/*-
 * Copyright (c) 2012-2014 Andrew Turner
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: stable/11/sys/arm64/arm64/locore.S 319196 2017-05-30 11:03:05Z andrew $
 */

#include "assym.s"
#include "opt_kstack_pages.h"
#include <sys/syscall.h>
#include <machine/asm.h>
#include <machine/armreg.h>
#include <machine/hypervisor.h>
#include <machine/param.h>
#include <machine/pte.h>
#include <machine/vmparam.h>

#define	VIRT_BITS	48
#define	DMAP_TABLES	((DMAP_MAX_ADDRESS - DMAP_MIN_ADDRESS) >> L0_SHIFT)

	.globl	kernbase
	.set	kernbase, KERNBASE

#define	DEVICE_MEM	0
#define	NORMAL_UNCACHED	1
#define	NORMAL_MEM	2

/*
 * We assume:
 *  MMU      on with an identity map, or off
 *  D-Cache: off
 *  I-Cache: on or off
 *  We are loaded at a 2MiB aligned address
 */

	.text
	.globl _start
_start:
	/* Drop to EL1 */
	bl	drop_to_el1

	/*
	 * Disable the MMU. We may have entered the kernel with it on and
	 * will need to update the tables later. If this has been set up
	 * with anything other than a VA == PA map then this will fail,
	 * but in this case the code to find where we are running from
	 * would have also failed.
	 */
	dsb	sy
	mrs	x2, sctlr_el1
	bic	x2, x2, SCTLR_M
	msr	sctlr_el1, x2
	isb

	/* Set the context id */
	msr	contextidr_el1, xzr

	/* Get the virt -> phys offset */
	bl	get_virt_delta

	/*
	 * At this point:
	 * x29 = PA - VA
	 * x28 = Our physical load address
	 */

	/* Create the page tables */
	bl	create_pagetables

	/*
	 * At this point:
	 * x27 = TTBR0 table
	 * x26 = Kernel L1 table
	 * x24 = TTBR1 table
	 */

	/* Enable the mmu */
	bl	start_mmu

	/* Jump to the virtual address space */
	ldr	x15, .Lvirtdone
	br	x15

virtdone:
	/* Set up the stack */
	adr	x25, initstack_end
	mov	sp, x25
	sub	sp, sp, #PCB_SIZE

	/* Zero the BSS */
	ldr	x15, .Lbss
	ldr	x14, .Lend
1:
	str	xzr, [x15], #8
	cmp	x15, x14
	b.lo	1b

	/* Backup the module pointer */
	mov	x1, x0

	/* Make the page table base a virtual address */
	sub	x26, x26, x29
	sub	x24, x24, x29

	sub	sp, sp, #(64 * 4)
	mov	x0, sp

	/* Degate the delda so it is VA -> PA */
	neg	x29, x29

	str	x1,  [x0]	/* modulep */
	str	x26, [x0, 8]	/* kern_l1pt */
	str	x29, [x0, 16]	/* kern_delta */
	str	x25, [x0, 24]	/* kern_stack */
	str	x24, [x0, 32]	/* kern_l0pt */

	/* trace back starts here */
	mov	fp, #0
	/* Branch to C code */
	bl	initarm
	bl	mi_startup

	/* We should not get here */
	brk	0

	.align 3
.Lvirtdone:
	.quad	virtdone
.Lbss:
	.quad	__bss_start
.Lend:
	.quad	_end

#ifdef SMP
/*
 * mpentry(unsigned long)
 *
 * Called by a core when it is being brought online.
 * The data in x0 is passed straight to init_secondary.
 */
ENTRY(mpentry)
	/* Disable interrupts */
	msr	daifset, #2

	/* Drop to EL1 */
	bl	drop_to_el1

	/* Set the context id */
	msr	contextidr_el1, x1

	/* Load the kernel page table */
	adr	x24, pagetable_l0_ttbr1
	/* Load the identity page table */
	adr	x27, pagetable_l0_ttbr0

	/* Enable the mmu */
	bl	start_mmu

	/* Jump to the virtual address space */
	ldr	x15, =mp_virtdone
	br	x15

mp_virtdone:
	ldr	x4, =secondary_stacks
	mov	x5, #(PAGE_SIZE * KSTACK_PAGES)
	mul	x5, x0, x5
	add	sp, x4, x5

	b	init_secondary
END(mpentry)
#endif

/*
 * If we are started in EL2, configure the required hypervisor
 * registers and drop to EL1.
 */
drop_to_el1:
	mrs	x1, CurrentEL
	lsr	x1, x1, #2
	cmp	x1, #0x2
	b.eq	1f
	ret
1:
	/* Configure the Hypervisor */
	mov	x2, #(HCR_RW)
	msr	hcr_el2, x2

	/* Load the Virtualization Process ID Register */
	mrs	x2, midr_el1
	msr	vpidr_el2, x2

	/* Load the Virtualization Multiprocess ID Register */
	mrs	x2, mpidr_el1
	msr	vmpidr_el2, x2

	/* Set the bits that need to be 1 in sctlr_el1 */
	ldr	x2, .Lsctlr_res1
	msr	sctlr_el1, x2

	/* Don't trap to EL2 for exceptions */
	mov	x2, #CPTR_RES1
	msr	cptr_el2, x2

	/* Don't trap to EL2 for CP15 traps */
	msr	hstr_el2, xzr

	/* Enable access to the physical timers at EL1 */
	mrs	x2, cnthctl_el2
	orr	x2, x2, #(CNTHCTL_EL1PCTEN | CNTHCTL_EL1PCEN)
	msr	cnthctl_el2, x2

	/* Set the counter offset to a known value */
	msr	cntvoff_el2, xzr

	/* Hypervisor trap functions */
	adr	x2, hyp_vectors
	msr	vbar_el2, x2

	mov	x2, #(PSR_F | PSR_I | PSR_A | PSR_D | PSR_M_EL1h)
	msr	spsr_el2, x2

	/* Configure GICv3 CPU interface */
	mrs	x2, id_aa64pfr0_el1
	/* Extract GIC bits from the register */
	ubfx	x2, x2, #ID_AA64PFR0_GIC_SHIFT, #ID_AA64PFR0_GIC_BITS
	/* GIC[3:0] == 0001 - GIC CPU interface via special regs. supported */
	cmp	x2, #(ID_AA64PFR0_GIC_CPUIF_EN >> ID_AA64PFR0_GIC_SHIFT)
	b.ne	2f

	mrs	x2, icc_sre_el2
	orr	x2, x2, #ICC_SRE_EL2_EN	/* Enable access from insecure EL1 */
	orr	x2, x2, #ICC_SRE_EL2_SRE	/* Enable system registers */
	msr	icc_sre_el2, x2
2:

	/* Set the address to return to our return address */
	msr	elr_el2, x30
	isb

	eret

	.align 3
.Lsctlr_res1:
	.quad SCTLR_RES1

#define	VECT_EMPTY	\
	.align 7;	\
	1:	b	1b

	.align 11
hyp_vectors:
	VECT_EMPTY	/* Synchronous EL2t */
	VECT_EMPTY	/* IRQ EL2t */
	VECT_EMPTY	/* FIQ EL2t */
	VECT_EMPTY	/* Error EL2t */

	VECT_EMPTY	/* Synchronous EL2h */
	VECT_EMPTY	/* IRQ EL2h */
	VECT_EMPTY	/* FIQ EL2h */
	VECT_EMPTY	/* Error EL2h */

	VECT_EMPTY	/* Synchronous 64-bit EL1 */
	VECT_EMPTY	/* IRQ 64-bit EL1 */
	VECT_EMPTY	/* FIQ 64-bit EL1 */
	VECT_EMPTY	/* Error 64-bit EL1 */

	VECT_EMPTY	/* Synchronous 32-bit EL1 */
	VECT_EMPTY	/* IRQ 32-bit EL1 */
	VECT_EMPTY	/* FIQ 32-bit EL1 */
	VECT_EMPTY	/* Error 32-bit EL1 */

/*
 * Get the delta between the physical address we were loaded to and the
 * virtual address we expect to run from. This is used when building the
 * initial page table.
 */
get_virt_delta:
	/* Load the physical address of virt_map */
	adr	x29, virt_map
	/* Load the virtual address of virt_map stored in virt_map */
	ldr	x28, [x29]
	/* Find PA - VA as PA' = VA' - VA + PA = VA' + (PA - VA) = VA' + x29 */
	sub	x29, x29, x28
	/* Find the load address for the kernel */
	mov	x28, #(KERNBASE)
	add	x28, x28, x29
	ret

	.align 3
virt_map:
	.quad	virt_map

/*
 * This builds the page tables containing the identity map, and the kernel
 * virtual map.
 *
 * It relys on:
 *  We were loaded to an address that is on a 2MiB boundary
 *  All the memory must not cross a 1GiB boundaty
 *  x28 contains the physical address we were loaded from
 *
 * TODO: This is out of date.
 *  There are at least 5 pages before that address for the page tables
 *   The pages used are:
 *    - The Kernel L2 table
 *    - The Kernel L1 table
 *    - The Kernel L0 table             (TTBR1)
 *    - The identity (PA = VA) L1 table
 *    - The identity (PA = VA) L0 table (TTBR0)
 *    - The DMAP L1 tables
 */
create_pagetables:
	/* Save the Link register */
	mov	x5, x30

	/* Clean the page table */
	adr	x6, pagetable
	mov	x26, x6
	adr	x27, pagetable_end
1:
	stp	xzr, xzr, [x6], #16
	stp	xzr, xzr, [x6], #16
	stp	xzr, xzr, [x6], #16
	stp	xzr, xzr, [x6], #16
	cmp	x6, x27
	b.lo	1b

	/*
	 * Build the TTBR1 maps.
	 */

	/* Find the size of the kernel */
	mov	x6, #(KERNBASE)
	ldr	x7, .Lend
	/* Find the end - begin */
	sub	x8, x7, x6
	/* Get the number of l2 pages to allocate, rounded down */
	lsr	x10, x8, #(L2_SHIFT)
	/* Add 8 MiB for any rounding above and the module data */
	add	x10, x10, #4

	/* Create the kernel space L2 table */
	mov	x6, x26
	mov	x7, #NORMAL_MEM
	mov	x8, #(KERNBASE & L2_BLOCK_MASK)
	mov	x9, x28
	bl	build_l2_block_pagetable

	/* Move to the l1 table */
	add	x26, x26, #PAGE_SIZE

	/* Link the l1 -> l2 table */
	mov	x9, x6
	mov	x6, x26
	bl	link_l1_pagetable

	/* Move to the l0 table */
	add	x24, x26, #PAGE_SIZE

	/* Link the l0 -> l1 table */
	mov	x9, x6
	mov	x6, x24
	mov	x10, #1
	bl	link_l0_pagetable

	/* Link the DMAP tables */
	ldr	x8, =DMAP_MIN_ADDRESS
	adr	x9, pagetable_dmap;
	mov	x10, #DMAP_TABLES
	bl	link_l0_pagetable

	/*
	 * Build the TTBR0 maps.
	 */
	add	x27, x24, #PAGE_SIZE

	mov	x6, x27		/* The initial page table */
#if defined(SOCDEV_PA) && defined(SOCDEV_VA)
	/* Create a table for the UART */
	mov	x7, #DEVICE_MEM
	mov	x8, #(SOCDEV_VA)	/* VA start */
	mov	x9, #(SOCDEV_PA)	/* PA start */
	mov	x10, #1
	bl	build_l1_block_pagetable
#endif

	/* Create the VA = PA map */
	mov	x7, #NORMAL_UNCACHED /* Uncached as it's only needed early on */
	mov	x9, x27
	mov	x8, x9		/* VA start (== PA start) */
	mov	x10, #1
	bl	build_l1_block_pagetable

	/* Move to the l0 table */
	add	x27, x27, #PAGE_SIZE

	/* Link the l0 -> l1 table */
	mov	x9, x6
	mov	x6, x27
	mov	x10, #1
	bl	link_l0_pagetable

	/* Restore the Link register */
	mov	x30, x5
	ret

/*
 * Builds an L0 -> L1 table descriptor
 *
 * This is a link for a 512GiB block of memory with up to 1GiB regions mapped
 * within it by build_l1_block_pagetable.
 *
 *  x6  = L0 table
 *  x8  = Virtual Address
 *  x9  = L1 PA (trashed)
 *  x10 = Entry count
 *  x11, x12 and x13 are trashed
 */
link_l0_pagetable:
	/*
	 * Link an L0 -> L1 table entry.
	 */
	/* Find the table index */
	lsr	x11, x8, #L0_SHIFT
	and	x11, x11, #L0_ADDR_MASK

	/* Build the L0 block entry */
	mov	x12, #L0_TABLE

	/* Only use the output address bits */
	lsr	x9, x9, #PAGE_SHIFT
1:	orr	x13, x12, x9, lsl #PAGE_SHIFT

	/* Store the entry */
	str	x13, [x6, x11, lsl #3]

	sub	x10, x10, #1
	add	x11, x11, #1
	add	x9, x9, #1
	cbnz	x10, 1b

	ret

/*
 * Builds an L1 -> L2 table descriptor
 *
 * This is a link for a 1GiB block of memory with up to 2MiB regions mapped
 * within it by build_l2_block_pagetable.
 *
 *  x6  = L1 table
 *  x8  = Virtual Address
 *  x9  = L2 PA (trashed)
 *  x11, x12 and x13 are trashed
 */
link_l1_pagetable:
	/*
	 * Link an L1 -> L2 table entry.
	 */
	/* Find the table index */
	lsr	x11, x8, #L1_SHIFT
	and	x11, x11, #Ln_ADDR_MASK

	/* Build the L1 block entry */
	mov	x12, #L1_TABLE

	/* Only use the output address bits */
	lsr	x9, x9, #PAGE_SHIFT
	orr	x13, x12, x9, lsl #PAGE_SHIFT

	/* Store the entry */
	str	x13, [x6, x11, lsl #3]

	ret

/*
 * Builds count 1 GiB page table entry
 *  x6  = L1 table
 *  x7  = Type (0 = Device, 1 = Normal)
 *  x8  = VA start
 *  x9  = PA start (trashed)
 *  x10 = Entry count
 *  x11, x12 and x13 are trashed
 */
build_l1_block_pagetable:
	/*
	 * Build the L1 table entry.
	 */
	/* Find the table index */
	lsr	x11, x8, #L1_SHIFT
	and	x11, x11, #Ln_ADDR_MASK

	/* Build the L1 block entry */
	lsl	x12, x7, #2
	orr	x12, x12, #L1_BLOCK
	orr	x12, x12, #(ATTR_AF)
#ifdef SMP
	orr	x12, x12, ATTR_SH(ATTR_SH_IS)
#endif

	/* Only use the output address bits */
	lsr	x9, x9, #L1_SHIFT

	/* Set the physical address for this virtual address */
1:	orr	x13, x12, x9, lsl #L1_SHIFT

	/* Store the entry */
	str	x13, [x6, x11, lsl #3]

	sub	x10, x10, #1
	add	x11, x11, #1
	add	x9, x9, #1
	cbnz	x10, 1b

	ret

/*
 * Builds count 2 MiB page table entry
 *  x6  = L2 table
 *  x7  = Type (0 = Device, 1 = Normal)
 *  x8  = VA start
 *  x9  = PA start (trashed)
 *  x10 = Entry count
 *  x11, x12 and x13 are trashed
 */
build_l2_block_pagetable:
	/*
	 * Build the L2 table entry.
	 */
	/* Find the table index */
	lsr	x11, x8, #L2_SHIFT
	and	x11, x11, #Ln_ADDR_MASK

	/* Build the L2 block entry */
	lsl	x12, x7, #2
	orr	x12, x12, #L2_BLOCK
	orr	x12, x12, #(ATTR_AF)
#ifdef SMP
	orr	x12, x12, ATTR_SH(ATTR_SH_IS)
#endif

	/* Only use the output address bits */
	lsr	x9, x9, #L2_SHIFT

	/* Set the physical address for this virtual address */
1:	orr	x13, x12, x9, lsl #L2_SHIFT

	/* Store the entry */
	str	x13, [x6, x11, lsl #3]

	sub	x10, x10, #1
	add	x11, x11, #1
	add	x9, x9, #1
	cbnz	x10, 1b

	ret

start_mmu:
	dsb	sy

	/* Load the exception vectors */
	ldr	x2, =exception_vectors
	msr	vbar_el1, x2

	/* Load ttbr0 and ttbr1 */
	msr	ttbr0_el1, x27
	msr	ttbr1_el1, x24
	isb

	/* Clear the Monitor Debug System control register */
	msr	mdscr_el1, xzr

	/* Invalidate the TLB */
	tlbi	vmalle1is

	ldr	x2, mair
	msr	mair_el1, x2

	/*
	 * Setup TCR according to PARange bits from ID_AA64MMFR0_EL1.
	 */
	ldr	x2, tcr
	mrs	x3, id_aa64mmfr0_el1
	bfi	x2, x3, #32, #3
	msr	tcr_el1, x2

	/* Setup SCTLR */
	ldr	x2, sctlr_set
	ldr	x3, sctlr_clear
	mrs	x1, sctlr_el1
	bic	x1, x1, x3	/* Clear the required bits */
	orr	x1, x1, x2	/* Set the required bits */
	msr	sctlr_el1, x1
	isb

	ret

	.align 3
mair:
		/* Device            Normal, no cache     Normal, write-back */
	.quad	MAIR_ATTR(0x00, 0) | MAIR_ATTR(0x44, 1) | MAIR_ATTR(0xff, 2)
tcr:
	.quad (TCR_TxSZ(64 - VIRT_BITS) | TCR_ASID_16 | TCR_TG1_4K | \
	    TCR_CACHE_ATTRS | TCR_SMP_ATTRS)
sctlr_set:
	/* Bits to set */
	.quad (SCTLR_LSMAOE | SCTLR_nTLSMD | SCTLR_UCI | SCTLR_SPAN | \
	    SCTLR_nTWE | SCTLR_nTWI | SCTLR_UCT | SCTLR_DZE | \
	    SCTLR_I | SCTLR_SED | SCTLR_SA0 | SCTLR_SA | SCTLR_C | SCTLR_M)
sctlr_clear:
	/* Bits to clear */
	.quad (SCTLR_EE | SCTLR_EOE | SCTLR_IESB | SCTLR_WXN | SCTLR_UMA | \
	    SCTLR_ITD | SCTLR_THEE | SCTLR_CP15BEN | SCTLR_A)

	.globl abort
abort:
	b abort

	//.section .init_pagetable
	.align 12 /* 4KiB aligned */
	/*
	 * 3 initial tables (in the following order):
	 *           L2 for kernel (High addresses)
	 *           L1 for kernel
	 *           L1 for user   (Low addresses)
	 */
pagetable:
	.space	PAGE_SIZE
pagetable_l1_ttbr1:
	.space	PAGE_SIZE
pagetable_l0_ttbr1:
	.space	PAGE_SIZE
pagetable_l1_ttbr0:
	.space	PAGE_SIZE
pagetable_l0_ttbr0:
	.space	PAGE_SIZE

	.globl pagetable_dmap
pagetable_dmap:
	.space	PAGE_SIZE * DMAP_TABLES
pagetable_end:

el2_pagetable:
	.space	PAGE_SIZE

	.globl init_pt_va
init_pt_va:
	.quad pagetable		/* XXX: Keep page tables VA */

	.align	4
initstack:
	.space	(PAGE_SIZE * KSTACK_PAGES)
initstack_end:


ENTRY(sigcode)
	mov	x0, sp
	add	x0, x0, #SF_UC

1:
	mov	x8, #SYS_sigreturn
	svc	0

	/* sigreturn failed, exit */
	mov	x8, #SYS_exit
	svc	0

	b	1b
END(sigcode)
	/* This may be copied to the stack, keep it 16-byte aligned */
	.align	3
esigcode:

	.data
	.align	3
	.global	szsigcode
szsigcode:
	.quad	esigcode - sigcode
