traps.c

linux-2.4.29操作系统的源码

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 1994 - 1999, 2000, 01 Ralf Baechle
 * Copyright (C) 1995, 1996 Paul M. Antoine
 * Copyright (C) 1998 Ulf Carlsson
 * Copyright (C) 1999 Silicon Graphics, Inc.
 * Kevin D. Kissell, [e-mail] and Carsten Langgaard, [e-mail]
 * Copyright (C) 2000, 01 MIPS Technologies, Inc.
 * Copyright (C) 2002, 2003, 2004  Maciej W. Rozycki
 */
#include <linux/config.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>

#include <asm/bootinfo.h>
#include <asm/branch.h>
#include <asm/break.h>
#include <asm/cpu.h>
#include <asm/fpu.h>
#include <asm/cachectl.h>
#include <asm/inst.h>
#include <asm/jazz.h>
#include <asm/module.h>
#include <asm/pgtable.h>
#include <asm/io.h>
#include <asm/siginfo.h>
#include <asm/watch.h>
#include <asm/tlbdebug.h>
#include <asm/types.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>

extern asmlinkage void handle_mod(void);
extern asmlinkage void handle_tlbl(void);
extern asmlinkage void handle_tlbs(void);
extern asmlinkage void handle_adel(void);
extern asmlinkage void handle_ades(void);
extern asmlinkage void handle_ibe(void);
extern asmlinkage void handle_dbe(void);
extern asmlinkage void handle_sys(void);
extern asmlinkage void handle_bp(void);
extern asmlinkage void handle_ri(void);
extern asmlinkage void handle_cpu(void);
extern asmlinkage void handle_ov(void);
extern asmlinkage void handle_tr(void);
extern asmlinkage void handle_fpe(void);
extern asmlinkage void handle_mdmx(void);
extern asmlinkage void handle_watch(void);
extern asmlinkage void handle_mcheck(void);
extern asmlinkage void handle_reserved(void);

extern int fpu_emulator_cop1Handler(int xcptno, struct pt_regs *xcp,
	struct mips_fpu_soft_struct *ctx);

void (*board_be_init)(void);
int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
void (*board_nmi_handler_setup)(void);

int kstack_depth_to_print = 24;

/*
 * These constant is for searching for possible module text segments.
 * MODULE_RANGE is a guess of how much space is likely to be vmalloced.
 */
#define MODULE_RANGE (8*1024*1024)

/*
 * If the address is either in the .text section of the
 * kernel, or in the vmalloc'ed module regions, it *may*
 * be the address of a calling routine
 */

#ifdef CONFIG_MODULES

extern struct module *module_list;
extern struct module kernel_module;

static inline int kernel_text_address(long addr)
{
	extern char _stext, _etext;
	int retval = 0;
	struct module *mod;

	if (addr >= (long) &_stext && addr <= (long) &_etext)
		return 1;

	for (mod = module_list; mod != &kernel_module; mod = mod->next) {
		/* mod_bound tests for addr being inside the vmalloc'ed
		 * module area. Of course it'd be better to test only
		 * for the .text subset... */
		if (mod_bound(addr, 0, mod)) {
			retval = 1;
			break;
		}
	}

	return retval;
}

#else

static inline int kernel_text_address(long addr)
{
	extern char _stext, _etext;

	return (addr >= (long) &_stext && addr <= (long) &_etext);
}

#endif

/*
 * This routine abuses get_user()/put_user() to reference pointers
 * with at least a bit of error checking ...
 */
void show_stack(long *sp)
{
	int i;
	long stackdata;

	sp = sp ? sp : (long *)&sp;

	printk("Stack:   ");
	i = 1;
	while ((long) sp & (PAGE_SIZE - 1)) {
		if (i && ((i % 8) == 0))
			printk("\n");
		if (i > 40) {
			printk(" ...");
			break;
		}

		if (__get_user(stackdata, sp++)) {
			printk(" (Bad stack address)");
			break;
		}

		printk(" %08lx", stackdata);
		i++;
	}
	printk("\n");
}

void show_trace(long *sp)
{
	int i;
	long addr;

	sp = sp ? sp : (long *) &sp;

	printk("Call Trace:  ");
	i = 1;
	while ((long) sp & (PAGE_SIZE - 1)) {

		if (__get_user(addr, sp++)) {
			if (i && ((i % 6) == 0))
				printk("\n");
			printk(" (Bad stack address)\n");
			break;
		}

		/*
		 * If the address is either in the text segment of the
		 * kernel, or in the region which contains vmalloc'ed
		 * memory, it *may* be the address of a calling
		 * routine; if so, print it so that someone tracing
		 * down the cause of the crash will be able to figure
		 * out the call path that was taken.
		 */

		if (kernel_text_address(addr)) {
			if (i && ((i % 6) == 0))
				printk("\n");
			if (i > 40) {
				printk(" ...");
				break;
			}

			printk(" [<%08lx>]", addr);
			i++;
		}
	}
	printk("\n");
}

void show_trace_task(struct task_struct *tsk)
{
	show_trace((long *)tsk->thread.reg29);
}

void show_code(unsigned int *pc)
{
	long i;

	printk("\nCode:");

	for(i = -3 ; i < 6 ; i++) {
		unsigned long insn;
		if (__get_user(insn, pc + i)) {
			printk(" (Bad address in epc)\n");
			break;
		}
		printk("%c%08lx%c",(i?' ':'<'),insn,(i?' ':'>'));
	}
}

void show_regs(struct pt_regs *regs)
{
	/*
	 * Saved main processor registers
	 */
	printk("$0 : %08x %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
	       0,             regs->regs[1], regs->regs[2], regs->regs[3],
	       regs->regs[4], regs->regs[5], regs->regs[6], regs->regs[7]);
	printk("$8 : %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
	       regs->regs[8],  regs->regs[9],  regs->regs[10], regs->regs[11],
	       regs->regs[12], regs->regs[13], regs->regs[14], regs->regs[15]);
	printk("$16: %08lx %08lx %08lx %08lx %08lx %08lx %08lx %08lx\n",
	       regs->regs[16], regs->regs[17], regs->regs[18], regs->regs[19],
	       regs->regs[20], regs->regs[21], regs->regs[22], regs->regs[23]);
	printk("$24: %08lx %08lx                   %08lx %08lx %08lx %08lx\n",
	       regs->regs[24], regs->regs[25],
	       regs->regs[28], regs->regs[29], regs->regs[30], regs->regs[31]);
	printk("Hi : %08lx\n", regs->hi);
	printk("Lo : %08lx\n", regs->lo);

	/*
	 * Saved cp0 registers
	 */
	printk("epc   : %08lx    %s\n", regs->cp0_epc, print_tainted());
	printk("Status: %08lx\n", regs->cp0_status);
	printk("Cause : %08lx\n", regs->cp0_cause);
	printk("PrId  : %08x\n", read_c0_prid());
}

void show_registers(struct pt_regs *regs)
{
	show_regs(regs);
	printk("Process %s (pid: %d, stackpage=%08lx)\n",
		current->comm, current->pid, (unsigned long) current);
	show_stack((long *) regs->regs[29]);
	show_trace((long *) regs->regs[29]);
	show_code((unsigned int *) regs->cp0_epc);
	printk("\n");
}

static spinlock_t die_lock = SPIN_LOCK_UNLOCKED;

void __die(const char * str, struct pt_regs * regs, const char * file,
	   const char * func, unsigned long line)
{
	console_verbose();
	spin_lock_irq(&die_lock);
	printk("%s", str);
	if (file && func)
		printk(" in %s:%s, line %ld", file, func, line);
	printk(":\n");
	show_registers(regs);
	spin_unlock_irq(&die_lock);
	do_exit(SIGSEGV);
}

void __die_if_kernel(const char * str, struct pt_regs * regs,
		     const char * file, const char * func, unsigned long line)
{
	if (!user_mode(regs))
		__die(str, regs, file, func, line);
}

extern const struct exception_table_entry __start___dbe_table[];
extern const struct exception_table_entry __stop___dbe_table[];

void __declare_dbe_table(void)
{
	__asm__ __volatile__(
	".section\t__dbe_table,\"a\"\n\t"
	".previous"
	);
}

static inline unsigned long
search_one_table(const struct exception_table_entry *first,
		 const struct exception_table_entry *last,
		 unsigned long value)
{
	const struct exception_table_entry *mid;
	long diff;

	while (first < last) {
		mid = (last - first) / 2 + first;
		diff = mid->insn - value;
		if (diff < 0)
			first = mid + 1;
		else
			last = mid;
	}
	return (first == last && first->insn == value) ? first->nextinsn : 0;
}

extern spinlock_t modlist_lock;

static inline unsigned long
search_dbe_table(unsigned long addr)
{
	unsigned long ret = 0;

#ifndef CONFIG_MODULES
	/* There is only the kernel to search.  */
	ret = search_one_table(__start___dbe_table, __stop___dbe_table-1, addr);
	return ret;
#else
	unsigned long flags;

	/* The kernel is the last "module" -- no need to treat it special.  */
	struct module *mp;
	struct archdata *ap;

	spin_lock_irqsave(&modlist_lock, flags);
	for (mp = module_list; mp != NULL; mp = mp->next) {
		if (!mod_member_present(mp, archdata_end) ||
		    !mod_archdata_member_present(mp, struct archdata,
						 dbe_table_end))
			continue;
		ap = (struct archdata *)(mp->archdata_start);

		if (ap->dbe_table_start == NULL ||
		    !(mp->flags & (MOD_RUNNING | MOD_INITIALIZING)))
			continue;
		ret = search_one_table(ap->dbe_table_start,
				       ap->dbe_table_end - 1, addr);
		if (ret)
			break;
	}
	spin_unlock_irqrestore(&modlist_lock, flags);
	return ret;
#endif
}

asmlinkage void do_be(struct pt_regs *regs)
{
	unsigned long new_epc;
	unsigned long fixup = 0;
	int data = regs->cp0_cause & 4;
	int action = MIPS_BE_FATAL;

	if (data && !user_mode(regs))
		fixup = search_dbe_table(exception_epc(regs));

	if (fixup)
		action = MIPS_BE_FIXUP;

	if (board_be_handler)
		action = board_be_handler(regs, fixup != 0);

	switch (action) {
	case MIPS_BE_DISCARD:
		return;
	case MIPS_BE_FIXUP:
		if (fixup) {
			new_epc = fixup_exception(dpf_reg, fixup,
						  regs->cp0_epc);
			regs->cp0_epc = new_epc;
			return;
		}
		break;
	default:
		break;
	}

	/*
	 * Assume it would be too dangerous to continue ...
	 */
	printk(KERN_ALERT "%s bus error, epc == %08lx, ra == %08lx\n",
	       data ? "Data" : "Instruction",
	       regs->cp0_epc, regs->regs[31]);
	die_if_kernel("Oops", regs);
	force_sig(SIGBUS, current);
}

static inline int get_insn_opcode(struct pt_regs *regs, unsigned int *opcode)
{
	unsigned int *epc;

	epc = (unsigned int *) regs->cp0_epc +
	      ((regs->cp0_cause & CAUSEF_BD) != 0);
	if (!get_user(*opcode, epc))
		return 0;

	force_sig(SIGSEGV, current);
	return 1;
}

/*
 * ll/sc emulation
 */

#define OPCODE 0xfc000000
#define BASE   0x03e00000
#define RT     0x001f0000
#define OFFSET 0x0000ffff
#define LL     0xc0000000
#define SC     0xe0000000

/*
 * The ll_bit is cleared by r*_switch.S
 */

unsigned long ll_bit;

static struct task_struct *ll_task = NULL;

static inline void simulate_ll(struct pt_regs *regs, unsigned int opcode)
{
	unsigned long value, *vaddr;
	long offset;
	int signal = 0;

	/*
	 * analyse the ll instruction that just caused a ri exception
	 * and put the referenced address to addr.
	 */

	/* sign extend offset */
	offset = opcode & OFFSET;
	offset <<= 16;
	offset >>= 16;

	vaddr = (unsigned long *)((long)(regs->regs[(opcode & BASE) >> 21]) + offset);

	if ((unsigned long)vaddr & 3) {
		signal = SIGBUS;
		goto sig;
	}
	if (get_user(value, vaddr)) {
		signal = SIGSEGV;
		goto sig;
	}

	if (ll_task == NULL || ll_task == current) {
		ll_bit = 1;
	} else {
		ll_bit = 0;
	}
	ll_task = current;

	regs->regs[(opcode & RT) >> 16] = value;

	compute_return_epc(regs);
	return;

sig:
	force_sig(signal, current);
}

static inline void simulate_sc(struct pt_regs *regs, unsigned int opcode)
{
	unsigned long *vaddr, reg;
	long offset;
	int signal = 0;

	/*
	 * analyse the sc instruction that just caused a ri exception
	 * and put the referenced address to addr.
	 */

	/* sign extend offset */
	offset = opcode & OFFSET;
	offset <<= 16;
	offset >>= 16;

	vaddr = (unsigned long *)((long)(regs->regs[(opcode & BASE) >> 21]) + offset);
	reg = (opcode & RT) >> 16;

	if ((unsigned long)vaddr & 3) {
		signal = SIGBUS;
		goto sig;
	}
	if (ll_bit == 0 || ll_task != current) {
		regs->regs[reg] = 0;
		compute_return_epc(regs);
		return;
	}

	if (put_user(regs->regs[reg], vaddr)) {
		signal = SIGSEGV;
		goto sig;
	}

	regs->regs[reg] = 1;

	compute_return_epc(regs);
	return;

sig:
	force_sig(signal, current);
}

/*
 * ll uses the opcode of lwc0 and sc uses the opcode of swc0.  That is both
 * opcodes are supposed to result in coprocessor unusable exceptions if
 * executed on ll/sc-less processors.  That's the theory.  In practice a
 * few processors such as NEC's VR4100 throw reserved instruction exceptions
 * instead, so we're doing the emulation thing in both exception handlers.
 */
static inline int simulate_llsc(struct pt_regs *regs)
{