sh: Use the generalized stacktrace ops

Copy the stacktrace ops code from x86 and provide a central function for
use by functions that need to dump a callstack.
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/include/asm/stacktrace.h

+/*
+ * Copyright (C) 2009  Matt Fleming
+ *
+ * Based on:
+ *	The x86 implementation - arch/x86/include/asm/stacktrace.h
+ */
+#ifndef _ASM_SH_STACKTRACE_H
+#define _ASM_SH_STACKTRACE_H
+
+/* Generic stack tracer with callbacks */
+
+struct stacktrace_ops {
+	void (*warning)(void *data, char *msg);
+	/* msg must contain %s for the symbol */
+	void (*warning_symbol)(void *data, char *msg, unsigned long symbol);
+	void (*address)(void *data, unsigned long address, int reliable);
+	/* On negative return stop dumping */
+	int (*stack)(void *data, char *name);
+};
+
+void dump_trace(struct task_struct *tsk, struct pt_regs *regs,
+		unsigned long *stack,
+		const struct stacktrace_ops *ops, void *data);
+
+#endif /* _ASM_SH_STACKTRACE_H */

arch/sh/kernel/Makefile_32

@@ -9,7 +9,7 @@ ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_ftrace.o = -pg
 endif
 
-obj-y	:= debugtraps.o idle.o io.o io_generic.o irq.o			\
+obj-y	:= debugtraps.o dumpstack.o idle.o io.o io_generic.o irq.o	\
 	   machvec.o process_32.o ptrace_32.o setup.o signal_32.o	\
 	   sys_sh.o sys_sh32.o syscalls_32.o time.o topology.o	\
 	   traps.o traps_32.o

arch/sh/kernel/dumpstack.c

+/*
+ *  Copyright (C) 1991, 1992  Linus Torvalds
+ *  Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
+ *  Copyright (C) 2009  Matt Fleming
+ */
+#include <linux/kallsyms.h>
+#include <linux/ftrace.h>
+#include <linux/debug_locks.h>
+
+#include <asm/stacktrace.h>
+
+void printk_address(unsigned long address, int reliable)
+{
+	printk(" [<%p>] %s%pS\n", (void *) address,
+			reliable ? "" : "? ", (void *) address);
+}
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static void
+print_ftrace_graph_addr(unsigned long addr, void *data,
+			const struct stacktrace_ops *ops,
+			struct thread_info *tinfo, int *graph)
+{
+	struct task_struct *task = tinfo->task;
+	unsigned long ret_addr;
+	int index = task->curr_ret_stack;
+
+	if (addr != (unsigned long)return_to_handler)
+		return;
+
+	if (!task->ret_stack || index < *graph)
+		return;
+
+	index -= *graph;
+	ret_addr = task->ret_stack[index].ret;
+
+	ops->address(data, ret_addr, 1);
+
+	(*graph)++;
+}
+#else
+static inline void
+print_ftrace_graph_addr(unsigned long addr, void *data,
+			const struct stacktrace_ops *ops,
+			struct thread_info *tinfo, int *graph)
+{ }
+#endif
+
+/*
+ * Unwind the call stack and pass information to the stacktrace_ops
+ * functions.
+ */
+void dump_trace(struct task_struct *task, struct pt_regs *regs,
+		unsigned long *sp, const struct stacktrace_ops *ops,
+		void *data)
+{
+	struct thread_info *context;
+	int graph = 0;
+
+	context = (struct thread_info *)
+		((unsigned long)sp & (~(THREAD_SIZE - 1)));
+
+	while (!kstack_end(sp)) {
+		unsigned long addr = *sp++;
+
+		if (__kernel_text_address(addr)) {
+			ops->address(data, addr, 0);
+
+			print_ftrace_graph_addr(addr, data, ops,
+						context, &graph);
+		}
+	}
+}
+EXPORT_SYMBOL(dump_trace);
+
+
+static void
+print_trace_warning_symbol(void *data, char *msg, unsigned long symbol)
+{
+	printk(data);
+	print_symbol(msg, symbol);
+	printk("\n");
+}
+
+static void print_trace_warning(void *data, char *msg)
+{
+	printk("%s%s\n", (char *)data, msg);
+}
+
+static int print_trace_stack(void *data, char *name)
+{
+	printk("%s <%s> ", (char *)data, name);
+	return 0;
+}
+
+/*
+ * Print one address/symbol entries per line.
+ */
+static void print_trace_address(void *data, unsigned long addr, int reliable)
+{
+	printk(data);
+	printk_address(addr, reliable);
+}
+
+static const struct stacktrace_ops print_trace_ops = {
+	.warning = print_trace_warning,
+	.warning_symbol = print_trace_warning_symbol,
+	.stack = print_trace_stack,
+	.address = print_trace_address,
+};
+
+void show_trace(struct task_struct *tsk, unsigned long *sp,
+		struct pt_regs *regs)
+{
+	if (regs && user_mode(regs))
+		return;
+
+	printk("\nCall trace:\n");
+
+	dump_trace(tsk, regs, sp, &print_trace_ops, "");
+
+	printk("\n");
+
+	if (!tsk)
+		tsk = current;
+
+	debug_show_held_locks(tsk);
+}

arch/sh/kernel/stacktrace.c

@@ -14,46 +14,81 @@
 #include <linux/thread_info.h>
 #include <linux/module.h>
 #include <asm/ptrace.h>
+#include <asm/stacktrace.h>
+
+static void save_stack_warning(void *data, char *msg)
+{
+}
+
+static void
+save_stack_warning_symbol(void *data, char *msg, unsigned long symbol)
+{
+}
+
+static int save_stack_stack(void *data, char *name)
+{
+	return 0;
+}
 
 /*
  * Save stack-backtrace addresses into a stack_trace buffer.
  */
+static void save_stack_address(void *data, unsigned long addr, int reliable)
+{
+	struct stack_trace *trace = data;
+
+	if (trace->skip > 0) {
+		trace->skip--;
+		return;
+	}
+
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = addr;
+}
+
+static const struct stacktrace_ops save_stack_ops = {
+	.warning = save_stack_warning,
+	.warning_symbol = save_stack_warning_symbol,
+	.stack = save_stack_stack,
+	.address = save_stack_address,
+};
+
 void save_stack_trace(struct stack_trace *trace)
 {
 	unsigned long *sp = (unsigned long *)current_stack_pointer;
 
-	while (!kstack_end(sp)) {
-		unsigned long addr = *sp++;
+	dump_trace(current, NULL, sp,  &save_stack_ops, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
 
-		if (__kernel_text_address(addr)) {
-			if (trace->skip > 0)
+static void
+save_stack_address_nosched(void *data, unsigned long addr, int reliable)
+{
+	struct stack_trace *trace = (struct stack_trace *)data;
+
+	if (in_sched_functions(addr))
+		return;
+
+	if (trace->skip > 0) {
 		trace->skip--;
-			else
-				trace->entries[trace->nr_entries++] = addr;
-			if (trace->nr_entries >= trace->max_entries)
-				break;
-		}
+		return;
 	}
+
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = addr;
 }
-EXPORT_SYMBOL_GPL(save_stack_trace);
+
+static const struct stacktrace_ops save_stack_ops_nosched = {
+	.warning = save_stack_warning,
+	.warning_symbol = save_stack_warning_symbol,
+	.stack = save_stack_stack,
+	.address = save_stack_address_nosched,
+};
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 {
 	unsigned long *sp = (unsigned long *)tsk->thread.sp;
 
-	while (!kstack_end(sp)) {
-		unsigned long addr = *sp++;
-
-		if (__kernel_text_address(addr)) {
-			if (in_sched_functions(addr))
-				break;
-			if (trace->skip > 0)
-				trace->skip--;
-			else
-				trace->entries[trace->nr_entries++] = addr;
-			if (trace->nr_entries >= trace->max_entries)
-				break;
-		}
-	}
+	dump_trace(current, NULL, sp,  &save_stack_ops_nosched, trace);
 }
 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);

arch/sh/kernel/traps_32.c

@@ -858,30 +858,6 @@ void __init trap_init(void)
 	per_cpu_trap_init();
 }
 
-void show_trace(struct task_struct *tsk, unsigned long *sp,
-		struct pt_regs *regs)
-{
-	unsigned long addr;
-
-	if (regs && user_mode(regs))
-		return;
-
-	printk("\nCall trace:\n");
-
-	while (!kstack_end(sp)) {
-		addr = *sp++;
-		if (kernel_text_address(addr))
-			print_ip_sym(addr);
-	}
-
-	printk("\n");
-
-	if (!tsk)
-		tsk = current;
-
-	debug_show_held_locks(tsk);
-}
-
 void show_stack(struct task_struct *tsk, unsigned long *sp)
 {
 	unsigned long stack;

arch/sh/oprofile/backtrace.c

@@ -20,6 +20,39 @@
 #include <asm/ptrace.h>
 #include <asm/uaccess.h>
 #include <asm/sections.h>
+#include <asm/stacktrace.h>
+
+static void backtrace_warning_symbol(void *data, char *msg,
+				     unsigned long symbol)
+{
+	/* Ignore warnings */
+}
+
+static void backtrace_warning(void *data, char *msg)
+{
+	/* Ignore warnings */
+}
+
+static int backtrace_stack(void *data, char *name)
+{
+	/* Yes, we want all stacks */
+	return 0;
+}
+
+static void backtrace_address(void *data, unsigned long addr, int reliable)
+{
+	unsigned int *depth = data;
+
+	if ((*depth)--)
+		oprofile_add_trace(addr);
+}
+
+static struct stacktrace_ops backtrace_ops = {
+	.warning = backtrace_warning,
+	.warning_symbol = backtrace_warning_symbol,
+	.stack = backtrace_stack,
+	.address = backtrace_address,
+};
 
 /* Limit to stop backtracing too far. */
 static int backtrace_limit = 20;
@@ -74,23 +107,6 @@ static int valid_kernel_stack(unsigned long *stackaddr, struct pt_regs *regs)
 	return ((unsigned long)stackaddr > stack) && ((unsigned long)stackaddr < stack_base);
 }
 
-static unsigned long *
-kernel_backtrace(unsigned long *stackaddr, struct pt_regs *regs)
-{
-	unsigned long addr;
-
-	/*
-	 * If not a valid kernel address, keep going till we find one
-	 * or the SP stops being a valid address.
-	 */
-	do {
-		addr = *stackaddr++;
-		oprofile_add_trace(addr);
-	} while (valid_kernel_stack(stackaddr, regs));
-
-	return stackaddr;
-}
-
 void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
 {
 	unsigned long *stackaddr;
@@ -103,9 +119,9 @@ void sh_backtrace(struct pt_regs * const regs, unsigned int depth)
 
 	stackaddr = (unsigned long *)regs->regs[15];
 	if (!user_mode(regs)) {
-		while (depth-- && valid_kernel_stack(stackaddr, regs))
-			stackaddr = kernel_backtrace(stackaddr, regs);
-
+		if (depth)
+			dump_trace(NULL, regs, stackaddr,
+				   &backtrace_ops, &depth);
 		return;
 	}