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

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