traps.c

嵌入式系统设计与实验教材二源码linux内核移植与编译

/*
 * 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
 * Modified for R3000 by Paul M. Antoine, 1995, 1996
 * Complete output from die() by Ulf Carlsson, 1998
 * Copyright (C) 1999 Silicon Graphics, Inc.
 *
 * Kevin D. Kissell, [e-mail] and Carsten Langgaard, [e-mail]
 * Copyright (C) 2000, 01 MIPS Technologies, Inc.
 */
#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/cpu.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/system.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>

/*
 * Machine specific interrupt handlers
 */
extern asmlinkage void acer_pica_61_handle_int(void);
extern asmlinkage void decstation_handle_int(void);
extern asmlinkage void deskstation_rpc44_handle_int(void);
extern asmlinkage void deskstation_tyne_handle_int(void);
extern asmlinkage void mips_magnum_4000_handle_int(void);

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_watch(void);
extern asmlinkage void handle_mcheck(void);
extern asmlinkage void handle_reserved(void);

extern int fpu_emulator_cop1Handler(struct pt_regs *);

char watch_available = 0;

void (*ibe_board_handler)(struct pt_regs *regs);
void (*dbe_board_handler)(struct pt_regs *regs);

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)

#ifndef CONFIG_CPU_HAS_LLSC
/*
 * This stuff is needed for the userland ll-sc emulation for R2300
 */
void simulate_ll(struct pt_regs *regs, unsigned int opcode);
void simulate_sc(struct pt_regs *regs, unsigned int opcode);

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

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

	stack = sp;
	i = 0;

	printk("Stack:");
	while ((unsigned long) stack & (PAGE_SIZE - 1)) {
		unsigned long stackdata;

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

		printk(" %08lx", stackdata);

		if (++i > 40) {
			printk(" ...");
			break;
		}

		if (i % 8 == 0)
			printk("\n      ");
	}
}

void show_trace(unsigned int *sp)
{
	int i;
	unsigned int *stack;
	unsigned long kernel_start, kernel_end;
	unsigned long module_start, module_end;
	extern char _stext, _etext;

	stack = sp;
	i = 0;

	kernel_start = (unsigned long) &_stext;
	kernel_end = (unsigned long) &_etext;
	module_start = VMALLOC_START;
	module_end = module_start + MODULE_RANGE;

	printk("\nCall Trace:");

	while ((unsigned long) stack & (PAGE_SIZE -1)) {
		unsigned long addr;

		if (__get_user(addr, stack++)) {
			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 ((addr >= kernel_start && addr < kernel_end) ||
		    (addr >= module_start && addr < module_end)) { 

			printk(" [<%08lx>]", addr);
			if (++i > 40) {
				printk(" ...");
				break;
			}
		}
	}
}

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?' ':'>'));
	}
}

spinlock_t die_lock;

extern void __die(const char * str, struct pt_regs * regs, const char *where,
                  unsigned long line)
{
	console_verbose();
	spin_lock_irq(&die_lock);
	printk("%s", str);
	if (where)
		printk(" in %s, line %ld", where, line);
	printk(":\n");
	show_regs(regs);
	printk("Process %s (pid: %d, stackpage=%08lx)\n",
		current->comm, current->pid, (unsigned long) current);
	show_stack((unsigned int *) regs->regs[29]);
	show_trace((unsigned int *) regs->regs[29]);
	show_code((unsigned int *) regs->cp0_epc);
	printk("\n");
	spin_unlock_irq(&die_lock);
	do_exit(SIGSEGV);
}

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

static void default_be_board_handler(struct pt_regs *regs)
{
	unsigned long new_epc;
	unsigned long fixup;
	int data = regs->cp0_cause & 4;

	if (data && !user_mode(regs)) {
		fixup = search_dbe_table(regs->cp0_epc);
		if (fixup) {
			new_epc = fixup_exception(dpf_reg, fixup,
						  regs->cp0_epc);
			regs->cp0_epc = new_epc;
			return;
		}
	}

	/*
	 * 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);
}

asmlinkage void do_ibe(struct pt_regs *regs)
{
	ibe_board_handler(regs);
}

asmlinkage void do_dbe(struct pt_regs *regs)
{
	dbe_board_handler(regs);
}

asmlinkage void do_ov(struct pt_regs *regs)
{
	if (compute_return_epc(regs))
		return;

	force_sig(SIGFPE, 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) {
		extern void save_fp(struct task_struct *);
		extern void restore_fp(struct task_struct *);
		int sig;
		/*
	 	 * 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(regs);

		/* 
		 * We can't allow the emulated instruction to leave the
		 * Unimplemented Operation bit set in $fcr31.
		 */
		current->thread.fpu.soft.sr &= ~FPU_CSR_UNI_X;

		/* Restore the hardware register state */
		restore_fp(current);

		/* If something went wrong, signal */
		if (sig)
			force_sig(sig, current);

		return;
	}

	if (compute_return_epc(regs))
		return;

	force_sig(SIGFPE, current);
	printk(KERN_DEBUG "Sent send SIGFPE to %s\n", current->comm);
}

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;
}

asmlinkage void do_bp(struct pt_regs *regs)
{
	siginfo_t info;
	unsigned int opcode, bcode;
	unsigned int *epc;

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

	/*
	 * There is the ancient bug in the MIPS assemblers that the break
	 * code starts left to bit 16 instead to bit 6 in the opcode.
	 * Gas is bug-compatible ...
	 */
	bcode = ((opcode >> 16) & ((1 << 20) - 1));

	/*
	 * (A short test says that IRIX 5.3 sends SIGTRAP for all break
	 * insns, even for break codes that indicate arithmetic failures.
	 * Weird ...)
	 * But should we continue the brokenness???  --macro
	 */
	switch (bcode) {
	case 6:
	case 7:
		if (bcode == 7)
			info.si_code = FPE_INTDIV;
		else
			info.si_code = FPE_INTOVF;
		info.si_signo = SIGFPE;
		info.si_errno = 0;
		info.si_addr = (void *)compute_return_epc(regs);
		force_sig_info(SIGFPE, &info, current);
		break;
	default:
		force_sig(SIGTRAP, current);
	}
	return;

sigsegv:
	force_sig(SIGSEGV, current);
}

asmlinkage void do_tr(struct pt_regs *regs)
{
	siginfo_t info;
	unsigned int opcode, bcode;
	unsigned *epc;

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

	bcode = ((opcode >> 6) & ((1 << 20) - 1));

	/*
	 * (A short test says that IRIX 5.3 sends SIGTRAP for all break
	 * insns, even for break codes that indicate arithmetic failures.
	 * Weird ...)
	 * But should we continue the brokenness???  --macro
	 */
	switch (bcode) {
	case 6:
	case 7:
		if (bcode == 7)
			info.si_code = FPE_INTDIV;
		else
			info.si_code = FPE_INTOVF;
		info.si_signo = SIGFPE;
		info.si_errno = 0;
		info.si_addr = (void *)compute_return_epc(regs);
		force_sig_info(SIGFPE, &info, current);
		break;
	default:
		force_sig(SIGTRAP, current);
	}
	return;

sigsegv:
	force_sig(SIGSEGV, current);