[PATCH v2] bootm: teach handle_decomp_error() about the noload decompression buffer

[Aristo Chen]

For a compressed kernel_noload image, bootm_load_os() allocates a
per-image decompression buffer of ALIGN(image_len * 8, SZ_1M) rather
than the global CONFIG_SYS_BOOTM_LEN. When decompression fails on that
path, handle_decomp_error() still prints

    Image too large: increase CONFIG_SYS_BOOTM_LEN

which is misleading: increasing CONFIG_SYS_BOOTM_LEN does not help
because the smaller per-image buffer is the actual bound. Commit
2ff26c1e378d ("bootm: fix overflow of the noload kernel decompression
buffer") worked around this by printing a follow-up note right after
handle_decomp_error() returned, but the boot log then reads as two
contradictory sentences.

Introduce enum bootm_decomp_limit and pass it into
handle_decomp_error() so the helper picks the right message in one
place. For the per-image path it now prints

    Image too large for the per-image decompression buffer (0x100000 bytes)

quoting the actual buffer size; the global path is unchanged. Drop the
trailing note in bootm_load_os() so only one line is printed.

Suggested-by: Simon Glass <sjg at chromium.org>
Signed-off-by: Aristo Chen <aristo.chen at canonical.com>
Reviewed-by: Tom Rini <trini at konsulko.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
---

Changes in v2:
 - Use %#zx and drop the (ulong) cast on buf_size, which is size_t. (Simon)
 - Reword the per-image "Image too large" message to say
   "per-image decompression buffer" instead of hard-coding
   "kernel_noload", matching the generic name of the enum, and update
   the sample output in the commit message to match. (Simon)
 - Drop the accidental double "noload" in the enum kerneldoc example.
 - Carried Tom's and Simon's Reviewed-by; all above are cosmetic and
   don't change the semantics.

 boot/bootm.c | 38 +++++++++++++++++++++++++++++---------
 1 file changed, 29 insertions(+), 9 deletions(-)

diff --git a/boot/bootm.c b/boot/bootm.c
index 803d6406be4..3bce8586834 100644
--- a/boot/bootm.c
+++ b/boot/bootm.c
@@ -575,6 +575,18 @@ static int bootm_find_other(ulong img_addr, const char *conf_ramdisk,
 #endif /* USE_HOSTC */
 
 #if !defined(USE_HOSTCC) || defined(CONFIG_FIT_SIGNATURE)
+/**
+ * enum bootm_decomp_limit - What bounded the decompression buffer.
+ * @BOOTM_DECOMP_LIMIT_GLOBAL:    Global CONFIG_SYS_BOOTM_LEN limit.
+ * @BOOTM_DECOMP_LIMIT_PER_IMAGE: Per-image buffer sized from the
+ *                                compressed image (e.g. the
+ *                                kernel_noload decompression buffer).
+ */
+enum bootm_decomp_limit {
+	BOOTM_DECOMP_LIMIT_GLOBAL,
+	BOOTM_DECOMP_LIMIT_PER_IMAGE,
+};
+
 /**
  * handle_decomp_error() - display a decompression error
  *
@@ -585,11 +597,14 @@ static int bootm_find_other(ulong img_addr, const char *conf_ramdisk,
  * @comp_type:		Compression type being used (IH_COMP_...)
  * @uncomp_size:	Number of bytes uncompressed
  * @buf_size:		Number of bytes the decompresion buffer was
+ * @limit:		Which allocation actually bounded the buffer, so the
+ *			hint points at the knob the reader can act on
  * @ret:		errno error code received from compression library
  * Return: Appropriate BOOTM_ERR_ error code
  */
 static int handle_decomp_error(int comp_type, size_t uncomp_size,
-			       size_t buf_size, int ret)
+			       size_t buf_size,
+			       enum bootm_decomp_limit limit, int ret)
 {
 	const char *name = genimg_get_comp_name(comp_type);
 
@@ -598,10 +613,15 @@ static int handle_decomp_error(int comp_type, size_t uncomp_size,
 		return BOOTM_ERR_UNIMPLEMENTED;
 
 	if ((comp_type == IH_COMP_GZIP && ret == Z_BUF_ERROR) ||
-	    uncomp_size >= buf_size)
-		printf("Image too large: increase CONFIG_SYS_BOOTM_LEN\n");
-	else
+	    uncomp_size >= buf_size) {
+		if (limit == BOOTM_DECOMP_LIMIT_PER_IMAGE)
+			printf("Image too large for the per-image decompression buffer (%#zx bytes)\n",
+			       buf_size);
+		else
+			printf("Image too large: increase CONFIG_SYS_BOOTM_LEN\n");
+	} else {
 		printf("%s: uncompress error %d\n", name, ret);
+	}
 
 	/*
 	 * The decompression routines are now safe, so will not write beyond
@@ -628,6 +648,7 @@ static int bootm_load_os(struct bootm_headers *images, int boot_progress)
 	ulong image_start = os.image_start;
 	ulong image_len = os.image_len;
 	ulong decomp_len = CONFIG_SYS_BOOTM_LEN;
+	enum bootm_decomp_limit decomp_limit = BOOTM_DECOMP_LIMIT_GLOBAL;
 	ulong flush_start;
 	bool no_overlap;
 	void *load_buf, *image_buf;
@@ -644,6 +665,7 @@ static int bootm_load_os(struct bootm_headers *images, int boot_progress)
 		phys_addr_t addr;
 
 		decomp_len = ALIGN(image_len * 8, SZ_1M);
+		decomp_limit = BOOTM_DECOMP_LIMIT_PER_IMAGE;
 		err = lmb_alloc_mem(LMB_MEM_ALLOC_ANY, SZ_2M, &addr,
 				    decomp_len, LMB_NONE);
 		if (err)
@@ -663,10 +685,7 @@ static int bootm_load_os(struct bootm_headers *images, int boot_progress)
 			   decomp_len, &load_end);
 	if (err) {
 		err = handle_decomp_error(os.comp, load_end - load,
-					  decomp_len, err);
-		if (os.type == IH_TYPE_KERNEL_NOLOAD && os.comp != IH_COMP_NONE)
-			printf("Note: noload decompression buffer is %#lx bytes (not CONFIG_SYS_BOOTM_LEN)\n",
-			       decomp_len);
+					  decomp_len, decomp_limit, err);
 		bootstage_error(BOOTSTAGE_ID_DECOMP_IMAGE);
 		return err;
 	}
@@ -1288,7 +1307,8 @@ static int bootm_host_load_image(const void *fit, int req_image_type,
 	free(load_buf);
 
 	if (ret) {
-		ret = handle_decomp_error(image_comp, load_end - 0, buf_size, ret);
+		ret = handle_decomp_error(image_comp, load_end - 0, buf_size,
+					  BOOTM_DECOMP_LIMIT_GLOBAL, ret);
 		if (ret != BOOTM_ERR_UNIMPLEMENTED)
 			return ret;
 	}
-- 
2.43.0