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#

# Copyright (c) 2005 Ondrej Palkovsky

# 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.

# - 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.

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

#   derived from this software without specific prior written permission.

#

# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.

#

#define IREGISTER_SPACE	72 

#define IOFFSET_RAX	0x0

#define IOFFSET_RCX	0x8

#define IOFFSET_RDX	0x10

#define IOFFSET_RSI	0x18

#define IOFFSET_RDI	0x20

#define IOFFSET_R8	0x28

#define IOFFSET_R9	0x30

#define IOFFSET_R10	0x38

#define IOFFSET_R11	0x40

#  Mask for interrupts 0 - 31 (bits 0 - 31) where 0 means that int has no error word

# and 1 means interrupt with error word

#define ERROR_WORD_INTERRUPT_LIST 0x00027D00

#include <arch/pm.h>

#include <arch/mm/page.h>

.text

.global interrupt_handlers

.global syscall_entry

.global panic_printf

panic_printf:

	movq $halt, (%rsp)

	jmp printf

.global cpuid

.global has_cpuid

.global get_cycle

.global read_efer_flag

.global set_efer_flag

.global memsetb

.global memsetw

.global memcpy

.global memcpy_from_uspace

.global memcpy_to_uspace

.global memcpy_from_uspace_failover_address

.global memcpy_to_uspace_failover_address

# Wrapper for generic memsetb

memsetb:

	jmp _memsetb

# Wrapper for generic memsetw

memsetw:

	jmp _memsetw

#define MEMCPY_DST	%rdi

#define MEMCPY_SRC	%rsi

#define MEMCPY_SIZE	%rdx

/**

 * Copy memory from/to userspace.

 *

 * This is almost conventional memcpy().

 * The difference is that there is a failover part

 * to where control is returned from a page fault if

 * the page fault occurs during copy_from_uspace()

 * or copy_to_uspace().

 *

 * @param MEMCPY_DST	Destination address.

 * @param MEMCPY_SRC	Source address.

 * @param MEMCPY_SIZE	Number of bytes to copy.

 *

 * @retrun MEMCPY_DST on success, 0 on failure.

 */

memcpy:

memcpy_from_uspace:

memcpy_to_uspace:

	movq MEMCPY_DST, %rax

	movq MEMCPY_SIZE, %rcx

	shrq $3, %rcx			/* size / 8 */

	rep movsq			/* copy as much as possible word by word */

	movq MEMCPY_SIZE, %rcx

	andq $7, %rcx			/* size % 8 */

	jz 0f

	rep movsb			/* copy the rest byte by byte */

0:

	ret				/* return MEMCPY_SRC, success */

memcpy_from_uspace_failover_address:

memcpy_to_uspace_failover_address:

	xorq %rax, %rax			/* return 0, failure */

	ret

## Determine CPUID support

#

# Return 0 in EAX if CPUID is not support, 1 if supported.

#

has_cpuid:

	pushfq			# store flags

	popq %rax		# read flags

	movq %rax,%rdx		# copy flags

	btcl $21,%edx		# swap the ID bit

	pushq %rdx

	popfq			# propagate the change into flags

	pushfq

	popq %rdx		# read flags	

	andl $(1<<21),%eax	# interested only in ID bit

	andl $(1<<21),%edx

	xorl %edx,%eax		# 0 if not supported, 1 if supported

	ret

cpuid:

	movq %rbx, %r10  # we have to preserve rbx across function calls

	movl %edi,%eax	# load the command into %eax

	cpuid	

	movl %eax,0(%rsi)

	movl %ebx,4(%rsi)

	movl %ecx,8(%rsi)

	movl %edx,12(%rsi)

	movq %r10, %rbx

	ret

get_cycle:

	xorq %rax,%rax

	rdtsc

	ret

set_efer_flag:

	movq $0xc0000080, %rcx

	rdmsr

	btsl %edi, %eax

	wrmsr

	ret

read_efer_flag:	

	movq $0xc0000080, %rcx

	rdmsr

	ret 		

# Push all volatile general purpose registers on stack

.macro save_all_gpr

	movq %rax, IOFFSET_RAX(%rsp)

	movq %rcx, IOFFSET_RCX(%rsp)

	movq %rdx, IOFFSET_RDX(%rsp)

	movq %rsi, IOFFSET_RSI(%rsp)

	movq %rdi, IOFFSET_RDI(%rsp)

	movq %r8, IOFFSET_R8(%rsp)

	movq %r9, IOFFSET_R9(%rsp)

	movq %r10, IOFFSET_R10(%rsp)

	movq %r11, IOFFSET_R11(%rsp)

.endm

.macro restore_all_gpr

	movq IOFFSET_RAX(%rsp), %rax

	movq IOFFSET_RCX(%rsp), %rcx

	movq IOFFSET_RDX(%rsp), %rdx

	movq IOFFSET_RSI(%rsp), %rsi

	movq IOFFSET_RDI(%rsp), %rdi

	movq IOFFSET_R8(%rsp), %r8

	movq IOFFSET_R9(%rsp), %r9

	movq IOFFSET_R10(%rsp), %r10

	movq IOFFSET_R11(%rsp), %r11

.endm

#define INTERRUPT_ALIGN 128

## Declare interrupt handlers

#

# Declare interrupt handlers for n interrupt

# vectors starting at vector i.

#

# The handlers call exc_dispatch().

#

.macro handler i n

	/*

	 * Choose between version with error code and version without error

	 * code. Both versions have to be of the same size. amd64 assembly is,

	 * however, a little bit tricky. For instance, subq $0x80, %rsp and

	 * subq $0x78, %rsp can result in two instructions with different

	 * op-code lengths.

	 * Therefore we align the interrupt handlers.

	 */

	.iflt \i-32

		.if (1 << \i) & ERROR_WORD_INTERRUPT_LIST

			/*

			 * Version with error word.

			 */

			subq $IREGISTER_SPACE, %rsp

		.else

			/*

			 * Version without error word,

			 */

			subq $(IREGISTER_SPACE+8), %rsp

		.endif

	.else

		/*

		 * Version without error word,

		 */

		subq $(IREGISTER_SPACE+8), %rsp

	.endif	

	save_all_gpr

	cld

	movq $(\i), %rdi   	# %rdi - first parameter

	movq %rsp, %rsi   	# %rsi - pointer to istate

	call exc_dispatch 	# exc_dispatch(i, istate)

	restore_all_gpr

	# $8 = Skip error word

	addq $(IREGISTER_SPACE+8), %rsp

	iretq

	.align INTERRUPT_ALIGN

	.if (\n-\i)-1

	handler "(\i+1)",\n

	.endif

.endm

.align INTERRUPT_ALIGN

interrupt_handlers:

h_start:

	handler 0 IDT_ITEMS

h_end:

## Low-level syscall handler

# 

# Registers on entry:

#

# @param rcx		Userspace return address.

# @param r11		Userspace RLFAGS.

#

# @param rax		Syscall number.

# @param rdi		1st syscall argument.

# @param rsi		2nd syscall argument.

# @param rdx		3rd syscall argument.

# @param r10		4th syscall argument. Used instead of RCX because the

#			SYSCALL instruction clobbers it.

# @param r8		5th syscall argument.

# @param r9		6th syscall argument.

#

# @return		Return value is in rax.

#

syscall_entry:

	swapgs			# Switch to hidden gs	

	# 

	# %gs:0			Scratch space for this thread's user RSP

	# %gs:8			Address to be used as this thread's kernel RSP

	#

	movq %rsp, %gs:0	# Save this thread's user RSP

	movq %gs:8, %rsp	# Set this thread's kernel RSP

	swapgs			# Switch back to remain consistent

	sti

	pushq %rcx

	pushq %r11

	movq %r10, %rcx		# Copy the 4th argument where it is expected 

	pushq %rax

	call syscall_handler

	addq $8, %rsp

	popq %r11

	popq %rcx

	cli

	swapgs

	movq %gs:0, %rsp	# Restore the user RSP

	swapgs

	sysretq

.data

.global interrupt_handler_size

interrupt_handler_size: .quad (h_end-h_start)/IDT_ITEMS