cbfs: Introduce cbfs_ro_map() and cbfs_ro_load()

This patch introduces two new CBFS API functions which are equivalent to
cbfs_map() and cbfs_load(), respectively, with the difference that they
always operate on the read-only CBFS region ("COREBOOT" FMAP section).
Use it to replace some of the simple cases that needed to use
cbfs_locate_file_in_region().

Change-Id: I9c55b022b6502a333a9805ab0e4891dd7b97ef7f
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39306
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 9 insertions, 3 deletions

diff --git a/src/include/cbfs.h b/src/include/cbfs.h
index 992b6583ca..8d4c2209d2 100644
--- a/src/include/cbfs.h
+++ b/src/include/cbfs.h
@@ -23,9 +23,12 @@ int cbfs_boot_locate(struct cbfsf *fh, const char *name, uint32_t *type);
    NOTE: Since this may return a direct pointer to memory-mapped hardware,
    compressed files are NOT transparently decompressed (unlike cbfs_load()). */
 void *cbfs_map(const char *name, size_t *size_out);
-/* Removes a mapping previously allocated with cbfs_map(). Should try to unmap
-   mappings in strict LIFO order where possible, since mapping backends often
-   don't support more complicated cases. */
+/* Like cbfs_map(), except that it will always read from the read-only CBFS
+   ("COREBOOT" FMAP region), even when CONFIG(VBOOT) is enabled. */
+void *cbfs_ro_map(const char *name, size_t *size_out);
+/* Removes a previously allocated CBFS mapping. Should try to unmap mappings in
+   strict LIFO order where possible, since mapping backends often don't support
+   more complicated cases. */
 int cbfs_unmap(void *mapping);
 /* Locate file in a specific region of fmap. Return 0 on success. < 0 on error*/
 int cbfs_locate_file_in_region(struct cbfsf *fh, const char *region_name,
@@ -34,6 +37,9 @@ int cbfs_locate_file_in_region(struct cbfsf *fh, const char *region_name,
    success or 0 on error. File will get decompressed as necessary. Same
    decompression requirements as cbfs_load_and_decompress(). */
 size_t cbfs_load(const char *name, void *buf, size_t buf_size);
+/* Like cbfs_load(), except that it will always read from the read-only CBFS
+   ("COREBOOT" FMAP region), even when CONFIG(VBOOT) is enabled. */
+size_t cbfs_ro_load(const char *name, void *buf, size_t buf_size);
 /* Load |in_size| bytes from |rdev| at |offset| to the |buffer_size| bytes
  * large |buffer|, decompressing it according to |compression| in the process.
  * Returns the decompressed file size, or 0 on error.