ARC: optimize kernel bss clearing in early boot code

using ARC ZOL which reduces tot num of instructions by half

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S
index 07a58f2..4d2481b 100644 (file)
--- a/arch/arc/kernel/head.S
+++ b/arch/arc/kernel/head.S
@@ -77,10 +77,11 @@ stext:
        ; Clear BSS before updating any globals
        ; XXX: use ZOL here
        mov     r5, __bss_start
-       mov     r6, __bss_stop
+       sub     r6, __bss_stop, r5
+       lsr.f   lp_count, r6, 2
+       lpnz    1f
+       st.ab   0, [r5, 4]
 1:
-       st.ab   0, [r5,4]
-       brlt    r5, r6, 1b
 
        ; Uboot - kernel ABI
        ;    r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2

diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
index 2555f58..dd35bde 100644 (file)
--- a/arch/arc/kernel/vmlinux.lds.S
+++ b/arch/arc/kernel/vmlinux.lds.S
@@ -116,7 +116,7 @@ SECTIONS
 
        _edata = .;
 
-       BSS_SECTION(0, 0, 0)
+       BSS_SECTION(4, 4, 4)
 
 #ifdef CONFIG_ARC_DW2_UNWIND
        . = ALIGN(PAGE_SIZE);