relocate.c File Reference

#include <ipxe/uaccess.h>
#include <ipxe/memmap.h>
#include <registers.h>

Go to the source code of this file.

Macros
#define	MAX_ADDR   (0xfff00000UL)
#define	ALIGN   4096

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
__asmcall void	relocate (struct i386_all_regs *ix86)
	Relocate iPXE. More...

Variables
char	_textdata []
char	_etextdata []

Macro Definition Documentation

MAX_ADDR

#define MAX_ADDR   (0xfff00000UL)

Definition at line 24 of file relocate.c.

ALIGN

#define ALIGN   4096

Definition at line 30 of file relocate.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

relocate()

__asmcall void relocate

(

struct i386_all_regs *

ix86

)

Relocate iPXE.

Parameters

ebp	Maximum address to use for relocation

Return values

esi	Current physical address
edi	New physical address
ecx	Length to copy

This finds a suitable location for iPXE near the top of 32-bit address space, and returns the physical address of the new location to the prefix in edi.

Definition at line 44 of file relocate.c.

                                                       {
        struct memmap_region region;
        physaddr_t start, end, max;
        physaddr_t new_start, new_end;
        physaddr_t r_start, r_end;
        size_t size, padded_size;

        /* Show whole memory map (for debugging) */
        memmap_dump_all ( 0 );

        /* Get current location */
        start = virt_to_phys ( _textdata );
        end = virt_to_phys ( _etextdata );
        size = ( end - start );
        padded_size = ( size + ALIGN - 1 );

        DBGC ( &region, "Relocate: currently at [%#08lx,%#08lx)\n"
               "...need %#zx bytes for %d-byte alignment\n",
               start, end, padded_size, ALIGN );

        /* Determine maximum usable address */
        max = MAX_ADDR;
        if ( ix86->regs.ebp < max ) {
                max = ix86->regs.ebp;
                DBGC ( &region, "Limiting relocation to [0,%#08lx)\n", max );
        }

        /* Walk through the memory map and find the highest address
         * above the current iPXE and below 4GB that iPXE will fit
         * into.
         */
        new_end = end;
        for_each_memmap_from ( &region, end, 0 ) {

                /* Truncate block to maximum address.  This will be
                 * strictly less than 4GB, which means that we can get
                 * away with using just 32-bit arithmetic after this
                 * stage.
                 */
                DBGC_MEMMAP ( &region, &region );
                if ( region.min > max ) {
                        DBGC ( &region, "...starts after max=%#08lx\n", max );
                        break;
                }
                r_start = region.min;
                if ( ! memmap_is_usable ( &region ) ) {
                        DBGC ( &region, "...not usable\n" );
                        continue;
                }
                r_end = ( r_start + memmap_size ( &region ) );
                if ( ( r_end == 0 ) || ( r_end > max ) ) {
                        DBGC ( &region, "...end truncated to max=%#08lx\n",
                               max );
                        r_end = max;
                }
                DBGC ( &region, "...usable portion is [%#08lx,%#08lx)\n",
                       r_start, r_end );

                /* Check that there is enough space to fit in iPXE */
                if ( ( r_end - r_start ) < padded_size ) {
                        DBGC ( &region, "...too small (need %#zx bytes)\n",
                               padded_size );
                        continue;
                }

                /* Use highest block with enough space */
                new_end = r_end;
                DBGC ( &region, "...new best block found.\n" );
        }

        /* Calculate new location of iPXE, and align it to the
         * required alignemnt.
         */
        new_start = new_end - padded_size;
        new_start += ( ( start - new_start ) & ( ALIGN - 1 ) );
        new_end = new_start + size;

        DBGC ( &region, "Relocating from [%#08lx,%#08lx) to [%#08lx,%#08lx)\n",
               start, end, new_start, new_end );

        /* Let prefix know what to copy */
        ix86->regs.esi = start;
        ix86->regs.edi = new_start;
        ix86->regs.ecx = size;
}

References _etextdata, _textdata, ALIGN, DBGC, DBGC_MEMMAP, i386_regs::ebp, i386_regs::ecx, i386_regs::edi, end, i386_regs::esi, for_each_memmap_from, max, MAX_ADDR, memmap_dump_all(), memmap_is_usable(), memmap_size(), memmap_region::min, i386_all_regs::regs, size, and start.

Variable Documentation

_textdata

char _textdata[]

Referenced by relocate().

_etextdata

char _etextdata[]

Referenced by relocate().