// buf: buffer returned by mmap_file()
// size: same size as supplied to the mmap_file()
void unmap(void* buf, size_t size)
{
assert(buf);
uintptr_t end = page_ceil((uintptr_t)buf + size);
uintptr_t start = page_floor((uintptr_t)buf);
assert(end > (uintptr_t)buf);
size_t len = end - start;
if (munmap((void*)start, len) < 0)
err(1, "munmap failed");
}
// mmap file content at given offset
// use unmap to release the mapping
void* mmap_file(int fd, off_t offset, size_t size)
{
off_t offset_end = offset + size;
assert(offset >= 0);
assert(offset_end >= offset); // No overflow
uintptr_t end = page_ceil(offset_end);
uintptr_t start = page_floor(offset);
uintptr_t len = end - start;
void* buf = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, start);
if (buf == MAP_FAILED)
err(1, "mmap failed");
return ((void *)((uintptr_t)buf + (offset - start)));
}
void elflink_parse_load( elfinfo_t *elf, Elf32_Phdr *hdr )
{
Elf32_Addr rstart, rend;
Elf32_Addr fstart, fend, frend;
Elf32_Addr caddr, cend, cmaddr;
physaddr_t cphys, pstart, fphys, cdstart, cfstart, csz, psz;
int flags;
/* Determine base address */
if ( elf->base == 0xFFFFFFFF ) {
elf->base = page_floor( hdr->p_vaddr );
elf->mbase = platldr_start_image( elf->id );
}
/* Setup page flags */
flags = PAGE_FLAG_GLOBAL;
if ( hdr->p_flags & PF_R )
flags |= PAGE_PERM_R;
if ( hdr->p_flags & PF_W )
flags |= PAGE_PERM_W;
if ( hdr->p_flags & PF_X )
flags |= PAGE_PERM_X;
//Note: Assume page size power of 2
/* Calculate the page boundaries of the LOAD */
rstart = page_floor( hdr->p_vaddr );
rend = page_ceil( hdr->p_vaddr + hdr->p_memsz );
fstart = hdr->p_vaddr;
fend = hdr->p_vaddr + hdr->p_filesz;
/* pstart contains the physical offset of the segment data */
pstart = (physaddr_t) elf->pstart;
pstart += page_floor(hdr->p_offset);
/* Calculate the page boundary of the last filled page */
frend = page_ceil(fend);
/* Determine image end address */
if ( rend > elf->end )
elf->end = rend;
/* Map all pages containing file data */
for ( caddr = rstart; caddr < frend; caddr = cend ) {
cend = caddr + ARCH_PAGE_SIZE;
cmaddr = (caddr - elf->base) + elf->mbase;
cphys = fphys = caddr - rstart + pstart;
if ( caddr < fstart ) {
/* This page does not fully contain the file */
/* Allocate a fresh frame for this page */
cphys = physmm_alloc_frame();
/* Calculate the padding size */
psz = fstart - caddr;
/* Clear the padded start */
memset( (void *) cphys, 0, psz );
/* Calculate the offsets */
cdstart = cphys + psz;
cfstart = fphys + psz;
csz = cend - fstart;
// printf("Copy over: 0x%x to 0x%x\n", cfstart, cdstart );
/* Copy in the data */
memcpy( (void *) cdstart, (void *) cfstart, csz );
} else if ( cend > fend ) {
/* This page does not fully contain the file */
/* Allocate a fresh frame for this page */
cphys = physmm_alloc_frame();
/* Calculate the padding size */
psz = cend - fend;
/* Calculate the data size and padding start */
csz = fend - caddr;
cdstart = cphys + csz;
/* Clear the padded end */
memset( (void *) cdstart, 0, psz );
// printf("Copy over: 0x%x to 0x%x %x bytes\n", fphys, cphys,
// csz);
/* Copy in the data */
memcpy( (void *) cphys, (void *) fphys, csz );
} /* If the page fully contains the file, map it */
// else printf("Nocopy\n");
platldr_map( elf->id, cmaddr, cphys, flags );
}
/* Map all pages which should not contain file data */
for ( caddr = frend; caddr < rend; caddr = cend ) {
cend = caddr + ARCH_PAGE_SIZE;
cphys = physmm_alloc_frame();
cmaddr = (caddr - elf->base) + elf->mbase;
memset( (void *) cphys, 0, ARCH_PAGE_SIZE );
platldr_map( elf->id, cmaddr, cphys, flags );
}
}