[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 000000000000..f851d0cc245f
--- /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;
+        }
+}