[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>

1 files changed, 111 insertions, 0 deletions

diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c
new file mode 100644
index 0000000..f851d0c
--- /dev/null
+++ b/arch/mips/kernel/stacktrace.c
@@ -0,0 +1,111 @@
+/*
+ * 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;
+	}
+}