efi/libstub: Rewrite file I/O routine

The file I/O routine that is used to load initrd or dtb files from
the EFI system partition suffers from a few issues:
- it converts the u8[] command line back to a UTF-16 string, which is
  pointless since we only handle initrd or dtb arguments provided via
  the loaded image protocol anyway, which is where we got the UTF-16[]
  command line from in the first place when booting via the PE entry
  point,
- in the far majority of cases, only a single initrd= option is present,
  but it optimizes for multiple options, by going over the command line
  twice, allocating heap buffers for dynamically sized arrays, etc.
- the coding style is hard to follow, with few comments, and all logic
  including string parsing etc all combined in a single routine.

Let's fix this by rewriting most of it, based on the idea that in the
case of multiple initrds, we can just allocate a new, bigger buffer
and copy over the data before freeing the old one.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index e057d509d5d8..60d929469b8b 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -327,7 +327,7 @@ typedef struct {
 	efi_time_t		last_access_time;
 	efi_time_t		modification_time;
 	__aligned_u64		attribute;
-	efi_char16_t		filename[1];
+	efi_char16_t		filename[];
 } efi_file_info_t;
 
 typedef struct efi_file_protocol efi_file_protocol_t;
@@ -607,15 +607,18 @@ efi_status_t efi_relocate_kernel(unsigned long *image_addr,
 				 unsigned long alignment,
 				 unsigned long min_addr);
 
-efi_status_t handle_cmdline_files(efi_loaded_image_t *image,
-				  char *cmd_line, char *option_string,
-				  unsigned long max_addr,
-				  unsigned long *load_addr,
-				  unsigned long *load_size);
-
 efi_status_t efi_parse_options(char const *cmdline);
 
 efi_status_t efi_setup_gop(struct screen_info *si, efi_guid_t *proto,
 			   unsigned long size);
 
+efi_status_t efi_load_dtb(efi_loaded_image_t *image,
+			  unsigned long *load_addr,
+			  unsigned long *load_size);
+
+efi_status_t efi_load_initrd(efi_loaded_image_t *image,
+			     unsigned long *load_addr,
+			     unsigned long *load_size,
+			     unsigned long max_addr);
+
 #endif