Hexagon: Add startup code
Signed-off-by: Richard Kuo <rkuo@codeaurora.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Richard Kuo
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Linus Torvalds
Linus Torvalds
parent
4b30f9652e
commit
e03167b26b
162
arch/hexagon/kernel/head.S
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162
arch/hexagon/kernel/head.S
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/*
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* Early kernel startup code for Hexagon
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*
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* Copyright (c) 2010-2011, Code Aurora Forum. All rights reserved.
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 and
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* only version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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#include <linux/linkage.h>
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#include <linux/init.h>
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#include <asm/asm-offsets.h>
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#include <asm/mem-layout.h>
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#include <asm/vm_mmu.h>
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#include <asm/page.h>
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__INIT
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ENTRY(stext)
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/*
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* VMM will already have set up true vector page, MMU, etc.
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* To set up initial kernel identity map, we have to pass
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* the VMM a pointer to some canonical page tables. In
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* this implementation, we're assuming that we've got
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* them precompiled. Generate value in R24, as we'll need
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* it again shortly.
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*/
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r24.L = #LO(swapper_pg_dir)
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r24.H = #HI(swapper_pg_dir)
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/*
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* Symbol is kernel segment address, but we need
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* the logical/physical address.
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*/
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r24 = asl(r24, #2)
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r24 = lsr(r24, #2)
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r0 = r24
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/*
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* Initialize a 16MB PTE to make the virtual and physical
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* addresses where the kernel was loaded be identical.
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*/
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#define PTE_BITS ( __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X \
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| __HEXAGON_C_WB_L2 << 6 \
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| __HVM_PDE_S_4MB)
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r1 = pc
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r2.H = #0xffc0
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r2.L = #0x0000
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r1 = and(r1,r2) /* round PC to 4MB boundary */
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r2 = lsr(r1, #22) /* 4MB page number */
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r2 = asl(r2, #2) /* times sizeof(PTE) (4bytes) */
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r0 = add(r0,r2) /* r0 = address of correct PTE */
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r2 = #PTE_BITS
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r1 = add(r1,r2) /* r1 = 4MB PTE for the first entry */
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r2.h = #0x0040
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r2.l = #0x0000 /* 4MB */
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memw(r0 ++ #4) = r1
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r1 = add(r1, r2)
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memw(r0 ++ #4) = r1
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r0 = r24
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/*
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* The subroutine wrapper around the virtual instruction touches
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* no memory, so we should be able to use it even here.
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*/
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call __vmnewmap;
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/* Jump into virtual address range. */
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r31.h = #hi(__head_s_vaddr_target)
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r31.l = #lo(__head_s_vaddr_target)
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jumpr r31
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/* Insert trippy space effects. */
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__head_s_vaddr_target:
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/*
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* Tear down VA=PA translation now that we are running
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* in the desgnated kernel segments.
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*/
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r0 = #__HVM_PDE_S_INVALID
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r1 = r24
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loop0(1f,#0x100)
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1:
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{
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memw(R1 ++ #4) = R0
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}:endloop0
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r0 = r24
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call __vmnewmap
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/* Go ahead and install the trap0 return so angel calls work */
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r0.h = #hi(_K_provisional_vec)
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r0.l = #lo(_K_provisional_vec)
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call __vmsetvec
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/*
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* OK, at this point we should start to be much more careful,
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* we're going to enter C code and start touching memory
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* in all sorts of places.
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* This means:
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* SGP needs to be OK
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* Need to lock shared resources
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* A bunch of other things that will cause
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* all kinds of painful bugs
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*/
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/*
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* Stack pointer should be pointed at the init task's
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* thread stack, which should have been declared in arch/init_task.c.
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* So uhhhhh...
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* It's accessible via the init_thread_union, which is a union
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* of a thread_info struct and a stack; of course, the top
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* of the stack is not for you. The end of the stack
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* is simply init_thread_union + THREAD_SIZE.
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*/
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{r29.H = #HI(init_thread_union); r0.H = #HI(_THREAD_SIZE); }
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{r29.L = #LO(init_thread_union); r0.L = #LO(_THREAD_SIZE); }
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/* initialize the register used to point to current_thread_info */
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/* Fixme: THREADINFO_REG can't be R2 because of that memset thing. */
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{r29 = add(r29,r0); THREADINFO_REG = r29; }
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/* Hack: zero bss; */
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{ r0.L = #LO(__bss_start); r1 = #0; r2.l = #LO(__bss_stop); }
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{ r0.H = #HI(__bss_start); r2.h = #HI(__bss_stop); }
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r2 = sub(r2,r0);
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call memset;
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/* Time to make the doughnuts. */
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call start_kernel
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/*
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* Should not reach here.
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*/
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1:
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jump 1b
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.p2align PAGE_SHIFT
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ENTRY(external_cmdline_buffer)
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.fill _PAGE_SIZE,1,0
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.data
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.p2align PAGE_SHIFT
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ENTRY(empty_zero_page)
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.fill _PAGE_SIZE,1,0
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