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-rw-r--r--src/boot/efi/devicetree.c154
1 files changed, 154 insertions, 0 deletions
diff --git a/src/boot/efi/devicetree.c b/src/boot/efi/devicetree.c
new file mode 100644
index 0000000..0312670
--- /dev/null
+++ b/src/boot/efi/devicetree.c
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <efi.h>
+
+#include "devicetree.h"
+#include "missing_efi.h"
+#include "util.h"
+
+#define FDT_V1_SIZE (7*4)
+
+static void *get_dtb_table(void) {
+ for (UINTN i = 0; i < ST->NumberOfTableEntries; i++)
+ if (memcmp(&EfiDtbTableGuid, &ST->ConfigurationTable[i].VendorGuid, sizeof(EfiDtbTableGuid)) == 0)
+ return ST->ConfigurationTable[i].VendorTable;
+ return NULL;
+}
+
+static EFI_STATUS devicetree_allocate(struct devicetree_state *state, UINTN size) {
+ UINTN pages = DIV_ROUND_UP(size, EFI_PAGE_SIZE);
+ EFI_STATUS err;
+
+ assert(state);
+
+ err = BS->AllocatePages(AllocateAnyPages, EfiACPIReclaimMemory, pages, &state->addr);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ state->pages = pages;
+ return err;
+}
+
+static UINTN devicetree_allocated(const struct devicetree_state *state) {
+ assert(state);
+ return state->pages * EFI_PAGE_SIZE;
+}
+
+static EFI_STATUS devicetree_fixup(struct devicetree_state *state, UINTN len) {
+ EFI_DT_FIXUP_PROTOCOL *fixup;
+ UINTN size;
+ EFI_STATUS err;
+
+ assert(state);
+
+ err = BS->LocateProtocol(&EfiDtFixupProtocol, NULL, (void **) &fixup);
+ if (err != EFI_SUCCESS)
+ return log_error_status_stall(EFI_SUCCESS,
+ L"Could not locate device tree fixup protocol, skipping.");
+
+ size = devicetree_allocated(state);
+ err = fixup->Fixup(fixup, PHYSICAL_ADDRESS_TO_POINTER(state->addr), &size,
+ EFI_DT_APPLY_FIXUPS | EFI_DT_RESERVE_MEMORY);
+ if (err == EFI_BUFFER_TOO_SMALL) {
+ EFI_PHYSICAL_ADDRESS oldaddr = state->addr;
+ UINTN oldpages = state->pages;
+ void *oldptr = PHYSICAL_ADDRESS_TO_POINTER(state->addr);
+
+ err = devicetree_allocate(state, size);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ memcpy(PHYSICAL_ADDRESS_TO_POINTER(state->addr), oldptr, len);
+ err = BS->FreePages(oldaddr, oldpages);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ size = devicetree_allocated(state);
+ err = fixup->Fixup(fixup, PHYSICAL_ADDRESS_TO_POINTER(state->addr), &size,
+ EFI_DT_APPLY_FIXUPS | EFI_DT_RESERVE_MEMORY);
+ }
+
+ return err;
+}
+
+EFI_STATUS devicetree_install(struct devicetree_state *state, EFI_FILE *root_dir, char16_t *name) {
+ _cleanup_(file_closep) EFI_FILE *handle = NULL;
+ _cleanup_free_ EFI_FILE_INFO *info = NULL;
+ UINTN len;
+ EFI_STATUS err;
+
+ assert(state);
+ assert(root_dir);
+ assert(name);
+
+ state->orig = get_dtb_table();
+ if (!state->orig)
+ return EFI_UNSUPPORTED;
+
+ err = root_dir->Open(root_dir, &handle, name, EFI_FILE_MODE_READ, EFI_FILE_READ_ONLY);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ err = get_file_info_harder(handle, &info, NULL);
+ if (err != EFI_SUCCESS)
+ return err;
+ if (info->FileSize < FDT_V1_SIZE || info->FileSize > 32 * 1024 * 1024)
+ /* 32MB device tree blob doesn't seem right */
+ return EFI_INVALID_PARAMETER;
+
+ len = info->FileSize;
+
+ err = devicetree_allocate(state, len);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ err = handle->Read(handle, &len, PHYSICAL_ADDRESS_TO_POINTER(state->addr));
+ if (err != EFI_SUCCESS)
+ return err;
+
+ err = devicetree_fixup(state, len);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ return BS->InstallConfigurationTable(&EfiDtbTableGuid, PHYSICAL_ADDRESS_TO_POINTER(state->addr));
+}
+
+EFI_STATUS devicetree_install_from_memory(struct devicetree_state *state,
+ const void *dtb_buffer, UINTN dtb_length) {
+
+ EFI_STATUS err;
+
+ assert(state);
+ assert(dtb_buffer && dtb_length > 0);
+
+ state->orig = get_dtb_table();
+ if (!state->orig)
+ return EFI_UNSUPPORTED;
+
+ err = devicetree_allocate(state, dtb_length);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ memcpy(PHYSICAL_ADDRESS_TO_POINTER(state->addr), dtb_buffer, dtb_length);
+
+ err = devicetree_fixup(state, dtb_length);
+ if (err != EFI_SUCCESS)
+ return err;
+
+ return BS->InstallConfigurationTable(&EfiDtbTableGuid, PHYSICAL_ADDRESS_TO_POINTER(state->addr));
+}
+
+void devicetree_cleanup(struct devicetree_state *state) {
+ EFI_STATUS err;
+
+ if (!state->pages)
+ return;
+
+ err = BS->InstallConfigurationTable(&EfiDtbTableGuid, state->orig);
+ /* don't free the current device tree if we can't reinstate the old one */
+ if (err != EFI_SUCCESS)
+ return;
+
+ BS->FreePages(state->addr, state->pages);
+ state->pages = 0;
+}