blob: e98dd36cb161abc2960c26a9343202519e308a72 [file] [log] [blame]
// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#include <efi.h>
#include <efilib.h>
// Here's a struct to locate the pointers we need to update in the zeropage
// structure. Everything else should already be hardcoded at compile time.
// See arch/x86/include/asm/bootparam.h in the kernel source for the real deal.
struct hacked_params {
uint8_t pad0[0x1c0];
uint32_t v0206_efi_signature; /* 1c0 */
uint32_t v0206_efi_system_table; /* 1c4 */
uint32_t v0206_efi_mem_desc_size; /* 1c8 */
uint32_t v0206_efi_mem_desc_version; /* 1cc */
uint32_t v0206_efi_mmap; /* 1d0 */
uint32_t v0206_efi_mmap_size; /* 1d4 */
uint32_t v0206_efi_system_table_hi; /* 1d8 */
uint32_t v0206_efi_mmap_hi; /* 1dc */
uint8_t pad1[0x214 - 0x1e0];
uint32_t code32_start; /* 214 */
uint8_t pad2[0x228 - 0x218];
uint32_t cmd_line_ptr; /* 228 */
} __attribute__ ((packed));
// Find where the preloaded params struct is located in RAM. At the moment
// we're assuming that it immediately precedes the start of the bootstub,
// aligned to a 4K boundary, because that's where our build system puts it.
struct hacked_params *find_params_struct(UINTN bootstub_location)
{
return (struct hacked_params *)(bootstub_location - 0x1000);
}
// Replace any %D with the device letter, and replace any %P with the partition
// number. For example, ("root=/dev/sd%D%P",2,3) gives "root=/dev/sdc3". The
// input string must be mutable and end with a trailing '\0'.
void update_cmdline_inplace(char *src, int devnum, int partnum)
{
char *dst;
// Use sane values (sda3) for ridiculous inputs.
if (devnum < 0 || devnum > 25 || partnum < 1 || partnum > 99)
{
devnum = 0;
partnum = 3;
}
for( dst = src; *src; src++, dst++ )
{
if ( src[0] == '%' )
{
switch (src[1])
{
case 'P':
if (partnum > 9)
*dst++ = '0' + (partnum / 10);
*dst = '0' + partnum % 10;
src++;
break;
case 'D':
*dst = 'a' + devnum;
src++;
break;
default:
*dst = *src;
}
}
else if (dst != src)
*dst = *src;
}
*dst = '\0';
}
// This is handy to write status codes to the LEDs for debugging.
static __inline void port80w (unsigned short int value)
{
__asm__ __volatile__ ("outw %w0,$0x80": :"a" (value));
}
// The code to switch to 32-bit mode and start the kernel.
extern void trampoline(unsigned long, void *);
// Reserve some space for the EFI memory map.
// Danger Will Robinson: this is just a guess at the size and alignment. If
// it's too small, the EFI GetMemoryMap() call will fail.
// FIXME: Make the size dynamic? Retry with larger size on failure?
static unsigned char mmap_buf[0x2000] __attribute__ ((aligned(0x200)));
// Parameters that we're given by the BIOS
typedef struct cros_boot_info {
UINTN drive_number; // 0 - 25
UINTN partition_number; // 1 - 99
UINTN original_address; // our RAM address prior to execution
} cros_boot_info_t;
// Here's the entry point. It will be loaded by the BIOS as a standard EFI
// application, which means it will be relocated.
EFI_STATUS efi_main (EFI_HANDLE image, EFI_SYSTEM_TABLE *systab)
{
UINTN mmap_size = sizeof(mmap_buf);
UINTN mmap_key = 0;
UINTN desc_size = 0;
UINT32 desc_version = 0;
EFI_LOADED_IMAGE *loaded_image;
EFI_GUID loaded_image_protocol = LOADED_IMAGE_PROTOCOL;
// I'm here.
port80w(0xc0de);
// Find the parameters that the BIOS has passed to us.
if (uefi_call_wrapper(systab->BootServices->HandleProtocol, 3,
image,
&loaded_image_protocol,
&loaded_image) != 0)
{
uefi_call_wrapper(systab->ConOut->OutputString, 3, systab->ConOut,
L"Can't locate protocol\r\n");
goto fail;
}
cros_boot_info_t *booting = loaded_image->LoadOptions;
// Find the parameters that we're passing to the kernel.
struct hacked_params *params = find_params_struct(booting->original_address);
// Update the kernel command-line string with the correct rootfs device
update_cmdline_inplace((char *)(unsigned long)(params->cmd_line_ptr),
booting->drive_number,
booting->partition_number + 1);
// Obtain the EFI memory map.
if (uefi_call_wrapper(systab->BootServices->GetMemoryMap, 5,
&mmap_size, mmap_buf, &mmap_key,
&desc_size, &desc_version) != 0)
{
uefi_call_wrapper(systab->ConOut->OutputString, 2, systab->ConOut,
L"Can't get memory map\r\n");
goto fail;
}
// Update the pointers to the EFI memory map and system table.
params->v0206_efi_signature = ('4' << 24 | '6' << 16 | 'L' << 8 | 'E');
params->v0206_efi_system_table = (uint32_t) (unsigned long)systab;
params->v0206_efi_mem_desc_size = desc_size;
params->v0206_efi_mem_desc_version = desc_version;
params->v0206_efi_mmap = (uint32_t) (unsigned long)mmap_buf;
params->v0206_efi_mmap_size = mmap_size;
params->v0206_efi_mmap_hi = (uint32_t)((uint64_t)mmap_buf >> 32);
params->v0206_efi_system_table_hi = (uint32_t) ((uint64_t)systab >> 32);
// Done with BIOS.
if (uefi_call_wrapper(systab->BootServices->ExitBootServices, 2,
image, mmap_key) != 0)
{
uefi_call_wrapper(systab->ConOut->OutputString, 2, systab->ConOut,
L"Can't exit boot services\r\n");
goto fail;
}
// Trampoline to 32-bit entry point. Should never return.
trampoline(params->code32_start, params);
fail:
// Bad Things happened.
port80w(0xdead);
return EFI_LOAD_ERROR;
}