On 12.03.25 09:54, Sughosh Ganu wrote:
The efi_install_fdt() function is called before booting an EFI binary,
either directly, or through a bootmanager. This function installs a
copy of the device-tree(DT) on the EFI configuration table, which is
passed on to the OS.
The current logic in this function does not install a DT if the table
already has a DT installed on it. However, this existing copy of the
The device-tree is the configuration table. Maybe better write:
... if a device-tree is already installed as an EFI configuration table.
DT might not be up-to-date, or it could be a wrong DT for the image
that is being booted. Always install a DT afresh to the configuration
table before booting the EFI binary.
Installing a new DT also involves some additional checks that are
needed to clean up memory associated with the existing DT copy. Check
for an existing copy, and free up that memory.
Signed-off-by: Sughosh Ganu <[email protected]>
---
Changes since V7:
* Change the type of fdt_pages to efi_uintn_t
* Remove the check for either of fdt_pages or new_fdt_addr being 0
* Change the format specifier for fdt_pages in the debug messages for
size_t
* Put the assignment of new_fdt_addr and fdt_pages on separate lines
to avoid checkpatch error
lib/efi_loader/efi_helper.c | 32 ++++++++++++++++++++++----------
1 file changed, 22 insertions(+), 10 deletions(-)
diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
index 15ad042bc61..37e5859741f 100644
--- a/lib/efi_loader/efi_helper.c
+++ b/lib/efi_loader/efi_helper.c
@@ -454,11 +454,21 @@ efi_status_t efi_env_set_load_options(efi_handle_t handle,
*/
static efi_status_t copy_fdt(void **fdtp)
{
- unsigned long fdt_pages;
efi_status_t ret = 0;
void *fdt, *new_fdt;
- u64 new_fdt_addr;
- uint fdt_size;
+ static u64 new_fdt_addr;
+ static efi_uintn_t fdt_pages;
+ ulong fdt_size;
+
+ if (new_fdt_addr) {
+ log_debug("%s: Found allocated memory at %#llx, with %#zx
pages\n",
+ __func__, new_fdt_addr, fdt_pages);
+ ret = efi_free_pages(new_fdt_addr, fdt_pages);
We should not free the memory before removing the configuration table.
Otherwise in an error situation we might end up with an invalid
device-tree pointer.
/* Ignoring EFI_NOT_FOUND if not device-tree is installed */
efi_install_configuration_table(&efi_guid_fdt, NULL);
if (new_fdt_addr) {
ret = efi_free_pages(new_fdt_addr, fdt_pages);
...
+ if (ret != EFI_SUCCESS) {
+ log_err("Unable to free up existing FDT memory
region\n");
> + return ret;> + }
Ok, something weird happened. But this should not stop booting.
Just set new_fdt_addr = 0 in any case.
if (ret!= EFI_SUCCES)
log_err("Failed to free existing FDT memory\n");
new_fdt_addr = 0;
+ }
/*
* Give us at least 12 KiB of breathing room in case the device tree
@@ -472,16 +482,21 @@ static efi_status_t copy_fdt(void **fdtp)
EFI_ACPI_RECLAIM_MEMORY, fdt_pages,
&new_fdt_addr);
if (ret != EFI_SUCCESS) {
+ new_fdt_addr = 0;
efi_allocate_pages() only updates new_fdt_addr() in case of success.
If we set new_fdt_addr = 0 above, this line might be removed.
+ fdt_pages = 0;
This line is not really needed as our if-statements don't use it.
Best regards
Heinrich
log_err("Failed to reserve space for FDT\n");
- goto done;
+ return ret;
}
+ log_debug("%s: Allocated memory at %#llx, with %#zx pages\n",
+ __func__, new_fdt_addr, fdt_pages);
+
new_fdt = (void *)(uintptr_t)new_fdt_addr;
memcpy(new_fdt, fdt, fdt_totalsize(fdt));
fdt_set_totalsize(new_fdt, fdt_size);
- *fdtp = (void *)(uintptr_t)new_fdt_addr;
-done:
- return ret;
+ *fdtp = new_fdt;
+
+ return EFI_SUCCESS;
}
/**
@@ -534,9 +549,6 @@ efi_status_t efi_install_fdt(void *fdt)
const char *fdt_opt;
uintptr_t fdt_addr;
- /* Look for device tree that is already installed */
- if (efi_get_configuration_table(&efi_guid_fdt))
- return EFI_SUCCESS;
/* Check if there is a hardware device tree */
fdt_opt = env_get("fdt_addr");
/* Use our own device tree as fallback */
