Implementation of Region API

At present reading data from storage in Vboot is a little fragmented. For
the firmware image, we expect the boot loader to handle this. For the disk
we have a block-level API. For the GBB (which also sits in the firmware
image) we expect the entire thing to be read before Vboot is called.

Add the concept of a region, and an API to read from a region. At present,
and most pressing, is reading from a GBB region. In the future this could
be extended to other parts of the firmware or even the disk.

Move all access to the GBB into this API so that the boot loader can provide
either a GBB region in one large contiguous chunk, or a function to deal with
read requests from vboot.

The call to VbExRegionRead() is behind a flag since not all boot loaders
support it yet.

The main change for boot loaders which don't support this new API is that
vboot will do more behind the scenes. For example, it will allocate memory
for chunks of data that it reads from the GBB, rather than just accessing it
directly. This approach is considerably simpler than trying to pass char **
everywhere and have vboot decide whether something needs to be allocated or
not.

The tests are updated, mainly to include setting up a GBB structure
accessible from VbCommonParams, which is now required by the firmware and
kernel functions. In normal operation this is set up at the start of
VbLoadFIrmware() and VbSelectAndLoadKernel() but for tests which call
children of these functions directly, the GBB structure must be set up
manually by the test.

BUG=chrome-os-partner:21115
BRANCH=none
TEST=manual
FEATURES=test sudo -E  emerge vboot_reference

Change-Id: I2c19e9dc2ed602d0642bbf4f7d27f79fe9fad873
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/63336
Reviewed-by: Randall Spangler <rspangler@chromium.org>

firmware/include/vboot_api.h

@@ -104,6 +104,14 @@ enum VbErrorPredefined_t {
 	VBERROR_VGA_OPROM_MISMATCH            = 0x10021,
 	/* Need EC to reboot to read-only code */
 	VBERROR_EC_REBOOT_TO_RO_REQUIRED      = 0x10022,
+	/* Invalid region read parameters */
+	VBERROR_REGION_READ_INVALID           = 0x10023,
+	/* Cannot read from region */
+	VBERROR_REGION_READ_FAILED            = 0x10024,
+	/* Unsupported region type */
+	VBERROR_UNSUPPORTED_REGION            = 0x10025,
+	/* No image present (returned from VbGbbReadImage() for missing image) */
+	VBERROR_NO_IMAGE_PRESENT              = 0x10026,
 
 	/* VbExEcGetExpectedRWHash() may return the following codes */
 	/* Compute expected RW hash from the EC image; BIOS doesn't have it */
@@ -167,6 +175,10 @@ typedef struct VbCommonParams {
 	 * the stack.
 	 */
 	void *caller_context;
+
+	/* For internal use of Vboot - do not examine or modify! */
+	struct GoogleBinaryBlockHeader *gbb;
+	struct BmpBlockHeader *bmp;
 } VbCommonParams;
 
 /* Flags for VbInitParams.flags */
@@ -827,4 +839,33 @@ enum {
  */
 int VbExLegacy(void);
 
+/* Regions for VbExRegionRead() */
+enum vb_firmware_region {
+	VB_REGION_GBB,	/* Google Binary Block - see gbbheader.h */
+
+	VB_REGION_COUNT,
+};
+
+/**
+ * Read data from a region of the firmware image
+ *
+ * Vboot wants access to a region, to read data from it. This function
+ * reads it (typically from the firmware image such as SPI flash) and
+ * returns the data.
+ *
+ * cparams is passed so that the boot loader has some context for the
+ * operation.
+ *
+ * @param cparams	Common parameters, e.g. use member caller_context
+ *			to point to useful context data
+ * @param region	Firmware region to read
+ * @param offset	Start offset within region
+ * @param size		Number of bytes to read
+ * @param buf		Place to put data
+ * @return VBERROR_... error, VBERROR_SUCCESS on success,
+ */
+VbError_t VbExRegionRead(VbCommonParams *cparams,
+			 enum vb_firmware_region region, uint32_t offset,
+			 uint32_t size, void *buf);
+
 #endif  /* VBOOT_REFERENCE_VBOOT_API_H_ */