libsel4platsupport: Fix 'new_fdt_ops'
Previously, we assumed that not being able to copy the FDT was a failure
condition. However, on some platforms, this is actually a valid
condition, e.g. x86 or platforms for which the kernel does not have a
DTS for. This commit fixes that assumption so that calling 'fdt_get'
with the interface returns a NULL pointer.
diff --git a/libsel4platsupport/src/io.c b/libsel4platsupport/src/io.c
index ed14c57..52b6944 100644
--- a/libsel4platsupport/src/io.c
+++ b/libsel4platsupport/src/io.c
@@ -291,32 +291,36 @@
}
ssize_t block_size = simple_get_extended_bootinfo_length(simple, SEL4_BOOTINFO_HEADER_FDT);
+ if (block_size > 0) {
+ int error = ps_calloc(malloc_ops, 1, block_size, &io_fdt->cookie);
+ if (error) {
+ ZF_LOGE("Failed to allocate %zu bytes for the FDT", block_size);
+ return -1;
+ }
- int error = ps_calloc(malloc_ops, 1, block_size, &io_fdt->cookie);
- if (error) {
- ZF_LOGE("Failed to allocate %zu bytes for the FDT", block_size);
- return -1;
+ /* Copy the FDT from the extended bootinfo */
+ ssize_t copied_size = simple_get_extended_bootinfo(simple, SEL4_BOOTINFO_HEADER_FDT,
+ io_fdt->cookie, block_size);
+ if (copied_size != block_size) {
+ ZF_LOGE("Failed to copy the FDT");
+ ZF_LOGF_IF(ps_free(malloc_ops, block_size, io_fdt->cookie),
+ "Failed to clean-up after a failed operation!");
+ return -1;
+ }
+
+ /* Cut off the bootinfo header from the start of the buffer */
+ ssize_t fdt_size = block_size - sizeof(seL4_BootInfoHeader);
+ void *fdt_start = io_fdt->cookie + sizeof(seL4_BootInfoHeader);
+ memmove(io_fdt->cookie, fdt_start, fdt_size);
+
+ /* Trim off the extra bytes at the end of the FDT */
+ void *fdt_end = io_fdt->cookie + fdt_size;
+ memset(fdt_end, 0, sizeof(seL4_BootInfoHeader));
+ } else {
+ /* No FDT is available so just set the cookie to NULL */
+ io_fdt->cookie = NULL;
}
- /* Copy the FDT from the extended bootinfo */
- ssize_t copied_size = simple_get_extended_bootinfo(simple, SEL4_BOOTINFO_HEADER_FDT,
- io_fdt->cookie, block_size);
- if (copied_size != block_size) {
- ZF_LOGE("Failed to copy the FDT");
- ZF_LOGF_IF(ps_free(malloc_ops, block_size, io_fdt->cookie),
- "Failed to clean-up after a failed operation!");
- return -1;
- }
-
- /* Cut off the bootinfo header from the start of the buffer */
- ssize_t fdt_size = block_size - sizeof(seL4_BootInfoHeader);
- void *fdt_start = io_fdt->cookie + sizeof(seL4_BootInfoHeader);
- memmove(io_fdt->cookie, fdt_start, fdt_size);
-
- /* Trim off the extra bytes at the end of the FDT */
- void *fdt_end = io_fdt->cookie + fdt_size;
- memset(fdt_end, 0, sizeof(seL4_BootInfoHeader));
-
/* Set the function pointer inside the io_fdt interface */
io_fdt->get_fn = sel4platsupport_io_fdt_get;
