[mirror_edk2.git] / OvmfPkg / Library / LoadLinuxLib / X64 / JumpToKernel.S

#------------------------------------------------------------------------------\r
#\r
# Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>\r
#\r
# This program and the accompanying materials\r
# are licensed and made available under the terms and conditions of the BSD License\r
# which accompanies this distribution.  The full text of the license may be found at\r
# http://opensource.org/licenses/bsd-license.php.\r
#\r
# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
#\r
#------------------------------------------------------------------------------\r
\r
ASM_GLOBAL ASM_PFX(JumpToKernel)\r
\r
#------------------------------------------------------------------------------\r
# VOID\r
# EFIAPI\r
# JumpToKernel (\r
#   VOID *KernelStart,         // %rcx\r
#   VOID *KernelBootParams     // %rdx\r
#   );\r
#------------------------------------------------------------------------------\r
ASM_PFX(JumpToKernel):\r
\r
    // Set up for executing kernel. BP in %esi, entry point on the stack\r
    // (64-bit when the 'ret' will use it as 32-bit, but we're little-endian)\r
    movq    %rdx, %rsi\r
    pushq   %rcx\r
\r
    // Jump into the compatibility mode CS\r
    pushq   $0x10\r
    leaq    1f, %rax\r
    pushq   %rax\r
    retfq\r
\r
1:  // Now in compatibility mode\r
.code32\r
    movl    $0x18, %eax\r
    movl    %eax, %ds\r
    movl    %eax, %es\r
    movl    %eax, %fs\r
    movl    %eax, %gs\r
    movl    %eax, %ss\r
\r
    // Disable paging\r
    movl    %cr0, %eax\r
    btcl    $31, %eax\r
    movl    %eax, %cr0\r
\r
    // Disable long mode in EFER\r
    movl    $0x0c0000080, %ecx\r
    rdmsr\r
    btcl    $8, %eax\r
    wrmsr\r
\r
    // Disable PAE\r
    movl    %cr4, %eax\r
    btcl    $5, %eax\r
    movl    %eax, %cr4\r
\r
    // Zero registers and 'return' to kernel\r
    xorl    %ebp, %ebp\r
    xorl    %edi, %edi\r
    xorl    %ebx, %ebx\r
    ret\r
.code64\r
\r
Commit	Line	Data
3c0a051f	1	#------------------------------------------------------------------------------\r
	2	#\r
	3	# Copyright (c) 2006 - 2011, Intel Corporation. All rights reserved.<BR>\r
	4	#\r
	5	# This program and the accompanying materials\r
	6	# are licensed and made available under the terms and conditions of the BSD License\r
	7	# which accompanies this distribution. The full text of the license may be found at\r
	8	# http://opensource.org/licenses/bsd-license.php.\r
	9	#\r
	10	# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
	11	# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	12	#\r
	13	#------------------------------------------------------------------------------\r
	14	\r
	15	ASM_GLOBAL ASM_PFX(JumpToKernel)\r
	16	\r
	17	#------------------------------------------------------------------------------\r
	18	# VOID\r
	19	# EFIAPI\r
	20	# JumpToKernel (\r
	21	# VOID *KernelStart, // %rcx\r
	22	# VOID *KernelBootParams // %rdx\r
	23	# );\r
	24	#------------------------------------------------------------------------------\r
	25	ASM_PFX(JumpToKernel):\r
61a114ba	26	\r
	27	// Set up for executing kernel. BP in %esi, entry point on the stack\r
	28	// (64-bit when the 'ret' will use it as 32-bit, but we're little-endian)\r
3c0a051f	29	movq %rdx, %rsi\r
61a114ba	30	pushq %rcx\r
	31	\r
	32	// Jump into the compatibility mode CS\r
	33	pushq $0x10\r
	34	leaq 1f, %rax\r
	35	pushq %rax\r
	36	retfq\r
	37	\r
	38	1: // Now in compatibility mode\r
	39	.code32\r
	40	movl $0x18, %eax\r
	41	movl %eax, %ds\r
	42	movl %eax, %es\r
	43	movl %eax, %fs\r
	44	movl %eax, %gs\r
	45	movl %eax, %ss\r
	46	\r
	47	// Disable paging\r
	48	movl %cr0, %eax\r
	49	btcl $31, %eax\r
	50	movl %eax, %cr0\r
	51	\r
	52	// Disable long mode in EFER\r
	53	movl $0x0c0000080, %ecx\r
	54	rdmsr\r
	55	btcl $8, %eax\r
	56	wrmsr\r
	57	\r
	58	// Disable PAE\r
	59	movl %cr4, %eax\r
	60	btcl $5, %eax\r
	61	movl %eax, %cr4\r
	62	\r
	63	// Zero registers and 'return' to kernel\r
	64	xorl %ebp, %ebp\r
	65	xorl %edi, %edi\r
	66	xorl %ebx, %ebx\r
3c0a051f	67	ret\r
61a114ba	68	.code64\r
3c0a051f	69	\r