efi: prefer plan9.ini from ESP we loaded from

currently the EFI loader's behavior is to search all disks in a
firmware-defined order.  we search the list returned by the firmware
in reverse order in the hopes of searching the first 9FAT instead of
the ESP, but this results in unintuitive behavior when there are
multiple FAT partitions (possibly in multiple disks), such as loading
a plan9.ini and kernel from a different disk than the one you executed
the EFI loader from.

to resolve this, we change the EFI loader to instead prefer read
plan9.ini and the kernel from the same disk as the EFI loader was read
from, and then fall back to the old behavior, since the old behavior
is relied on by current installations.

3 files changed, 51 insertions, 3 deletions

diff --git a/sys/src/boot/efi/efi.h b/sys/src/boot/efi/efi.h
index b78040f3d..aa411c63b 100644
--- a/sys/src/boot/efi/efi.h
+++ b/sys/src/boot/efi/efi.h
@@ -49,6 +49,22 @@ typedef struct {
 } EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL;
 
 typedef struct {
+	UINT32		Revision;
+	EFI_HANDLE	ParentHandle;
+	void		*SystemTable;
+	EFI_HANDLE	DeviceHandle;
+	void		*FilePath;
+	void		*Reserved;
+	UINT32		LoadOptionsSize;
+	void		*LoadOptions;
+	void		*ImageBase;
+	UINT64		ImageSize;
+	UINT32		ImageCodeType;
+	UINT32		ImageDataType;
+	void		*Unload;
+} EFI_LOADED_IMAGE_PROTOCOL;
+
+typedef struct {
 	UINT32		RedMask;
 	UINT32		GreenMask;
 	UINT32		BlueMask;
diff --git a/sys/src/boot/efi/fs.c b/sys/src/boot/efi/fs.c
index 5a13b3b6a..807dbdbcb 100644
--- a/sys/src/boot/efi/fs.c
+++ b/sys/src/boot/efi/fs.c
@@ -32,6 +32,12 @@ EFI_GUID EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID = {
 	0xc9, 0x69, 0x72, 0x3b,
 };
 
+static EFI_GUID EFI_LOADED_IMAGE_PROTOCOL_GUID = {
+	0x5b1b31a1, 0x9562, 0x11d2,
+	0x8e, 0x3f, 0x00, 0xa0,
+	0xc9, 0x69, 0x72, 0x3b,
+};
+
 static
 EFI_FILE_PROTOCOL *fsroot;
 
@@ -87,12 +93,37 @@ int
 fsinit(void **pf)
 {
 	EFI_SIMPLE_FILE_SYSTEM_PROTOCOL *fs;
+	EFI_LOADED_IMAGE_PROTOCOL *image;
 	EFI_FILE_PROTOCOL *root;
 	EFI_HANDLE *Handles;
 	void *f;
 	UINTN Count;
 	int i;
 
+	image = nil;
+
+	/* locate kernel and plan9.ini by deriving a fs protocol
+	 * from the device the loader was read from.
+	 * if that fails, fall back to old method.
+	 */
+	if(eficall(ST->BootServices->HandleProtocol, IH,
+		&EFI_LOADED_IMAGE_PROTOCOL_GUID, &image) == 0 &&
+		eficall(ST->BootServices->HandleProtocol, image->DeviceHandle,
+		&EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID, &fs) == 0 &&
+		eficall(fs->OpenVolume, fs, &root) == 0){
+
+		fsroot = root;
+		f = fsopen("/plan9.ini");
+		if(f != nil){
+			if(pf != nil)
+				*pf = f;
+			else
+				fsclose(f);
+
+			goto gotit;
+		}
+	}
+
 	Count = 0;
 	Handles = nil;
 	if(eficall(ST->BootServices->LocateHandleBuffer,
@@ -126,6 +157,7 @@ fsinit(void **pf)
 	if(fsroot == nil)
 		return -1;
 
+gotit:
 	read = fsread;
 	close = fsclose;
 	open = fsopen;
diff --git a/sys/src/boot/efi/iso.c b/sys/src/boot/efi/iso.c
index 05b54ca4a..74e414a19 100644
--- a/sys/src/boot/efi/iso.c
+++ b/sys/src/boot/efi/iso.c
@@ -62,7 +62,7 @@ typedef struct {
 } EFI_BLOCK_IO_PROTOCOL;
 
 static EFI_GUID
-EFI_BLOCK_IO_PROTOCO_GUID = {
+EFI_BLOCK_IO_PROTOCOL_GUID = {
 	0x964e5b21, 0x6459, 0x11d2,
 	0x8e, 0x39, 0x00, 0xa0,
 	0xc9, 0x69, 0x72, 0x3b,
@@ -191,13 +191,13 @@ isoinit(void **fp)
 	Count = 0;
 	Handles = nil;
 	if(eficall(ST->BootServices->LocateHandleBuffer,
-		ByProtocol, &EFI_BLOCK_IO_PROTOCO_GUID, nil, &Count, &Handles))
+		ByProtocol, &EFI_BLOCK_IO_PROTOCOL_GUID, nil, &Count, &Handles))
 		return -1;
 
 	for(i=0; i<Count; i++){
 		bio = nil;
 		if(eficall(ST->BootServices->HandleProtocol,
-			Handles[i], &EFI_BLOCK_IO_PROTOCO_GUID, &bio))
+			Handles[i], &EFI_BLOCK_IO_PROTOCOL_GUID, &bio))
 			continue;
 	
 		media = bio->Media;