com32.c File Reference

SYSLINUX COM32 image format. More...

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <assert.h>
#include <realmode.h>
#include <basemem.h>
#include <comboot.h>
#include <ipxe/uaccess.h>
#include <ipxe/image.h>
#include <ipxe/segment.h>
#include <ipxe/init.h>
#include <ipxe/memmap.h>
#include <ipxe/console.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER)
static int	com32_exec_loop (struct image *image)
	Execute COMBOOT image. More...
static int	com32_identify (struct image *image)
	Check image name extension. More...
static int	com32_load_image (struct image *image)
	Load COM32 image into memory. More...
static int	com32_prepare_bounce_buffer (struct image *image)
	Prepare COM32 low memory bounce buffer. More...
static int	com32_probe (struct image *image)
	Probe COM32 image. More...
static int	com32_exec (struct image *image)
	Execute COMBOOT image. More...
struct image_type com32_image_type	__image_type (PROBE_NORMAL)
	SYSLINUX COM32 image type. More...

Detailed Description

SYSLINUX COM32 image format.

Definition in file com32.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER

)

com32_exec_loop()

static int com32_exec_loop ( struct image *  image )

static

Execute COMBOOT image.

Parameters

image

COM32 image

Return values

rc	Return status code

Definition at line 51 of file com32.c.

                                                   {
        struct memmap_region region;
        int state;
        uint32_t avail_mem_top;

        state = rmsetjmp ( comboot_return );

        switch ( state ) {
        case 0: /* First time through; invoke COM32 program */

                /* Find end of block covering COM32 image loading area */
                memmap_describe ( COM32_START_PHYS, 1, &region );
                assert ( memmap_is_usable ( &region ) );
                avail_mem_top = ( COM32_START_PHYS + memmap_size ( &region ) );
                DBGC ( image, "COM32 %s: available memory top = 0x%x\n",
                       image->name, avail_mem_top );
                assert ( avail_mem_top != 0 );

                /* Hook COMBOOT API interrupts */
                hook_comboot_interrupts();

                /* Unregister image, so that a "boot" command doesn't
                 * throw us into an execution loop.  We never
                 * reregister ourselves; COMBOOT images expect to be
                 * removed on exit.
                 */
                unregister_image ( image );

                __asm__ __volatile__ ( PHYS_CODE (
                        /* Preserve registers */
                        "pushal\n\t"
                        /* Preserve stack pointer */
                        "subl $4, %k0\n\t"
                        "movl %%esp, (%k0)\n\t"
                        /* Switch to COM32 stack */
                        "movl %k0, %%esp\n\t"
                        /* Enable interrupts */
                        "sti\n\t"
                        /* Construct stack frame */
                        "pushl %k1\n\t"
                        "pushl %k2\n\t"
                        "pushl %k3\n\t"
                        "pushl %k4\n\t"
                        "pushl %k5\n\t"
                        "pushl %k6\n\t"
                        "pushl $6\n\t"
                        /* Call COM32 entry point */
                        "movl %k7, %k0\n\t"
                        "call *%k0\n\t"
                        /* Disable interrupts */
                        "cli\n\t"
                        /* Restore stack pointer */
                        "movl 28(%%esp), %%esp\n\t"
                        /* Restore registers */
                        "popal\n\t" )
                        :
                        : "R" ( avail_mem_top ),
                          "R" ( virt_to_phys ( com32_cfarcall_wrapper ) ),
                          "R" ( virt_to_phys ( com32_farcall_wrapper ) ),
                          "R" ( get_fbms() * 1024 - ( COM32_BOUNCE_SEG << 4 ) ),
                          "i" ( COM32_BOUNCE_SEG << 4 ),
                          "R" ( virt_to_phys ( com32_intcall_wrapper ) ),
                          "R" ( virt_to_phys ( image->cmdline ?
                                               image->cmdline : "" ) ),
                          "i" ( COM32_START_PHYS )
                        : "memory" );
                DBGC ( image, "COM32 %s: returned\n", image->name );
                break;

        case COMBOOT_EXIT:
                DBGC ( image, "COM32 %s: exited\n", image->name );
                break;

        case COMBOOT_EXIT_RUN_KERNEL:
                assert ( image->replacement );
                DBGC ( image, "COM32 %s: exited to run kernel %s\n",
                       image->name, image->replacement->name );
                break;

        case COMBOOT_EXIT_COMMAND:
                DBGC ( image, "COM32 %s: exited after executing command\n",
                       image->name );
                break;

        default:
                assert ( 0 );
                break;
        }

        unhook_comboot_interrupts();
        comboot_force_text_mode();

        return 0;
}

References __asm__(), __volatile__(), assert(), image::cmdline, COM32_BOUNCE_SEG, com32_cfarcall_wrapper(), com32_farcall_wrapper(), com32_intcall_wrapper(), COM32_START_PHYS, COMBOOT_EXIT, COMBOOT_EXIT_COMMAND, COMBOOT_EXIT_RUN_KERNEL, comboot_force_text_mode(), comboot_return, DBGC, get_fbms(), hook_comboot_interrupts(), memmap_describe(), memmap_is_usable(), memmap_size(), image::name, PHYS_CODE, image::replacement, rmsetjmp, state, unhook_comboot_interrupts(), and unregister_image().

Referenced by com32_exec().

com32_identify()

static int com32_identify ( struct image *  image )

static

Check image name extension.

Parameters

image

COM32 image

Return values

rc	Return status code

Definition at line 152 of file com32.c.

                                                  {
        const char *ext;
        static const uint8_t magic[] = { 0xB8, 0xFF, 0x4C, 0xCD, 0x21 };

        if ( image->len >= sizeof ( magic ) ) {
                /* Check for magic number
                 * mov eax,21cd4cffh
                 * B8 FF 4C CD 21
                 */
                if ( memcmp ( image->data, magic, sizeof ( magic) ) == 0 ) {
                        DBGC ( image, "COM32 %s: found magic number\n",
                               image->name );
                        return 0;
                }
        }

        /* Magic number not found; check filename extension */

        ext = strrchr( image->name, '.' );

        if ( ! ext ) {
                DBGC ( image, "COM32 %s: no extension\n",
                       image->name );
                return -ENOEXEC;
        }

        ++ext;

        if ( strcasecmp( ext, "c32" ) ) {
                DBGC ( image, "COM32 %s: unrecognized extension %s\n",
                       image->name, ext );
                return -ENOEXEC;
        }

        return 0;
}

References image::data, DBGC, ENOEXEC, ext, image::len, magic, memcmp(), image::name, strcasecmp(), and strrchr().

Referenced by com32_probe().

com32_load_image()

static int com32_load_image ( struct image *  image )

static

Load COM32 image into memory.

Parameters

image

COM32 image

Return values

rc	Return status code

Definition at line 195 of file com32.c.

                                                    {
        size_t filesz, memsz;
        void *buffer;
        int rc;

        filesz = image->len;
        memsz = filesz;
        buffer = phys_to_virt ( COM32_START_PHYS );
        if ( ( rc = prep_segment ( buffer, filesz, memsz ) ) != 0 ) {
                DBGC ( image, "COM32 %s: could not prepare segment: %s\n",
                       image->name, strerror ( rc ) );
                return rc;
        }

        /* Copy image to segment */
        memcpy ( buffer, image->data, filesz );

        return 0;
}

References buffer, COM32_START_PHYS, image::data, DBGC, image::len, memcpy(), memsz, image::name, prep_segment(), rc, and strerror().

Referenced by com32_exec().

com32_prepare_bounce_buffer()

static int com32_prepare_bounce_buffer ( struct image *  image )

static

Prepare COM32 low memory bounce buffer.

Parameters

image

COM32 image

Return values

rc	Return status code

Definition at line 220 of file com32.c.

                                                                {
        void *seg;
        size_t filesz, memsz;
        int rc;

        seg = real_to_virt ( COM32_BOUNCE_SEG, 0 );

        /* Ensure the entire 64k segment is free */
        memsz = 0xFFFF;
        filesz = 0;

        /* Prepare, verify, and load the real-mode segment */
        if ( ( rc = prep_segment ( seg, filesz, memsz ) ) != 0 ) {
                DBGC ( image, "COM32 %s: could not prepare bounce buffer segment: %s\n",
                       image->name, strerror ( rc ) );
                return rc;
        }

        return 0;
}

References COM32_BOUNCE_SEG, DBGC, memsz, image::name, prep_segment(), rc, real_to_virt(), seg, and strerror().

Referenced by com32_exec().

com32_probe()

static int com32_probe ( struct image *  image )

static

Probe COM32 image.

Parameters

image

COM32 image

Return values

rc	Return status code

Definition at line 247 of file com32.c.

                                               {
        int rc;

        /* Check if this is a COMBOOT image */
        if ( ( rc = com32_identify ( image ) ) != 0 ) {
                return rc;
        }

        return 0;
}

References com32_identify(), and rc.

com32_exec()

static int com32_exec ( struct image *  image )

static

Execute COMBOOT image.

Parameters

image

COM32 image

Return values

rc	Return status code

Definition at line 264 of file com32.c.

                                              {
        int rc;

        /* Load image */
        if ( ( rc = com32_load_image ( image ) ) != 0 ) {
                return rc;
        }

        /* Prepare bounce buffer segment */
        if ( ( rc = com32_prepare_bounce_buffer ( image ) ) != 0 ) {
                return rc;
        }

        /* Reset console */
        console_reset();

        return com32_exec_loop ( image );
}

References com32_exec_loop(), com32_load_image(), com32_prepare_bounce_buffer(), console_reset(), and rc.

__image_type()

struct image_type com32_image_type __image_type

(

PROBE_NORMAL

)

SYSLINUX COM32 image type.