On 3/5/21 11:22 PM, Ilias Apalodimas wrote:
On the following patches we allow for an initrd path to be stored in
Boot#### variables. Specifically we encode in the FIlePathList[] of
the EFI_LOAD_OPTIONS for each Boot#### variable.
The FilePathList[] array looks like this:
kernel - 0xff - VenMedia(initrd GUID) - 0x01 - initrd1 - 0x01 initrd2 -0xff
So let's add the relevant functions to concatenate and retrieve a device
path based on a Vendor GUID.
Signed-off-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
---
include/efi_loader.h | 4 ++
lib/efi_loader/efi_device_path.c | 72 ++++++++++++++++++++++++++++++++
2 files changed, 76 insertions(+)
diff --git a/include/efi_loader.h b/include/efi_loader.h
index f470bbd636f4..eb11a8c7d4b1 100644
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -738,6 +738,10 @@ struct efi_load_option {
const u8 *optional_data;
};
+struct efi_device_path *efi_dp_from_lo(struct efi_load_option *lo,
+ efi_uintn_t *size, efi_guid_t guid);
+struct efi_device_path *efi_dp_concat(const struct efi_device_path *dp1,
+ const struct efi_device_path *dp2);
efi_status_t efi_deserialize_load_option(struct efi_load_option *lo, u8 *data,
efi_uintn_t *size);
unsigned long efi_serialize_load_option(struct efi_load_option *lo, u8
**data);
diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index c9315dd45857..cf1321828e87 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -310,6 +310,41 @@ struct efi_device_path *efi_dp_append(const struct
efi_device_path *dp1,
return ret;
}
+/** efi_dp_concat() - Concatenate 2 device paths. The final device path will
contain
+ * two device paths separated by and end node (0xff).
+ *
+ * @dp1: First device path
+ * @size: Second device path
+ *
+ * Return: concatenated device path or NULL. Caller must free the returned
value
+ */
+struct efi_device_path *efi_dp_concat(const struct efi_device_path *dp1,
+ const struct efi_device_path *dp2)
+{
+ struct efi_device_path *ret;
+ efi_uintn_t sz1, sz2;
+ void *p;
+
+ if (!dp1 || !dp2)
+ return NULL;
+ sz1 = efi_dp_size(dp1);
+ sz2 = efi_dp_size(dp2);
+ p = dp_alloc(sz1 + sz2 + (2 * sizeof(END)));
+ /* both dp1 and dp2 are non-null */
+ if (!p)
+ return NULL;
+ ret = p;
+ memcpy(p, dp1, sz1);
+ p += sz1;
+ memcpy(p, &END, sizeof(END));
+ p += sizeof(END);
+ memcpy(p, dp2, sz2);
+ p += sz2;
+ memcpy(p, &END, sizeof(END));
+
+ return ret;
+}
+
struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
const struct efi_device_path *node)
{
@@ -1160,3 +1195,40 @@ ssize_t efi_dp_check_length(const struct efi_device_path
*dp,
dp = (const struct efi_device_path *)((const u8 *)dp + len);
}
}
+
+/**
+ * efi_dp_from_lo() - Get the instance of a Vendor Device Path
+ * in a multi-instance device path that matches
+ * a specific GUID
The description does make it clear that you are looking for a VenMedia()
node.
Please, describe what the function is good for (find the device path for
an initrd or dtb in a load option).
+ *
+ * @load_option: device paths to search
+ * @size: size of the discovered device path
+ * @guid: guid to search for
+ *
+ * Return: device path or NULL. Caller must free the returned value
Please, keep the text aligned.
Do we need a copy? Isn't a pointer good enough?
+ */
+struct
+efi_device_path *efi_dp_from_lo(struct efi_load_option *lo,
+ efi_uintn_t *size, efi_guid_t guid)
+{
+ struct efi_device_path *fp = lo->file_path;
+ struct efi_device_path_vendor *vendor;
+ int lo_len = lo->file_path_length;
+
+ while (lo_len) {
lo_len must be at least sizeof(struct efi_device_path).
+ if (fp->type != DEVICE_PATH_TYPE_MEDIA_DEVICE ||
+ fp->sub_type != DEVICE_PATH_SUB_TYPE_VENDOR_PATH) {
+ lo_len -= fp->length;
Could the last device path in the array be followed by zero bytes for
padding?
Should we check that fp->length >= sizeof(struct efi_device_path)?
+ fp = (void *)fp + fp->length;
Please, avoid code duplication.
E.g.
for (; lo_len >= sizeof(struct efi_device_path);
lo_len -= fp->length, fp = (void *)fp + fp->length) {
+ continue;
+ }
+
+ vendor = (struct efi_device_path_vendor *)fp;
+ if (!guidcmp(&vendor->guid, &guid))
+ return efi_dp_dup(fp);
Should we strip of the VenMedia() node here?
Best regards
Heinrich
+ lo_len -= fp->length;
+ fp = (void *)fp + fp->length;
+ }
+
+ return NULL;
+}
