16 @@ ENTRY(startup_64)
.org 0x210
mov %rcx, %rdi
mov %rdx, %rsi
pushq %rdi
pushq %rsi
call make_boot_params
cmpq $0,%rax
je 1f
mov %rax, %rdx
popq %rsi
popq %rdi
.org 0x230,0x90
call efi_main
movq %rax,%rsi
cmpq $0,%rax

4
arch/x86/boot/header.S
View File

@ -263,7 +263,7 @@ _start:
# Part 2 of the header, from the old setup.S
.ascii "HdrS" # header signature
.word 0x020a # header version number (>= 0x0105)
.word 0x020b # header version number (>= 0x0105)
# or else old loadlin-1.5 will fail)
.globl realmode_swtch
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
@ -381,6 +381,8 @@ pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
#define INIT_SIZE VO_INIT_SIZE
#endif
init_size: .long INIT_SIZE # kernel initialization size
handover_offset: .long 0x30 # offset to the handover
# protocol entry point
# End of setup header #####################################################

1
arch/x86/include/asm/bootparam.h
View File

@ -66,6 +66,7 @@ struct setup_header {
__u64 setup_data;
__u64 pref_address;
__u32 init_size;
__u32 handover_offset;
} __attribute__((packed));
struct sys_desc_table {