cpu/intel/fit: Add the FIT table as a separate CBFS file

With CBnT a digest needs to be made of the IBB, Initial BootBlock, in
this case the bootblock. After that a pointer to the BPM, Boot Policy
Manifest, containing the IBB digest needs to be added to the FIT
table.

If the fit table is inside the IBB, updating it with a pointer to the
BPM, would make the digest invalid.
The proper solution is to move the FIT table out of the bootblock.

The FIT table itself does not need to be covered by the digest as it
just contains pointers to structures that can by verified by the
hardware itself, such as microcode and ACMs (Authenticated Code
Modules).

Change-Id: I352e11d5f7717147a877be16a87e9ae35ae14856
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50926
Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Christian Walter <christian.walter@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

3 files changed, 49 insertions, 24 deletions

diff --git a/src/cpu/intel/fit/Makefile.inc b/src/cpu/intel/fit/Makefile.inc
index 3b18e0b6aa..ee6d55885d 100644
--- a/src/cpu/intel/fit/Makefile.inc
+++ b/src/cpu/intel/fit/Makefile.inc
@@ -1,5 +1,20 @@
 bootblock-y += fit.S
 
+# The FIT table is generated as a separate CBFS file.
+# The FIT pointer is reserved in fit.c and updated to point to the 'intel_fit'
+# CBFS file using 'ifittool -F'.
+# With a TOP_SWAP enabled bootblock the FIT pointer at the top swap offset
+# will point to the 'intel_fit_ts' CBFS file.
+
+cbfs-files-y += intel_fit
+intel_fit-file := fit_table.c:struct
+intel_fit-type := raw
+intel_fit-align := 16
+
+$(call add_intermediate, set_fit_ptr, $(IFITTOOL))
+	@printf "    UPDATE-FIT set FIT pointer to table\n"
+	$(IFITTOOL) -f $< -F -n intel_fit -r COREBOOT
+
 FIT_ENTRY=$(call strip_quotes, $(CONFIG_INTEL_TOP_SWAP_FIT_ENTRY_FMAP_REG))
 
 ifneq ($(CONFIG_UPDATE_IMAGE),y) # never update the bootblock
@@ -13,13 +28,23 @@ $(call add_intermediate, add_mcu_fit, $(IFITTOOL))
 # Second FIT in TOP_SWAP bootblock
 ifeq ($(CONFIG_INTEL_ADD_TOP_SWAP_BOOTBLOCK),y)
 
-$(call add_intermediate, add_ts_mcu_fit, $(IFITTOOL))
+$(call add_intermediate, add_ts_mcu_fit, $(IFITTOOL) set_fit_ptr_ts)
 	@printf "    UPDATE-FIT Top Swap: Microcode\n"
 ifneq ($(FIT_ENTRY),)
 	$(IFITTOOL) -f $< -A -n $(FIT_ENTRY) -t 1 -s $(CONFIG_CPU_INTEL_NUM_FIT_ENTRIES) $(TS_OPTIONS) -r COREBOOT
 endif # FIT_ENTRY
 	$(IFITTOOL) -f $< -a -n cpu_microcode_blob.bin -t 1 -s $(CONFIG_CPU_INTEL_NUM_FIT_ENTRIES) $(TS_OPTIONS) -r COREBOOT
 
+cbfs-files-y += intel_fit_ts
+intel_fit_ts-file := fit_table.c:struct
+intel_fit_ts-type := raw
+intel_fit_ts-align := 16
+
+PHONY += set_ts_fit_ptr
+set_ts_fit_ptr: $(obj)/coreboot.pre $(IFITTOOL)
+	@printf "    UPDATE-FIT Top Swap: set FIT pointer to table\n"
+	$(IFITTOOL) -f $< -F -n intel_fit_ts -r COREBOOT -t $(TS_OPTIONS)
+
 endif # CONFIG_INTEL_ADD_TOP_SWAP_BOOTBLOCK
 
 endif # CONFIG_CPU_MICROCODE_CBFS_NONE
diff --git a/src/cpu/intel/fit/fit.S b/src/cpu/intel/fit/fit.S
index afecacdcd8..ca95a90c2f 100644
--- a/src/cpu/intel/fit/fit.S
+++ b/src/cpu/intel/fit/fit.S
@@ -2,29 +2,8 @@
 
 .section ".fit_pointer", "a", @progbits
 	.code32
+/* This will get updated by ifittool later on to point to the cbfs 'intel_fit' file. */
 .global fit_pointer
 fit_pointer:
-.long fit_table
 .long 0
-
-.section .text
-.align 16
-.global fit_table
-.global fit_table_end
-fit_table:
-/* Address for type 0 is '_FIT_   ' */
-.long 0x5449465f
-.long 0x2020205f
-/*
- * There is 1 entry in the table. Other tools will have to update the size
- * and checksum when adding entries.
- */
-.long 0x00000001
-/* Version */
-.word 0x0100
-/* Type 0 with checksum valid. */
-.byte 0x80
-/* Checksum byte - must add to zero. */
-.byte 0x7d
-.fill CONFIG_CPU_INTEL_NUM_FIT_ENTRIES*16
-fit_table_end:
+.long 0
diff --git a/src/cpu/intel/fit/fit_table.c b/src/cpu/intel/fit/fit_table.c
new file mode 100644
index 0000000000..62d624f5b0
--- /dev/null
+++ b/src/cpu/intel/fit/fit_table.c
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <stdint.h>
+
+struct fit_entry {
+	uint8_t address[sizeof(uint64_t)];
+	uint32_t size_reserved;
+	uint16_t version;
+	uint8_t  type_checksum_valid;
+	uint8_t  checksum;
+} __packed;
+
+__attribute((used)) static struct fit_entry fit_table[CONFIG_CPU_INTEL_NUM_FIT_ENTRIES + 1] = {
+	[0] = {
+		.address = {'_', 'F', 'I', 'T', '_', ' ', ' ', ' '},
+		.size_reserved = 1,
+		.version = 0x100,
+		.type_checksum_valid = 0x80,
+		.checksum = 0x7d,
+	}
+};