From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/blackfin/kernel/ftrace.c | 125 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 arch/blackfin/kernel/ftrace.c

(limited to 'arch/blackfin/kernel/ftrace.c')

diff --git a/arch/blackfin/kernel/ftrace.c b/arch/blackfin/kernel/ftrace.c
new file mode 100644
index 000000000..095de0fa0
--- /dev/null
+++ b/arch/blackfin/kernel/ftrace.c
@@ -0,0 +1,125 @@
+/*
+ * ftrace graph code
+ *
+ * Copyright (C) 2009-2010 Analog Devices Inc.
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/ftrace.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/atomic.h>
+#include <asm/cacheflush.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static const unsigned char mnop[] = {
+	0x03, 0xc0, 0x00, 0x18, /* MNOP; */
+	0x03, 0xc0, 0x00, 0x18, /* MNOP; */
+};
+
+static void bfin_make_pcrel24(unsigned char *insn, unsigned long src,
+                              unsigned long dst)
+{
+	uint32_t pcrel = (dst - src) >> 1;
+	insn[0] = pcrel >> 16;
+	insn[1] = 0xe3;
+	insn[2] = pcrel;
+	insn[3] = pcrel >> 8;
+}
+#define bfin_make_pcrel24(insn, src, dst) bfin_make_pcrel24(insn, src, (unsigned long)(dst))
+
+static int ftrace_modify_code(unsigned long ip, const unsigned char *code,
+                              unsigned long len)
+{
+	int ret = probe_kernel_write((void *)ip, (void *)code, len);
+	flush_icache_range(ip, ip + len);
+	return ret;
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
+                    unsigned long addr)
+{
+	/* Turn the mcount call site into two MNOPs as those are 32bit insns */
+	return ftrace_modify_code(rec->ip, mnop, sizeof(mnop));
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	/* Restore the mcount call site */
+	unsigned char call[8];
+	call[0] = 0x67; /* [--SP] = RETS; */
+	call[1] = 0x01;
+	bfin_make_pcrel24(&call[2], rec->ip + 2, addr);
+	call[6] = 0x27; /* RETS = [SP++]; */
+	call[7] = 0x01;
+	return ftrace_modify_code(rec->ip, call, sizeof(call));
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	unsigned char call[4];
+	unsigned long ip = (unsigned long)&ftrace_call;
+	bfin_make_pcrel24(call, ip, func);
+	return ftrace_modify_code(ip, call, sizeof(call));
+}
+
+int __init ftrace_dyn_arch_init(void)
+{
+	return 0;
+}
+
+#endif
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+# ifdef CONFIG_DYNAMIC_FTRACE
+
+extern void ftrace_graph_call(void);
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+	unsigned long ip = (unsigned long)&ftrace_graph_call;
+	uint16_t jump_pcrel12 = ((unsigned long)&ftrace_graph_caller - ip) >> 1;
+	jump_pcrel12 |= 0x2000;
+	return ftrace_modify_code(ip, (void *)&jump_pcrel12, sizeof(jump_pcrel12));
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+	return ftrace_modify_code((unsigned long)&ftrace_graph_call, empty_zero_page, 2);
+}
+
+# endif
+
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+                           unsigned long frame_pointer)
+{
+	struct ftrace_graph_ent trace;
+	unsigned long return_hooker = (unsigned long)&return_to_handler;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		return;
+
+	if (ftrace_push_return_trace(*parent, self_addr, &trace.depth,
+	                             frame_pointer) == -EBUSY)
+		return;
+
+	trace.func = self_addr;
+
+	/* Only trace if the calling function expects to */
+	if (!ftrace_graph_entry(&trace)) {
+		current->curr_ret_stack--;
+		return;
+	}
+
+	/* all is well in the world !  hijack RETS ... */
+	*parent = return_hooker;
+}
+
+#endif
-- 
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