traps.c

h内核

/*
 * 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 <linux/kallsyms.h>

#include <asm/bootinfo.h>
#include <asm/branch.h>
#include <asm/break.h>
#include <asm/cpu.h>
#include <asm/fpu.h>
#include <asm/module.h>
#include <asm/pgtable.h>
#include <asm/ptrace.h>
#include <asm/sections.h>
#include <asm/system.h>
#include <asm/tlbdebug.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/watch.h>
#include <asm/types.h>

extern asmlinkage void handle_tlbm(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);

/*
 * 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)

/*
 * This routine abuses get_user()/put_user() to reference pointers
 * with at least a bit of error checking ...
 */
void show_stack(struct task_struct *task, unsigned long *sp)
{
	const int field = 2 * sizeof(unsigned long);
	long stackdata;
	int i;

	if (!sp) {
		if (task && task != current)
			sp = (unsigned long *) task->thread.reg29;
		else
			sp = (unsigned long *) &sp;
	}

	printk("Stack :");
	i = 0;
	while ((unsigned long) sp & (PAGE_SIZE - 1)) {
		if (i && ((i % (64 / field)) == 0))
			printk("\n       ");
		if (i > 39) {
			printk(" ...");
			break;
		}

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

		printk(" %0*lx", field, stackdata);
		i++;
	}
	printk("\n");
}

void show_trace(struct task_struct *task, unsigned long *stack)
{
	const int field = 2 * sizeof(unsigned long);
	unsigned long addr;

	if (!stack) {
		if (task && task != current)
			stack = (unsigned long *) task->thread.reg29;
		else
			stack = (unsigned long *) &stack;
	}

	printk("Call Trace:");
#ifdef CONFIG_KALLSYMS
	printk("\n");
#endif
	while (!kstack_end(stack)) {
		addr = *stack++;
		if (__kernel_text_address(addr)) {
			printk(" [<%0*lx>] ", field, addr);
			print_symbol("%s\n", addr);
		}
	}
	printk("\n");
}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
	unsigned long stack;

	show_trace(current, &stack);
}

EXPORT_SYMBOL(dump_stack);

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

	printk("\nCode:");

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

void show_regs(struct pt_regs *regs)
{
	const int field = 2 * sizeof(unsigned long);
	unsigned int cause = regs->cp0_cause;
	int i;

	printk("Cpu %d\n", smp_processor_id());

	/*
	 * Saved main processor registers
	 */
	for (i = 0; i < 32; ) {
		if ((i % 4) == 0)
			printk("$%2d   :", i);
		if (i == 0)
			printk(" %0*lx", field, 0UL);
		else if (i == 26 || i == 27)
			printk(" %*s", field, "");
		else
			printk(" %0*lx", field, regs->regs[i]);

		i++;
		if ((i % 4) == 0)
			printk("\n");
	}

	printk("Hi    : %0*lx\n", field, regs->hi);
	printk("Lo    : %0*lx\n", field, regs->lo);

	/*
	 * Saved cp0 registers
	 */
	printk("epc   : %0*lx ", field, regs->cp0_epc);
	print_symbol("%s ", regs->cp0_epc);
	printk("    %s\n", print_tainted());
	printk("ra    : %0*lx ", field, regs->regs[31]);
	print_symbol("%s\n", regs->regs[31]);

	printk("Status: %08x    ", (uint32_t) regs->cp0_status);

	if (regs->cp0_status & ST0_KX)
		printk("KX ");
	if (regs->cp0_status & ST0_SX)
		printk("SX ");
	if (regs->cp0_status & ST0_UX)
		printk("UX ");
	switch (regs->cp0_status & ST0_KSU) {
	case KSU_USER:
		printk("USER ");
		break;
	case KSU_SUPERVISOR:
		printk("SUPERVISOR ");
		break;
	case KSU_KERNEL:
		printk("KERNEL ");
		break;
	default:
		printk("BAD_MODE ");
		break;
	}
	if (regs->cp0_status & ST0_ERL)
		printk("ERL ");
	if (regs->cp0_status & ST0_EXL)
		printk("EXL ");
	if (regs->cp0_status & ST0_IE)
		printk("IE ");
	printk("\n");

	printk("Cause : %08x\n", cause);

	cause = (cause & CAUSEF_EXCCODE) >> CAUSEB_EXCCODE;
	if (1 <= cause && cause <= 5)
		printk("BadVA : %0*lx\n", field, regs->cp0_badvaddr);

	printk("PrId  : %08x\n", read_c0_prid());
}

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

static DEFINE_SPINLOCK(die_lock);

NORET_TYPE void __die(const char * str, struct pt_regs * regs,
	const char * file, const char * func, unsigned long line)
{
	static int die_counter;

	console_verbose();
	spin_lock_irq(&die_lock);
	printk("%s", str);
	if (file && func)
		printk(" in %s:%s, line %ld", file, func, line);
	printk("[#%d]:\n", ++die_counter);
	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"
	);
}

/* Given an address, look for it in the exception tables. */
static const struct exception_table_entry *search_dbe_tables(unsigned long addr)
{
	const struct exception_table_entry *e;

	e = search_extable(__start___dbe_table, __stop___dbe_table - 1, addr);
	if (!e)
		e = search_module_dbetables(addr);
	return e;
}

asmlinkage void do_be(struct pt_regs *regs)
{
	const int field = 2 * sizeof(unsigned long);
	const struct exception_table_entry *fixup = NULL;
	int data = regs->cp0_cause & 4;
	int action = MIPS_BE_FATAL;

	/* XXX For now.  Fixme, this searches the wrong table ...  */
	if (data && !user_mode(regs))
		fixup = search_dbe_tables(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) {
			regs->cp0_epc = fixup->nextinsn;
			return;
		}
		break;
	default:
		break;
	}

	/*
	 * Assume it would be too dangerous to continue ...
	 */
	printk(KERN_ALERT "%s bus error, epc == %0*lx, ra == %0*lx\n",
	       data ? "Data" : "Instruction",
	       field, regs->cp0_epc, field, 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;
	}

	preempt_disable();

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

	preempt_enable();

	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;
	}

	preempt_disable();

	if (ll_bit == 0 || ll_task != current) {
		regs->regs[reg] = 0;
		preempt_enable();
		compute_return_epc(regs);
		return;
	}

	preempt_enable();

	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)
{
	unsigned int opcode;

	if (unlikely(get_insn_opcode(regs, &opcode)))
		return -EFAULT;

	if ((opcode & OPCODE) == LL) {
		simulate_ll(regs, opcode);
		return 0;
	}
	if ((opcode & OPCODE) == SC) {
		simulate_sc(regs, opcode);
		return 0;
	}

	return -EFAULT;			/* Strange things going on ... */
}

asmlinkage void do_ov(struct pt_regs *regs)
{
	siginfo_t info;

	info.si_code = FPE_INTOVF;
	info.si_signo = SIGFPE;
	info.si_errno = 0;
	info.si_addr = (void *)regs->cp0_epc;
	force_sig_info(SIGFPE, &info, current);
}

/*
 * XXX Delayed fp exceptions when doing a lazy ctx switch XXX
 */
asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
{
	if (fcr31 & FPU_CSR_UNI_X) {
		int sig;

		preempt_disable();

		/*
	 	 * Unimplemented operation exception.  If we've got the full
		 * software emulator on-board, let's use it...
		 *
		 * Force FPU to dump state into task/thread context.  We're
		 * moving a lot of data here for what is probably a single
		 * instruction, but the alternative is to pre-decode the FP
		 * register operands before invoking the emulator, which seems
		 * a bit extreme for what should be an infrequent event.
		 */
		save_fp(current);

		/* Run the emulator */
		sig = fpu_emulator_cop1Handler (0, regs,
			&current->thread.fpu.soft);

		/*
		 * We can't allow the emulated instruction to leave any of