File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S
new file mode 100644
index 0000000..689dd86
--- /dev/null
+++ b/arch/arc/kernel/head.S
@@ -0,0 +1,135 @@
+/*
+ * ARC CPU startup Code
+ *
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Vineetg: Dec 2007
+ * -Check if we are running on Simulator or on real hardware
+ * to skip certain things during boot on simulator
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/entry.h>
+#include <asm/arcregs.h>
+#include <asm/cache.h>
+
+.macro CPU_EARLY_SETUP
+
+ ; Setting up Vectror Table (in case exception happens in early boot
+ sr @_int_vec_base_lds, [AUX_INTR_VEC_BASE]
+
+ ; Disable I-cache/D-cache if kernel so configured
+ lr r5, [ARC_REG_IC_BCR]
+ breq r5, 0, 1f ; I$ doesn't exist
+ lr r5, [ARC_REG_IC_CTRL]
+#ifdef CONFIG_ARC_HAS_ICACHE
+ bclr r5, r5, 0 ; 0 - Enable, 1 is Disable
+#else
+ bset r5, r5, 0 ; I$ exists, but is not used
+#endif
+ sr r5, [ARC_REG_IC_CTRL]
+
+1:
+ lr r5, [ARC_REG_DC_BCR]
+ breq r5, 0, 1f ; D$ doesn't exist
+ lr r5, [ARC_REG_DC_CTRL]
+ bclr r5, r5, 6 ; Invalidate (discard w/o wback)
+#ifdef CONFIG_ARC_HAS_DCACHE
+ bclr r5, r5, 0 ; Enable (+Inv)
+#else
+ bset r5, r5, 0 ; Disable (+Inv)
+#endif
+ sr r5, [ARC_REG_DC_CTRL]
+
+1:
+.endm
+
+ .section .init.text, "ax",@progbits
+
+;----------------------------------------------------------------
+; Default Reset Handler (jumped into from Reset vector)
+; - Don't clobber r0,r1,r2 as they might have u-boot provided args
+; - Platforms can override this weak version if needed
+;----------------------------------------------------------------
+WEAK(res_service)
+ j stext
+END(res_service)
+
+;----------------------------------------------------------------
+; Kernel Entry point
+;----------------------------------------------------------------
+ENTRY(stext)
+
+ CPU_EARLY_SETUP
+
+#ifdef CONFIG_SMP
+ GET_CPU_ID r5
+ cmp r5, 0
+ mov.nz r0, r5
+#ifdef CONFIG_ARC_SMP_HALT_ON_RESET
+ ; Non-Master can proceed as system would be booted sufficiently
+ jnz first_lines_of_secondary
+#else
+ ; Non-Masters wait for Master to boot enough and bring them up
+ jnz arc_platform_smp_wait_to_boot
+#endif
+ ; Master falls thru
+#endif
+
+ ; Clear BSS before updating any globals
+ ; XXX: use ZOL here
+ mov r5, __bss_start
+ sub r6, __bss_stop, r5
+ lsr.f lp_count, r6, 2
+ lpnz 1f
+ st.ab 0, [r5, 4]
+1:
+
+#ifdef CONFIG_ARC_UBOOT_SUPPORT
+ ; Uboot - kernel ABI
+ ; r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
+ ; r1 = magic number (board identity, unused as of now
+ ; r2 = pointer to uboot provided cmdline or external DTB in mem
+ ; These are handled later in setup_arch()
+ st r0, [@uboot_tag]
+ st r2, [@uboot_arg]
+#endif
+
+ ; setup "current" tsk and optionally cache it in dedicated r25
+ mov r9, @init_task
+ SET_CURR_TASK_ON_CPU r9, r0 ; r9 = tsk, r0 = scratch
+
+ ; setup stack (fp, sp)
+ mov fp, 0
+
+ ; tsk->thread_info is really a PAGE, whose bottom hoists stack
+ GET_TSK_STACK_BASE r9, sp ; r9 = tsk, sp = stack base(output)
+
+ j start_kernel ; "C" entry point
+END(stext)
+
+#ifdef CONFIG_SMP
+;----------------------------------------------------------------
+; First lines of code run by secondary before jumping to 'C'
+;----------------------------------------------------------------
+ .section .text, "ax",@progbits
+ENTRY(first_lines_of_secondary)
+
+ ; setup per-cpu idle task as "current" on this CPU
+ ld r0, [@secondary_idle_tsk]
+ SET_CURR_TASK_ON_CPU r0, r1
+
+ ; setup stack (fp, sp)
+ mov fp, 0
+
+ ; set it's stack base to tsk->thread_info bottom
+ GET_TSK_STACK_BASE r0, sp
+
+ j start_kernel_secondary
+END(first_lines_of_secondary)
+#endif