/*
* ReBuild the initial GDT separating the kernel from the user memory
* area.
*
* See the memory layout in the linker script.
*
* Kernel code starts at 0x100000 (1MB), and is 1 MB long
* Kernel data starts at 0x200000 (2MB), and is 1 MB long
* Kernel stack starts at 0x400000 (4MB), and is 1 MB long
* (Stack grows downwards from 0x400000 to 0x300000)
*
* But there are other memory areas, esp. low ones (e.g. Video
* memory), that we need to access. So the kernel data _segment_ has
* to start from lowest memory. :-).
*
* User area starts from 0x401000 (4MB start offset of stack, and 1
* page size length), and is to the end of the memory. Define two
* segments that overlap. We need to control specific
* allocation. :-).
*
* For the moment, merging stack and data segments ...
* => kernel code seg starts at 0, and ends at 2 MB!
* => kernel data+stack seg starts at 2MB and is 2 MB long
*/
int
initialise_gdt_with_disjoint_kernel_and_user_memory (void)
{
int retval = FALSE;
int i = 0;
for (i = 0; i < 8192; i++)
global_descriptor_table[i].descriptor = 0;
i = set_total_gdt_entries (0);
retval = make_descriptor(0,
0,
NULL_DESCRIPTOR_FLAGS,
0
);
i = inc_total_gdt_entries ();
/* RING_0, DESC_CODEDATA, SEG_EXECUTE_READ, */
retval = make_descriptor ((MEMORYORIGIN),
((KERNELCODESTART + KERNELCODELENGTH)),
RING_0_CODEDATA_DESC_READ_EXECUTE,
1
);
i = inc_total_gdt_entries ();
/* RING_0, DESC_CODEDATA, SEG_READ_WRITE, */
retval = make_descriptor ((MEMORYORIGIN),
(TOTALKERNEL),
RING_0_CODEDATA_DESC_READ_WRITE,
2
);
i = inc_total_gdt_entries ();
/* RING_3, DESC_CODEDATA, SEG_EXECUTE_READ, */
retval = make_descriptor ((USERMEMORYSTART),
MAXMEMPAGES,
RING_3_CODEDATA_DESC_READ_EXECUTE,
3
);
i = inc_total_gdt_entries ();
/* RING_3, DESC_CODEDATA, SEG_READ_WRITE, */
retval = make_descriptor ((USERMEMORYSTART),
MAXMEMPAGES,
RING_3_CODEDATA_DESC_READ_WRITE,
4
);
i = get_total_gdt_entries ();
load_gdt (); /* Could some status flags tell us if we did ok? */
return retval;
}
/*
* Build the initial GDT.
*/
static
int
initialise_gdt (void)
{
int retval = FALSE;
int i = 0;
/* for (i = 0; i < sizeof(global_descriptor_table); i++) */
for (i = 0; i < 8192; i++)
global_descriptor_table[i].descriptor = 0;
retval = make_descriptor(0,
0,
NULL_DESCRIPTOR_FLAGS,
0
);
i = inc_total_gdt_entries ();
/* RING_0, DESC_CODEDATA, SEG_EXECUTE_READ, */
retval = make_descriptor ((MEMORYORIGIN),
MAXMEMPAGES,
RING_0_CODEDATA_DESC_READ_EXECUTE,
1
);
i = inc_total_gdt_entries ();
/* RING_0, DESC_CODEDATA, SEG_READ_WRITE, */
retval = make_descriptor ((MEMORYORIGIN),
MAXMEMPAGES,
RING_0_CODEDATA_DESC_READ_WRITE,
2
);
i = inc_total_gdt_entries ();
/* RING_3, DESC_CODEDATA, SEG_EXECUTE_READ, */
retval = make_descriptor ((MEMORYORIGIN),
MAXMEMPAGES,
RING_3_CODEDATA_DESC_READ_EXECUTE,
3
);
i = inc_total_gdt_entries ();
/* RING_3, DESC_CODEDATA, SEG_READ_WRITE, */
retval = make_descriptor ((MEMORYORIGIN),
MAXMEMPAGES,
RING_3_CODEDATA_DESC_READ_WRITE,
4
);
/* load_gdt (); /\* Could some status flags tell us if we did ok? *\/ */
return retval;
}
uint8_t *
build_disk(const struct disk_descriptor *desc, uint64_t *disk_size)
{
struct vmdk_marker marker = { 0 };
struct vmdk_grain_marker gmarker = { 0 };
struct vmdk_sparse_extent_header *header;
uint8_t *descriptor;
uint8_t *rawdisk, *diskp;
uint32_t *gd, *gt;
uint64_t extent, gcoverage, gtcoverage, gtsize, gdsize, gtbase;
uint32_t block_index;
header = make_header(desc->capacity);
if (header == NULL) {
return NULL;
}
descriptor = make_descriptor(desc->capacity);
if (descriptor == NULL) {
free(header);
return NULL;
}
gcoverage = header->grain_size * BYTES_PER_SECTOR;
gtcoverage = header->num_gtes_per_gt * gcoverage;
gtsize = header->num_gtes_per_gt * sizeof(uint32_t);
gdsize = ((header->capacity * BYTES_PER_SECTOR + gtcoverage - 1) /
gtcoverage) * sizeof(uint32_t);
#define ROUND(x) ((((x) + BYTES_PER_SECTOR - 1) / \
BYTES_PER_SECTOR) * BYTES_PER_SECTOR)
/* Compute how much space we need */
extent = 2 * BYTES_PER_SECTOR; /* header + descriptor */
for (block_index = 0, gtbase = 0;
block_index < desc->nblocks;
block_index++) {
if (desc->blocks[block_index].lba >= gtbase) {
/* New grain table needed */
extent += ROUND(gtsize) + sizeof(struct vmdk_marker);
/* Skip empty grain tables */
while (gtbase <= desc->blocks[block_index].lba) {
gtbase += gtcoverage;
}
}
/* Add on size of block */
extent += ROUND(sizeof(struct vmdk_grain_marker) +
desc->blocks[block_index].size);
}
/* Add on size of grain directory */
extent += ROUND(gdsize) + sizeof(struct vmdk_marker);
extent += 3 * BYTES_PER_SECTOR; /* footer marker, footer, EOS */
gt = calloc(1, gtsize);
if (gt == NULL) {
free(descriptor);
free(header);
return NULL;
}
gd = calloc(1, gdsize);
if (gd == NULL) {
free(gt);
free(descriptor);
free(header);
return NULL;
}
/* Build the disk */
diskp = rawdisk = calloc(1, extent);
if (rawdisk == NULL) {
free(gd);
free(gt);
free(descriptor);
free(header);
return NULL;
}
/* Emit header and descriptor */
memcpy(diskp, header, sizeof(struct vmdk_sparse_extent_header));
diskp += sizeof(struct vmdk_sparse_extent_header);
memcpy(diskp, descriptor, BYTES_PER_SECTOR);
diskp += BYTES_PER_SECTOR;
marker.num_sectors = ROUND(gtsize) / BYTES_PER_SECTOR;
marker.size = 0;
marker.type = 1; /* Grain table */
/* Emit blocks */
for (block_index = 0, gtbase = 0;
block_index < desc->nblocks;
block_index++) {
if (desc->blocks[block_index].lba >= gtbase) {
/* New grain table needed */
if (block_index > 0) {
/* Record location in grain directory */
gd[desc->blocks[block_index - 1].lba /
gtcoverage] = (diskp +
sizeof(struct vmdk_marker) -
rawdisk) /
BYTES_PER_SECTOR;
/* Emit current grain table */
memcpy(diskp, &marker,
sizeof(struct vmdk_marker));
diskp += sizeof(struct vmdk_marker);
memcpy(diskp, gt, gtsize);
diskp += ROUND(gtsize);
memset(gt, 0, gtsize);
}
/* Skip empty grain tables */
while (gtbase <= desc->blocks[block_index].lba) {
gtbase += gtcoverage;
}
}
/* Record block location in grain table */
gt[(desc->blocks[block_index].lba % gtcoverage) /
gcoverage] = (diskp - rawdisk) / BYTES_PER_SECTOR;
/* Emit block */
gmarker.lba = desc->blocks[block_index].lba / BYTES_PER_SECTOR;
gmarker.size = desc->blocks[block_index].size;
memcpy(diskp, &gmarker, sizeof(struct vmdk_grain_marker));
memset(diskp + sizeof(struct vmdk_grain_marker),
desc->blocks[block_index].fill,
desc->blocks[block_index].size);
diskp += ROUND(sizeof(struct vmdk_grain_marker) +
desc->blocks[block_index].size);
}
if (block_index > 0) {
/* Record final grain table location in grain directory */
gd[desc->blocks[block_index - 1].lba / gtcoverage] =
(diskp + sizeof(struct vmdk_marker) - rawdisk) /
BYTES_PER_SECTOR;
/* Emit final grain table */
memcpy(diskp, &marker, sizeof(struct vmdk_marker));
diskp += sizeof(struct vmdk_marker);
memcpy(diskp, gt, gtsize);
diskp += ROUND(gtsize);
}
/* Emit grain directory marker */
marker.num_sectors = ROUND(gdsize) / BYTES_PER_SECTOR;
marker.size = 0;
marker.type = 2; /* Grain directory */
memcpy(diskp, &marker, sizeof(struct vmdk_marker));
diskp += sizeof(struct vmdk_marker);
/* Record grain directory location in footer */
header->gd_offset = (diskp - rawdisk) / BYTES_PER_SECTOR;
/* Emit grain directory */
memcpy(diskp, gd, gdsize);
diskp += ROUND(gdsize);
/* Emit footer marker */
marker.num_sectors = 1;
marker.size = 0;
marker.type = 3; /* Footer */
memcpy(diskp, &marker, sizeof(struct vmdk_marker));
diskp += sizeof(struct vmdk_marker);
/* Emit footer */
memcpy(diskp, header, sizeof(struct vmdk_sparse_extent_header));
diskp += sizeof(struct vmdk_sparse_extent_header);
/* Emit EOS marker */
marker.num_sectors = 0;
marker.size = 0;
marker.type = 0;
memcpy(diskp, &marker, sizeof(struct vmdk_marker));
diskp += sizeof(struct vmdk_marker);
assert(diskp - rawdisk == extent);
/* Clean up */
free(gd);
free(gt);
free(descriptor);
free(header);
*disk_size = extent;
return rawdisk;
}
