[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, 41 insertions, 75 deletions

diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index 678557260a35..146ebdbdc302 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c
@@ -16,26 +16,8 @@
 #include <asm/kdebug.h>
 #include <asm/mmu_context.h>
 #include <asm/sysreg.h>
-#include <asm/uaccess.h>
 #include <asm/tlb.h>
-
-#ifdef DEBUG
-static void dump_code(unsigned long pc)
-{
-        char *p = (char *)pc;
-        char val;
-        int i;
-
-
-        printk(KERN_DEBUG "Code:");
-        for (i = 0; i < 16; i++) {
-                if (__get_user(val, p + i))
-                        break;
-                printk(" %02x", val);
-        }
-        printk("\n");
-}
-#endif
+#include <asm/uaccess.h>
 
 #ifdef CONFIG_KPROBES
 ATOMIC_NOTIFIER_HEAD(notify_page_fault_chain);
@@ -68,17 +50,19 @@ static inline int notify_page_fault(enum die_val val, struct pt_regs *regs,
 }
 #endif
 
+int exception_trace = 1;
+
 /*
  * This routine handles page faults. It determines the address and the
  * problem, and then passes it off to one of the appropriate routines.
  *
  * ecr is the Exception Cause Register. Possible values are:
- *   5:  Page not found (instruction access)
  *   6:  Protection fault (instruction access)
- *   12: Page not found (read access)
- *   13: Page not found (write access)
- *   14: Protection fault (read access)
- *   15: Protection fault (write access)
+ *   15: Protection fault (read access)
+ *   16: Protection fault (write access)
+ *   20: Page not found (instruction access)
+ *   24: Page not found (read access)
+ *   28: Page not found (write access)
  */
 asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 {
@@ -88,7 +72,9 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
         const struct exception_table_entry *fixup;
         unsigned long address;
         unsigned long page;
-        int writeaccess = 0;
+        int writeaccess;
+        long signr;
+        int code;
 
         if (notify_page_fault(DIE_PAGE_FAULT, regs,
                               ecr, SIGSEGV) == NOTIFY_STOP)
@@ -99,6 +85,9 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
         tsk = current;
         mm = tsk->mm;
 
+        signr = SIGSEGV;
+        code = SEGV_MAPERR;
+
         /*
          * If we're in an interrupt or have no user context, we must
          * not take the fault...
@@ -125,7 +114,9 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
          * can handle it...
          */
 good_area:
-        //pr_debug("good area: vm_flags = 0x%lx\n", vma->vm_flags);
+        code = SEGV_ACCERR;
+        writeaccess = 0;
+
         switch (ecr) {
         case ECR_PROTECTION_X:
         case ECR_TLB_MISS_X:
@@ -176,46 +167,24 @@ survive:
          * map. Fix it, but check if it's kernel or user first...
          */
 bad_area:
-        pr_debug("Bad area [%s:%u]: addr %08lx, ecr %lu\n",
-                 tsk->comm, tsk->pid, address, ecr);
-
         up_read(&mm->mmap_sem);
 
         if (user_mode(regs)) {
-                /* Hmm...we have to pass address and ecr somehow... */
-                /* tsk->thread.address = address;
-                   tsk->thread.error_code = ecr; */
-#ifdef DEBUG
-                show_regs(regs);
-                dump_code(regs->pc);
-
-                page = sysreg_read(PTBR);
-                printk("ptbr = %08lx", page);
-                if (page) {
-                        page = ((unsigned long *)page)[address >> 22];
-                        printk(" pgd = %08lx", page);
-                        if (page & _PAGE_PRESENT) {
-                                page &= PAGE_MASK;
-                                address &= 0x003ff000;
-                                page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
-                                printk(" pte = %08lx\n", page);
-                        }
-                }
-#endif
-                pr_debug("Sending SIGSEGV to PID %d...\n",
-                        tsk->pid);
-                force_sig(SIGSEGV, tsk);
+                if (exception_trace)
+                        printk("%s%s[%d]: segfault at %08lx pc %08lx "
+                               "sp %08lx ecr %lu\n",
+                               is_init(tsk) ? KERN_EMERG : KERN_INFO,
+                               tsk->comm, tsk->pid, address, regs->pc,
+                               regs->sp, ecr);
+                _exception(SIGSEGV, regs, code, address);
                 return;
         }
 
 no_context:
-        pr_debug("No context\n");
-
         /* Are we prepared to handle this kernel fault? */
         fixup = search_exception_tables(regs->pc);
         if (fixup) {
                 regs->pc = fixup->fixup;
-                pr_debug("Found fixup at %08lx\n", fixup->fixup);
                 return;
         }
 
@@ -230,7 +199,6 @@ no_context:
                 printk(KERN_ALERT
                        "Unable to handle kernel paging request");
         printk(" at virtual address %08lx\n", address);
-        printk(KERN_ALERT "pc = %08lx\n", regs->pc);
 
         page = sysreg_read(PTBR);
         printk(KERN_ALERT "ptbr = %08lx", page);
@@ -241,20 +209,20 @@ no_context:
                         page &= PAGE_MASK;
                         address &= 0x003ff000;
                         page = ((unsigned long *)__va(page))[address >> PAGE_SHIFT];
-                        printk(" pte = %08lx\n", page);
+                        printk(" pte = %08lx", page);
                 }
         }
-        die("\nOops", regs, ecr);
-        do_exit(SIGKILL);
+        printk("\n");
+        die("Kernel access of bad area", regs, signr);
+        return;
 
         /*
          * We ran out of memory, or some other thing happened to us
          * that made us unable to handle the page fault gracefully.
          */
 out_of_memory:
-        printk("Out of memory\n");
         up_read(&mm->mmap_sem);
-        if (current->pid == 1) {
+        if (is_init(current)) {
                 yield();
                 down_read(&mm->mmap_sem);
                 goto survive;
@@ -267,21 +235,20 @@ out_of_memory:
 do_sigbus:
         up_read(&mm->mmap_sem);
 
-        /*
-         * Send a sigbus, regardless of whether we were in kernel or
-         * user mode.
-         */
-        /* address, error_code, trap_no, ... */
-#ifdef DEBUG
-        show_regs(regs);
-        dump_code(regs->pc);
-#endif
-        pr_debug("Sending SIGBUS to PID %d...\n", tsk->pid);
-        force_sig(SIGBUS, tsk);
-
         /* Kernel mode? Handle exceptions or die */
+        signr = SIGBUS;
+        code = BUS_ADRERR;
         if (!user_mode(regs))
                 goto no_context;
+
+        if (exception_trace)
+                printk("%s%s[%d]: bus error at %08lx pc %08lx "
+                       "sp %08lx ecr %lu\n",
+                       is_init(tsk) ? KERN_EMERG : KERN_INFO,
+                       tsk->comm, tsk->pid, address, regs->pc,
+                       regs->sp, ecr);
+
+        _exception(SIGBUS, regs, BUS_ADRERR, address);
 }
 
 asmlinkage void do_bus_error(unsigned long addr, int write_access,
@@ -292,8 +259,7 @@ asmlinkage void do_bus_error(unsigned long addr, int write_access,
                addr, write_access ? "write" : "read");
         printk(KERN_INFO "DTLB dump:\n");
         dump_dtlb();
-        die("Bus Error", regs, write_access);
-        do_exit(SIGKILL);
+        die("Bus Error", regs, SIGKILL);
 }
 
 /*