[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>

4 files changed, 116 insertions, 34 deletions

diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 881c467c6982..cd9cec9e39e9 100644
--- a/arch/mips/kernel/Makefile
+++ b/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
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 2613a0dd4b82..695538031c69 100644
--- a/arch/mips/kernel/process.c
+++ b/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);
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;
+        }
+}
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index e51d8fd9a152..440b8651fd8b 100644
--- a/arch/mips/kernel/traps.c
+++ b/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);
 }