boot.c

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#include <console/console.h>
#include <ip_checksum.h>
#include <boot/elf.h>
#include <boot/elf_boot.h>
#include <string.h>
#include <cpu/x86/multiboot.h>


#ifndef CMD_LINE
#define CMD_LINE ""
#endif



#define UPSZ(X) ((sizeof(X) + 3) &~3)

static struct {
        Elf_Bhdr hdr;
        Elf_Nhdr ft_hdr;
        unsigned char ft_desc[UPSZ(FIRMWARE_TYPE)];
        Elf_Nhdr bl_hdr;
        unsigned char bl_desc[UPSZ(BOOTLOADER)];
        Elf_Nhdr blv_hdr;
        unsigned char blv_desc[UPSZ(BOOTLOADER_VERSION)];
        Elf_Nhdr cmd_hdr;
        unsigned char cmd_desc[UPSZ(CMD_LINE)];
} elf_boot_notes = {
        .hdr = {
                .b_signature = 0x0E1FB007,
                .b_size = sizeof(elf_boot_notes),
                .b_checksum = 0,
                .b_records = 4,
        },
        .ft_hdr = {
                .n_namesz = 0,
                .n_descsz = sizeof(FIRMWARE_TYPE),
                .n_type = EBN_FIRMWARE_TYPE,
        },
        .ft_desc = FIRMWARE_TYPE,
        .bl_hdr = {
                .n_namesz = 0,
                .n_descsz = sizeof(BOOTLOADER),
                .n_type = EBN_BOOTLOADER_NAME,
        },
        .bl_desc = BOOTLOADER,
        .blv_hdr = {
                .n_namesz = 0,
                .n_descsz = sizeof(BOOTLOADER_VERSION),
                .n_type = EBN_BOOTLOADER_VERSION,
        },
        .blv_desc = BOOTLOADER_VERSION,
        .cmd_hdr = {
                .n_namesz = 0,
                .n_descsz = sizeof(CMD_LINE),
                .n_type = EBN_COMMAND_LINE,
        },
        .cmd_desc = CMD_LINE,
};


int elf_check_arch(Elf_ehdr *ehdr)
{
        return (
                ((ehdr->e_machine == EM_386) || (ehdr->e_machine == EM_486)) &&
                (ehdr->e_ident[EI_CLASS] == ELFCLASS32) &&
                (ehdr->e_ident[EI_DATA] == ELFDATA2LSB) 
                );
        
}

void jmp_to_elf_entry(void *entry, unsigned long buffer)
{
        extern unsigned char _ram_seg, _eram_seg;
        unsigned long lb_start, lb_size;
        unsigned long adjust, adjusted_boot_notes;
        unsigned long type;

        elf_boot_notes.hdr.b_checksum = 
                compute_ip_checksum(&elf_boot_notes, sizeof(elf_boot_notes));

        type = 0x0E1FB007;
        lb_start = (unsigned long)&_ram_seg;
        lb_size = (unsigned long)(&_eram_seg - &_ram_seg);
        adjust = buffer + lb_size - lb_start;

        adjusted_boot_notes = (unsigned long)&elf_boot_notes;
        adjusted_boot_notes += adjust; 

        printk_spew("entry    = 0x%08lx\n", (unsigned long)entry);
        printk_spew("lb_start = 0x%08lx\n", lb_start);
        printk_spew("lb_size  = 0x%08lx\n", lb_size);
        printk_spew("adjust   = 0x%08lx\n", adjust);
        printk_spew("buffer   = 0x%08lx\n", buffer);
        printk_spew("     elf_boot_notes = 0x%08lx\n", (unsigned long)&elf_boot_notes);
        printk_spew("adjusted_boot_notes = 0x%08lx\n", adjusted_boot_notes);
        
        /* Jump to kernel */
        __asm__ __volatile__(
                "       cld     \n\t"
                /* Save the callee save registers... */
                "       pushl   %%esi\n\t"
                "       pushl   %%edi\n\t"
                "       pushl   %%ebx\n\t"
                /* Save the parameters I was passed */
                "       pushl   $0\n\t" /* 20 adjust */
                "       pushl   %0\n\t" /* 16 lb_start */
                "       pushl   %1\n\t" /* 12 buffer */
                "       pushl   %2\n\t" /*  8 lb_size */
                "       pushl   %3\n\t" /*  4 entry */
                "       pushl   %4\n\t" /*  0 elf_boot_notes */
                /* Compute the adjustment */
                "       xorl    %%eax, %%eax\n\t"
                "       subl    16(%%esp), %%eax\n\t"
                "       addl    12(%%esp), %%eax\n\t"
                "       addl     8(%%esp), %%eax\n\t"
                "       movl    %%eax, 20(%%esp)\n\t"
                /* Place a copy of coreboot in it's new location */
                /* Move ``longs'' the coreboot size is 4 byte aligned */
                "       movl    12(%%esp), %%edi\n\t"
                "       addl     8(%%esp), %%edi\n\t"
                "       movl    16(%%esp), %%esi\n\t"
                "       movl     8(%%esp), %%ecx\n\n"
                "       shrl    $2, %%ecx\n\t"
                "       rep     movsl\n\t"

                /* Adjust the stack pointer to point into the new coreboot image */
                "       addl    20(%%esp), %%esp\n\t"
                /* Adjust the instruction pointer to point into the new coreboot image */
                "       movl    $1f, %%eax\n\t"
                "       addl    20(%%esp), %%eax\n\t"
                "       jmp     *%%eax\n\t"
                "1:     \n\t"

                /* Copy the coreboot bounce buffer over coreboot */
                /* Move ``longs'' the coreboot size is 4 byte aligned */
                "       movl    16(%%esp), %%edi\n\t"
                "       movl    12(%%esp), %%esi\n\t"
                "       movl     8(%%esp), %%ecx\n\t"
                "       shrl    $2, %%ecx\n\t"
                "       rep     movsl\n\t"

                /* Now jump to the loaded image */
                "       movl    %5, %%eax\n\t"
                "       movl     0(%%esp), %%ebx\n\t"
                "       call    *4(%%esp)\n\t"

                /* The loaded image returned? */
                "       cli     \n\t"
                "       cld     \n\t"

                /* Copy the saved copy of coreboot where coreboot runs */
                /* Move ``longs'' the coreboot size is 4 byte aligned */
                "       movl    16(%%esp), %%edi\n\t"
                "       movl    12(%%esp), %%esi\n\t"
                "       addl     8(%%esp), %%esi\n\t"
                "       movl     8(%%esp), %%ecx\n\t"
                "       shrl    $2, %%ecx\n\t"
                "       rep     movsl\n\t"

                /* Adjust the stack pointer to point into the old coreboot image */
                "       subl    20(%%esp), %%esp\n\t"

                /* Adjust the instruction pointer to point into the old coreboot image */
                "       movl    $1f, %%eax\n\t"
                "       subl    20(%%esp), %%eax\n\t"
                "       jmp     *%%eax\n\t"
                "1:     \n\t"

                /* Drop the parameters I was passed */
                "       addl    $24, %%esp\n\t"

                /* Restore the callee save registers */
                "       popl    %%ebx\n\t"
                "       popl    %%edi\n\t"
                "       popl    %%esi\n\t"

                :: 
                "g" (lb_start), "g" (buffer), "g" (lb_size),
                "g" (entry),
#if CONFIG_MULTIBOOT
                "g"(mbi), "g" (MB_MAGIC2)
#else
                "g"(adjusted_boot_notes), "g" (0x0E1FB007)
#endif
                );
}

---