cmd_bootm.c: Correct BOOTM_ERR_OVERLAP handling

With 35fc84fa1 [Refactor the bootm command to reduce code duplication]
we stopped checking the return value of bootm_load_os (unintentionally!)
and simply returned if we had a non-zero return value from the function.
This broke the valid case of a legacy image file of a single kernel
loaded into an overlapping memory area (the default way of booting
nearly all TI platforms).

The best way to fix this problem in the new code is to make
bootm_load_os be the one to see if we have a problem with this, and if
it's fatal return BOOTM_ERR_RESET and if it's not BOOTM_ERR_OVERLAP, so
that we can avoid calling lmb_reserve() but continue with booting.  We
however still need to handle the other BOOTM_ERR values so re-work
do_bootm_states so that we have an error handler at the bottom we can
goto for problems from bootm_load_os, or problems from the other callers
(as the code was before).  Add a comment to do_bootm_states noting the
existing restriction on negative return values.

Signed-off-by: Tom Rini <trini@ti.com>

---
Changes in v2:
- Rework so that only bootm_load_os and boot_selected_os head down into
  the err case code, and other errors simply return back to the caller.
  Fixes 'spl export'.

common/cmd_bootm.c

@@ -345,8 +345,10 @@ static int bootm_find_other(cmd_tbl_t *cmdtp, int flag, int argc,
 #define BOOTM_ERR_RESET		-1
 #define BOOTM_ERR_OVERLAP	-2
 #define BOOTM_ERR_UNIMPLEMENTED	-3
-static int bootm_load_os(image_info_t os, ulong *load_end, int boot_progress)
+static int bootm_load_os(bootm_headers_t *images, unsigned long *load_end,
+		int boot_progress)
 {
+	image_info_t os = images->os;
 	uint8_t comp = os.comp;
 	ulong load = os.load;
 	ulong blob_start = os.start;
@@ -464,7 +466,17 @@ static int bootm_load_os(image_info_t os, ulong *load_end, int boot_progress)
 		debug("images.os.load = 0x%lx, load_end = 0x%lx\n", load,
 			*load_end);
 
-		return BOOTM_ERR_OVERLAP;
+		/* Check what type of image this is. */
+		if (images->legacy_hdr_valid) {
+			if (image_get_type(&images->legacy_hdr_os_copy)
+					== IH_TYPE_MULTI)
+				puts("WARNING: legacy format multi component image overwritten\n");
+			return BOOTM_ERR_OVERLAP;
+		} else {
+			puts("ERROR: new format image overwritten - must RESET the board to recover\n");
+			bootstage_error(BOOTSTAGE_ID_OVERWRITTEN);
+			return BOOTM_ERR_RESET;
+		}
 	}
 
 	return 0;
@@ -558,6 +570,10 @@ static int boot_selected_os(int argc, char * const argv[], int state,
  * Note that if states contains more than one flag it MUST contain
  * BOOTM_STATE_START, since this handles and consumes the command line args.
  *
+ * Also note that aside from boot_os_fn functions and bootm_load_os no other
+ * functions we store the return value of in 'ret' may use a negative return
+ * value, without special handling.
+ *
  * @param cmdtp		Pointer to bootm command table entry
  * @param flag		Command flags (CMD_FLAG_...)
  * @param argc		Number of subcommand arguments (0 = no arguments)
@@ -599,11 +615,15 @@ static int do_bootm_states(cmd_tbl_t *cmdtp, int flag, int argc,
 	if (!ret && (states & BOOTM_STATE_LOADOS)) {
 		ulong load_end;
 
-		ret = bootm_load_os(images->os, &load_end, 0);
-		if (!ret) {
+		ret = bootm_load_os(images, &load_end, 0);
+		if (ret && ret != BOOTM_ERR_OVERLAP)
+			goto err;
+
+		if (ret == 0)
 			lmb_reserve(&images->lmb, images->os.load,
 				    (load_end - images->os.load));
-		}
+		else if (ret == BOOTM_ERR_OVERLAP)
+			ret = 0;
 	}
 
 	/* Relocate the ramdisk */
@@ -660,34 +680,25 @@ static int do_bootm_states(cmd_tbl_t *cmdtp, int flag, int argc,
 	}
 #endif
 	/* Now run the OS! We hope this doesn't return */
-	if (!ret && (states & BOOTM_STATE_OS_GO))
+	if (!ret && (states & BOOTM_STATE_OS_GO)) {
 		ret = boot_selected_os(argc, argv, BOOTM_STATE_OS_GO,
 				images, boot_fn, &iflag);
+		if (ret)
+			goto err;
+	}
+
+	return ret;
 
 	/* Deal with any fallout */
-	if (ret < 0) {
-		if (ret == BOOTM_ERR_UNIMPLEMENTED) {
-			if (iflag)
-				enable_interrupts();
-			bootstage_error(BOOTSTAGE_ID_DECOMP_UNIMPL);
-			return 1;
-		} else if (ret == BOOTM_ERR_OVERLAP) {
-			if (images->legacy_hdr_valid) {
-				if (image_get_type(&images->legacy_hdr_os_copy)
-						== IH_TYPE_MULTI)
-					puts("WARNING: legacy format multi component image overwritten\n");
-			} else {
-				puts("ERROR: new format image overwritten - must RESET the board to recover\n");
-				bootstage_error(BOOTSTAGE_ID_OVERWRITTEN);
-				ret = BOOTM_ERR_RESET;
-			}
-		}
-		if (ret == BOOTM_ERR_RESET)
-			do_reset(cmdtp, flag, argc, argv);
-	}
+err:
 	if (iflag)
 		enable_interrupts();
-	if (ret)
+
+	if (ret == BOOTM_ERR_UNIMPLEMENTED)
+		bootstage_error(BOOTSTAGE_ID_DECOMP_UNIMPL);
+	else if (ret == BOOTM_ERR_RESET)
+		do_reset(cmdtp, flag, argc, argv);
+	else
 		puts("subcommand not supported\n");
 
 	return ret;