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[fdt] Identify free space (if any) at end of parsed tree 

Signed-off-by: Michael Brown <mcb30@ipxe.org>
master
Michael Brown 2025-04-01 13:04:10 +01:00
parent 0a48bb3214
commit d853448887
2 changed files with 31 additions and 4 deletions
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31
src/core/fdt.c
View File

@ -458,10 +458,11 @@ int fdt_mac ( struct fdt *fdt, unsigned int offset,
* @ret rc Return status code
*/
int fdt_parse ( struct fdt *fdt, struct fdt_header *hdr, size_t max_len ) {
const uint8_t *end;
const uint8_t *nul;
size_t end;
/* Sanity check */
if ( sizeof ( fdt ) > max_len ) {
if ( sizeof ( *hdr ) > max_len ) {
DBGC ( fdt, "FDT length %#zx too short for header\n",
max_len );
goto err;
@ -470,6 +471,7 @@ int fdt_parse ( struct fdt *fdt, struct fdt_header *hdr, size_t max_len ) {
/* Record device tree location */
fdt->hdr = hdr;
fdt->len = be32_to_cpu ( hdr->totalsize );
fdt->used = sizeof ( *hdr );
if ( fdt->len > max_len ) {
DBGC ( fdt, "FDT has invalid length %#zx / %#zx\n",
fdt->len, max_len );
@ -507,6 +509,9 @@ int fdt_parse ( struct fdt *fdt, struct fdt_header *hdr, size_t max_len ) {
DBGC ( fdt, "FDT structure block is misaligned\n" );
goto err;
}
end = ( fdt->structure + fdt->structure_len );
if ( fdt->used < end )
fdt->used = end;
/* Record strings block location */
fdt->strings = be32_to_cpu ( hdr->off_dt_strings );
@ -518,11 +523,14 @@ int fdt_parse ( struct fdt *fdt, struct fdt_header *hdr, size_t max_len ) {
DBGC ( fdt, "FDT strings block exceeds table\n" );
goto err;
}
end = ( fdt->strings + fdt->strings_len );
if ( fdt->used < end )
fdt->used = end;
/* Shrink strings block to ensure NUL termination safety */
end = ( fdt->raw + fdt->strings + fdt->strings_len );
nul = ( fdt->raw + fdt->strings + fdt->strings_len );
for ( ; fdt->strings_len ; fdt->strings_len-- ) {
if ( *(--end) == '\0' )
if ( *(--nul) == '\0' )
break;
}
if ( fdt->strings_len != be32_to_cpu ( hdr->size_dt_strings ) ) {
@ -530,6 +538,21 @@ int fdt_parse ( struct fdt *fdt, struct fdt_header *hdr, size_t max_len ) {
fdt->strings, ( fdt->strings + fdt->strings_len ) );
}
/* Record memory reservation block location */
fdt->reservations = be32_to_cpu ( hdr->off_mem_rsvmap );
DBGC ( fdt, "FDT memory reservations at +[%#04x,...)\n",
fdt->reservations );
if ( fdt->used <= fdt->reservations ) {
/* No size field exists: assume whole table is used */
fdt->used = fdt->len;
}
/* Identify free space (if any) */
if ( fdt->used < fdt->len ) {
DBGC ( fdt, "FDT free space at +[%#04zx,%#04zx)\n",
fdt->used, fdt->len );
}
/* Print model name (for debugging) */
DBGC ( fdt, "FDT model is \"%s\"\n", fdt_string ( fdt, 0, "model" ) );

4
src/include/ipxe/fdt.h
View File

@ -84,6 +84,8 @@ struct fdt {
};
/** Length of tree */
size_t len;
/** Used length of tree */
size_t used;
/** Offset to structure block */
unsigned int structure;
/** Length of structure block */
@ -92,6 +94,8 @@ struct fdt {
unsigned int strings;
/** Length of strings block */
size_t strings_len;
/** Offset to memory reservation block */
unsigned int reservations;
};
extern struct image_tag fdt_image __image_tag;