From 13d92cf67aa55fc5d4f4991e69a6c9ebb2cc8819 Mon Sep 17 00:00:00 2001 From: Andre Guedes Date: Wed, 15 Apr 2015 15:03:51 -0300 Subject: [PATCH] x86: Initialize Interrupt Descriptor Table This patch adds code to handle Interrupt Descriptor Table (IDT) initialization. The IDT is initialized with null descriptors therefore any interrupt at this point will cause a triple fault. The IDT initialization is part of x86 CPU initialization. Strictly speaking, there is no need to use attribute packed in struct intr_gate_desc however we use it for readability reasons. --- cpu/x86/Makefile.x86 | 2 +- cpu/x86/idt.c | 89 ++++++++++++++++++++++++++++++++++++++++++++ cpu/x86/idt.h | 39 +++++++++++++++++++ 3 files changed, 129 insertions(+), 1 deletion(-) create mode 100644 cpu/x86/idt.c create mode 100644 cpu/x86/idt.h diff --git a/cpu/x86/Makefile.x86 b/cpu/x86/Makefile.x86 index dd79ec7d3..6b3757da5 100644 --- a/cpu/x86/Makefile.x86 +++ b/cpu/x86/Makefile.x86 @@ -1,6 +1,6 @@ CONTIKI_CPU_DIRS = . -CONTIKI_SOURCEFILES += mtarch.c gdt.c helpers.S +CONTIKI_SOURCEFILES += mtarch.c gdt.c helpers.S idt.c ### Compiler definitions CC = gcc diff --git a/cpu/x86/idt.c b/cpu/x86/idt.c new file mode 100644 index 000000000..a75b704e8 --- /dev/null +++ b/cpu/x86/idt.c @@ -0,0 +1,89 @@ +/* + * Copyright (C) 2015, Intel Corporation. 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. + * + * 3. Neither the name of the copyright holder nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 + * COPYRIGHT HOLDER 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. + */ + +#include + +#include "helpers.h" + +#define NUM_DESC 256 + +typedef struct idtr { + uint16_t limit; + uint32_t base; +} __attribute__((packed)) idtr_t; + +typedef struct intr_gate_desc { + uint16_t offset_low; + uint16_t selector; /* Segment Selector for destination code segment */ + uint16_t fixed:11; + uint16_t d:1; /* Size of gate: 1 = 32 bits; 0 = 16 bits */ + uint16_t pad:1; + uint16_t dpl:2; /* Descriptor Privilege Level */ + uint16_t p:1; /* Segment Present flag */ + uint16_t offset_high; + +} __attribute__((packed)) intr_gate_desc_t; + +/* According to Intel Combined Manual, Vol. 3, Section 6.10, the base addresses + * of the IDT should be aligned on an 8-byte boundary to maximize performance + * of cache line fills. + */ +static intr_gate_desc_t idt[NUM_DESC] __attribute__ ((aligned(8))); + +void +idt_set_intr_gate_desc(int intr_num, uint32_t offset) +{ + intr_gate_desc_t *desc = &idt[intr_num]; + + desc->offset_low = offset & 0xFFFF; + desc->selector = 0x08; /* Offset in GDT for code segment */ + desc->fixed = BIT(9) | BIT(10); + desc->d = 1; + desc->dpl = 0; + desc->p = 1; + desc->offset_high = (offset >> 16) & 0xFFFF; +} +/*---------------------------------------------------------------------------*/ +/* Initialize Interrupt Descriptor Table. The IDT is initialized with + * null descriptors. Therefore, any interrupt at this point will cause + * a triple fault. + */ +void +idt_init(void) +{ + idtr_t idtr; + + /* Initialize idtr structure */ + idtr.limit = (sizeof(intr_gate_desc_t) * NUM_DESC) - 1; + idtr.base = (uint32_t)&idt; + + /* Load IDTR register */ + __asm__("lidt %0\n\t" :: "m" (idtr)); +} diff --git a/cpu/x86/idt.h b/cpu/x86/idt.h new file mode 100644 index 000000000..d29b97153 --- /dev/null +++ b/cpu/x86/idt.h @@ -0,0 +1,39 @@ +/* + * Copyright (C) 2015, Intel Corporation. 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. + * + * 3. Neither the name of the copyright holder nor the names of its + * contributors may be used to endorse or promote products derived + * from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 + * COPYRIGHT HOLDER 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. + */ + +#ifndef IDT_H +#define IDT_H + +#include + +void idt_init(void); +void idt_set_intr_gate_desc(int intr_num, uint32_t offset); + +#endif /* IDT_H */