1 files changed, 399 insertions, 0 deletions
diff --git a/src/image/initrd.c b/src/image/initrd.c
new file mode 100644
index 000000000..ba550a8f2
--- /dev/null
+++ b/src/image/initrd.c
@@ -0,0 +1,399 @@
+/*
+ * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#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>
+
+/** @file
+ *
+ * Initial ramdisk (initrd) reshuffling
+ *
+ */
+
+/** End of reshuffle region */
+static physaddr_t initrd_end;
+
+/**
+ * Squash initrds as high as possible in memory
+ *
+ * @v start		Start of reshuffle region
+ * @v end		End of reshuffle region
+ */
+static void initrd_squash_high ( physaddr_t start, physaddr_t end ) {
+	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;
+	}
+}
+
+/**
+ * Reverse aligned memory region
+ *
+ * @v data		Memory region
+ * @v len		Length of region
+ */
+static void initrd_reverse ( void *data, size_t len ) {
+	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;
+	}
+}
+
+/**
+ * Swap position of two adjacent initrds
+ *
+ * @v low		Lower initrd
+ * @v high		Higher initrd
+ */
+static void initrd_swap ( struct image *low, struct image *high ) {
+	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 );
+}
+
+/**
+ * Swap position of any two adjacent initrds not currently in the correct order
+ *
+ * @v start		Start of reshuffle region
+ * @v end		End of reshuffle region
+ * @ret swapped		A pair of initrds was swapped
+ */
+static int initrd_swap_any ( physaddr_t start, physaddr_t end ) {
+	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;
+}
+
+/**
+ * Dump initrd locations (for debug)
+ *
+ */
+static void initrd_dump ( void ) {
+	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 );
+	}
+}
+
+/**
+ * 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.
+ */
+void initrd_reshuffle ( void ) {
+	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();
+}
+
+/**
+ * Load initrd
+ *
+ * @v initrd		initrd image
+ * @v address		Address at which to load, or NULL
+ * @ret len		Length of loaded image, excluding zero-padding
+ */
+static size_t initrd_load ( struct image *initrd, void *address ) {
+	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;
+}
+
+/**
+ * Load all initrds
+ *
+ * @v address		Load address, or NULL
+ * @ret 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.
+ */
+size_t initrd_load_all ( void *address ) {
+	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;
+}
+
+/**
+ * Calculate post-reshuffle initrd load region
+ *
+ * @v len		Length of initrds (from initrd_len())
+ * @v region		Region descriptor to fill in
+ * @ret 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.)
+ */
+int initrd_region ( size_t len, struct memmap_region *region ) {
+	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;
+}
+
+/**
+ * initrd startup function
+ *
+ */
+static void initrd_startup ( void ) {
+
+	/* 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 );
+	}
+}
+
+/** initrd startup function */
+struct startup_fn startup_initrd __startup_fn ( STARTUP_LATE ) = {
+	.name = "initrd",
+	.startup = initrd_startup,
+};