[PATCH v2 3/6] x86/stacktrace: convert save_stack_trace_*() to use the new unwinder

[Josh Poimboeuf]

Convert save_stack_trace_*() to use the new unwinder.  dump_trace() has
been deprecated.

Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
 arch/x86/kernel/stacktrace.c | 74 +++++++++++++++++---------------------------
 1 file changed, 29 insertions(+), 45 deletions(-)

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 23fa81e..0653788 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -8,73 +8,59 @@
 #include <linux/export.h>
 #include <linux/uaccess.h>
 #include <asm/stacktrace.h>
+#include <asm/unwind.h>
 
-static int save_stack_stack(void *data, const char *name)
+static int save_stack_address(struct stack_trace *trace, unsigned long addr,
+                             bool nosched)
 {
-       return 0;
-}
-
-static int
-__save_stack_address(void *data, unsigned long addr, bool reliable, bool 
nosched)
-{
-       struct stack_trace *trace = data;
-#ifdef CONFIG_FRAME_POINTER
-       if (!reliable)
-               return 0;
-#endif
        if (nosched && in_sched_functions(addr))
                return 0;
+
        if (trace->skip > 0) {
                trace->skip--;
                return 0;
        }
-       if (trace->nr_entries < trace->max_entries) {
-               trace->entries[trace->nr_entries++] = addr;
-               return 0;
-       } else {
-               return -1; /* no more room, stop walking the stack */
-       }
-}
 
-static int save_stack_address(void *data, unsigned long addr, int reliable)
-{
-       return __save_stack_address(data, addr, reliable, false);
+       if (trace->nr_entries >= trace->max_entries)
+               return -1;
+
+       trace->entries[trace->nr_entries++] = addr;
+       return 0;
 }
 
-static int
-save_stack_address_nosched(void *data, unsigned long addr, int reliable)
+static void __save_stack_trace(struct stack_trace *trace,
+                              struct task_struct *task, struct pt_regs *regs,
+                              bool nosched)
 {
-       return __save_stack_address(data, addr, reliable, true);
-}
+       struct unwind_state state;
+       unsigned long addr;
 
-static const struct stacktrace_ops save_stack_ops = {
-       .stack          = save_stack_stack,
-       .address        = save_stack_address,
-       .walk_stack     = print_context_stack,
-};
+       if (regs)
+               save_stack_address(trace, regs->ip, nosched);
 
-static const struct stacktrace_ops save_stack_ops_nosched = {
-       .stack          = save_stack_stack,
-       .address        = save_stack_address_nosched,
-       .walk_stack     = print_context_stack,
-};
+       for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
+            unwind_next_frame(&state)) {
+               addr = unwind_get_return_address(&state);
+               if (!addr || save_stack_address(trace, addr, nosched))
+                       break;
+       }
+
+       if (trace->nr_entries < trace->max_entries)
+               trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
 
 /*
  * Save stack-backtrace addresses into a stack_trace buffer.
  */
 void save_stack_trace(struct stack_trace *trace)
 {
-       dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
-       if (trace->nr_entries < trace->max_entries)
-               trace->entries[trace->nr_entries++] = ULONG_MAX;
+       __save_stack_trace(trace, current, NULL, false);
 }
 EXPORT_SYMBOL_GPL(save_stack_trace);
 
 void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
 {
-       dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
-       if (trace->nr_entries < trace->max_entries)
-               trace->entries[trace->nr_entries++] = ULONG_MAX;
+       __save_stack_trace(trace, current, regs, false);
 }
 
 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
@@ -82,9 +68,7 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct 
stack_trace *trace)
        if (!try_get_task_stack(tsk))
                return;
 
-       dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
-       if (trace->nr_entries < trace->max_entries)
-               trace->entries[trace->nr_entries++] = ULONG_MAX;
+       __save_stack_trace(trace, tsk, NULL, true);
 
        put_task_stack(tsk);
 }
-- 
2.7.4