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arch/x86/walkcbfs.S: Use FMAP instead of "cbfs master header" 

Tested on qemu/i440fx on X86_64:
- Page tables are found in cbfs (finding a file works)
- returns 0 when a file is not found
- works when there is no cbfs file at the start of the FMAP, e.g. with
  the cbfs master header removed.

Change-Id: Ibab657cc40cd5c09c3a73c54950b98ac45a98dbf
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52879
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Arthur Heymans 2021-05-04 08:46:58 +02:00 committed by Patrick Georgi
parent a033d8c808
commit 50ece62d3c
2 changed files with 6 additions and 25 deletions
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1
src/arch/x86/Makefile.inc
View File

@ -91,6 +91,7 @@ else
$(eval $(call early_x86_stage,bootblock,elf64-x86-64))
endif
$(call src-to-obj,bootblock,$(dir)/walkcbfs.S): $(obj)/fmap_config.h
bootblock-y += walkcbfs.S
endif # CONFIG_ARCH_BOOTBLOCK_X86_32 / CONFIG_ARCH_BOOTBLOCK_X86_64

30
src/arch/x86/walkcbfs.S
View File

@ -1,13 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#define CBFS_HEADER_PTR 0xfffffffc
#define CBFS_HEADER_MAGIC 0
#define CBFS_HEADER_VERSION (CBFS_HEADER_MAGIC + 4)
#define CBFS_HEADER_ROMSIZE (CBFS_HEADER_VERSION + 4)
#define CBFS_HEADER_BOOTBLOCKSIZE (CBFS_HEADER_ROMSIZE + 4)
#define CBFS_HEADER_ALIGN (CBFS_HEADER_BOOTBLOCKSIZE + 4)
#define CBFS_HEADER_OFFSET (CBFS_HEADER_ALIGN + 4)
#include <fmap_config.h>
/* we use this instead of CBFS_HEADER_ALIGN because the latter is retired. */
#define CBFS_ALIGNMENT 64
@ -33,14 +26,7 @@
walkcbfs_asm:
cld
mov CBFS_HEADER_PTR, %eax
mov CBFS_HEADER_ROMSIZE(%eax), %ecx
bswap %ecx
mov $0, %ebx
sub %ecx, %ebx /* ROM base address in ebx */
mov CBFS_HEADER_OFFSET(%eax), %ecx
bswap %ecx
add %ecx, %ebx /* address where we start looking for LARCHIVEs */
movl $FMAP_SECTION_COREBOOT_START, %ebx
/* determine filename length */
mov $0, %eax
@ -96,17 +82,11 @@ tryharder:
mov %ecx, %ebx
check_for_exit:
/* look if we should exit: did we pass into the bootblock already? */
mov CBFS_HEADER_PTR, %ecx
mov CBFS_HEADER_BOOTBLOCKSIZE(%ecx), %ecx
bswap %ecx
not %ecx
add $1, %ecx
/* if addr <= COREBOOT_END - 1, continue */
#define FMAP_SECTION_COREBOOT_END (FMAP_SECTION_COREBOOT_START - 1 + FMAP_SECTION_COREBOOT_SIZE)
movl $FMAP_SECTION_COREBOOT_END, %ecx
cmp %ecx, %ebx
/* if bootblockstart >= addr (==we're still in the data area),
* jump back
*/
jbe walker
out: