[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>

arch/avr32/Kconfig

@@ -68,6 +68,11 @@ config GENERIC_CALIBRATE_DELAY
 	bool
 	default y
 
+config GENERIC_BUG
+	bool
+	default y
+	depends on BUG
+
 source "init/Kconfig"
 
 menu "System Type and features"

arch/avr32/kernel/module.c

@@ -12,10 +12,11 @@
  * published by the Free Software Foundation.
  */
 
-#include <linux/moduleloader.h>
-#include <linux/module.h>
-#include <linux/kernel.h>
+#include <linux/bug.h>
 #include <linux/elf.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/moduleloader.h>
 #include <linux/vmalloc.h>
 
 void *module_alloc(unsigned long size)
@@ -315,10 +316,10 @@ int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
 	vfree(module->arch.syminfo);
 	module->arch.syminfo = NULL;
 
-	return 0;
+	return module_bug_finalize(hdr, sechdrs, module);
 }
 
 void module_arch_cleanup(struct module *module)
 {
-
+	module_bug_cleanup(module);
 }

arch/avr32/kernel/process.c

@@ -11,6 +11,7 @@
 #include <linux/fs.h>
 #include <linux/ptrace.h>
 #include <linux/reboot.h>
+#include <linux/uaccess.h>
 #include <linux/unistd.h>
 
 #include <asm/sysreg.h>
@@ -115,39 +116,178 @@ void release_thread(struct task_struct *dead_task)
 	/* do nothing */
 }
 
+static void dump_mem(const char *str, const char *log_lvl,
+		     unsigned long bottom, unsigned long top)
+{
+	unsigned long p;
+	int i;
+
+	printk("%s%s(0x%08lx to 0x%08lx)\n", log_lvl, str, bottom, top);
+
+	for (p = bottom & ~31; p < top; ) {
+		printk("%s%04lx: ", log_lvl, 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 void show_trace_log_lvl(struct task_struct *tsk, unsigned long *sp,
+			       struct pt_regs *regs, const char *log_lvl)
+{
+	unsigned long lr, fp;
+	struct thread_info *tinfo;
+
+	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.
+	 */
+	tinfo = task_thread_info(tsk);
+	printk("%sCall trace:\n", log_lvl);
+	while (valid_stack_ptr(tinfo, fp)) {
+		unsigned long new_fp;
+
+		lr = *(unsigned long *)fp;
+#ifdef CONFIG_KALLSYMS
+		printk("%s [<%08lx>] ", log_lvl, lr);
+#else
+		printk(" [<%08lx>] ", lr);
+#endif
+		print_symbol("%s\n", lr);
+
+		new_fp = *(unsigned long *)(fp + 4);
+		if (new_fp <= fp)
+			break;
+		fp = new_fp;
+	}
+	printk("\n");
+}
+#else
+static void show_trace_log_lvl(struct task_struct *tsk, unsigned long *sp,
+			       struct pt_regs *regs, const char *log_lvl)
+{
+	unsigned long addr;
+
+	printk("%sCall trace:\n", log_lvl);
+
+	while (!kstack_end(sp)) {
+		addr = *sp++;
+		if (kernel_text_address(addr)) {
+#ifdef CONFIG_KALLSYMS
+			printk("%s [<%08lx>] ", log_lvl, addr);
+#else
+			printk(" [<%08lx>] ", addr);
+#endif
+			print_symbol("%s\n", addr);
+		}
+	}
+	printk("\n");
+}
+#endif
+
+void show_stack_log_lvl(struct task_struct *tsk, unsigned long sp,
+			struct pt_regs *regs, const char *log_lvl)
+{
+	struct thread_info *tinfo;
+
+	if (sp == 0) {
+		if (tsk)
+			sp = tsk->thread.cpu_context.ksp;
+		else
+			sp = (unsigned long)&tinfo;
+	}
+	if (!tsk)
+		tsk = current;
+
+	tinfo = task_thread_info(tsk);
+
+	if (valid_stack_ptr(tinfo, sp)) {
+		dump_mem("Stack: ", log_lvl, sp,
+			 THREAD_SIZE + (unsigned long)tinfo);
+		show_trace_log_lvl(tsk, (unsigned long *)sp, regs, log_lvl);
+	}
+}
+
+void show_stack(struct task_struct *tsk, unsigned long *stack)
+{
+	show_stack_log_lvl(tsk, (unsigned long)stack, NULL, "");
+}
+
+void dump_stack(void)
+{
+	unsigned long stack;
+
+	show_trace_log_lvl(current, &stack, NULL, "");
+}
+EXPORT_SYMBOL(dump_stack);
+
 static const char *cpu_modes[] = {
 	"Application", "Supervisor", "Interrupt level 0", "Interrupt level 1",
 	"Interrupt level 2", "Interrupt level 3", "Exception", "NMI"
 };
 
-void show_regs(struct pt_regs *regs)
+void show_regs_log_lvl(struct pt_regs *regs, const char *log_lvl)
 {
 	unsigned long sp = regs->sp;
 	unsigned long lr = regs->lr;
 	unsigned long mode = (regs->sr & MODE_MASK) >> MODE_SHIFT;
 
-	if (!user_mode(regs))
+	if (!user_mode(regs)) {
 		sp = (unsigned long)regs + FRAME_SIZE_FULL;
 
-	print_symbol("PC is at %s\n", instruction_pointer(regs));
-	print_symbol("LR is at %s\n", lr);
-	printk("pc : [<%08lx>]    lr : [<%08lx>]    %s\n"
-	       "sp : %08lx  r12: %08lx  r11: %08lx\n",
-	       instruction_pointer(regs),
-	       lr, print_tainted(), sp, regs->r12, regs->r11);
-	printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
-	       regs->r10, regs->r9, regs->r8);
-	printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
-	       regs->r7, regs->r6, regs->r5, regs->r4);
-	printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
-	       regs->r3, regs->r2, regs->r1, regs->r0);
-	printk("Flags: %c%c%c%c%c\n",
+		printk("%s", log_lvl);
+		print_symbol("PC is at %s\n", instruction_pointer(regs));
+		printk("%s", log_lvl);
+		print_symbol("LR is at %s\n", lr);
+	}
+
+	printk("%spc : [<%08lx>]    lr : [<%08lx>]    %s\n"
+	       "%ssp : %08lx  r12: %08lx  r11: %08lx\n",
+	       log_lvl, instruction_pointer(regs), lr, print_tainted(),
+	       log_lvl, sp, regs->r12, regs->r11);
+	printk("%sr10: %08lx  r9 : %08lx  r8 : %08lx\n",
+	       log_lvl, regs->r10, regs->r9, regs->r8);
+	printk("%sr7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
+	       log_lvl, regs->r7, regs->r6, regs->r5, regs->r4);
+	printk("%sr3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
+	       log_lvl, regs->r3, regs->r2, regs->r1, regs->r0);
+	printk("%sFlags: %c%c%c%c%c\n", log_lvl,
 	       regs->sr & SR_Q ? 'Q' : 'q',
 	       regs->sr & SR_V ? 'V' : 'v',
 	       regs->sr & SR_N ? 'N' : 'n',
 	       regs->sr & SR_Z ? 'Z' : 'z',
 	       regs->sr & SR_C ? 'C' : 'c');
-	printk("Mode bits: %c%c%c%c%c%c%c%c%c\n",
+	printk("%sMode bits: %c%c%c%c%c%c%c%c%c\n", log_lvl,
 	       regs->sr & SR_H ? 'H' : 'h',
 	       regs->sr & SR_R ? 'R' : 'r',
 	       regs->sr & SR_J ? 'J' : 'j',
@@ -157,9 +297,21 @@ void show_regs(struct pt_regs *regs)
 	       regs->sr & SR_I1M ? '1' : '.',
 	       regs->sr & SR_I0M ? '0' : '.',
 	       regs->sr & SR_GM ? 'G' : 'g');
-	printk("CPU Mode: %s\n", cpu_modes[mode]);
+	printk("%sCPU Mode: %s\n", log_lvl, cpu_modes[mode]);
+	printk("%sProcess: %s [%d] (task: %p thread: %p)\n",
+	       log_lvl, current->comm, current->pid, current,
+	       task_thread_info(current));
+}
+
+void show_regs(struct pt_regs *regs)
+{
+	unsigned long sp = regs->sp;
+
+	if (!user_mode(regs))
+		sp = (unsigned long)regs + FRAME_SIZE_FULL;
 
-	show_trace(NULL, (unsigned long *)sp, regs);
+	show_regs_log_lvl(regs, "");
+	show_trace_log_lvl(current, (unsigned long *)sp, regs, "");
 }
 EXPORT_SYMBOL(show_regs);
 

arch/avr32/kernel/vmlinux.lds.c

@@ -26,6 +26,12 @@ SECTIONS
 			_sinittext = .;
 			*(.text.reset)
 			*(.init.text)
+			/*
+			 * .exit.text is discarded at runtime, not
+			 * link time, to deal with references from
+			 * __bug_table
+			 */
+			*(.exit.text)
 			_einittext = .;
 		. = ALIGN(4);
 		__tagtable_begin = .;
@@ -86,6 +92,8 @@ SECTIONS
 		__stop___ex_table = .;
 	}
 
+	BUG_TABLE
+
 	RODATA
 
 	. = ALIGN(8192);
@@ -126,7 +134,6 @@ SECTIONS
 	 * thrown away, as cleanup code is never called unless it's a module.
 	 */
 	/DISCARD/       	: {
-		*(.exit.text)
 		*(.exit.data)
 		*(.exitcall.exit)
 	}

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 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 	 * 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 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 		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 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 			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 @@ asmlinkage void do_page_fault(unsigned long ecr, struct pt_regs *regs)
 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);
 }
 
 /*

include/asm-avr32/bug.h

@@ -18,27 +18,53 @@
 
 #ifdef CONFIG_DEBUG_BUGVERBOSE
 
-#define BUG()								\
-	do {								\
-		asm volatile(".hword	%0\n\t"				\
-			     ".hword	%1\n\t"				\
-			     ".long	%2"				\
-			     :						\
-			     : "n"(AVR32_BUG_OPCODE),			\
-			       "i"(__LINE__), "X"(__FILE__));		\
-	} while (0)
+#define _BUG_OR_WARN(flags)						\
+	asm volatile(							\
+		"1:	.hword	%0\n"					\
+		"	.section __bug_table,\"a\",@progbits\n"		\
+		"2:	.long	1b\n"					\
+		"	.long	%1\n"					\
+		"	.short	%2\n"					\
+		"	.short	%3\n"					\
+		"	.org	2b + %4\n"				\
+		"	.previous"					\
+		:							\
+		: "i"(AVR32_BUG_OPCODE), "i"(__FILE__),			\
+		  "i"(__LINE__), "i"(flags),				\
+		  "i"(sizeof(struct bug_entry)))
 
 #else
 
+#define _BUG_OR_WARN(flags)						\
+	asm volatile(							\
+		"1:	.hword	%0\n"					\
+		"	.section __bug_table,\"a\",@progbits\n"		\
+		"2:	.long	1b\n"					\
+		"	.short	%1\n"					\
+		"	.org	2b + %2\n"				\
+		"	.previous"					\
+		:							\
+		: "i"(AVR32_BUG_OPCODE), "i"(flags),			\
+		  "i"(sizeof(struct bug_entry)))
+
+#endif /* CONFIG_DEBUG_BUGVERBOSE */
+
 #define BUG()								\
 	do {								\
-		asm volatile(".hword	%0\n\t"				\
-			     : : "n"(AVR32_BUG_OPCODE));		\
+		_BUG_OR_WARN(0);					\
+		for (;;);						\
 	} while (0)
 
-#endif /* CONFIG_DEBUG_BUGVERBOSE */
+#define WARN_ON(condition)							\
+	({								\
+		typeof(condition) __ret_warn_on = (condition);		\
+		if (unlikely(__ret_warn_on))				\
+			_BUG_OR_WARN(BUGFLAG_WARNING);			\
+		unlikely(__ret_warn_on);				\
+	})
 
 #define HAVE_ARCH_BUG
+#define HAVE_ARCH_WARN_ON
 
 #endif /* CONFIG_BUG */
 

include/asm-avr32/processor.h

@@ -134,10 +134,10 @@ extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 #define thread_saved_pc(tsk)    ((tsk)->thread.cpu_context.pc)
 
 struct pt_regs;
-void show_trace(struct task_struct *task, unsigned long *stack,
-		struct pt_regs *regs);
-
 extern unsigned long get_wchan(struct task_struct *p);
+extern void show_regs_log_lvl(struct pt_regs *regs, const char *log_lvl);
+extern void show_stack_log_lvl(struct task_struct *tsk, unsigned long sp,
+			       struct pt_regs *regs, const char *log_lvl);
 
 #define KSTK_EIP(tsk)	((tsk)->thread.cpu_context.pc)
 #define KSTK_ESP(tsk)	((tsk)->thread.cpu_context.ksp)

include/asm-avr32/system.h

@@ -9,6 +9,7 @@
 #define __ASM_AVR32_SYSTEM_H
 
 #include <linux/compiler.h>
+#include <linux/linkage.h>
 #include <linux/types.h>
 
 #include <asm/ptrace.h>
@@ -140,15 +141,9 @@ static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
 				   sizeof(*(ptr))))
 
 struct pt_regs;
-extern void __die(const char *, struct pt_regs *, unsigned long,
-		  const char *, const char *, unsigned long);
-extern void __die_if_kernel(const char *, struct pt_regs *, unsigned long,
-			    const char *, const char *, unsigned long);
-
-#define die(msg, regs, err)					\
-	__die(msg, regs, err, __FILE__ ":", __FUNCTION__, __LINE__)
-#define die_if_kernel(msg, regs, err)					\
-	__die_if_kernel(msg, regs, err, __FILE__ ":", __FUNCTION__, __LINE__)
+void NORET_TYPE die(const char *str, struct pt_regs *regs, long err);
+void _exception(long signr, struct pt_regs *regs, int code,
+		unsigned long addr);
 
 #define arch_align_stack(x)	(x)