[MIPS] Stacktrace build-fix and improvement

Fix build error due to stacktrace API change.  Now save_stack_trace()
tries to save all kernel context, including interrupts and exception.
Also some asm code are changed a bit so that we can detect the end of
current context easily.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 27 insertions, 33 deletions

diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index 37fda3dcdfc5..af6ef2fd8300 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -220,8 +220,8 @@ NESTED(except_vec_vi_handler, 0, sp)
         CLI
         TRACE_IRQS_OFF
         move    a0, sp
-        jalr    v0
-        j       ret_from_irq
+        PTR_LA  ra, ret_from_irq
+        jr      v0
         END(except_vec_vi_handler)
 
 /*
@@ -349,8 +349,8 @@ NESTED(nmi_handler, PT_SIZE, sp)
         .set    at
         __BUILD_\verbose \exception
         move    a0, sp
-        jal     do_\handler
-        j       ret_from_exception
+        PTR_LA  ra, ret_from_exception
+        j       do_\handler
         END(handle_\exception)
         .endm
 
diff --git a/arch/mips/kernel/stacktrace.c b/arch/mips/kernel/stacktrace.c
index f851d0cc245f..676e6f69d24b 100644
--- a/arch/mips/kernel/stacktrace.c
+++ b/arch/mips/kernel/stacktrace.c
@@ -13,7 +13,7 @@
  * 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 reg29)
 {
         unsigned long *sp = (unsigned long *)reg29;
         unsigned long addr;
@@ -21,10 +21,10 @@ static void save_raw_context_stack(struct stack_trace *trace,
         while (!kstack_end(sp)) {
                 addr = *sp++;
                 if (__kernel_text_address(addr)) {
-                        if (!skip)
-                                trace->entries[trace->nr_entries++] = addr;
+                        if (trace->skip > 0)
+                                trace->skip--;
                         else
-                                skip--;
+                                trace->entries[trace->nr_entries++] = addr;
                         if (trace->nr_entries >= trace->max_entries)
                                 break;
                 }
@@ -32,37 +32,40 @@ static void save_raw_context_stack(struct stack_trace *trace,
 }
 
 static struct pt_regs * save_context_stack(struct stack_trace *trace,
-        unsigned int skip, struct task_struct *task, struct pt_regs *regs)
+        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;
+        unsigned long stack_page =
+                (unsigned long)task_stack_page(task);
         extern void ret_from_irq(void);
+        extern void ret_from_exception(void);
 
         if (raw_show_trace || !__kernel_text_address(pc)) {
-                save_raw_context_stack(trace, skip, sp);
+                if (stack_page && sp >= stack_page &&
+                    sp <= stack_page + THREAD_SIZE - 32)
+                        save_raw_context_stack(trace, sp);
                 return NULL;
         }
         do {
-                if (!skip)
-                        trace->entries[trace->nr_entries++] = pc;
+                if (trace->skip > 0)
+                        trace->skip--;
                 else
-                        skip--;
+                        trace->entries[trace->nr_entries++] = pc;
                 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;
+                if (pc == (unsigned long)ret_from_irq ||
+                    pc == (unsigned long)ret_from_exception) {
+                        if (stack_page && sp >= stack_page &&
+                            sp <= stack_page + THREAD_SIZE - 32)
+                                return (struct pt_regs *)sp;
+                        break;
                 }
                 pc = unwind_stack(task, &sp, pc, ra);
                 ra = 0;
@@ -76,12 +79,8 @@ static struct pt_regs * save_context_stack(struct stack_trace *trace,
 
 /*
  * 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)
+void save_stack_trace(struct stack_trace *trace, struct task_struct *task)
 {
         struct pt_regs dummyregs;
         struct pt_regs *regs = &dummyregs;
@@ -99,13 +98,8 @@ void save_stack_trace(struct stack_trace *trace,
         }
 
         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)
+                regs = save_context_stack(trace, task, regs);
+                if (!regs || trace->nr_entries >= trace->max_entries)
                         break;
-                skip = 0;
         }
 }