initrd.c File Reference

Initial ramdisk (initrd) reshuffling. More...

#include <string.h>
#include <errno.h>
#include <ipxe/image.h>
#include <ipxe/uaccess.h>
#include <ipxe/init.h>
#include <ipxe/cpio.h>
#include <ipxe/uheap.h>
#include <ipxe/initrd.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static void	initrd_squash_high (physaddr_t start, physaddr_t end)
	Squash initrds as high as possible in memory. More...
static void	initrd_reverse (void *data, size_t len)
	Reverse aligned memory region. More...
static void	initrd_swap (struct image *low, struct image *high)
	Swap position of two adjacent initrds. More...
static int	initrd_swap_any (physaddr_t start, physaddr_t end)
	Swap position of any two adjacent initrds not currently in the correct order. More...
static void	initrd_dump (void)
	Dump initrd locations (for debug) More...
void	initrd_reshuffle (void)
	Reshuffle initrds into desired order at top of memory. More...
static size_t	initrd_load (struct image *initrd, void *address)
	Load initrd. More...
size_t	initrd_load_all (void *address)
	Load all initrds. More...
int	initrd_region (size_t len, struct memmap_region *region)
	Calculate post-reshuffle initrd load region. More...
static void	initrd_startup (void)
	initrd startup function More...
struct startup_fn startup_initrd	__startup_fn (STARTUP_LATE)
	initrd startup function More...

Variables
static physaddr_t	initrd_end
	End of reshuffle region. More...

Detailed Description

Initial ramdisk (initrd) reshuffling.

Definition in file initrd.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

initrd_squash_high()

static void initrd_squash_high ( physaddr_t  start, physaddr_t  end  )

static

Squash initrds as high as possible in memory.

Parameters

start	Start of reshuffle region
end	End of reshuffle region

Definition at line 50 of file initrd.c.

                                                                    {
        physaddr_t current = end;
        struct image *initrd;
        struct image *highest;
        void *data;

        /* Squash up any initrds already within the region */
        while ( 1 ) {

                /* Find the highest image not yet in its final position */
                highest = NULL;
                for_each_image ( initrd ) {
                        if ( ( virt_to_phys ( initrd->data ) >= start ) &&
                             ( virt_to_phys ( initrd->data ) < current ) &&
                             ( ( highest == NULL ) ||
                               ( virt_to_phys ( initrd->data ) >
                                 virt_to_phys ( highest->data ) ) ) ) {
                                highest = initrd;
                        }
                }
                if ( ! highest )
                        break;

                /* Calculate final position */
                current -= initrd_align ( highest->len );
                if ( current <= virt_to_phys ( highest->data ) ) {
                        /* Already at (or crossing) end of region */
                        current = virt_to_phys ( highest->data );
                        continue;
                }

                /* Move this image to its final position */
                DBGC ( &images, "INITRD squashing %s [%#08lx,%#08lx)->"
                       "[%#08lx,%#08lx)\n", highest->name,
                       virt_to_phys ( highest->data ),
                       ( virt_to_phys ( highest->data ) + highest->len ),
                       current, ( current + highest->len ) );
                data = phys_to_virt ( current );
                memmove ( data, highest->data, highest->len );
                highest->data = data;
        }
}

References data, image::data, DBGC, end, for_each_image, images, initrd_align(), image::len, memmove(), image::name, NULL, and start.

Referenced by initrd_reshuffle().

initrd_reverse()

static void initrd_reverse ( void *  data, size_t  len  )

static

Reverse aligned memory region.

Parameters

data	Memory region
len	Length of region

Definition at line 99 of file initrd.c.

                                                      {
        unsigned long *low = data;
        unsigned long *high = ( data + len );
        unsigned long tmp;

        /* Reverse region */
        for ( high-- ; low < high ; low++, high-- ) {
                tmp = *low;
                *low = *high;
                *high = tmp;
        }
}

References data, high, len, low, and tmp.

Referenced by initrd_swap().

initrd_swap()

static void initrd_swap ( struct image *  low, struct image *  high  )

static

Swap position of two adjacent initrds.

Parameters

low	Lower initrd
high	Higher initrd

Definition at line 118 of file initrd.c.

                                                                  {
        size_t low_len;
        size_t high_len;
        size_t len;
        void *data;

        DBGC ( &images, "INITRD swapping %s [%#08lx,%#08lx)<->[%#08lx,%#08lx) "
               "%s\n", low->name, virt_to_phys ( low->data ),
               ( virt_to_phys ( low->data ) + low->len ),
               virt_to_phys ( high->data ),
               ( virt_to_phys ( high->data ) + high->len ), high->name );

        /* Calculate padded lengths */
        low_len = initrd_align ( low->len );
        high_len = initrd_align ( high->len );
        len = ( low_len + high_len );
        data = low->rwdata;
        assert ( high->data == ( data + low_len ) );

        /* Adjust data pointers */
        high->data -= low_len;
        low->data += high_len;
        assert ( high->data == data );

        /* Swap content via triple reversal */
        initrd_reverse ( data, len );
        initrd_reverse ( low->rwdata, low_len );
        initrd_reverse ( high->rwdata, high_len );
}

References assert(), data, DBGC, high, images, initrd_align(), initrd_reverse(), len, and low.

Referenced by initrd_swap_any().

initrd_swap_any()

static int initrd_swap_any ( physaddr_t  start, physaddr_t  end  )

static

Swap position of any two adjacent initrds not currently in the correct order.

Parameters

start	Start of reshuffle region
end	End of reshuffle region

Return values

swapped

A pair of initrds was swapped

Definition at line 155 of file initrd.c.

                                                                {
        struct image *low;
        struct image *high;
        const void *adjacent;
        physaddr_t addr;

        /* Find any pair of initrds that can be swapped */
        for_each_image ( low ) {

                /* Ignore images wholly outside the reshuffle region */
                addr = virt_to_phys ( low->data );
                if ( ( addr < start ) || ( addr >= end ) )
                        continue;

                /* Calculate location of adjacent image (if any) */
                adjacent = ( low->data + initrd_align ( low->len ) );

                /* Search for adjacent image */
                for_each_image ( high ) {

                        /* Ignore images wholly outside the reshuffle region */
                        addr = virt_to_phys ( high->data );
                        if ( ( addr < start ) || ( addr >= end ) )
                                continue;

                        /* Stop search if all remaining potential
                         * adjacent images are already in the correct
                         * order.
                         */
                        if ( high == low )
                                break;

                        /* If we have found the adjacent image, swap and exit */
                        if ( high->data == adjacent ) {
                                initrd_swap ( low, high );
                                return 1;
                        }
                }
        }

        /* Nothing swapped */
        return 0;
}

References addr, end, for_each_image, high, initrd_align(), initrd_swap(), low, and start.

Referenced by initrd_reshuffle().

initrd_dump()

static void initrd_dump ( void  )

static

Dump initrd locations (for debug)

Definition at line 203 of file initrd.c.

                                 {
        struct image *initrd;

        /* Do nothing unless debugging is enabled */
        if ( ! DBG_LOG )
                return;

        /* Dump initrd locations */
        for_each_image ( initrd ) {
                DBGC ( &images, "INITRD %s at [%#08lx,%#08lx)\n",
                       initrd->name, virt_to_phys ( initrd->data ),
                       ( virt_to_phys ( initrd->data ) + initrd->len ) );
                DBGC2_MD5A ( &images, virt_to_phys ( initrd->data ),
                             initrd->data, initrd->len );
        }
}

References image::data, DBG_LOG, DBGC, DBGC2_MD5A, for_each_image, images, image::len, and image::name.

Referenced by initrd_reshuffle().

initrd_reshuffle()

void initrd_reshuffle

(

void

)

Reshuffle initrds into desired order at top of memory.

After this function returns, the initrds have been rearranged in memory and the external heap structures will have been corrupted. Reshuffling must therefore take place immediately prior to jumping to the loaded OS kernel; no further execution within iPXE is permitted.

Definition at line 229 of file initrd.c.

                               {
        physaddr_t start;
        physaddr_t end;

        /* Calculate limits of reshuffle region */
        start = uheap_limit;
        end = ( initrd_end ? initrd_end : uheap_end );

        /* Debug */
        initrd_dump();

        /* Squash initrds as high as possible in memory */
        initrd_squash_high ( start, end );

        /* Bubble-sort initrds into desired order */
        while ( initrd_swap_any ( start, end ) ) {}

        /* Debug */
        initrd_dump();
}

References end, initrd_dump(), initrd_end, initrd_squash_high(), initrd_swap_any(), start, uheap_end, and uheap_limit.

Referenced by bzimage_load_initrds(), and lkrn_exec().

initrd_load()

static size_t initrd_load ( struct image *  initrd, void *  address  )

static

Load initrd.

Parameters

initrd	initrd image
address	Address at which to load, or NULL

Return values

len	Length of loaded image, excluding zero-padding

Definition at line 257 of file initrd.c.

                                                                  {
        const char *filename = cpio_name ( initrd );
        struct cpio_header cpio;
        size_t offset;
        size_t cpio_len;
        size_t len;
        unsigned int i;

        /* Sanity check */
        assert ( ( address == NULL ) ||
                 ( ( virt_to_phys ( address ) & ( INITRD_ALIGN - 1 ) ) == 0 ));

        /* Skip hidden images */
        if ( initrd->flags & IMAGE_HIDDEN )
                return 0;

        /* Determine length of cpio headers for non-prebuilt images */
        len = 0;
        for ( i = 0 ; ( cpio_len = cpio_header ( initrd, i, &cpio ) ) ; i++ )
                len += ( cpio_len + cpio_pad_len ( cpio_len ) );

        /* Copy in initrd image body and construct any cpio headers */
        if ( address ) {
                memmove ( ( address + len ), initrd->data, initrd->len );
                memset ( address, 0, len );
                offset = 0;
                for ( i = 0 ; ( cpio_len = cpio_header ( initrd, i, &cpio ) ) ;
                      i++ ) {
                        memcpy ( ( address + offset ), &cpio,
                                 sizeof ( cpio ) );
                        memcpy ( ( address + offset + sizeof ( cpio ) ),
                                 filename, ( cpio_len - sizeof ( cpio ) ) );
                        offset += ( cpio_len + cpio_pad_len ( cpio_len ) );
                }
                assert ( offset == len );
                DBGC ( &images, "INITRD %s [%#08lx,%#08lx,%#08lx)%s%s\n",
                       initrd->name, virt_to_phys ( address ),
                       ( virt_to_phys ( address ) + offset ),
                       ( virt_to_phys ( address ) + offset + initrd->len ),
                       ( filename ? " " : "" ), ( filename ? filename : "" ) );
                DBGC2_MD5A ( &images, ( virt_to_phys ( address ) + offset ),
                             ( address + offset ), initrd->len );
        }
        len += initrd->len;

        return len;
}

References address, assert(), cpio_header(), cpio_name(), cpio_pad_len(), image::data, DBGC, DBGC2_MD5A, image::flags, IMAGE_HIDDEN, images, INITRD_ALIGN, image::len, len, memcpy(), memmove(), memset(), image::name, NULL, and offset.

Referenced by initrd_load_all().

initrd_load_all()

size_t initrd_load_all

(

void *

address

)

Load all initrds.

Parameters

address

Load address, or NULL

Return values

len

Length

This function is called after the point of no return, when the external heap has been corrupted by reshuffling and there is no way to resume normal execution. The caller must have previously ensured that there is no way for installation to this address to fail.

Definition at line 317 of file initrd.c.

                                         {
        struct image *initrd;
        size_t len = 0;
        size_t pad_len;
        void *dest;

        /* Load all initrds */
        for_each_image ( initrd ) {

                /* Zero-pad to next INITRD_ALIGN boundary */
                pad_len = ( ( -len ) & ( INITRD_ALIGN - 1 ) );
                if ( address )
                        memset ( ( address + len ), 0, pad_len );
                len += pad_len;
                assert ( len == initrd_align ( len ) );

                /* Load initrd */
                dest = ( address ? ( address + len ) : NULL );
                len += initrd_load ( initrd, dest );
        }

        return len;
}

References address, assert(), dest, for_each_image, INITRD_ALIGN, initrd_align(), initrd_load(), len, memset(), NULL, and pad_len.

Referenced by bzimage_load_initrds(), initrd_len(), and lkrn_exec().

initrd_region()

int initrd_region	(	size_t	len,
		struct memmap_region *	region
	)

Calculate post-reshuffle initrd load region.

Parameters

len	Length of initrds (from initrd_len())
region	Region descriptor to fill in

Return values

rc	Return status code

If successful, then any suitably aligned range within the region may be used as the load address after reshuffling. The caller does not need to call prep_segment() for a range in this region. (Calling prep_segment() would probably fail, since prior to reshuffling the region is still in use by the external heap.)

Definition at line 354 of file initrd.c.

                                                               {
        physaddr_t min;
        size_t available;

        /* Calculate limits of available space for initrds */
        min = uheap_limit;
        available = ( ( initrd_end ? initrd_end : uheap_end ) - min );
        if ( available < len )
                return -ENOSPC;
        DBGC ( &images, "INITRD post-reshuffle region is [%#08lx,%#08lx)\n",
               min, ( min + available ) );

        /* Populate region descriptor */
        region->min = min;
        region->max = ( min + available - 1 );
        region->flags = MEMMAP_FL_MEMORY;
        region->name = "initrd";

        return 0;
}

References DBGC, ENOSPC, memmap_region::flags, images, initrd_end, len, memmap_region::max, MEMMAP_FL_MEMORY, min, memmap_region::min, memmap_region::name, uheap_end, and uheap_limit.

Referenced by bzimage_check_initrds(), and lkrn_exec().

initrd_startup()

static void initrd_startup ( void  )

static

initrd startup function

Definition at line 379 of file initrd.c.

                                    {

        /* Record address above which reshuffling cannot take place.
         * If any external heap allocations have been made during
         * driver startup (e.g. large host memory blocks for
         * Infiniband devices, which may still be in use at the time
         * of rearranging if a SAN device is hooked), then we must not
         * overwrite these allocations during reshuffling.
         */
        initrd_end = uheap_start;
        if ( initrd_end ) {
                DBGC ( &images, "INITRD limiting reshuffling to below "
                       "%#08lx\n", initrd_end );
        }
}

References DBGC, images, initrd_end, and uheap_start.

__startup_fn()

struct startup_fn startup_initrd __startup_fn

(

STARTUP_LATE

)

initrd startup function

Variable Documentation

initrd_end

physaddr_t initrd_end

static

End of reshuffle region.

Definition at line 42 of file initrd.c.

Referenced by comboot_fetch_kernel(), initrd_region(), initrd_reshuffle(), and initrd_startup().