Merge branch 'sh/dwarf-unwinder' of git://github.com/mfleming/linux-2.6 into sh/dwarf-unwinder

arch/sh/include/asm/bug.h

 #ifndef __ASM_SH_BUG_H
 #define __ASM_SH_BUG_H
 
+#define TRAPA_UNWINDER_BUG_OPCODE 0xc33b /* trapa #0x3b */
 #define TRAPA_BUG_OPCODE	0xc33e	/* trapa #0x3e */
 
 #ifdef CONFIG_GENERIC_BUG
@@ -72,6 +73,30 @@ do {							\
 	unlikely(__ret_warn_on);				\
 })
 
+#define UNWINDER_BUG()						\
+do {							\
+	__asm__ __volatile__ (				\
+		"1:\t.short %O0\n"			\
+		_EMIT_BUG_ENTRY		\
+		 :					\
+		 : "n" (TRAPA_UNWINDER_BUG_OPCODE),	\
+		   "i" (__FILE__),			\
+		   "i" (__LINE__), "i" (0),		\
+		   "i" (sizeof(struct bug_entry)));	\
+} while (0)
+
+#define UNWINDER_BUG_ON(x) ({					\
+	int __ret_unwinder_on = !!(x);				\
+	if (__builtin_constant_p(__ret_unwinder_on)) {		\
+		if (__ret_unwinder_on)				\
+			UNWINDER_BUG();				\
+	} else {						\
+		if (unlikely(__ret_unwinder_on))		\
+			UNWINDER_BUG();				\
+	}							\
+	unlikely(__ret_unwinder_on);				\
+})
+
 #endif /* CONFIG_GENERIC_BUG */
 
 #include <asm-generic/bug.h>

arch/sh/include/asm/dwarf.h

@@ -265,10 +265,7 @@ struct dwarf_frame {
 
 	unsigned long pc;
 
-	struct dwarf_reg *regs;
-	unsigned int num_regs;	/* how many regs are allocated? */
-
-	unsigned int depth;	/* what level are we in the callstack? */
+	struct list_head reg_list;
 
 	unsigned long cfa;
 
@@ -292,20 +289,15 @@ struct dwarf_frame {
  *	@flags: Describes how to calculate the value of this register
  */
 struct dwarf_reg {
+	struct list_head link;
+
+	unsigned int number;
+
 	unsigned long addr;
 	unsigned long flags;
 #define DWARF_REG_OFFSET	(1 << 0)
-};
-
-/**
- *	dwarf_stack - a DWARF stack contains a collection of DWARF frames
- *	@depth: the number of frames in the stack
- *	@level: an array of DWARF frames, indexed by stack level
- *
- */
-struct dwarf_stack {
-	unsigned int depth;
-	struct dwarf_frame **level;
+#define DWARF_VAL_OFFSET	(1 << 1)
+#define DWARF_UNDEFINED		(1 << 2)
 };
 
 /*
@@ -372,13 +364,14 @@ static inline unsigned int DW_CFA_operand(unsigned long insn)
 
 extern struct dwarf_frame *dwarf_unwind_stack(unsigned long,
 					      struct dwarf_frame *);
-#endif /* __ASSEMBLY__ */
+#endif /* !__ASSEMBLY__ */
 
 #define CFI_STARTPROC	.cfi_startproc
 #define CFI_ENDPROC	.cfi_endproc
 #define CFI_DEF_CFA	.cfi_def_cfa
 #define CFI_REGISTER	.cfi_register
 #define CFI_REL_OFFSET	.cfi_rel_offset
+#define CFI_UNDEFINED	.cfi_undefined
 
 #else
 
@@ -392,6 +385,7 @@ extern struct dwarf_frame *dwarf_unwind_stack(unsigned long,
 #define CFI_DEF_CFA	CFI_IGNORE
 #define CFI_REGISTER	CFI_IGNORE
 #define CFI_REL_OFFSET	CFI_IGNORE
+#define CFI_UNDEFINED	CFI_IGNORE
 
 #ifndef __ASSEMBLY__
 static inline void dwarf_unwinder_init(void)

arch/sh/include/asm/system.h

@@ -181,6 +181,11 @@ BUILD_TRAP_HANDLER(breakpoint);
 BUILD_TRAP_HANDLER(singlestep);
 BUILD_TRAP_HANDLER(fpu_error);
 BUILD_TRAP_HANDLER(fpu_state_restore);
+BUILD_TRAP_HANDLER(unwinder);
+
+#ifdef CONFIG_BUG
+extern void handle_BUG(struct pt_regs *);
+#endif
 
 #define arch_align_stack(x) (x)
 

arch/sh/include/asm/unwinder.h

@@ -22,4 +22,10 @@ extern void stack_reader_dump(struct task_struct *, struct pt_regs *,
 			      unsigned long *, const struct stacktrace_ops *,
 			      void *);
 
+/*
+ * Used by fault handling code to signal to the unwinder code that it
+ * should switch to a different unwinder.
+ */
+extern int unwinder_faulted;
+
 #endif /* _LINUX_UNWINDER_H */

arch/sh/kernel/cpu/sh3/entry.S

@@ -508,6 +508,8 @@ ENTRY(handle_interrupt)
 	bsr	save_regs	! needs original pr value in k3
 	 mov	#-1, k2		! default vector kept in k2
 
+	setup_frame_reg
+
 	! Setup return address and jump to do_IRQ
 	mov.l	4f, r9		! fetch return address
 	lds	r9, pr		! put return address in pr

arch/sh/kernel/debugtraps.S

@@ -19,6 +19,10 @@
 
 #if !defined(CONFIG_SH_STANDARD_BIOS)
 #define sh_bios_handler			debug_trap_handler
+#endif
+
+#if !defined(CONFIG_DWARF_UNWINDER)
+#define unwinder_trap_handler		debug_trap_handler
 #endif
 
 	.data
@@ -35,7 +39,7 @@ ENTRY(debug_trap_table)
 	.long debug_trap_handler	/* 0x38 */
 	.long debug_trap_handler	/* 0x39 */
 	.long debug_trap_handler	/* 0x3a */
-	.long debug_trap_handler	/* 0x3b */
+	.long unwinder_trap_handler	/* 0x3b */
 	.long breakpoint_trap_handler	/* 0x3c */
 	.long singlestep_trap_handler	/* 0x3d */
 	.long bug_trap_handler		/* 0x3e */

arch/sh/kernel/traps.c

@@ -8,7 +8,7 @@
 #include <asm/system.h>
 
 #ifdef CONFIG_BUG
-static void handle_BUG(struct pt_regs *regs)
+void handle_BUG(struct pt_regs *regs)
 {
 	enum bug_trap_type tt;
 	tt = report_bug(regs->pc, regs);
@@ -29,7 +29,10 @@ int is_valid_bugaddr(unsigned long addr)
 	if (probe_kernel_address((insn_size_t *)addr, opcode))
 		return 0;
 
-	return opcode == TRAPA_BUG_OPCODE;
+	if (opcode == TRAPA_BUG_OPCODE || opcode == TRAPA_UNWINDER_BUG_OPCODE)
+		return 1;
+
+	return 0;
 }
 #endif
 

arch/sh/kernel/traps_32.c

@@ -136,6 +136,7 @@ static void die_if_no_fixup(const char * str, struct pt_regs * regs, long err)
 			regs->pc = fixup->fixup;
 			return;
 		}
+
 		die(str, regs, err);
 	}
 }

arch/sh/kernel/unwinder.c

@@ -54,8 +54,6 @@ static struct list_head unwinder_list = {
 
 static DEFINE_SPINLOCK(unwinder_lock);
 
-static atomic_t unwinder_running = ATOMIC_INIT(0);
-
 /**
  * select_unwinder - Select the best registered stack unwinder.
  *
@@ -123,6 +121,8 @@ int unwinder_register(struct unwinder *u)
 	return ret;
 }
 
+int unwinder_faulted = 0;
+
 /*
  * Unwind the call stack and pass information to the stacktrace_ops
  * functions. Also handle the case where we need to switch to a new
@@ -145,20 +145,41 @@ void unwind_stack(struct task_struct *task, struct pt_regs *regs,
 	 * Hopefully this will give us a semi-reliable stacktrace so we
 	 * can diagnose why curr_unwinder->dump() faulted.
 	 */
-	if (atomic_inc_return(&unwinder_running) != 1) {
+	if (unwinder_faulted) {
 		spin_lock_irqsave(&unwinder_lock, flags);
 
-		if (!list_is_singular(&unwinder_list)) {
+		/* Make sure no one beat us to changing the unwinder */
+		if (unwinder_faulted && !list_is_singular(&unwinder_list)) {
 			list_del(&curr_unwinder->list);
 			curr_unwinder = select_unwinder();
+
+			unwinder_faulted = 0;
 		}
 
 		spin_unlock_irqrestore(&unwinder_lock, flags);
-		atomic_dec(&unwinder_running);
 	}
 
 	curr_unwinder->dump(task, regs, sp, ops, data);
+}
+
+/*
+ * Trap handler for UWINDER_BUG() statements. We must switch to the
+ * unwinder with the next highest rating.
+ */
+BUILD_TRAP_HANDLER(unwinder)
+{
+	insn_size_t insn;
+	TRAP_HANDLER_DECL;
+
+	/* Rewind */
+	regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
+	insn = *(insn_size_t *)instruction_pointer(regs);
+
+	/* Switch unwinders when unwind_stack() is called */
+	unwinder_faulted = 1;
 
-	atomic_dec(&unwinder_running);
+#ifdef CONFIG_BUG
+	handle_BUG(regs);
+#endif
 }
 EXPORT_SYMBOL_GPL(unwind_stack);