[coreboot-gerrit] New patch to review for coreboot: 4db4b86 libpayload: arm: add code to clear bss

[Marc Jones (marc.jones@se-eng.com)]

Marc Jones (marc.jones at se-eng.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/8060

-gerrit

commit 4db4b86fb5eeb24ee06cc798ab2f2f328df1c1fe
Author: Vadim Bendebury <vbendeb at chromium.org>
Date:   Tue May 27 16:16:50 2014 -0700

    libpayload: arm: add code to clear bss
    
    This adds some assembly code to clear .bss segment. It might have been
    already cleared by the loader, but it is not guaranteed. This also
    helps when the program is loaded by the debugger.
    
    BUG=none
    TEST=observed that .bss is now initialized when the program is
         restarted. Verified correct boundaries of the segment.
    
    Original-Change-Id: I0aed0070da53881e4cf8c27049459040c006e765
    Original-Signed-off-by: Vadim Bendebury <vbendeb at chromium.org>
    Original-Reviewed-on: https://chromium-review.googlesource.com/201784
    Original-Reviewed-by: Vincent Palatin <vpalatin at chromium.org>
    Original-Reviewed-by: Trevor Bourget <tbourget at codeaurora.org>
    (cherry picked from commit c89ecee5ddfc33a438d4d1926d3756a48f3c2576)
    Signed-off-by: Marc Jones <marc.jones at se-eng.com>
    
    Change-Id: Ic0c33d2a8ad22cd23b3ccb73c603cb14ae2aab29
---
 payloads/libpayload/arch/arm/head.S | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/payloads/libpayload/arch/arm/head.S b/payloads/libpayload/arch/arm/head.S
index c5c96ea..788e328 100644
--- a/payloads/libpayload/arch/arm/head.S
+++ b/payloads/libpayload/arch/arm/head.S
@@ -34,14 +34,25 @@
  */
 ENTRY(_entry)
 
+	/* TODO: disable interrupts */
+
+	/* Clear BSS */
+	mov r12, #0
+	ldr r2, bss_boundaries
+	ldr r3, bss_boundaries + 4
+	cmp r2, r3
+	beq no_bss
+
+	sub r3, #4 /* Account for late condition check. */
+loop:
+	cmp r2, r3
+	str r12, [r2], #4
+	blt loop
+no_bss:
 	/* Save off the location of the coreboot tables */
 	ldr r1, 1f
 	str r0, [r1]
 
-	/* TODO: disable interrupts */
-
-	/* TODO: Clear BSS */
-
 	/* Setup new stack */
 	ldr sp, 2f
 
@@ -59,6 +70,9 @@ ENTRY(_entry)
 ENDPROC(_entry)
 
 .align 4
+bss_boundaries:
+	.word _edata
+	.word _end
 1:
 .word	cb_header_ptr
 2: