Patch by Anders Larsen, 09 Jan 2004:

ARM memory layout fixes: the abort-stack is now set up in the
correct RAM area, and the BSS is zeroed out as it should be.

Furthermore, the magic variables 'armboot_end' and 'armboot_end_data'
of the linker scripts are replaced by '__bss_start' and '_end',
resp., which is a further step to eliminate unnecessary differences
between the implementation of the CPU architectures.

2 files changed, 27 insertions, 17 deletions

diff --git a/cpu/arm920t/cpu.c b/cpu/arm920t/cpu.c
index e638c1f8dde..2a2b5780171 100644
--- a/cpu/arm920t/cpu.c
+++ b/cpu/arm920t/cpu.c
@@ -92,7 +92,7 @@ int cpu_init (void)
 #ifdef CONFIG_USE_IRQ
 	DECLARE_GLOBAL_DATA_PTR;
 
-	IRQ_STACK_START = _armboot_start - CFG_MALLOC_LEN - CFG_GBL_DATA_LEN - 4;
+	IRQ_STACK_START = _armboot_start - CFG_MALLOC_LEN - CFG_GBL_DATA_SIZE - 4;
 	FIQ_STACK_START = IRQ_STACK_START - CONFIG_STACKSIZE_IRQ;
 #endif
 	return 0;
diff --git a/cpu/arm920t/start.S b/cpu/arm920t/start.S
index d640942d8aa..49264da9927 100644
--- a/cpu/arm920t/start.S
+++ b/cpu/arm920t/start.S
@@ -80,16 +80,15 @@ _armboot_start:
 	.word _start
 
 /*
- * Note: _armboot_end_data and _armboot_end are defined
- * by the (board-dependent) linker script.
- * _armboot_end_data is the first usable FLASH address after armboot
+ * These are defined in the board-specific linker script.
  */
-.globl _armboot_end_data
-_armboot_end_data:
-	.word armboot_end_data
-.globl _armboot_end
-_armboot_end:
-	.word armboot_end
+.globl _bss_start
+_bss_start:
+	.word __bss_start
+
+.globl _bss_end
+_bss_end:
+	.word _end
 
 #ifdef CONFIG_USE_IRQ
 /* IRQ stack memory (calculated at run-time) */
@@ -170,7 +169,7 @@ relocate:				/* relocate U-Boot to RAM	    */
 	beq     stack_setup
 
 	ldr	r2, _armboot_start
-	ldr	r3, _armboot_end
+	ldr	r3, _bss_start
 	sub	r2, r3, r2		/* r2 <- size of armboot            */
 	add	r2, r0, r2		/* r2 <- source end address         */
 
@@ -190,6 +189,17 @@ stack_setup:
 #endif
 	sub	sp, r0, #12		/* leave 3 words for abort-stack    */
 
+clear_bss:
+	ldr	r0, _bss_start		/* find start of bss segment        */
+	add	r0, r0, #4		/* start at first byte of bss       */
+	ldr	r1, _bss_end		/* stop here                        */
+	mov 	r2, #0x00000000		/* clear                            */
+
+clbss_l:str	r2, [r0]		/* clear loop...                    */
+	add	r0, r0, #4
+	cmp	r0, r1
+	bne	clbss_l
+
 #if 0
 	/* try doing this stuff after the relocation */
 	ldr     r0, =pWTCON
@@ -303,9 +313,9 @@ cpu_init_crit:
 	.macro	bad_save_user_regs
 	sub	sp, sp, #S_FRAME_SIZE
 	stmia	sp, {r0 - r12}			@ Calling r0-r12
-	ldr	r2, _armboot_end
-	add	r2, r2, #CONFIG_STACKSIZE
-	sub	r2, r2, #8
+	ldr	r2, _armboot_start
+	sub	r2, r2, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)
+	sub	r2, r2, #(CFG_GBL_DATA_SIZE+8)  @ set base 2 words into abort stack
 	ldmia	r2, {r2 - r3}			@ get pc, cpsr
 	add	r0, sp, #S_FRAME_SIZE		@ restore sp_SVC
 
@@ -336,9 +346,9 @@ cpu_init_crit:
 	.endm
 
 	.macro get_bad_stack
-	ldr	r13, _armboot_end		@ setup our mode stack
-	add	r13, r13, #CONFIG_STACKSIZE	@ resides at top of normal stack
-	sub	r13, r13, #8
+	ldr	r13, _armboot_start		@ setup our mode stack
+	sub	r13, r13, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)
+	sub	r13, r13, #(CFG_GBL_DATA_SIZE+8) @ reserved a couple spots in abort stack
 
 	str	lr, [r13]			@ save caller lr / spsr
 	mrs	lr, spsr