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#

# Copyright (C) 2005 Jakub Jermar

# All rights reserved.

#

# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions

# are met:

#

# - Redistributions of source code must retain the above copyright

#   notice, this list of conditions and the following disclaimer.

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#   notice, this list of conditions and the following disclaimer in the

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# - The name of the author may not be used to endorse or promote products

#   derived from this software without specific prior written permission.

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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

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# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

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# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

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#

#include <arch/arch.h>

#include <arch/regdef.h>

#include <arch/boot/boot.h>

#include <arch/stack.h>

#include <arch/mm/mmu.h>

#include <arch/mm/tlb.h>

#include <arch/mm/tte.h>

#ifdef CONFIG_SMP

#include <arch/context_offset.h>

#endif

.register %g2, #scratch

.register %g3, #scratch

.section K_TEXT_START, "ax"

#define BSP_FLAG	1

/*

 * Here is where the kernel is passed control from the boot loader.

 * 

 * The registers are expected to be in this state:

 * - %o0 starting address of physical memory + bootstrap processor flag

 * 	bits 63...1:	physical memory starting address / 2

 *	bit 0:		non-zero on BSP processor, zero on AP processors

 * - %o1 bootinfo structure address (BSP only)

 * - %o2 bootinfo structure size (BSP only)

 *

 * Moreover, we depend on boot having established the following environment:

 * - TLBs are on

 * - identity mapping for the kernel image

 */

.global kernel_image_start

kernel_image_start:

	mov BSP_FLAG, %l0

	and %o0, %l0, %l7				! l7 <= bootstrap processor?

	andn %o0, %l0, %l6				! l6 <= start of physical memory

	! Get bits 40:13 of physmem_base.

	srlx %l6, 13, %l5

	sllx %l5, 13 + (63 - 40), %l5

	srlx %l5, 63 - 40, %l5				! l5 <= physmem_base[40:13]

	/*

	 * Setup basic runtime environment.

	 */

	wrpr %g0, NWINDOWS - 2, %cansave	! set maximum saveable windows

	wrpr %g0, 0, %canrestore		! get rid of windows we will never need again

	wrpr %g0, 0, %otherwin			! make sure the window state is consistent

	wrpr %g0, NWINDOWS - 1, %cleanwin	! prevent needless clean_window traps for kernel

	wrpr %g0, 0, %tl			! TL = 0, primary context register is used

	wrpr %g0, PSTATE_PRIV_BIT, %pstate	! Disable interrupts and disable 32-bit address masking.

	wrpr %g0, 0, %pil			! intialize %pil

	/*

	 * Switch to kernel trap table.

	 */

	sethi %hi(trap_table), %g1

	wrpr %g1, %lo(trap_table), %tba

	/* 

	 * Take over the DMMU by installing global locked

	 * TTE entry identically mapping the first 4M

	 * of memory.

	 *

	 * In case of DMMU, no FLUSH instructions need to be

	 * issued. Because of that, the old DTLB contents can

	 * be demapped pretty straightforwardly and without

	 * causing any traps.

	 */

	wr %g0, ASI_DMMU, %asi

#define SET_TLB_DEMAP_CMD(r1, context_id) \

	set (TLB_DEMAP_CONTEXT<<TLB_DEMAP_TYPE_SHIFT) | (context_id<<TLB_DEMAP_CONTEXT_SHIFT), %r1

	! demap context 0

	SET_TLB_DEMAP_CMD(g1, TLB_DEMAP_NUCLEUS)

	stxa %g0, [%g1] ASI_DMMU_DEMAP			

	membar #Sync

#define SET_TLB_TAG(r1, context) \

	set VMA | (context<<TLB_TAG_ACCESS_CONTEXT_SHIFT), %r1

	! write DTLB tag

	SET_TLB_TAG(g1, MEM_CONTEXT_KERNEL)

	stxa %g1, [VA_DMMU_TAG_ACCESS] %asi			

	membar #Sync

#define SET_TLB_DATA(r1, r2, imm) \

	set TTE_CV | TTE_CP | TTE_P | LMA | imm, %r1; \

	or %r1, %l5, %r1; \

	mov PAGESIZE_4M, %r2; \

	sllx %r2, TTE_SIZE_SHIFT, %r2; \

	or %r1, %r2, %r1; \

	mov 1, %r2; \

	sllx %r2, TTE_V_SHIFT, %r2; \

	or %r1, %r2, %r1;

	! write DTLB data and install the kernel mapping

	SET_TLB_DATA(g1, g2, TTE_L | TTE_W)	! use non-global mapping

	stxa %g1, [%g0] ASI_DTLB_DATA_IN_REG		

	membar #Sync

	/*

	 * Because we cannot use global mappings (because we want to

	 * have separate 64-bit address spaces for both the kernel

	 * and the userspace), we prepare the identity mapping also in

	 * context 1. This step is required by the

	 * code installing the ITLB mapping.

	 */

	! write DTLB tag of context 1 (i.e. MEM_CONTEXT_TEMP)

	SET_TLB_TAG(g1, MEM_CONTEXT_TEMP)

	stxa %g1, [VA_DMMU_TAG_ACCESS] %asi			

	membar #Sync

	! write DTLB data and install the kernel mapping in context 1

	SET_TLB_DATA(g1, g2, TTE_W)			! use non-global mapping

	stxa %g1, [%g0] ASI_DTLB_DATA_IN_REG		

	membar #Sync

	/*

	 * Now is time to take over the IMMU.

	 * Unfortunatelly, it cannot be done as easily as the DMMU,

	 * because the IMMU is mapping the code it executes.

	 *

	 * [ Note that brave experiments with disabling the IMMU

	 * and using the DMMU approach failed after a dozen

	 * of desparate days with only little success. ]

	 *

	 * The approach used here is inspired from OpenBSD.

	 * First, the kernel creates IMMU mapping for itself

	 * in context 1 (MEM_CONTEXT_TEMP) and switches to

	 * it. Context 0 (MEM_CONTEXT_KERNEL) can be demapped

	 * afterwards and replaced with the kernel permanent

	 * mapping. Finally, the kernel switches back to

	 * context 0 and demaps context 1.

	 *

	 * Moreover, the IMMU requires use of the FLUSH instructions.

	 * But that is OK because we always use operands with

	 * addresses already mapped by the taken over DTLB.

	 */

	set kernel_image_start, %g5

	! write ITLB tag of context 1

	SET_TLB_TAG(g1, MEM_CONTEXT_TEMP)

	mov VA_DMMU_TAG_ACCESS, %g2

	stxa %g1, [%g2] ASI_IMMU

	flush %g5

	! write ITLB data and install the temporary mapping in context 1

	SET_TLB_DATA(g1, g2, 0)			! use non-global mapping

	stxa %g1, [%g0] ASI_ITLB_DATA_IN_REG		

	flush %g5

	! switch to context 1

	mov MEM_CONTEXT_TEMP, %g1

	stxa %g1, [VA_PRIMARY_CONTEXT_REG] %asi	! ASI_DMMU is correct here !!!

	flush %g5

	! demap context 0

	SET_TLB_DEMAP_CMD(g1, TLB_DEMAP_NUCLEUS)

	stxa %g0, [%g1] ASI_IMMU_DEMAP			

	flush %g5

	! write ITLB tag of context 0

	SET_TLB_TAG(g1, MEM_CONTEXT_KERNEL)

	mov VA_DMMU_TAG_ACCESS, %g2

	stxa %g1, [%g2] ASI_IMMU

	flush %g5

	! write ITLB data and install the permanent kernel mapping in context 0

	SET_TLB_DATA(g1, g2, TTE_L)		! use non-global mapping

	stxa %g1, [%g0] ASI_ITLB_DATA_IN_REG		

	flush %g5

	! enter nucleus - using context 0

	wrpr %g0, 1, %tl

	! demap context 1

	SET_TLB_DEMAP_CMD(g1, TLB_DEMAP_PRIMARY)

	stxa %g0, [%g1] ASI_IMMU_DEMAP			

	flush %g5

	! set context 0 in the primary context register

	stxa %g0, [VA_PRIMARY_CONTEXT_REG] %asi	! ASI_DMMU is correct here !!!

	flush %g5

	! leave nucleus - using primary context, i.e. context 0

	wrpr %g0, 0, %tl

	brz %l7, 1f				! skip if you are not the bootstrap CPU

	nop

	/*

	 * Save physmem_base for use by the mm subsystem.

	 * %l6 contains starting physical address

	 */

	sethi %hi(physmem_base), %l4

	stx %l6, [%l4 + %lo(physmem_base)]

	/*

	 * Precompute kernel 8K TLB data template.

	 * %l5 contains starting physical address bits [40:13]

	 */

	sethi %hi(kernel_8k_tlb_data_template), %l4

	ldx [%l4 + %lo(kernel_8k_tlb_data_template)], %l3

	or %l3, %l5, %l3

	stx %l3, [%l4 + %lo(kernel_8k_tlb_data_template)]

	/*

	 * So far, we have not touched the stack.

	 * It is a good idea to set the kernel stack to a known state now.

	 */

	sethi %hi(temporary_boot_stack), %sp

	or %sp, %lo(temporary_boot_stack), %sp

	sub %sp, STACK_BIAS, %sp

	sethi %hi(bootinfo), %o0

	call memcpy				! copy bootinfo

	or %o0, %lo(bootinfo), %o0

	call arch_pre_main

	nop

	call main_bsp

	nop

	/* Not reached. */

0:

	ba 0b

	nop

	/*

	 * Read MID from the processor.

	 */

1:

	ldxa [%g0] ASI_UPA_CONFIG, %g1

	srlx %g1, UPA_CONFIG_MID_SHIFT, %g1

	and %g1, UPA_CONFIG_MID_MASK, %g1

#ifdef CONFIG_SMP

	/*

	 * Active loop for APs until the BSP picks them up.

	 * A processor cannot leave the loop until the

	 * global variable 'waking_up_mid' equals its

	 * MID.

	 */

	set waking_up_mid, %g2

2:

	ldx [%g2], %g3

	cmp %g3, %g1

	bne 2b

	nop

	/*

	 * Configure stack for the AP.

	 * The AP is expected to use the stack saved

	 * in the ctx global variable.

	 */

	set ctx, %g1

	add %g1, OFFSET_SP, %g1

	ldx [%g1], %o6

	call main_ap

	nop

	/* Not reached. */

#endif

0:

	ba 0b

	nop

.section K_DATA_START, "aw", @progbits

/*

 * Create small stack to be used by the bootstrap processor.

 * It is going to be used only for a very limited period of

 * time, but we switch to it anyway, just to be sure we are

 * properly initialized.

 *

 * What is important is that this piece of memory is covered

 * by the 4M DTLB locked entry and therefore there will be

 * no surprises like deadly combinations of spill trap and

 * and TLB miss on the stack address.

 */

#define INITIAL_STACK_SIZE	1024

.align STACK_ALIGNMENT

	.space INITIAL_STACK_SIZE

.align STACK_ALIGNMENT

temporary_boot_stack:

	.space STACK_WINDOW_SAVE_AREA_SIZE

.data

.align 8

.global physmem_base		! copy of the physical memory base address

physmem_base:

	.quad 0

/*

 * This variable is used by the fast_data_MMU_miss trap handler.

 * In runtime, it is further modified to reflect the starting address of

 * physical memory.

 */

.global kernel_8k_tlb_data_template

kernel_8k_tlb_data_template:

	.quad ((1 << TTE_V_SHIFT) | TTE_CV | TTE_CP | TTE_P | TTE_W)