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authorStefan Reinauer <stepan@coresystems.de>2009-01-19 21:20:22 +0000
committerStefan Reinauer <stepan@openbios.org>2009-01-19 21:20:22 +0000
commit269563a423f9291e84b5a93859a3e17767cf27a0 (patch)
treed7bfed265b6ade33667641589e85db06b5e337ee /src/cpu/x86/smm/smmhandler.S
parent0fd183ce72c44f42859924de5739c73c249e7df0 (diff)
First shot at factoring SMM code into generic parts and southbridge specific
parts. This should help to reduce the code duplication for Rudolf's K8/VIA SMM implementation... Signed-off-by: Stefan Reinauer <stepan@coresystems.de> Acked-by: Joseph Smith <joe@settoplinux.org> git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3870 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
Diffstat (limited to 'src/cpu/x86/smm/smmhandler.S')
-rw-r--r--src/cpu/x86/smm/smmhandler.S201
1 files changed, 201 insertions, 0 deletions
diff --git a/src/cpu/x86/smm/smmhandler.S b/src/cpu/x86/smm/smmhandler.S
new file mode 100644
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+++ b/src/cpu/x86/smm/smmhandler.S
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+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2008 coresystems GmbH
+ *
+ * This program 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 of
+ * the License.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+/* NOTE: This handler assumes the SMM window goes from 0xa0000
+ * to 0xaffff. In fact, at least on Intel Core CPUs (i945 chipset)
+ * the SMM window is 128K big, covering 0xa0000 to 0xbffff.
+ * So there is a lot of potential for growth in here. Let's stick
+ * to 64k if we can though.
+ */
+
+/*
+ * +--------------------------------+ 0xaffff
+ * | Save State Map Node 0 |
+ * | Save State Map Node 1 |
+ * | Save State Map Node 2 |
+ * | Save State Map Node 3 |
+ * | ... |
+ * +--------------------------------+ 0xaf000
+ * | |
+ * | |
+ * | |
+ * +--------------------------------+ 0xa8400
+ * | SMM Entry Node 0 (+ stack) |
+ * +--------------------------------+ 0xa8000
+ * | SMM Entry Node 1 (+ stack) |
+ * | SMM Entry Node 2 (+ stack) |
+ * | SMM Entry Node 3 (+ stack) |
+ * | ... |
+ * +--------------------------------+ 0xa7400
+ * | |
+ * | SMM Handler |
+ * | |
+ * +--------------------------------+ 0xa0000
+ *
+ */
+
+#include <arch/asm.h>
+
+#define LAPIC_ID 0xfee00020
+
+/* SMM_HANDLER_OFFSET is the 16bit offset within the ASEG
+ * at which smm_handler_start lives. At the moment the handler
+ * lives right at 0xa0000, so the offset is 0.
+ */
+
+#define SMM_HANDLER_OFFSET 0x0000
+
+/* initially SMM is some sort of real mode. Let gcc know
+ * how to treat the SMM handler stub
+ */
+
+.section ".handler", "a", @progbits
+
+.code16
+
+/**
+ * SMM code to enable protected mode and jump to the
+ * C-written function void smi_handler(u32 smm_revision)
+ *
+ * All the bad magic is not all that bad after all.
+ */
+smm_handler_start:
+ movw $(smm_gdtptr16 - smm_handler_start + SMM_HANDLER_OFFSET), %bx
+ data32 lgdt %cs:(%bx)
+
+ movl %cr0, %eax
+ andl $0x7FFAFFD1, %eax /* PG,AM,WP,NE,TS,EM,MP = 0 */
+ orl $0x60000001, %eax /* CD, NW, PE = 1 */
+ movl %eax, %cr0
+
+ /* Enable protected mode */
+ data32 ljmp $0x08, $1f
+
+.code32
+1:
+ /* Use flat data segment */
+ movw $0x10, %ax
+ movw %ax, %ds
+ movw %ax, %es
+ movw %ax, %ss
+ movw %ax, %fs
+ movw %ax, %gs
+
+ /* Get this CPU's LAPIC ID */
+ movl $LAPIC_ID, %esi
+ movl (%esi), %ecx
+ shr $24, %ecx
+
+ /* calculate stack offset by multiplying the APIC ID
+ * by 1024 (0x400), and save that offset in ebp.
+ */
+ shl $10, %ecx
+ movl %ecx, %ebp
+
+ /* We put the stack for each core right above
+ * its SMM entry point. Core 0 starts at 0xa8000,
+ * we spare 0x10 bytes for the jump to be sure.
+ */
+ movl $0xa8010, %eax
+ subl %ecx, %eax /* subtract offset, see above */
+ movl %eax, %ebx /* Save bottom of stack in ebx */
+
+#define SMM_STACK_SIZE (0x400 - 0x10)
+ /* clear stack */
+ cld
+ movl %eax, %edi
+ movl $(SMM_STACK_SIZE >> 2), %ecx
+ xorl %eax, %eax
+ rep stosl
+
+ /* set new stack */
+ addl $SMM_STACK_SIZE, %ebx
+ movl %ebx, %esp
+
+ /* Get SMM revision */
+ movl $0xa8000 + 0x7efc, %ebx /* core 0 address */
+ subl %ebp, %ebx /* subtract core X offset */
+ movl (%ebx), %eax
+ pushl %eax
+
+ /* Call 32bit C handler */
+ call smi_handler
+
+ /* To return, just do rsm. It will "clean up" protected mode */
+ rsm
+
+.code16
+
+.align 4, 0xff
+
+smm_gdtptr16:
+ .word smm_gdt_end - smm_gdt - 1
+ .long smm_gdt - smm_handler_start + 0xa0000 + SMM_HANDLER_OFFSET
+
+.code32
+
+smm_gdt:
+ /* The first GDT entry can not be used. Keep it zero */
+ .long 0x00000000, 0x00000000
+
+ /* gdt selector 0x08, flat code segment */
+ .word 0xffff, 0x0000
+ .byte 0x00, 0x9b, 0xcf, 0x00 /* G=1 and 0x0f, 4GB limit */
+
+ /* gdt selector 0x10, flat data segment */
+ .word 0xffff, 0x0000
+ .byte 0x00, 0x93, 0xcf, 0x00
+
+smm_gdt_end:
+
+
+.section ".jumptable", "a", @progbits
+
+/* This is the SMM jump table. All cores use the same SMM handler
+ * for simplicity. But SMM Entry needs to be different due to the
+ * save state area. The jump table makes sure all CPUs jump into the
+ * real handler on SMM entry.
+ */
+
+/* This code currently supports up to 4 CPU cores. If more than 4 CPU cores
+ * shall be used, below table has to be updated, as well as smm.ld
+ */
+
+/* GNU AS/LD will always generate code that assumes CS is 0xa000. In reality
+ * CS will be set to SMM_BASE[19:4] though. Knowing that the smm handler is the
+ * first thing in the ASEG, we do a far jump here, to set CS to 0xa000.
+ */
+
+.code16
+jumptable:
+ /* core 3 */
+ ljmp $0xa000, $SMM_HANDLER_OFFSET
+.align 1024, 0x00
+ /* core 2 */
+ ljmp $0xa000, $SMM_HANDLER_OFFSET
+.align 1024, 0x00
+ /* core 1 */
+ ljmp $0xa000, $SMM_HANDLER_OFFSET
+.align 1024, 0x00
+ /* core 0 */
+ ljmp $0xa000, $SMM_HANDLER_OFFSET
+.align 1024, 0x00
+