traps.c

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/*
 * File:         arch/blackfin/kernel/traps.c
 * Based on:
 * Author:       Hamish Macdonald
 *
 * Created:
 * Description:  uses S/W interrupt 15 for the system calls
 *
 * Modified:
 *               Copyright 2004-2006 Analog Devices Inc.
 *
 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/uaccess.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/fs.h>
#include <asm/traps.h>
#include <asm/cacheflush.h>
#include <asm/blackfin.h>
#include <asm/irq_handler.h>
#include <asm/trace.h>
#include <asm/fixed_code.h>

#ifdef CONFIG_KGDB
# include <linux/debugger.h>
# include <linux/kgdb.h>

# define CHK_DEBUGGER_TRAP() \
	do { \
		CHK_DEBUGGER(trapnr, sig, info.si_code, fp, ); \
	} while (0)
# define CHK_DEBUGGER_TRAP_MAYBE() \
	do { \
		if (kgdb_connected) \
			CHK_DEBUGGER_TRAP(); \
	} while (0)
#else
# define CHK_DEBUGGER_TRAP() do { } while (0)
# define CHK_DEBUGGER_TRAP_MAYBE() do { } while (0)
#endif

/* Initiate the event table handler */
void __init trap_init(void)
{
	CSYNC();
	bfin_write_EVT3(trap);
	CSYNC();
}

int kstack_depth_to_print = 48;

static void decode_address(char *buf, unsigned long address)
{
	struct vm_list_struct *vml;
	struct task_struct *p;
	struct mm_struct *mm;
	unsigned long flags, offset;
	unsigned int in_exception = bfin_read_IPEND() & 0x10;

#ifdef CONFIG_KALLSYMS
	unsigned long symsize;
	const char *symname;
	char *modname;
	char *delim = ":";
	char namebuf[128];

	/* look up the address and see if we are in kernel space */
	symname = kallsyms_lookup(address, &symsize, &offset, &modname, namebuf);

	if (symname) {
		/* yeah! kernel space! */
		if (!modname)
			modname = delim = "";
		sprintf(buf, "<0x%p> { %s%s%s%s + 0x%lx }",
		              (void *)address, delim, modname, delim, symname,
		              (unsigned long)offset);
		return;

	}
#endif

	/* Problem in fixed code section? */
	if (address >= FIXED_CODE_START && address < FIXED_CODE_END) {
		sprintf(buf, "<0x%p> /* Maybe fixed code section */", (void *)address);
		return;
	}

	/* Problem somewhere before the kernel start address */
	if (address < CONFIG_BOOT_LOAD) {
		sprintf(buf, "<0x%p> /* Maybe null pointer? */", (void *)address);
		return;
	}

	/* looks like we're off in user-land, so let's walk all the
	 * mappings of all our processes and see if we can't be a whee
	 * bit more specific
	 */
	write_lock_irqsave(&tasklist_lock, flags);
	for_each_process(p) {
		mm = (in_exception ? p->mm : get_task_mm(p));
		if (!mm)
			continue;

		vml = mm->context.vmlist;
		while (vml) {
			struct vm_area_struct *vma = vml->vma;

			if (address >= vma->vm_start && address < vma->vm_end) {
				char *name = p->comm;
				struct file *file = vma->vm_file;
				if (file) {
					char _tmpbuf[256];
					name = d_path(file->f_dentry,
					              file->f_vfsmnt,
					              _tmpbuf,
					              sizeof(_tmpbuf));
				}

				/* FLAT does not have its text aligned to the start of
				 * the map while FDPIC ELF does ...
				 */
				if (current->mm &&
				    (address > current->mm->start_code) &&
				    (address < current->mm->end_code))
					offset = address - current->mm->start_code;
				else
					offset = (address - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);

				sprintf(buf, "<0x%p> [ %s + 0x%lx ]",
					(void *)address, name, offset);
				if (!in_exception)
					mmput(mm);
				goto done;
			}

			vml = vml->next;
		}
		if (!in_exception)
			mmput(mm);
	}

	/* we were unable to find this address anywhere */
	sprintf(buf, "<0x%p> /* unknown address */", (void *)address);

done:
	write_unlock_irqrestore(&tasklist_lock, flags);
}

asmlinkage void double_fault_c(struct pt_regs *fp)
{
	console_verbose();
	oops_in_progress = 1;
	printk(KERN_EMERG "\n" KERN_EMERG "Double Fault\n");
	dump_bfin_process(fp);
	dump_bfin_mem((void *)fp->retx);
	show_regs(fp);
	panic("Double Fault - unrecoverable event\n");

}

asmlinkage void trap_c(struct pt_regs *fp)
{
#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
	int j;
#endif
	int sig = 0;
	siginfo_t info;
	unsigned long trapnr = fp->seqstat & SEQSTAT_EXCAUSE;

	trace_buffer_save(j);

	/* Important - be very careful dereferncing pointers - will lead to
	 * double faults if the stack has become corrupt
	 */

	/* If the fault was caused by a kernel thread, or interrupt handler
	 * we will kernel panic, so the system reboots.
	 * If KGDB is enabled, don't set this for kernel breakpoints
	*/
	if ((bfin_read_IPEND() & 0xFFC0)
#ifdef CONFIG_KGDB
		&& trapnr != VEC_EXCPT02
#endif
	){
		console_verbose();
		oops_in_progress = 1;
	} else if (current) {
		if (current->mm == NULL) {
			console_verbose();
			oops_in_progress = 1;
		}
	}

	/* trap_c() will be called for exceptions. During exceptions
	 * processing, the pc value should be set with retx value.
	 * With this change we can cleanup some code in signal.c- TODO
	 */
	fp->orig_pc = fp->retx;
	/* printk("exception: 0x%x, ipend=%x, reti=%x, retx=%x\n",
		trapnr, fp->ipend, fp->pc, fp->retx); */

	/* send the appropriate signal to the user program */
	switch (trapnr) {

	/* This table works in conjuction with the one in ./mach-common/entry.S
	 * Some exceptions are handled there (in assembly, in exception space)
	 * Some are handled here, (in C, in interrupt space)
	 * Some, like CPLB, are handled in both, where the normal path is
	 * handled in assembly/exception space, and the error path is handled
	 * here
	 */

	/* 0x00 - Linux Syscall, getting here is an error */
	/* 0x01 - userspace gdb breakpoint, handled here */
	case VEC_EXCPT01:
		info.si_code = TRAP_ILLTRAP;
		sig = SIGTRAP;
		CHK_DEBUGGER_TRAP_MAYBE();
		/* Check if this is a breakpoint in kernel space */
		if (fp->ipend & 0xffc0)
			return;
		else
			break;
#ifdef CONFIG_KGDB
	case VEC_EXCPT02 :		 /* gdb connection */
		info.si_code = TRAP_ILLTRAP;
		sig = SIGTRAP;
		CHK_DEBUGGER_TRAP();
		return;
#else
	/* 0x02 - User Defined, Caught by default */
#endif
	/* 0x03 - User Defined, userspace stack overflow */
	case VEC_EXCPT03:
		info.si_code = SEGV_STACKFLOW;
		sig = SIGSEGV;
		printk(KERN_NOTICE EXC_0x03(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x04 - User Defined, Caught by default */
	/* 0x05 - User Defined, Caught by default */
	/* 0x06 - User Defined, Caught by default */
	/* 0x07 - User Defined, Caught by default */
	/* 0x08 - User Defined, Caught by default */
	/* 0x09 - User Defined, Caught by default */
	/* 0x0A - User Defined, Caught by default */
	/* 0x0B - User Defined, Caught by default */
	/* 0x0C - User Defined, Caught by default */
	/* 0x0D - User Defined, Caught by default */
	/* 0x0E - User Defined, Caught by default */
	/* 0x0F - User Defined, Caught by default */
	/* 0x10 HW Single step, handled here */
	case VEC_STEP:
		info.si_code = TRAP_STEP;
		sig = SIGTRAP;
		CHK_DEBUGGER_TRAP_MAYBE();
		/* Check if this is a single step in kernel space */
		if (fp->ipend & 0xffc0)
			return;
		else
			break;
	/* 0x11 - Trace Buffer Full, handled here */
	case VEC_OVFLOW:
		info.si_code = TRAP_TRACEFLOW;
		sig = SIGTRAP;
		printk(KERN_NOTICE EXC_0x11(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x12 - Reserved, Caught by default */
	/* 0x13 - Reserved, Caught by default */
	/* 0x14 - Reserved, Caught by default */
	/* 0x15 - Reserved, Caught by default */
	/* 0x16 - Reserved, Caught by default */
	/* 0x17 - Reserved, Caught by default */
	/* 0x18 - Reserved, Caught by default */
	/* 0x19 - Reserved, Caught by default */
	/* 0x1A - Reserved, Caught by default */
	/* 0x1B - Reserved, Caught by default */
	/* 0x1C - Reserved, Caught by default */
	/* 0x1D - Reserved, Caught by default */
	/* 0x1E - Reserved, Caught by default */
	/* 0x1F - Reserved, Caught by default */
	/* 0x20 - Reserved, Caught by default */
	/* 0x21 - Undefined Instruction, handled here */
	case VEC_UNDEF_I:
		info.si_code = ILL_ILLOPC;
		sig = SIGILL;
		printk(KERN_NOTICE EXC_0x21(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x22 - Illegal Instruction Combination, handled here */
	case VEC_ILGAL_I:
		info.si_code = ILL_ILLPARAOP;
		sig = SIGILL;
		printk(KERN_NOTICE EXC_0x22(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x23 - Data CPLB protection violation, handled here */
	case VEC_CPLB_VL:
		info.si_code = ILL_CPLB_VI;
		sig = SIGBUS;
		printk(KERN_NOTICE EXC_0x23(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x24 - Data access misaligned, handled here */
	case VEC_MISALI_D:
		info.si_code = BUS_ADRALN;
		sig = SIGBUS;
		printk(KERN_NOTICE EXC_0x24(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x25 - Unrecoverable Event, handled here */
	case VEC_UNCOV:
		info.si_code = ILL_ILLEXCPT;
		sig = SIGILL;
		printk(KERN_NOTICE EXC_0x25(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x26 - Data CPLB Miss, normal case is handled in _cplb_hdr,
		error case is handled here */
	case VEC_CPLB_M:
		info.si_code = BUS_ADRALN;
		sig = SIGBUS;
		printk(KERN_NOTICE EXC_0x26(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x27 - Data CPLB Multiple Hits - Linux Trap Zero, handled here */
	case VEC_CPLB_MHIT:
		info.si_code = ILL_CPLB_MULHIT;
#ifdef CONFIG_DEBUG_HUNT_FOR_ZERO
		sig = SIGSEGV;
		printk(KERN_NOTICE "NULL pointer access (probably)\n");
#else
		sig = SIGILL;
		printk(KERN_NOTICE EXC_0x27(KERN_NOTICE));
#endif
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x28 - Emulation Watchpoint, handled here */
	case VEC_WATCH:
		info.si_code = TRAP_WATCHPT;
		sig = SIGTRAP;
		pr_debug(EXC_0x28(KERN_DEBUG));
		CHK_DEBUGGER_TRAP_MAYBE();
		/* Check if this is a watchpoint in kernel space */
		if (fp->ipend & 0xffc0)
			return;
		else
			break;
#ifdef CONFIG_BF535
	/* 0x29 - Instruction fetch access error (535 only) */
	case VEC_ISTRU_VL:      /* ADSP-BF535 only (MH) */
		info.si_code = BUS_OPFETCH;
		sig = SIGBUS;
		printk(KERN_NOTICE "BF535: VEC_ISTRU_VL\n");
		CHK_DEBUGGER_TRAP();
		break;
#else
	/* 0x29 - Reserved, Caught by default */
#endif
	/* 0x2A - Instruction fetch misaligned, handled here */
	case VEC_MISALI_I:
		info.si_code = BUS_ADRALN;
		sig = SIGBUS;
		printk(KERN_NOTICE EXC_0x2A(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x2B - Instruction CPLB protection violation, handled here */
	case VEC_CPLB_I_VL:
		info.si_code = ILL_CPLB_VI;
		sig = SIGBUS;
		printk(KERN_NOTICE EXC_0x2B(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x2C - Instruction CPLB miss, handled in _cplb_hdr */
	case VEC_CPLB_I_M:
		info.si_code = ILL_CPLB_MISS;
		sig = SIGBUS;
		printk(KERN_NOTICE EXC_0x2C(KERN_NOTICE));
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x2D - Instruction CPLB Multiple Hits, handled here */
	case VEC_CPLB_I_MHIT:
		info.si_code = ILL_CPLB_MULHIT;
#ifdef CONFIG_DEBUG_HUNT_FOR_ZERO
		sig = SIGSEGV;
		printk(KERN_NOTICE "Jump to address 0 - 0x0fff\n");
#else
		sig = SIGILL;
		printk(KERN_NOTICE EXC_0x2D(KERN_NOTICE));
#endif
		CHK_DEBUGGER_TRAP();
		break;
	/* 0x2E - Illegal use of Supervisor Resource, handled here */
	case VEC_ILL_RES:
		info.si_code = ILL_PRVOPC;
		sig = SIGILL;
		printk(KERN_NOTICE EXC_0x2E(KERN_NOTICE));