[MIPS] lockdep: Add STACKTRACE_SUPPORT and enable LOCKDEP_SUPPORT

Implement stacktrace interface by using unwind_stack() and enable lockdep
support in Kconfig.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1841,6 +1841,14 @@ config RWSEM_GENERIC_SPINLOCK
 	bool
 	default y
 
+config LOCKDEP_SUPPORT
+	bool
+	default y
+
+config STACKTRACE_SUPPORT
+	bool
+	default y
+
 source "init/Kconfig"
 
 menu "Bus options (PCI, PCMCIA, EISA, ISA, TC)"

arch/mips/kernel/Makefile

@@ -11,6 +11,7 @@ obj-y		+= cpu-probe.o branch.o entry.o genex.o irq.o process.o \
 binfmt_irix-objs	:= irixelf.o irixinv.o irixioctl.o irixsig.o	\
 			   irix5sys.o sysirix.o
 
+obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
 obj-$(CONFIG_APM)		+= apm.o

arch/mips/kernel/process.c

@@ -40,6 +40,7 @@
 #include <asm/elf.h>
 #include <asm/isadep.h>
 #include <asm/inst.h>
+#include <asm/stacktrace.h>
 #ifdef CONFIG_MIPS_MT_SMTC
 #include <asm/mipsmtregs.h>
 extern void smtc_idle_loop_hook(void);

arch/mips/kernel/stacktrace.c

+/*
+ * arch/mips/kernel/stacktrace.c
+ *
+ * Stack trace management functions
+ *
+ *  Copyright (C) 2006 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
+ */
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+#include <asm/stacktrace.h>
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer:
+ */
+static void save_raw_context_stack(struct stack_trace *trace,
+	unsigned int skip, unsigned long reg29)
+{
+	unsigned long *sp = (unsigned long *)reg29;
+	unsigned long addr;
+
+	while (!kstack_end(sp)) {
+		addr = *sp++;
+		if (__kernel_text_address(addr)) {
+			if (!skip)
+				trace->entries[trace->nr_entries++] = addr;
+			else
+				skip--;
+			if (trace->nr_entries >= trace->max_entries)
+				break;
+		}
+	}
+}
+
+static struct pt_regs * save_context_stack(struct stack_trace *trace,
+	unsigned int skip, struct task_struct *task, struct pt_regs *regs)
+{
+	unsigned long sp = regs->regs[29];
+#ifdef CONFIG_KALLSYMS
+	unsigned long ra = regs->regs[31];
+	unsigned long pc = regs->cp0_epc;
+	extern void ret_from_irq(void);
+
+	if (raw_show_trace || !__kernel_text_address(pc)) {
+		save_raw_context_stack(trace, skip, sp);
+		return NULL;
+	}
+	do {
+		if (!skip)
+			trace->entries[trace->nr_entries++] = pc;
+		else
+			skip--;
+		if (trace->nr_entries >= trace->max_entries)
+			break;
+		/*
+		 * If we reached the bottom of interrupt context,
+		 * return saved pt_regs.
+		 */
+		if (pc == (unsigned long)ret_from_irq) {
+			unsigned long stack_page =
+				(unsigned long)task_stack_page(task);
+			if (!stack_page ||
+			    sp < stack_page ||
+			    sp > stack_page + THREAD_SIZE - 32)
+				break;
+			return (struct pt_regs *)sp;
+		}
+		pc = unwind_stack(task, &sp, pc, ra);
+		ra = 0;
+	} while (pc);
+#else
+	save_raw_context_stack(sp);
+#endif
+
+	return NULL;
+}
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ * If all_contexts is set, all contexts (hardirq, softirq and process)
+ * are saved. If not set then only the current context is saved.
+ */
+void save_stack_trace(struct stack_trace *trace,
+		      struct task_struct *task, int all_contexts,
+		      unsigned int skip)
+{
+	struct pt_regs dummyregs;
+	struct pt_regs *regs = &dummyregs;
+
+	WARN_ON(trace->nr_entries || !trace->max_entries);
+
+	if (task && task != current) {
+		regs->regs[29] = task->thread.reg29;
+		regs->regs[31] = 0;
+		regs->cp0_epc = task->thread.reg31;
+	} else {
+		if (!task)
+			task = current;
+		prepare_frametrace(regs);
+	}
+
+	while (1) {
+		regs = save_context_stack(trace, skip, task, regs);
+		if (!all_contexts || !regs ||
+		    trace->nr_entries >= trace->max_entries)
+			break;
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+		if (trace->nr_entries >= trace->max_entries)
+			break;
+		skip = 0;
+	}
+}

arch/mips/kernel/traps.c

@@ -41,6 +41,7 @@
 #include <asm/mmu_context.h>
 #include <asm/watch.h>
 #include <asm/types.h>
+#include <asm/stacktrace.h>
 
 extern asmlinkage void handle_int(void);
 extern asmlinkage void handle_tlbm(void);
@@ -92,16 +93,14 @@ static void show_raw_backtrace(unsigned long reg29)
 }
 
 #ifdef CONFIG_KALLSYMS
-static int raw_show_trace;
+int raw_show_trace;
 static int __init set_raw_show_trace(char *str)
 {
 	raw_show_trace = 1;
 	return 1;
 }
 __setup("raw_show_trace", set_raw_show_trace);
-
-extern unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
-				  unsigned long pc, unsigned long ra);
+#endif
 
 static void show_backtrace(struct task_struct *task, struct pt_regs *regs)
 {
@@ -121,9 +120,6 @@ static void show_backtrace(struct task_struct *task, struct pt_regs *regs)
 	} while (pc);
 	printk("\n");
 }
-#else
-#define show_backtrace(task, r) show_raw_backtrace((r)->regs[29]);
-#endif
 
 /*
  * This routine abuses get_user()/put_user() to reference pointers
@@ -158,28 +154,6 @@ static void show_stacktrace(struct task_struct *task, struct pt_regs *regs)
 	show_backtrace(task, regs);
 }
 
-static __always_inline void prepare_frametrace(struct pt_regs *regs)
-{
-	__asm__ __volatile__(
-		".set push\n\t"
-		".set noat\n\t"
-#ifdef CONFIG_64BIT
-		"1: dla $1, 1b\n\t"
-		"sd $1, %0\n\t"
-		"sd $29, %1\n\t"
-		"sd $31, %2\n\t"
-#else
-		"1: la $1, 1b\n\t"
-		"sw $1, %0\n\t"
-		"sw $29, %1\n\t"
-		"sw $31, %2\n\t"
-#endif
-		".set pop\n\t"
-		: "=m" (regs->cp0_epc),
-		"=m" (regs->regs[29]), "=m" (regs->regs[31])
-		: : "memory");
-}
-
 void show_stack(struct task_struct *task, unsigned long *sp)
 {
 	struct pt_regs regs;
@@ -206,11 +180,6 @@ void dump_stack(void)
 {
 	struct pt_regs regs;
 
-	/*
-	 * Remove any garbage that may be in regs (specially func
-	 * addresses) to avoid show_raw_backtrace() to report them
-	 */
-	memset(&regs, 0, sizeof(regs));
 	prepare_frametrace(&regs);
 	show_backtrace(current, &regs);
 }

include/asm-mips/stacktrace.h

+#ifndef _ASM_STACKTRACE_H
+#define _ASM_STACKTRACE_H
+
+#include <asm/ptrace.h>
+
+#ifdef CONFIG_KALLSYMS
+extern int raw_show_trace;
+extern unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
+				  unsigned long pc, unsigned long ra);
+#else
+#define raw_show_trace 1
+#define unwind_stack(task, sp, pc, ra)	0
+#endif
+
+static __always_inline void prepare_frametrace(struct pt_regs *regs)
+{
+#ifndef CONFIG_KALLSYMS
+	/*
+	 * Remove any garbage that may be in regs (specially func
+	 * addresses) to avoid show_raw_backtrace() to report them
+	 */
+	memset(regs, 0, sizeof(*regs));
+#endif
+	__asm__ __volatile__(
+		".set push\n\t"
+		".set noat\n\t"
+#ifdef CONFIG_64BIT
+		"1: dla $1, 1b\n\t"
+		"sd $1, %0\n\t"
+		"sd $29, %1\n\t"
+		"sd $31, %2\n\t"
+#else
+		"1: la $1, 1b\n\t"
+		"sw $1, %0\n\t"
+		"sw $29, %1\n\t"
+		"sw $31, %2\n\t"
+#endif
+		".set pop\n\t"
+		: "=m" (regs->cp0_epc),
+		"=m" (regs->regs[29]), "=m" (regs->regs[31])
+		: : "memory");
+}
+
+#endif /* _ASM_STACKTRACE_H */