WebSVN – HelenOS – Blame – //branches/tracing/kernel/arch/arm32/src/mm/page_fault.c

Rev	Author	Line No.	Line
2464	jermar	1	/*
		2	* Copyright (c) 2007 Pavel Jancik, Michal Kebrt
		3	* All rights reserved.
		4	*
		5	* Redistribution and use in source and binary forms, with or without
		6	* modification, are permitted provided that the following conditions
		7	* are met:
		8	*
		9	* - Redistributions of source code must retain the above copyright
		10	* notice, this list of conditions and the following disclaimer.
		11	* - Redistributions in binary form must reproduce the above copyright
		12	* notice, this list of conditions and the following disclaimer in the
		13	* documentation and/or other materials provided with the distribution.
		14	* - The name of the author may not be used to endorse or promote products
		15	* derived from this software without specific prior written permission.
		16	*
		17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
		18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
		20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		27	*/
		28
		29	/** @addtogroup arm32mm
		30	* @{
		31	*/
		32	/** @file
		33	* @brief Page fault related functions.
		34	*/
		35	#include <panic.h>
		36	#include <arch/exception.h>
		37	#include <arch/debug/print.h>
		38	#include <arch/mm/page_fault.h>
		39	#include <mm/as.h>
		40	#include <genarch/mm/page_pt.h>
		41	#include <arch.h>
		42	#include <interrupt.h>
3424	svoboda	43	#include <print.h>
2464	jermar	44
		45	/** Returns value stored in fault status register.
		46	*
		47	* @return Value stored in CP15 fault status register (FSR).
		48	*/
		49	static inline fault_status_t read_fault_status_register(void)
		50	{
		51	fault_status_union_t fsu;
		52
		53	/* fault status is stored in CP15 register 5 */
		54	asm volatile (
		55	"mrc p15, 0, %0, c5, c0, 0"
		56	: "=r"(fsu.dummy)
		57	);
		58	return fsu.fs;
		59	}
		60
		61	/** Returns FAR (fault address register) content.
		62	*
		63	* @return FAR (fault address register) content (address that caused a page
		64	* fault)
		65	*/
		66	static inline uintptr_t read_fault_address_register(void)
		67	{
		68	uintptr_t ret;
		69
		70	/* fault adress is stored in CP15 register 6 */
		71	asm volatile (
		72	"mrc p15, 0, %0, c6, c0, 0"
		73	: "=r"(ret)
		74	);
		75	return ret;
		76	}
		77
		78	/** Decides whether the instruction is load/store or not.
		79	*
		80	* @param instr Instruction
		81	*
		82	* @return true when instruction is load/store, false otherwise
		83	*/
		84	static inline bool is_load_store_instruction(instruction_t instr)
		85	{
		86	/* load store immediate offset */
		87	if (instr.type == 0x2) {
		88	return true;
		89	}
		90
		91	/* load store register offset */
		92	if (instr.type == 0x3 && instr.bit4 == 0) {
		93	return true;
		94	}
		95
		96	/* load store multiple */
		97	if (instr.type == 0x4) {
		98	return true;
		99	}
		100
		101	/* oprocessor load/store */
		102	if (instr.type == 0x6) {
		103	return true;
		104	}
		105
		106	return false;
		107	}
		108
		109	/** Decides whether the instruction is swap or not.
		110	*
		111	* @param instr Instruction
		112	*
		113	* @return true when instruction is swap, false otherwise
		114	*/
		115	static inline bool is_swap_instruction(instruction_t instr)
		116	{
		117	/* swap, swapb instruction */
		118	if (instr.type == 0x0 &&
		119	(instr.opcode == 0x8 \|\| instr.opcode == 0xa) &&
		120	instr.access == 0x0 && instr.bits567 == 0x4 && instr.bit4 == 1) {
		121	return true;
		122	}
		123
		124	return false;
		125	}
		126
		127	/** Decides whether read or write into memory is requested.
		128	*
		129	* @param instr_addr Address of instruction which tries to access memory.
		130	* @param badvaddr Virtual address the instruction tries to access.
		131	*
		132	* @return Type of access into memory, PF_ACCESS_EXEC if no memory access is
		133	* requested.
		134	*/
		135	static pf_access_t get_memory_access_type(uint32_t instr_addr,
		136	uintptr_t badvaddr)
		137	{
		138	instruction_union_t instr_union;
		139	instr_union.pc = instr_addr;
		140
		141	instruction_t instr = *(instr_union.instr);
		142
		143	/* undefined instructions */
		144	if (instr.condition == 0xf) {
		145	panic("page_fault - instruction doesn't access memory "
		146	"(instr_code: %x, badvaddr:%x)", instr, badvaddr);
		147	return PF_ACCESS_EXEC;
		148	}
		149
		150	/* load store instructions */
		151	if (is_load_store_instruction(instr)) {
		152	if (instr.access == 1) {
		153	return PF_ACCESS_READ;
		154	} else {
		155	return PF_ACCESS_WRITE;
		156	}
		157	}
		158
		159	/* swap, swpb instruction */
		160	if (is_swap_instruction(instr)) {
		161	return PF_ACCESS_WRITE;
		162	}
		163
		164	panic("page_fault - instruction doesn't access memory "
		165	"(instr_code: %x, badvaddr:%x)", instr, badvaddr);
		166
		167	return PF_ACCESS_EXEC;
		168	}
		169
		170	/** Handles "data abort" exception (load or store at invalid address).
		171	*
		172	* @param exc_no Exception number.
		173	* @param istate CPU state when exception occured.
		174	*/
		175	void data_abort(int exc_no, istate_t *istate)
		176	{
2772	jermar	177	fault_status_t fsr __attribute__ ((unused)) =
		178	read_fault_status_register();
2464	jermar	179	uintptr_t badvaddr = read_fault_address_register();
		180
		181	pf_access_t access = get_memory_access_type(istate->pc, badvaddr);
		182
		183	int ret = as_page_fault(badvaddr, access, istate);
		184
		185	if (ret == AS_PF_FAULT) {
		186	print_istate(istate);
		187	dprintf("page fault - pc: %x, va: %x, status: %x(%x), "
		188	"access:%d\n", istate->pc, badvaddr, fsr.status, fsr,
		189	access);
		190
		191	fault_if_from_uspace(istate, "Page fault: %#x", badvaddr);
		192	panic("page fault\n");
		193	}
		194	}
		195
3431	svoboda	196	#ifdef CONFIG_UDEBUG
		197
3125	svoboda	198	/** Check whether the abort was caused by a bkpt instruction.
		199	*
		200	* This must be called after (possibly) fetching the faulting page.
		201	*
		202	* TODO: When paging-out is implemented, make sure the page
		203	* is still present when reading the instruction (we don't want
		204	* to trigger another exception).
		205	*/
		206	static void bkpt_check(istate_t *istate)
		207	{
		208	uint32_t instr_addr = (uint32_t ) istate->pc;
		209	uint32_t opcode = *instr_addr;
		210
		211	if ((opcode & 0xfff000f0) == 0xe1200070) {
		212	/* Bkpt */
3431	svoboda	213
3125	svoboda	214	if (istate_from_uspace(istate)) {
		215	udebug_breakpoint_event(0);
3431	svoboda	216	return;
3125	svoboda	217	} else {
		218	panic("Unexpected BKPT instruction at 0x%x",
		219	istate->pc);
		220	}
		221	}
		222	}
		223
3431	svoboda	224	#endif
		225
2464	jermar	226	/** Handles "prefetch abort" exception (instruction couldn't be executed).
		227	*
		228	* @param exc_no Exception number.
		229	* @param istate CPU state when exception occured.
		230	*/
		231	void prefetch_abort(int exc_no, istate_t *istate)
		232	{
		233	int ret = as_page_fault(istate->pc, PF_ACCESS_EXEC, istate);
		234
		235	if (ret == AS_PF_FAULT) {
		236	dprintf("prefetch_abort\n");
		237	print_istate(istate);
		238	panic("page fault - prefetch_abort at address: %x\n",
		239	istate->pc);
		240	}
3125	svoboda	241
3431	svoboda	242	#ifdef CONFIG_UDEBUG
3125	svoboda	243	/* Now check if the abort was caused by a breakpoint instruction */
		244	bkpt_check(istate);
3431	svoboda	245	#else
		246	panic("Unexpected BKPT instruction at 0x%x", istate->pc);
		247	#endif
		248
2464	jermar	249	}
		250
		251	/** @}
		252	*/

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