unicore32 core architecture: process/thread related codes

This patch implements process/thread related codes. Backtrace and stacktrace are here.

Signed-off-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 131 insertions, 0 deletions

diff --git a/arch/unicore32/kernel/stacktrace.c b/arch/unicore32/kernel/stacktrace.c
new file mode 100644
index 00000000000..b34030bdabe
--- /dev/null
+++ b/arch/unicore32/kernel/stacktrace.c
@@ -0,0 +1,131 @@
+/*
+ * linux/arch/unicore32/kernel/stacktrace.c
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+
+#include <asm/stacktrace.h>
+
+#if defined(CONFIG_FRAME_POINTER)
+/*
+ * Unwind the current stack frame and store the new register values in the
+ * structure passed as argument. Unwinding is equivalent to a function return,
+ * hence the new PC value rather than LR should be used for backtrace.
+ *
+ * With framepointer enabled, a simple function prologue looks like this:
+ *      mov     ip, sp
+ *      stmdb   sp!, {fp, ip, lr, pc}
+ *      sub     fp, ip, #4
+ *
+ * A simple function epilogue looks like this:
+ *      ldm     sp, {fp, sp, pc}
+ *
+ * Note that with framepointer enabled, even the leaf functions have the same
+ * prologue and epilogue, therefore we can ignore the LR value in this case.
+ */
+int notrace unwind_frame(struct stackframe *frame)
+{
+        unsigned long high, low;
+        unsigned long fp = frame->fp;
+
+        /* only go to a higher address on the stack */
+        low = frame->sp;
+        high = ALIGN(low, THREAD_SIZE);
+
+        /* check current frame pointer is within bounds */
+        if (fp < (low + 12) || fp + 4 >= high)
+                return -EINVAL;
+
+        /* restore the registers from the stack frame */
+        frame->fp = *(unsigned long *)(fp - 12);
+        frame->sp = *(unsigned long *)(fp - 8);
+        frame->pc = *(unsigned long *)(fp - 4);
+
+        return 0;
+}
+#endif
+
+void notrace walk_stackframe(struct stackframe *frame,
+                     int (*fn)(struct stackframe *, void *), void *data)
+{
+        while (1) {
+                int ret;
+
+                if (fn(frame, data))
+                        break;
+                ret = unwind_frame(frame);
+                if (ret < 0)
+                        break;
+        }
+}
+EXPORT_SYMBOL(walk_stackframe);
+
+#ifdef CONFIG_STACKTRACE
+struct stack_trace_data {
+        struct stack_trace *trace;
+        unsigned int no_sched_functions;
+        unsigned int skip;
+};
+
+static int save_trace(struct stackframe *frame, void *d)
+{
+        struct stack_trace_data *data = d;
+        struct stack_trace *trace = data->trace;
+        unsigned long addr = frame->pc;
+
+        if (data->no_sched_functions && in_sched_functions(addr))
+                return 0;
+        if (data->skip) {
+                data->skip--;
+                return 0;
+        }
+
+        trace->entries[trace->nr_entries++] = addr;
+
+        return trace->nr_entries >= trace->max_entries;
+}
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+        struct stack_trace_data data;
+        struct stackframe frame;
+
+        data.trace = trace;
+        data.skip = trace->skip;
+
+        if (tsk != current) {
+                data.no_sched_functions = 1;
+                frame.fp = thread_saved_fp(tsk);
+                frame.sp = thread_saved_sp(tsk);
+                frame.lr = 0;           /* recovered from the stack */
+                frame.pc = thread_saved_pc(tsk);
+        } else {
+                register unsigned long current_sp asm("sp");
+
+                data.no_sched_functions = 0;
+                frame.fp = (unsigned long)__builtin_frame_address(0);
+                frame.sp = current_sp;
+                frame.lr = (unsigned long)__builtin_return_address(0);
+                frame.pc = (unsigned long)save_stack_trace_tsk;
+        }
+
+        walk_stackframe(&frame, save_trace, &data);
+        if (trace->nr_entries < trace->max_entries)
+                trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
+void save_stack_trace(struct stack_trace *trace)
+{
+        save_stack_trace_tsk(current, trace);
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+#endif