/*
 * hal_cpu.S - Miscellaneous CPU functions
 *
 * Copyright (c) 2017 Maxime Villard
 *
 * This file is part of ALMOS-MKH.
 *
 * ALMOS-MKH is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2.0 of the License.
 *
 * ALMOS-MKH is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#define x86_ASM
#include <hal_boot.h>
#include <hal_segmentation.h>
#include <hal_register.h>
#include <hal_kentry.h>

ASM_ENTRY(lgdt)
	lgdt	(%rdi)
	/* Reload the prefetch queue */
	jmp	1f
	nop
1:	/* Reload stale selectors */
	movl	$GDT_FIXED_SEL(GDT_KDATA_SEL, SEL_KPL),%eax
	movl	%eax,%ds
	movl	%eax,%es
	movl	%eax,%ss
	ret

ASM_ENTRY(lidt)
	lidt	(%rdi)
	ret

ASM_ENTRY(ltr)
	ltr	%di
	ret

ASM_ENTRY(invlpg)
	invlpg	(%rdi)
	ret

ASM_ENTRY(sti)
	sti
	ret

ASM_ENTRY(cli)
	cli
	ret

ASM_ENTRY(rdtsc)
	xorq	%rax,%rax
	rdtsc
	shlq	$32,%rdx
	orq	%rdx,%rax
	ret

ASM_ENTRY(in8)
	movq	%rdi,%rdx
	xorq	%rax,%rax
	inb	%dx,%al
	ret

ASM_ENTRY(in16)
	movq	%rdi,%rdx
	xorq	%rax,%rax
	inw	%dx,%ax
	ret

ASM_ENTRY(out8)
	movq	%rdi,%rdx
	movq	%rsi,%rax
	outb	%al,%dx
	ret

ASM_ENTRY(out16)
	movq	%rdi,%rdx
	movq	%rsi,%rax
	outw	%ax,%dx
	ret

ASM_ENTRY(rdmsr)
	movq	%rdi,%rcx
	xorq	%rax,%rax
	rdmsr
	shlq	$32,%rdx
	orq	%rdx,%rax
	ret

ASM_ENTRY(wrmsr)
	movq	%rdi,%rcx
	movq	%rsi,%rax
	movq	%rsi,%rdx
	shrq	$32,%rdx
	wrmsr
	ret

ASM_ENTRY(mfence)
	mfence
	ret

ASM_ENTRY(rcr0)
	movq	%cr0,%rax
	ret

ASM_ENTRY(rcr2)
	movq	%cr2,%rax
	ret

ASM_ENTRY(rcr3)
	movq	%cr3,%rax
	ret

ASM_ENTRY(rcr4)
	movq	%cr4,%rax
	ret

ASM_ENTRY(lcr4)
	movq	%rdi,%cr4
	ret

ASM_ENTRY(cpuid)
	movq	%rbx,%r8
	movq	%rdi,%rax
	movq	%rsi,%rcx
	movq	%rdx,%rsi
	cpuid
	movl	%eax,0(%rsi)
	movl	%ebx,4(%rsi)
	movl	%ecx,8(%rsi)
	movl	%edx,12(%rsi)
	movq	%r8,%rbx
	ret

/*
 * To flush all TLB entries, we must re-set the CR4_PGE flag in %cr4.
 */
ASM_ENTRY(tlbflushg)
	movq	%cr4,%rax
	movq	%rax,%rdx
	andq	$~CR4_PGE,%rdx
	movq	%rdx,%cr4
	movq	%rax,%cr4
	ret

ASM_ENTRY(tlbflush)
	movq	%cr3,%rax
	movq	%rax,%cr3
	ret

ASM_ENTRY(clts)
	clts
	ret

ASM_ENTRY(stts)
	movq	%cr0,%rax
	orq	$CR0_TS,%rax
	movq	%rax,%cr0
	ret

ASM_ENTRY(x86_stop) /* debug only */
	int	$0x0b
	ret

ASM_ENTRY(pause)
	pause
	ret

ASM_ENTRY(wbinvd)
	wbinvd
	ret

/* -------------------------------------------------------------------------- */

ASM_ENTRY(cpu_context_switch)
	pushq	%r12
	pushq	%r13

	movq	%rdi,%r13	/* oldctx */
	movq	%rsi,%r12	/* newctx */

	/*
	 * Save the current stack in %rdx, and switch to the trap frame of
	 * the old thread.
	 */
	movq	%rsp,%rdx
	movq	CTX_TF(%r13),%rsp
	addq	$TF_SIZE,%rsp	/* end of the structure */

	/* Build the trap frame */
	movl	%ss,%eax
	pushq	%rax		/* tf_ss */
	pushq	%rdx		/* tf_rsp */
	pushfq			/* tf_rflags */
	movl	%cs,%eax
	pushq	%rax		/* tf_cs */
	movabsq	$thr_resume,%rax
	pushq	%rax		/* tf_rip */
	pushq	$0		/* tf_err */
	pushq	$T_ASTFLT	/* tf_trapno */
	INTR_SAVE_REGS

	/* Switch rsp0 */
	movq	CTX_RSP0(%r12),%rax
	movq	TLSVAR(RSP0),%rdx
	movq	%rax,(%rdx)

	/* Switch to the new trap frame */
	movq	CTX_TF(%r12),%rsp

	/*
	 * Restore the context, and jump into the new thread.
	 */
	INTR_RESTORE_REGS
	iretq

thr_resume:
	/*
	 * Only pop %r12 and %r13, and return.
	 */
	popq	%r13
	popq	%r12

	ret

/* -------------------------------------------------------------------------- */

ASM_ENTRY(atomic_cas_32)
	movl	%esi,%eax
	lock
	cmpxchgl %edx,(%rdi)
	/* %eax now contains the old value */
	ret

ASM_ENTRY(atomic_add_32)
	movl	%esi,%eax
	lock
	xaddl	%eax,(%rdi)
	/* %eax now contains the old value */
	ret

ASM_ENTRY(atomic_and_32)
	movl	(%rdi),%eax
1:
	movl	%eax,%ecx
	andl	%esi,%ecx
	lock
	cmpxchgl %ecx,(%rdi)
	jnz	1b
	/* %eax now contains the old value */
	ret

ASM_ENTRY(atomic_or_32)
	movl	(%rdi),%eax
1:
	movl	%eax,%ecx
	orl	%esi,%ecx
	lock
	cmpxchgl %ecx,(%rdi)
	jnz	1b
	/* %eax now contains the old value */
	ret

