Joshua Wise's Git repositories - netwatch.git/blame_incremental

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Commit	Line	Data
	1	/* traps.c
	2	* Trap handling routines
	3	* NetWatch system management mode administration console
	4	*
	5	* Copyright (c) 2008 Jacob Potter and Joshua Wise. All rights reserved.
	6	* This program is free software; you can redistribute and/or modify it under
	7	* the terms found in the file LICENSE in the root of this source tree.
	8	*
	9	*/
	10
	11	#include <output.h>
	12	#include <io.h>
	13	#include <paging.h>
	14
	15	#include "traps.h"
	16
	17	#define CS_SEGSEL 0x8
	18
	19	#define FAULT_WRAPPER(func_name) asm ( \
	20	".global " #func_name "_wrapper\n" \
	21	#func_name "_wrapper:\n" \
	22	"mov %cr2, %eax\n" \
	23	"push %eax\n" \
	24	"push %esp\n" \
	25	"call " #func_name "\n" \
	26	); void func_name##_wrapper(void);
	27
	28	#define WRAPPER_INSTALL(idt, idt4_value, func_name, int_number) { \
	29	(int )((void )idt + (8 int_number)) = \
	30	((int)func_name##_wrapper & 0xFFFF) \| \
	31	(CS_SEGSEL << 16); \
	32	(int )((void )idt + (8 int_number) + 4) = \
	33	((int)func_name##_wrapper & 0xFFFF0000) \| idt4_value; \
	34	}
	35
	36	/* The 16 bits at offset 4 from the start of an interrupt gate are a
	37	* bitfield, according to the Intel spec:
	38	* 15 P - Segment Present - set to 1
	39	* 14-13 DPL - Descriptor privilege level - set to 11 for trap/int, 00 for IPI
	40	* 12-8 01111 for 32-bit trap gates, 01110 for 32-bit interrupt gates
	41	* 7-0 Set to 0
	42	* Trap: binary 11101111 0000000, hex EF00.
	43	* Interrupt: binary 11101110 0000000, hex EE00.
	44	*/
	45	#define TRAP 0xEF00
	46	#define INTERRUPT 0xEE00
	47
	48	typedef struct trap_t {
	49	int cr2;
	50	int error_code;
	51	int eip;
	52	int cs;
	53	int eflags;
	54	int esp;
	55	int ss;
	56	} trap_t;
	57
	58	void die(struct trap_t * trap) {
	59	outputf("Error %08x %%eip %08x", trap->error_code, trap->eip);
	60	outputf("%%esp %08x %%eflags %08x", trap->esp, trap->eflags);
	61	while(1) asm("hlt");
	62	}
	63
	64	void fault_gp(struct trap_t * trap) {
	65	outputf("GENERAL PROTECTION FAULT");
	66	die(trap);
	67	}
	68
	69	void fault_page(struct trap_t * trap) {
	70	outputf("PAGE FAULT: %08x", trap->cr2);
	71	die(trap);
	72	}
	73	void fault_divide(struct trap_t * trap) {
	74	outputf("DIVISION FAULT");
	75	die(trap);
	76	}
	77	void double_fault(struct trap_t * trap) {
	78	outputf("DOUBLE FAULT");
	79	die(trap);
	80	}
	81
	82	FAULT_WRAPPER(fault_gp);
	83	FAULT_WRAPPER(fault_page);
	84	FAULT_WRAPPER(fault_divide);
	85	FAULT_WRAPPER(double_fault);
	86
	87	/* pseudo_descriptor and x86_gate structs from 15-410 basis code. */
	88
	89	struct x86_gate {
	90	unsigned int filler[2]; //64 bits; or 8 bytes.
	91	};
	92
	93	static struct x86_gate idt[64];
	94
	95	struct pseudo_descriptor {
	96	short pad;
	97	unsigned short limit;
	98	unsigned long linear_base;
	99	} __attribute__((packed));
	100
	101	void traps_install(void) {
	102
	103	struct pseudo_descriptor pdesc;
	104	pdesc.limit = sizeof(idt) - 1;
	105	pdesc.linear_base = v2p(&idt);
	106
	107	WRAPPER_INSTALL(idt, TRAP, fault_divide, T_DIVIDE_ERROR);
	108	WRAPPER_INSTALL(idt, TRAP, fault_gp, T_GENERAL_PROTECTION);
	109	WRAPPER_INSTALL(idt, TRAP, fault_page, T_PAGE_FAULT);
	110	WRAPPER_INSTALL(idt, TRAP, double_fault, T_DOUBLE_FAULT);
	111
	112	outb(0x80, 0xCC);
	113	asm volatile("lidt %0" : : "m" (pdesc.limit));
	114	outb(0x80, 0xCD);
	115	}