740a3e677b
This enables the same functionality that sh64 has for sh32. When running on simulated hardware or via remote memory via the debug interface, memory is gauranteed to be zero on boot already, and skipping the zeroing of BSS has measurable boot time benefits. Signed-off-by: Paul Mundt <lethal@linux-sh.org>
132 lines
2.9 KiB
ArmAsm
132 lines
2.9 KiB
ArmAsm
/* $Id: head.S,v 1.7 2003/09/01 17:58:19 lethal Exp $
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*
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* arch/sh/kernel/head.S
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*
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* Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Head.S contains the SH exception handlers and startup code.
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*/
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#include <linux/linkage.h>
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#include <asm/thread_info.h>
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#ifdef CONFIG_CPU_SH4A
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#define SYNCO() synco
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#define PREFI(label, reg) \
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mov.l label, reg; \
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prefi @reg
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#else
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#define SYNCO()
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#define PREFI(label, reg)
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#endif
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.section .empty_zero_page, "aw"
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ENTRY(empty_zero_page)
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.long 1 /* MOUNT_ROOT_RDONLY */
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.long 0 /* RAMDISK_FLAGS */
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.long 0x0200 /* ORIG_ROOT_DEV */
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.long 1 /* LOADER_TYPE */
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.long 0x00000000 /* INITRD_START */
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.long 0x00000000 /* INITRD_SIZE */
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#ifdef CONFIG_32BIT
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.long 0x53453f00 + 32 /* "SE?" = 32 bit */
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#else
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.long 0x53453f00 + 29 /* "SE?" = 29 bit */
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#endif
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1:
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.skip PAGE_SIZE - empty_zero_page - 1b
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.section .text.head, "ax"
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/*
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* Condition at the entry of _stext:
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*
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* BSC has already been initialized.
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* INTC may or may not be initialized.
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* VBR may or may not be initialized.
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* MMU may or may not be initialized.
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* Cache may or may not be initialized.
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* Hardware (including on-chip modules) may or may not be initialized.
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*
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*/
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ENTRY(_stext)
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! Initialize Status Register
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mov.l 1f, r0 ! MD=1, RB=0, BL=0, IMASK=0xF
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ldc r0, sr
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! Initialize global interrupt mask
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#ifdef CONFIG_CPU_HAS_SR_RB
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mov #0, r0
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ldc r0, r6_bank
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#endif
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/*
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* Prefetch if possible to reduce cache miss penalty.
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*
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* We do this early on for SH-4A as a micro-optimization,
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* as later on we will have speculative execution enabled
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* and this will become less of an issue.
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*/
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PREFI(5f, r0)
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PREFI(6f, r0)
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!
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mov.l 2f, r0
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mov r0, r15 ! Set initial r15 (stack pointer)
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#ifdef CONFIG_CPU_HAS_SR_RB
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mov.l 7f, r0
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ldc r0, r7_bank ! ... and initial thread_info
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#endif
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#ifndef CONFIG_SH_NO_BSS_INIT
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/*
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* Don't clear BSS if running on slow platforms such as an RTL simulation,
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* remote memory via SHdebug link, etc. For these the memory can be guaranteed
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* to be all zero on boot anyway.
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*/
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! Clear BSS area
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#ifdef CONFIG_SMP
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mov.l 3f, r0
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cmp/eq #0, r0 ! skip clear if set to zero
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bt 10f
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#endif
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mov.l 3f, r1
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add #4, r1
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mov.l 4f, r2
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mov #0, r0
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9: cmp/hs r2, r1
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bf/s 9b ! while (r1 < r2)
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mov.l r0,@-r2
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10:
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#endif
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! Additional CPU initialization
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mov.l 6f, r0
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jsr @r0
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nop
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SYNCO() ! Wait for pending instructions..
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! Start kernel
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mov.l 5f, r0
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jmp @r0
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nop
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.balign 4
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#if defined(CONFIG_CPU_SH2)
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1: .long 0x000000F0 ! IMASK=0xF
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#else
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1: .long 0x400080F0 ! MD=1, RB=0, BL=0, FD=1, IMASK=0xF
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#endif
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ENTRY(stack_start)
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2: .long init_thread_union+THREAD_SIZE
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3: .long __bss_start
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4: .long _end
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5: .long start_kernel
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6: .long sh_cpu_init
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7: .long init_thread_union
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