[U-Boot-Users] [PATCH] API: Optimize signature searching scheme in the glue layer.

[Rafal Jaworowski]

De-hard code the range in RAM we search for API signature, which might not be
uniform accross architectures and board configurations. Instead use current
global_data pointer as a hint to narrow down the range the [malloc'ed] signature
could reside.

Signed-off-by: Rafal Czubak <rcz at semihalf.com>
Signed-off-by: Rafal Jaworowski <raj at semihalf.com>
---
 api_examples/crt0.S |   17 +++++++++++------
 api_examples/glue.c |   17 ++++++++++++-----
 api_examples/glue.h |    6 +++---
 3 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/api_examples/crt0.S b/api_examples/crt0.S
index 8d4f706..80b7297 100644
--- a/api_examples/crt0.S
+++ b/api_examples/crt0.S
@@ -24,14 +24,16 @@
  */
 
 #if defined(CONFIG_PPC)
-
 	.text
 
 	.globl _start
 _start:
+	/* Store global data ptr as a hint for U-Boot address range */
+	lis	%r11, gd_ptr at ha
+	addi	%r11, %r11, gd_ptr at l
+	stw	%r2, 0(%r11)
 	b	main
 
-
 	.globl syscall
 syscall:
 	lis	%r11, syscall_ptr at ha
@@ -39,12 +41,15 @@ syscall:
 	lwz	%r11, 0(%r11)
 	mtctr	%r11
 	bctr
-
+#else
+#error No support for this arch!
+#endif
 
 	.globl syscall_ptr
 syscall_ptr:
 	.align	4
 	.long	0
-#else
-#error No support for this arch!
-#endif
+
+	.globl gd_ptr
+gd_ptr:
+	.long	0
diff --git a/api_examples/glue.c b/api_examples/glue.c
index 2bf47ae..7218b86 100644
--- a/api_examples/glue.c
+++ b/api_examples/glue.c
@@ -1,5 +1,5 @@
 /*
- * (C) Copyright 2007 Semihalf
+ * (C) Copyright 2007-2008 Semihalf
  *
  * Written by: Rafal Jaworowski <raj at semihalf.com>
  *
@@ -57,16 +57,23 @@ static int valid_sig(struct api_signature *sig)
  *
  * returns 1/0 depending on found/not found result
  */
-int api_search_sig(struct api_signature **sig) {
-
+int api_search_sig(struct api_signature **sig)
+{
 	unsigned char *sp;
+	uint32_t start = 0, end = 0;
 
 	if (sig == NULL)
 		return 0;
 
-	sp = (unsigned char *)API_SEARCH_START;
+	if (gd_ptr == NULL)
+		return 0;
+
+	/* Global data ptr helps to narrow down the search range */
+	start = (uint32_t)gd_ptr & ~(API_SEARCH_LEN - 1);
+	end = start + API_SEARCH_LEN - API_SIG_MAGLEN;
 
-	while ((sp + (int)API_SIG_MAGLEN) < (unsigned char *)API_SEARCH_END) {
+	sp = (unsigned char *)start;
+	while ((sp + API_SIG_MAGLEN) < (unsigned char *)end) {
 		if (!memcmp(sp, API_SIG_MAGIC, API_SIG_MAGLEN)) {
 			*sig = (struct api_signature *)sp;
 			if (valid_sig(*sig))
diff --git a/api_examples/glue.h b/api_examples/glue.h
index a82f783..76cb580 100644
--- a/api_examples/glue.h
+++ b/api_examples/glue.h
@@ -30,11 +30,11 @@
 #ifndef _API_GLUE_H_
 #define _API_GLUE_H_
 
-#define API_SEARCH_START	(255 * 1024 * 1024)	/* start at 1MB below top RAM */
-#define API_SEARCH_END		(256 * 1024 * 1024 - 1)	/* ...and search to the end */
+#define API_SEARCH_LEN	(2 * 1024 * 1024)	/* 2MB search range */
 
 int	syscall(int, int *, ...);
-void *	syscall_ptr;
+extern void *syscall_ptr;
+extern gd_t *gd_ptr;
 
 int	api_search_sig(struct api_signature **sig);
 
-- 
1.5.2.2