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Update buffer-handling code to enable expandable buffers.

This commit is contained in:
Michael Brown 2007-01-11 03:50:47 +00:00
parent bb2024c6d6
commit e2dcd05b67
6 changed files with 187 additions and 291 deletions
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69
src/arch/i386/core/load_buffer.c
View File

@ -1,69 +0,0 @@
#include "io.h"
#include "load_buffer.h"
/*
* Initialise a buffer in an unused portion of memory, to be used for
* loading an image
*
*/
#ifdef KEEP_IT_REAL
/*
* Under KEEP_IT_REAL, always use 07c0:0000 as the load buffer.
*
*/
int init_load_buffer ( struct buffer *buffer ) {
buffer->start = 0x7c00;
buffer->end = 0xa0000;
DBG ( "LOAD_BUFFER using [%x,%x)\n", buffer->start, buffer->end );
init_buffer ( buffer );
return 1;
}
void trim_load_buffer ( struct buffer *buffer ) {
/* Nothing to do */
}
void done_load_buffer ( struct buffer *buffer ) {
/* Nothing to do */
}
#else /* KEEP_IT_REAL */
/*
* Without KEEP_IT_REAL, use all remaining heap space as the load buffer.
*
*/
int init_load_buffer ( struct buffer *buffer ) {
void *data;
size_t size;
data = emalloc_all ( &size );
if ( ! data )
return 0;
buffer->start = virt_to_phys ( data );
buffer->end = buffer->start + size;
DBG ( "LOAD_BUFFER using [%x,%x)\n", buffer->start, buffer->end );
init_buffer ( buffer );
return 1;
}
void trim_load_buffer ( struct buffer *buffer ) {
void *new_start;
/* Shrink buffer */
new_start = erealloc ( phys_to_virt ( buffer->start ), buffer->fill );
DBG ( "LOAD_BUFFER shrunk from [%x,%x) to [%x,%x)\n", buffer->start,
buffer->end, virt_to_phys ( new_start ), buffer->end );
buffer->start = virt_to_phys ( new_start );
}
void done_load_buffer ( struct buffer *buffer ) {
efree ( phys_to_virt ( buffer->start ) );
DBG ( "LOAD_BUFFER freed [%x,%x)\n", buffer->start, buffer->end );
}
#endif

270
src/core/buffer.c
View File

@ -1,3 +1,27 @@
/*
* Copyright (C) 2007 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <io.h>
#include <gpxe/buffer.h>
/** @file
*
@ -7,27 +31,22 @@
* which is "filled" and the remainder of which is "free". The
* "filled" and "free" spaces are not necessarily contiguous.
*
* When a buffer is initialised via init_buffer(), it consists of a
* single free space. As data is added to the buffer via
* fill_buffer(), this free space decreases and can become fragmented.
* At the start of a buffer's life, it consists of a single free
* space. As data is added to the buffer via fill_buffer(), this free
* space decreases and can become fragmented.
*
* Each free block within a buffer starts with a "tail byte". If the
* tail byte is non-zero, this indicates that the free block is the
* tail of the buffer, i.e. occupies all the remaining space up to the
* end of the buffer. When the tail byte is non-zero, it indicates
* that a descriptor (a @c struct @c buffer_free_block) follows the
* tail byte. The descriptor describes the size of the free block and
* the address of the next free block.
*
* We cannot simply always start a free block with a descriptor,
* because it is conceivable that we will, at some point, encounter a
* situation in which the final free block of a buffer is too small to
* contain a descriptor. Consider a protocol with a blocksize of 512
* downloading a 1025-byte file into a 1025-byte buffer. Suppose that
* the first two blocks are received; we have now filled 1024 of the
* 1025 bytes in the buffer, and our only free block consists of the
* 1025th byte. Using a "tail byte" solves this problem.
* Each free block within a buffer (except the last) starts with a @c
* struct @c buffer_free_block. This describes the size of the free
* block, and the offset to the next free block.
*
* We cannot simply start every free block (including the last) with a
* descriptor, because it is conceivable that we will, at some point,
* encounter a situation in which the final free block of a buffer is
* too small to contain a descriptor. Consider a protocol with a
* blocksize of 512 downloading a 1025-byte file into a 1025-byte
* buffer. Suppose that the first two blocks are received; we have
* now filled 1024 of the 1025 bytes in the buffer, and our only free
* block consists of the 1025th byte.
*
* Note that the rather convoluted way of manipulating the buffer
* descriptors (using copy_{to,from}_phys rather than straightforward
@ -38,107 +57,76 @@
*
*/
#include "stddef.h"
#include "string.h"
#include "io.h"
#include "errno.h"
#include <assert.h>
#include <gpxe/buffer.h>
/**
* A free block descriptor
*
* This is the data structure that is found at the start of a free
* block within a data buffer.
*/
struct buffer_free_block {
/** Starting offset of the free block */
size_t start;
/** Ending offset of the free block */
size_t end;
/** Offset of next free block */
size_t next;
};
/**
* Initialise a buffer.
* Get next free block within the buffer
*
* @v buffer The buffer to be initialised
* @ret None -
* @err None -
*
* Set @c buffer->start and @c buffer->end before calling init_buffer().
* init_buffer() will initialise the buffer to the state of being
* empty.
* @v buffer Data buffer
* @v block Previous free block descriptor
* @ret block Next free block descriptor
* @ret rc Return status code
*
* Set @c block->next=buffer->free before first call to
* get_next_free_block().
*/
void init_buffer ( struct buffer *buffer ) {
char tail = 1;
static int get_next_free_block ( struct buffer *buffer,
struct buffer_free_block *block ) {
buffer->fill = 0;
if ( buffer->end != buffer->start )
copy_to_phys ( buffer->start, &tail, sizeof ( tail ) );
/* Check for end of buffer */
if ( block->end >= buffer->len )
return -ENOENT;
DBG ( "BUFFER [%x,%x) initialised\n", buffer->start, buffer->end );
}
/**
* Move to the next block in the free list
*
* @v block The current free block
* @v buffer The buffer
* @ret True Successfully moved to the next free block
* @ret False There are no more free blocks
* @ret block The next free block
* @err None -
*
* Move to the next block in the free block list, filling in @c block
* with the descriptor for this next block. If the next block is the
* tail block, @c block will be filled with the values calculated for
* the tail block, otherwise the descriptor will be read from the free
* block itself.
*
* If there are no more free blocks, next_free_block() returns False
* and leaves @c block with invalid contents.
*
* Set <tt> block->next = buffer->start + buffer->fill </tt> for the
* first call to next_free_block().
*/
static inline int next_free_block ( struct buffer_free_block *block,
struct buffer *buffer ) {
/* Move to next block */
block->start = block->next;
/* If at end of buffer, return 0 */
if ( block->start >= buffer->end )
return 0;
/* Set up ->next and ->end as for a tail block */
block->next = block->end = buffer->end;
/* Read tail marker from block */
copy_from_phys ( &block->tail, block->start, sizeof ( block->tail ) );
/* If not a tail block, read whole block descriptor from block */
if ( ! block->tail ) {
copy_from_phys ( block, block->start, sizeof ( *block ) );
if ( block->start >= buffer->free ) {
/* Final block; no in-band descriptor */
block->end = buffer->len;
} else {
/* Retrieve block descriptor */
copy_from_phys ( block, ( buffer->addr + block->start ),
sizeof ( *block ) );
}
return 1;
return 0;
}
/**
* Store a free block descriptor
* Write free block descriptor back to buffer
*
* @v block The free block descriptor to store
* @ret None -
* @err None -
*
* Writes a free block descriptor back to a free block. If the block
* is a tail block, only the tail marker will be written, otherwise
* the whole block descriptor will be written.
* @v buffer Data buffer
* @v block Free block descriptor
*/
static inline void store_free_block ( struct buffer_free_block *block ) {
copy_to_phys ( block->start, block,
( block->tail ?
sizeof ( block->tail ) : sizeof ( *block ) ) );
static void store_free_block ( struct buffer *buffer,
struct buffer_free_block *block ) {
size_t free_block_size = ( block->end - block->start );
assert ( free_block_size >= sizeof ( *block ) );
copy_to_phys ( ( buffer->addr + block->start ), block,
sizeof ( *block ) );
}
/**
* Write data into a buffer.
* Write data into a buffer
*
* @v buffer The buffer into which to write the data
* @v data The data to be written
* @v buffer Data buffer
* @v data Data to be written
* @v offset Offset within the buffer at which to write the data
* @v len Length of data to be written
* @ret True Data was successfully written
* @ret False Data was not written
* @err ENOMEM Buffer is too small to contain the data
* @ret rc Return status code
*
* Writes a block of data into the buffer. The block need not be
* aligned to any particular boundary, or be of any particular size,
@ -166,29 +154,37 @@ static inline void store_free_block ( struct buffer_free_block *block ) {
*
*/
int fill_buffer ( struct buffer *buffer, const void *data,
off_t offset, size_t len ) {
size_t offset, size_t len ) {
struct buffer_free_block block, before, after;
physaddr_t data_start, data_end;
size_t data_start = offset;
size_t data_end = ( data_start + len );
int rc;
/* Calculate start and end addresses of data */
data_start = buffer->start + offset;
data_end = data_start + len;
DBG ( "BUFFER [%x,%x) writing portion [%x,%x)\n",
buffer->start, buffer->end, data_start, data_end );
DBGC ( buffer, "BUFFER %p [%lx,%lx) filling portion [%lx,%lx)\n",
buffer, buffer->addr, ( buffer->addr + buffer->len ),
( buffer->addr + data_start ), ( buffer->addr + data_end ) );
/* Check buffer bounds */
if ( data_end > buffer->end ) {
DBG ( "BUFFER [%x,%x) too small for data!\n",
buffer->start, buffer->end );
errno = ENOMEM;
return 0;
/* Check that block fits within buffer, expand if necessary */
if ( data_end > buffer->len ) {
if ( ! buffer->expand ) {
DBGC ( buffer, "BUFFER %p not expandable\n", buffer );
return -ENOBUFS;
}
if ( ( rc = buffer->expand ( buffer, data_end ) ) != 0 ) {
DBGC ( buffer, "BUFFER %p could not expand :%s\n",
buffer, strerror ( rc ) );
return rc;
}
DBGC ( buffer, "BUFFER %p expanded to [%lx,%lx)\n", buffer,
buffer->addr, ( buffer->addr + buffer->len ) );
assert ( buffer->len >= data_end );
}
/* Find 'before' and 'after' blocks, if any */
before.start = before.end = 0;
after.start = after.end = buffer->end;
block.next = buffer->start + buffer->fill;
while ( next_free_block ( &block, buffer ) ) {
after.start = after.end = buffer->len;
block.next = buffer->fill;
while ( get_next_free_block ( buffer, &block ) == 0 ) {
if ( ( block.start < data_start ) &&
( block.start >= before.start ) )
memcpy ( &before, &block, sizeof ( before ) );
@ -206,33 +202,35 @@ int fill_buffer ( struct buffer *buffer, const void *data,
/* Link 'after' block to 'before' block */
before.next = after.start;
DBGC ( buffer, "BUFFER %p split before [%lx,%lx) after [%lx,%lx)\n",
buffer, ( buffer->addr + before.start ),
( buffer->addr + before.end ), ( buffer->addr + after.start ),
( buffer->addr + after.end ) );
/* Write back 'before' block, if any */
if ( before.start ) {
before.tail = 0;
assert ( ( before.end - before.start ) >=
sizeof ( struct buffer_free_block ) );
store_free_block ( &before );
if ( before.end == 0 ) {
/* No 'before' block: update buffer->fill */
buffer->fill = after.start;
DBGC ( buffer, "BUFFER %p full up to %lx\n", buffer,
( buffer->addr + buffer->fill ) );
} else {
buffer->fill = before.next - buffer->start;
/* Write back 'before' block */
store_free_block ( buffer, &before );
}
/* Write back 'after' block, if any */
if ( after.start < buffer->end ) {
assert ( after.tail ||
( ( after.end - after.start ) >=
sizeof ( struct buffer_free_block ) ) );
store_free_block ( &after );
/* Write back 'after' block */
if ( after.end == buffer->len ) {
/* 'After' block is the final block: update buffer->free */
buffer->free = after.start;
DBGC ( buffer, "BUFFER %p free from %lx onwards\n", buffer,
( buffer->addr + buffer->free ) );
} else {
/* Write back 'after' block */
store_free_block ( buffer, &after );
}
DBG ( "BUFFER [%x,%x) before [%x,%x) after [%x,%x)\n",
buffer->start, buffer->end, before.start, before.end,
after.start, after.end );
/* Copy data into buffer */
copy_to_phys ( data_start, data, len );
copy_to_phys ( ( buffer->addr + data_start ), data, len );
DBG ( "BUFFER [%x,%x) full up to %x\n",
buffer->start, buffer->end, buffer->start + buffer->fill );
return 1;
return 0;
}

1
src/core/image.c
View File

@ -1,6 +1,5 @@
#include "dev.h"
#include <gpxe/buffer.h>
#include "load_buffer.h"
#include "image.h"
#include <console.h>

97
src/include/gpxe/buffer.h
View File

@ -1,8 +1,8 @@
#ifndef _GPXE_BUFFER_H
#define _GPXE_BUFFER_H
#include "compiler.h" /* for doxygen */
#include "stdint.h"
#include <stdint.h>
#include <io.h>
/** @file
*
@ -15,14 +15,8 @@
* Some protocols do not provide a mechanism for us to know the size
* of the file before we happen to receive a particular block
* (e.g. the final block in an MTFTP transfer). In addition, some
* protocols (all the multicast protocols plus any TCP-based protocol)
* can, in theory, provide the data in any order.
*
* Rather than requiring each protocol to implement its own equivalent
* of "dd" to arrange the data into well-sized pieces before handing
* off to the image loader, we provide these generic buffer functions
* which assemble a file into a single contiguous block. The whole
* block is then passed to the image loader.
* protocols (e.g. the multicast protocols) can, in theory, provide
* the data in any order.
*
* Example usage:
*
@ -33,65 +27,78 @@
* off_t offset;
* size_t len;
*
* // We have an area of memory [buf_start,buf_end) into which we want
* // to load a file, where buf_start and buf_end are physical addresses.
* // We have an area of memory [buf_start,buf_start+len) into which to
* // load a file, where buf_start is a physical addresse.
* memset ( &buffer, 0, sizeof ( buffer ) );
* buffer->start = buf_start;
* buffer->end = buf_end;
* init_buffer ( &buffer );
* buffer->len = len;
* ...
* while ( get_file_block ( ... ) ) {
* // Downloaded block is stored in [data,data+len), and represents
* // the portion of the file at offsets [offset,offset+len)
* if ( ! fill_buffer ( &buffer, data, offset, len ) ) {
* if ( fill_buffer ( &buffer, data, offset, len ) != 0 ) {
* // An error occurred
* return 0;
* }
* ...
* }
* ...
* // The whole file is now present at [buf_start,buf_start+filesize),
* // where buf_start is a physical address. The struct buffer can simply
* // be discarded; there is no done_buffer() call.
* // be discarded.
*
* @endcode
*
* For a description of the internal operation, see buffer.c.
*
*/
/**
* A buffer
* A data buffer
*
* #start and #end denote the real boundaries of the buffer, and are
* physical addresses. #fill denotes the offset to the first free
* block in the buffer. (If the buffer is full, #fill will equal
* #end-#start.)
* A buffer looks something like this:
*
* @code
*
* XXXXXXXXXXXXXXXXX.........XXX..........XXXXXXX........XXXXXX.........
*
* ^
* |
* start
*
* <----- fill ---->
*
* <------------------------ free ---------------------------->
*
* <------------------------------ len -------------------------------->
*
* @endcode
*
* #start and #len denote the real boundaries of the buffer. #fill
* denotes the offset to the first free block in the buffer. (If the
* buffer is full, #fill, #free and #len will all be equal.)
*
*/
struct buffer {
physaddr_t start; /**< Start of buffer in memory */
physaddr_t end; /**< End of buffer in memory */
off_t fill; /**< Offset to first gap in buffer */
/** Physical start address of buffer */
physaddr_t addr;
/** Total length of buffer */
size_t len;
/** Offset to first free block within buffer */
size_t fill;
/** Offset to last free block within buffer */
size_t free;
/** Expand data buffer
*
* @v buffer Data buffer
* @v new_len New length
* @ret rc Return status code
*
* Expand the data buffer to accommodate more data. This
* method is optional; if it is @c NULL then the buffer will
* not be expandable.
*/
int ( * expand ) ( struct buffer *buffer, size_t new_len );
};
/**
* A free block descriptor.
*
* See buffer.c for a full description of the fields.
*
*/
struct buffer_free_block {
char tail; /**< Tail byte marker */
char reserved[3]; /**< Padding */
physaddr_t start; /**< Address of this free block */
physaddr_t next; /**< Address of next free block */
physaddr_t end; /**< End of this block */
} __attribute__ (( packed ));
/* Functions in buffer.c */
extern void init_buffer ( struct buffer *buffer );
extern int fill_buffer ( struct buffer *buffer, const void *data,
off_t offset, size_t len );
size_t offset, size_t len );
#endif /* _GPXE_BUFFER_H */

39
src/include/load_buffer.h
View File

@ -1,39 +0,0 @@
#ifndef LOAD_BUFFER_H
#define LOAD_BUFFER_H
#include <gpxe/buffer.h>
/*
* These functions are architecture-dependent, but the interface must
* be identical between architectures.
*
*/
/*
* Initialise a buffer suitable for loading an image. Pass in a
* pointer to an uninitialised struct buffer.
*
* Note that this function may (for example) allocate all remaining
* allocatable memory, so it must be called *after* any other code
* that might want to allocate memory (e.g. device driver
* initialisation).
*
*/
extern int init_load_buffer ( struct buffer *buffer );
/*
* Cut a load buffer down to size once the image has been loaded.
* This will shrink the buffer down to the size of the data contained
* within the buffer, freeing up unused memory if applicable.
*
*/
extern void trim_load_buffer ( struct buffer *buffer );
/*
* Finish using a load buffer, once the image has been moved into its
* target location in memory.
*
*/
extern void done_load_buffer ( struct buffer *buffer );
#endif /* LOAD_BUFFER_H */

2
src/proto/slam.c
View File

@ -314,7 +314,7 @@ static unsigned char *reinit_slam_state(
return 0;
}
bitmap_len = (state.total_packets + 1 + 7)/8;
state.image = phys_to_virt ( state.buffer->start );
state.image = phys_to_virt ( state.buffer->addr );
/* We don't use the buffer routines properly yet; fake it */
state.buffer->fill = total_bytes;
state.bitmap = state.image + total_bytes;