Merge branch 'sh/dwarf-unwinder'

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

arch/sh/include/asm/bug.h

@@ -2,6 +2,7 @@
 #define __ASM_SH_BUG_H
 
 #define TRAPA_BUG_OPCODE	0xc33e	/* trapa #0x3e */
+#define BUGFLAG_UNWINDER	(1 << 1)
 
 #ifdef CONFIG_GENERIC_BUG
 #define HAVE_ARCH_BUG
@@ -72,6 +73,36 @@ do {							\
 	unlikely(__ret_warn_on);				\
 })
 
+#define UNWINDER_BUG()					\
+do {							\
+	__asm__ __volatile__ (				\
+		"1:\t.short %O0\n"			\
+		_EMIT_BUG_ENTRY				\
+		 :					\
+		 : "n" (TRAPA_BUG_OPCODE),		\
+		   "i" (__FILE__),			\
+		   "i" (__LINE__),			\
+		   "i" (BUGFLAG_UNWINDER),		\
+		   "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);				\
+})
+
+#else
+
+#define UNWINDER_BUG	BUG
+#define UNWINDER_BUG_ON	BUG_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)
 };
 
 /*
@@ -370,17 +362,16 @@ static inline unsigned int DW_CFA_operand(unsigned long insn)
 #define DW_EXT_HI	0xffffffff
 #define DW_EXT_DWARF64	DW_EXT_HI
 
-extern void dwarf_unwinder_init(void);
-
 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
 
@@ -394,6 +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
+
 	stc	sr, r0	! get status register
 	shlr2	r0
 	and	#0x3c, r0

arch/sh/kernel/irq.c

@@ -14,7 +14,6 @@
 #include <asm/processor.h>
 #include <asm/machvec.h>
 #include <asm/uaccess.h>
-#include <asm/dwarf.h>
 #include <asm/thread_info.h>
 #include <cpu/mmu_context.h>
 
@@ -262,9 +261,6 @@ void __init init_IRQ(void)
 		sh_mv.mv_init_irq();
 
 	irq_ctx_init(smp_processor_id());
-
-	/* This needs to be early, but not too early.. */
-	dwarf_unwinder_init();
 }
 
 #ifdef CONFIG_SPARSE_IRQ

arch/sh/kernel/traps.c

@@ -5,18 +5,32 @@
 #include <linux/signal.h>
 #include <linux/sched.h>
 #include <linux/uaccess.h>
+#include <asm/unwinder.h>
 #include <asm/system.h>
 
 #ifdef CONFIG_BUG
-static void handle_BUG(struct pt_regs *regs)
+void handle_BUG(struct pt_regs *regs)
 {
+	const struct bug_entry *bug;
+	unsigned long bugaddr = regs->pc;
 	enum bug_trap_type tt;
-	tt = report_bug(regs->pc, regs);
+
+	if (!is_valid_bugaddr(bugaddr))
+		goto invalid;
+
+	bug = find_bug(bugaddr);
+
+	/* Switch unwinders when unwind_stack() is called */
+	if (bug->flags & BUGFLAG_UNWINDER)
+		unwinder_faulted = 1;
+
+	tt = report_bug(bugaddr, regs);
 	if (tt == BUG_TRAP_TYPE_WARN) {
-		regs->pc += instruction_size(regs->pc);
+		regs->pc += instruction_size(bugaddr);
 		return;
 	}
 
+invalid:
 	die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
 }
 
@@ -28,8 +42,10 @@ int is_valid_bugaddr(unsigned long addr)
 		return 0;
 	if (probe_kernel_address((insn_size_t *)addr, opcode))
 		return 0;
+	if (opcode == TRAPA_BUG_OPCODE)
+		return 1;
 
-	return opcode == TRAPA_BUG_OPCODE;
+	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

@@ -11,6 +11,7 @@
 #include <linux/errno.h>
 #include <linux/list.h>
 #include <linux/spinlock.h>
+#include <linux/module.h>
 #include <asm/unwinder.h>
 #include <asm/atomic.h>
 
@@ -53,8 +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.
  *
@@ -122,6 +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
@@ -144,19 +145,20 @@ 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);
-
-	atomic_dec(&unwinder_running);
 }
+EXPORT_SYMBOL_GPL(unwind_stack);