[AVR32] Clean up exception handling code

  * Use generic BUG() handling
  * Remove some useless debug statements
  * Use a common function _exception() to send signals or oops when
    an exception can't be handled. This makes sure init doesn't
    enter an infinite exception loop as well. Borrowed from powerpc.
  * Add some basic exception tracing support to the page fault code.
  * Rework dump_stack(), show_regs() and friends and move everything
    into process.c
  * Print information about configuration options and chip type when
    oopsing

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>

1 files changed, 127 insertions, 294 deletions

diff --git a/arch/avr32/kernel/traps.c b/arch/avr32/kernel/traps.c
index adc01a12d154..4f0382d8483f 100644
--- a/arch/avr32/kernel/traps.c
+++ b/arch/avr32/kernel/traps.c
@@ -5,158 +5,25 @@
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
-#undef DEBUG
-#include <linux/sched.h>
+
+#include <linux/bug.h>
 #include <linux/init.h>
-#include <linux/module.h>
 #include <linux/kallsyms.h>
+#include <linux/module.h>
 #include <linux/notifier.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
 
-#include <asm/traps.h>
-#include <asm/sysreg.h>
 #include <asm/addrspace.h>
-#include <asm/ocd.h>
 #include <asm/mmu_context.h>
-#include <asm/uaccess.h>
-
-static void dump_mem(const char *str, unsigned long bottom, unsigned long top)
-{
-        unsigned long p;
-        int i;
-
-        printk("%s(0x%08lx to 0x%08lx)\n", str, bottom, top);
-
-        for (p = bottom & ~31; p < top; ) {
-                printk("%04lx: ", p & 0xffff);
-
-                for (i = 0; i < 8; i++, p += 4) {
-                        unsigned int val;
-
-                        if (p < bottom || p >= top)
-                                printk("         ");
-                        else {
-                                if (__get_user(val, (unsigned int __user *)p)) {
-                                        printk("\n");
-                                        goto out;
-                                }
-                                printk("%08x ", val);
-                        }
-                }
-                printk("\n");
-        }
-
-out:
-        return;
-}
-
-static inline int valid_stack_ptr(struct thread_info *tinfo, unsigned long p)
-{
-        return (p > (unsigned long)tinfo)
-                && (p < (unsigned long)tinfo + THREAD_SIZE - 3);
-}
-
-#ifdef CONFIG_FRAME_POINTER
-static inline void __show_trace(struct task_struct *tsk, unsigned long *sp,
-                                struct pt_regs *regs)
-{
-        unsigned long lr, fp;
-        struct thread_info *tinfo;
-
-        tinfo = (struct thread_info *)
-                ((unsigned long)sp & ~(THREAD_SIZE - 1));
-
-        if (regs)
-                fp = regs->r7;
-        else if (tsk == current)
-                asm("mov %0, r7" : "=r"(fp));
-        else
-                fp = tsk->thread.cpu_context.r7;
-
-        /*
-         * Walk the stack as long as the frame pointer (a) is within
-         * the kernel stack of the task, and (b) it doesn't move
-         * downwards.
-         */
-        while (valid_stack_ptr(tinfo, fp)) {
-                unsigned long new_fp;
-
-                lr = *(unsigned long *)fp;
-                printk(" [<%08lx>] ", lr);
-                print_symbol("%s\n", lr);
-
-                new_fp = *(unsigned long *)(fp + 4);
-                if (new_fp <= fp)
-                        break;
-                fp = new_fp;
-        }
-        printk("\n");
-}
-#else
-static inline void __show_trace(struct task_struct *tsk, unsigned long *sp,
-                                struct pt_regs *regs)
-{
-        unsigned long addr;
-
-        while (!kstack_end(sp)) {
-                addr = *sp++;
-                if (kernel_text_address(addr)) {
-                        printk(" [<%08lx>] ", addr);
-                        print_symbol("%s\n", addr);
-                }
-        }
-}
-#endif
-
-void show_trace(struct task_struct *tsk, unsigned long *sp,
-                       struct pt_regs *regs)
-{
-        if (regs &&
-            (((regs->sr & MODE_MASK) == MODE_EXCEPTION) ||
-             ((regs->sr & MODE_MASK) == MODE_USER)))
-                return;
-
-        printk ("Call trace:");
-#ifdef CONFIG_KALLSYMS
-        printk("\n");
-#endif
-
-        __show_trace(tsk, sp, regs);
-        printk("\n");
-}
-
-void show_stack(struct task_struct *tsk, unsigned long *sp)
-{
-        unsigned long stack;
-
-        if (!tsk)
-                tsk = current;
-        if (sp == 0) {
-                if (tsk == current) {
-                        register unsigned long *real_sp __asm__("sp");
-                        sp = real_sp;
-                } else {
-                        sp = (unsigned long *)tsk->thread.cpu_context.ksp;
-                }
-        }
-
-        stack = (unsigned long)sp;
-        dump_mem("Stack: ", stack,
-                 THREAD_SIZE + (unsigned long)tsk->thread_info);
-        show_trace(tsk, sp, NULL);
-}
-
-void dump_stack(void)
-{
-        show_stack(NULL, NULL);
-}
-EXPORT_SYMBOL(dump_stack);
+#include <asm/ocd.h>
+#include <asm/sysreg.h>
+#include <asm/traps.h>
 
 ATOMIC_NOTIFIER_HEAD(avr32_die_chain);
 
 int register_die_notifier(struct notifier_block *nb)
 {
-        pr_debug("register_die_notifier: %p\n", nb);
-
         return atomic_notifier_chain_register(&avr32_die_chain, nb);
 }
 EXPORT_SYMBOL(register_die_notifier);
@@ -169,93 +36,103 @@ EXPORT_SYMBOL(unregister_die_notifier);
 
 static DEFINE_SPINLOCK(die_lock);
 
-void __die(const char *str, struct pt_regs *regs, unsigned long err,
-           const char *file, const char *func, unsigned long line)
+void NORET_TYPE die(const char *str, struct pt_regs *regs, long err)
 {
-        struct task_struct *tsk = current;
         static int die_counter;
 
         console_verbose();
         spin_lock_irq(&die_lock);
         bust_spinlocks(1);
 
-        printk(KERN_ALERT "%s", str);
-        if (file && func)
-                printk(" in %s:%s, line %ld", file, func, line);
-        printk("[#%d]:\n", ++die_counter);
-        print_modules();
-        show_regs(regs);
-        printk("Process %s (pid: %d, stack limit = 0x%p)\n",
-               tsk->comm, tsk->pid, tsk->thread_info + 1);
-
-        if (!user_mode(regs) || in_interrupt()) {
-                dump_mem("Stack: ", regs->sp,
-                         THREAD_SIZE + (unsigned long)tsk->thread_info);
+        printk(KERN_ALERT "Oops: %s, sig: %ld [#%d]\n" KERN_EMERG,
+               str, err, ++die_counter);
+#ifdef CONFIG_PREEMPT
+        printk("PREEMPT ");
+#endif
+#ifdef CONFIG_FRAME_POINTER
+        printk("FRAME_POINTER ");
+#endif
+        if (current_cpu_data.features & AVR32_FEATURE_OCD) {
+                unsigned long did = __mfdr(DBGREG_DID);
+                printk("chip: 0x%03lx:0x%04lx rev %lu\n",
+                       (did >> 1) & 0x7ff,
+                       (did >> 12) & 0x7fff,
+                       (did >> 28) & 0xf);
+        } else {
+                printk("cpu: arch %u r%u / core %u r%u\n",
+                       current_cpu_data.arch_type,
+                       current_cpu_data.arch_revision,
+                       current_cpu_data.cpu_type,
+                       current_cpu_data.cpu_revision);
         }
 
+        print_modules();
+        show_regs_log_lvl(regs, KERN_EMERG);
+        show_stack_log_lvl(current, regs->sp, regs, KERN_EMERG);
         bust_spinlocks(0);
         spin_unlock_irq(&die_lock);
-        do_exit(SIGSEGV);
+
+        if (in_interrupt())
+                panic("Fatal exception in interrupt");
+
+        if (panic_on_oops)
+                panic("Fatal exception");
+
+        do_exit(err);
 }
 
-void __die_if_kernel(const char *str, struct pt_regs *regs, unsigned long err,
-                     const char *file, const char *func, unsigned long line)
+void _exception(long signr, struct pt_regs *regs, int code,
+                unsigned long addr)
 {
+        siginfo_t info;
+
         if (!user_mode(regs))
-                __die(str, regs, err, file, func, line);
-}
+                die("Unhandled exception in kernel mode", regs, signr);
+
+        memset(&info, 0, sizeof(info));
+        info.si_signo = signr;
+        info.si_code = code;
+        info.si_addr = (void __user *)addr;
+        force_sig_info(signr, &info, current);
 
-asmlinkage void do_nmi(unsigned long ecr, struct pt_regs *regs)
-{
-#ifdef CONFIG_SUBARCH_AVR32B
         /*
-         * The exception entry always saves RSR_EX. For NMI, this is
-         * wrong; it should be RSR_NMI
+         * Init gets no signals that it doesn't have a handler for.
+         * That's all very well, but if it has caused a synchronous
+         * exception and we ignore the resulting signal, it will just
+         * generate the same exception over and over again and we get
+         * nowhere.  Better to kill it and let the kernel panic.
          */
-        regs->sr = sysreg_read(RSR_NMI);
-#endif
+        if (is_init(current)) {
+                __sighandler_t handler;
+
+                spin_lock_irq(&current->sighand->siglock);
+                handler = current->sighand->action[signr-1].sa.sa_handler;
+                spin_unlock_irq(&current->sighand->siglock);
+                if (handler == SIG_DFL) {
+                        /* init has generated a synchronous exception
+                           and it doesn't have a handler for the signal */
+                        printk(KERN_CRIT "init has generated signal %ld "
+                               "but has no handler for it\n", signr);
+                        do_exit(signr);
+                }
+        }
+}
 
-        printk("NMI taken!!!!\n");
-        die("NMI", regs, ecr);
-        BUG();
+asmlinkage void do_nmi(unsigned long ecr, struct pt_regs *regs)
+{
+        printk(KERN_ALERT "Got Non-Maskable Interrupt, dumping regs\n");
+        show_regs_log_lvl(regs, KERN_ALERT);
+        show_stack_log_lvl(current, regs->sp, regs, KERN_ALERT);
 }
 
 asmlinkage void do_critical_exception(unsigned long ecr, struct pt_regs *regs)
 {
-        printk("Unable to handle critical exception %lu at pc = %08lx!\n",
-               ecr, regs->pc);
-        die("Oops", regs, ecr);
-        BUG();
+        die("Critical exception", regs, SIGKILL);
 }
 
 asmlinkage void do_address_exception(unsigned long ecr, struct pt_regs *regs)
 {
-        siginfo_t info;
-
-        die_if_kernel("Oops: Address exception in kernel mode", regs, ecr);
-
-#ifdef DEBUG
-        if (ecr == ECR_ADDR_ALIGN_X)
-                pr_debug("Instruction Address Exception at pc = %08lx\n",
-                         regs->pc);
-        else if (ecr == ECR_ADDR_ALIGN_R)
-                pr_debug("Data Address Exception (Read) at pc = %08lx\n",
-                         regs->pc);
-        else if (ecr == ECR_ADDR_ALIGN_W)
-                pr_debug("Data Address Exception (Write) at pc = %08lx\n",
-                         regs->pc);
-        else
-                BUG();
-
-        show_regs(regs);
-#endif
-
-        info.si_signo = SIGBUS;
-        info.si_errno = 0;
-        info.si_code = BUS_ADRALN;
-        info.si_addr = (void __user *)regs->pc;
-
-        force_sig_info(SIGBUS, &info, current);
+        _exception(SIGBUS, regs, BUS_ADRALN, regs->pc);
 }
 
 /* This way of handling undefined instructions is stolen from ARM */
@@ -280,7 +157,8 @@ static int do_cop_absent(u32 insn)
 {
         int cop_nr;
         u32 cpucr;
-        if ( (insn & 0xfdf00000) == 0xf1900000 )
+
+        if ((insn & 0xfdf00000) == 0xf1900000)
                 /* LDC0 */
                 cop_nr = 0;
         else
@@ -292,136 +170,91 @@ static int do_cop_absent(u32 insn)
         sysreg_write(CPUCR, cpucr);
 
         cpucr = sysreg_read(CPUCR);
-        if ( !(cpucr & (1 << (24 + cop_nr))) ){
-                printk("Coprocessor #%i not found!\n", cop_nr);
-                return -1;
-        }
+        if (!(cpucr & (1 << (24 + cop_nr))))
+                return -ENODEV;
 
         return 0;
 }
 
-#ifdef CONFIG_BUG
-#ifdef CONFIG_DEBUG_BUGVERBOSE
-static inline void do_bug_verbose(struct pt_regs *regs, u32 insn)
-{
-        char *file;
-        u16 line;
-        char c;
-
-        if (__get_user(line, (u16 __user *)(regs->pc + 2)))
-                return;
-        if (__get_user(file, (char * __user *)(regs->pc + 4))
-            || (unsigned long)file < PAGE_OFFSET
-            || __get_user(c, file))
-                file = "<bad filename>";
-
-        printk(KERN_ALERT "kernel BUG at %s:%d!\n", file, line);
-}
-#else
-static inline void do_bug_verbose(struct pt_regs *regs, u32 insn)
+int is_valid_bugaddr(unsigned long pc)
 {
+        unsigned short opcode;
+
+        if (pc < PAGE_OFFSET)
+                return 0;
+        if (probe_kernel_address((u16 *)pc, opcode))
+                return 0;
 
+        return opcode == AVR32_BUG_OPCODE;
 }
-#endif
-#endif
 
 asmlinkage void do_illegal_opcode(unsigned long ecr, struct pt_regs *regs)
 {
         u32 insn;
         struct undef_hook *hook;
-        siginfo_t info;
         void __user *pc;
+        long code;
 
-        if (!user_mode(regs))
-                goto kernel_trap;
+        if (!user_mode(regs) && (ecr == ECR_ILLEGAL_OPCODE)) {
+                enum bug_trap_type type;
+
+                type = report_bug(regs->pc);
+                switch (type) {
+                case BUG_TRAP_TYPE_NONE:
+                        break;
+                case BUG_TRAP_TYPE_WARN:
+                        regs->pc += 2;
+                        return;
+                case BUG_TRAP_TYPE_BUG:
+                        die("Kernel BUG", regs, SIGKILL);
+                }
+        }
 
         local_irq_enable();
 
-        pc = (void __user *)instruction_pointer(regs);
-        if (__get_user(insn, (u32 __user *)pc))
-                goto invalid_area;
+        if (user_mode(regs)) {
+                pc = (void __user *)instruction_pointer(regs);
+                if (get_user(insn, (u32 __user *)pc))
+                        goto invalid_area;
 
-        if (ecr == ECR_COPROC_ABSENT) {
-                if (do_cop_absent(insn) == 0)
+                if (ecr == ECR_COPROC_ABSENT && !do_cop_absent(insn))
                         return;
-        }
 
-        spin_lock_irq(&undef_lock);
-        list_for_each_entry(hook, &undef_hook, node) {
-                if ((insn & hook->insn_mask) == hook->insn_val) {
-                        if (hook->fn(regs, insn) == 0) {
-                                spin_unlock_irq(&undef_lock);
-                                return;
+                spin_lock_irq(&undef_lock);
+                list_for_each_entry(hook, &undef_hook, node) {
+                        if ((insn & hook->insn_mask) == hook->insn_val) {
+                                if (hook->fn(regs, insn) == 0) {
+                                        spin_unlock_irq(&undef_lock);
+                                        return;
+                                }
                         }
                 }
+                spin_unlock_irq(&undef_lock);
         }
-        spin_unlock_irq(&undef_lock);
-
-invalid_area:
 
-#ifdef DEBUG
-        printk("Illegal instruction at pc = %08lx\n", regs->pc);
-        if (regs->pc < TASK_SIZE) {
-                unsigned long ptbr, pgd, pte, *p;
-
-                ptbr = sysreg_read(PTBR);
-                p = (unsigned long *)ptbr;
-                pgd = p[regs->pc >> 22];
-                p = (unsigned long *)((pgd & 0x1ffff000) | 0x80000000);
-                pte = p[(regs->pc >> 12) & 0x3ff];
-                printk("page table: 0x%08lx -> 0x%08lx -> 0x%08lx\n", ptbr, pgd, pte);
-        }
-#endif
-
-        info.si_signo = SIGILL;
-        info.si_errno = 0;
-        info.si_addr = (void __user *)regs->pc;
         switch (ecr) {
-        case ECR_ILLEGAL_OPCODE:
-        case ECR_UNIMPL_INSTRUCTION:
-                info.si_code = ILL_ILLOPC;
-                break;
         case ECR_PRIVILEGE_VIOLATION:
-                info.si_code = ILL_PRVOPC;
+                code = ILL_PRVOPC;
                 break;
         case ECR_COPROC_ABSENT:
-                info.si_code = ILL_COPROC;
+                code = ILL_COPROC;
                 break;
         default:
-                BUG();
+                code = ILL_ILLOPC;
+                break;
         }
 
-        force_sig_info(SIGILL, &info, current);
+        _exception(SIGILL, regs, code, regs->pc);
         return;
 
-kernel_trap:
-#ifdef CONFIG_BUG
-        if (__kernel_text_address(instruction_pointer(regs))) {
-                insn = *(u16 *)instruction_pointer(regs);
-                if (insn == AVR32_BUG_OPCODE) {
-                        do_bug_verbose(regs, insn);
-                        die("Kernel BUG", regs, 0);
-                        return;
-                }
-        }
-#endif
-
-        die("Oops: Illegal instruction in kernel code", regs, ecr);
+invalid_area:
+        _exception(SIGSEGV, regs, SEGV_MAPERR, regs->pc);
 }
 
 asmlinkage void do_fpe(unsigned long ecr, struct pt_regs *regs)
 {
-        siginfo_t info;
-
-        printk("Floating-point exception at pc = %08lx\n", regs->pc);
-
-        /* We have no FPU... */
-        info.si_signo = SIGILL;
-        info.si_errno = 0;
-        info.si_addr = (void __user *)regs->pc;
-        info.si_code = ILL_COPROC;
-
-        force_sig_info(SIGILL, &info, current);
+        /* We have no FPU yet */
+        _exception(SIGILL, regs, ILL_COPROC, regs->pc);
 }