1 files changed, 275 insertions, 0 deletions
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
new file mode 100644
index 00000000000..68b067040d8
--- /dev/null
+++ b/arch/mips/kernel/ftrace.c
@@ -0,0 +1,275 @@
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ * Copyright (C) 2009 DSLab, Lanzhou University, China
+ * Author: Wu Zhangjin <wuzj@lemote.com>
+ *
+ * Thanks goes to Steven Rostedt for writing the original x86 version.
+ */
+
+#include <linux/uaccess.h>
+#include <linux/init.h>
+#include <linux/ftrace.h>
+
+#include <asm/cacheflush.h>
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define JAL 0x0c000000		/* jump & link: ip --> ra, jump to target */
+#define ADDR_MASK 0x03ffffff	/*  op_code|addr : 31...26|25 ....0 */
+#define jump_insn_encode(op_code, addr) \
+	((unsigned int)((op_code) | (((addr) >> 2) & ADDR_MASK)))
+
+static unsigned int ftrace_nop = 0x00000000;
+
+static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
+{
+	int faulted;
+
+	/* *(unsigned int *)ip = new_code; */
+	safe_store_code(new_code, ip, faulted);
+
+	if (unlikely(faulted))
+		return -EFAULT;
+
+	flush_icache_range(ip, ip + 8);
+
+	return 0;
+}
+
+static int lui_v1;
+static int jal_mcount;
+
+int ftrace_make_nop(struct module *mod,
+		    struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned int new;
+	int faulted;
+	unsigned long ip = rec->ip;
+
+	/* We have compiled module with -mlong-calls, but compiled the kernel
+	 * without it, we need to cope with them respectively. */
+	if (ip & 0x40000000) {
+		/* record it for ftrace_make_call */
+		if (lui_v1 == 0) {
+			/* lui_v1 = *(unsigned int *)ip; */
+			safe_load_code(lui_v1, ip, faulted);
+
+			if (unlikely(faulted))
+				return -EFAULT;
+		}
+
+		/* lui v1, hi_16bit_of_mcount        --> b 1f (0x10000004)
+		 * addiu v1, v1, low_16bit_of_mcount
+		 * move at, ra
+		 * jalr v1
+		 * nop
+		 * 				     1f: (ip + 12)
+		 */
+		new = 0x10000004;
+	} else {
+		/* record/calculate it for ftrace_make_call */
+		if (jal_mcount == 0) {
+			/* We can record it directly like this:
+			 *     jal_mcount = *(unsigned int *)ip;
+			 * Herein, jump over the first two nop instructions */
+			jal_mcount = jump_insn_encode(JAL, (MCOUNT_ADDR + 8));
+		}
+
+		/* move at, ra
+		 * jalr v1		--> nop
+		 */
+		new = ftrace_nop;
+	}
+	return ftrace_modify_code(ip, new);
+}
+
+static int modified;	/* initialized as 0 by default */
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned int new;
+	unsigned long ip = rec->ip;
+
+	/* We just need to remove the "b ftrace_stub" at the fist time! */
+	if (modified == 0) {
+		modified = 1;
+		ftrace_modify_code(addr, ftrace_nop);
+	}
+	/* ip, module: 0xc0000000, kernel: 0x80000000 */
+	new = (ip & 0x40000000) ? lui_v1 : jal_mcount;
+
+	return ftrace_modify_code(ip, new);
+}
+
+#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	unsigned int new;
+
+	new = jump_insn_encode(JAL, (unsigned long)func);
+
+	return ftrace_modify_code(FTRACE_CALL_IP, new);
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+	/* The return code is retured via data */
+	*(unsigned long *)data = 0;
+
+	return 0;
+}
+#endif				/* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+extern void ftrace_graph_call(void);
+#define JMP	0x08000000	/* jump to target directly */
+#define CALL_FTRACE_GRAPH_CALLER \
+	jump_insn_encode(JMP, (unsigned long)(&ftrace_graph_caller))
+#define FTRACE_GRAPH_CALL_IP	((unsigned long)(&ftrace_graph_call))
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
+				  CALL_FTRACE_GRAPH_CALLER);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+	return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, ftrace_nop);
+}
+
+#endif				/* !CONFIG_DYNAMIC_FTRACE */
+
+#ifndef KBUILD_MCOUNT_RA_ADDRESS
+#define S_RA_SP	(0xafbf << 16)	/* s{d,w} ra, offset(sp) */
+#define S_R_SP	(0xafb0 << 16)  /* s{d,w} R, offset(sp) */
+#define OFFSET_MASK	0xffff	/* stack offset range: 0 ~ PT_SIZE */
+
+unsigned long ftrace_get_parent_addr(unsigned long self_addr,
+				     unsigned long parent,
+				     unsigned long parent_addr,
+				     unsigned long fp)
+{
+	unsigned long sp, ip, ra;
+	unsigned int code;
+	int faulted;
+
+	/* in module or kernel? */
+	if (self_addr & 0x40000000) {
+		/* module: move to the instruction "lui v1, HI_16BIT_OF_MCOUNT" */
+		ip = self_addr - 20;
+	} else {
+		/* kernel: move to the instruction "move ra, at" */
+		ip = self_addr - 12;
+	}
+
+	/* search the text until finding the non-store instruction or "s{d,w}
+	 * ra, offset(sp)" instruction */
+	do {
+		ip -= 4;
+
+		/* get the code at "ip": code = *(unsigned int *)ip; */
+		safe_load_code(code, ip, faulted);
+
+		if (unlikely(faulted))
+			return 0;
+
+		/* If we hit the non-store instruction before finding where the
+		 * ra is stored, then this is a leaf function and it does not
+		 * store the ra on the stack. */
+		if ((code & S_R_SP) != S_R_SP)
+			return parent_addr;
+
+	} while (((code & S_RA_SP) != S_RA_SP));
+
+	sp = fp + (code & OFFSET_MASK);
+
+	/* ra = *(unsigned long *)sp; */
+	safe_load_stack(ra, sp, faulted);
+	if (unlikely(faulted))
+		return 0;
+
+	if (ra == parent)
+		return sp;
+	return 0;
+}
+
+#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 fp)
+{
+	unsigned long old;
+	struct ftrace_graph_ent trace;
+	unsigned long return_hooker = (unsigned long)
+	    &return_to_handler;
+	int faulted;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		return;
+
+	/* "parent" is the stack address saved the return address of the caller
+	 * of _mcount.
+	 *
+	 * if the gcc < 4.5, a leaf function does not save the return address
+	 * in the stack address, so, we "emulate" one in _mcount's stack space,
+	 * and hijack it directly, but for a non-leaf function, it save the
+	 * return address to the its own stack space, we can not hijack it
+	 * directly, but need to find the real stack address,
+	 * ftrace_get_parent_addr() does it!
+	 *
+	 * if gcc>= 4.5, with the new -mmcount-ra-address option, for a
+	 * non-leaf function, the location of the return address will be saved
+	 * to $12 for us, and for a leaf function, only put a zero into $12. we
+	 * do it in ftrace_graph_caller of mcount.S.
+	 */
+
+	/* old = *parent; */
+	safe_load_stack(old, parent, faulted);
+	if (unlikely(faulted))
+		goto out;
+#ifndef KBUILD_MCOUNT_RA_ADDRESS
+	parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old,
+							 (unsigned long)parent,
+							 fp);
+	/* If fails when getting the stack address of the non-leaf function's
+	 * ra, stop function graph tracer and return */
+	if (parent == 0)
+		goto out;
+#endif
+	/* *parent = return_hooker; */
+	safe_store_stack(return_hooker, parent, faulted);
+	if (unlikely(faulted))
+		goto out;
+
+	if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) ==
+	    -EBUSY) {
+		*parent = old;
+		return;
+	}
+
+	trace.func = self_addr;
+
+	/* Only trace if the calling function expects to */
+	if (!ftrace_graph_entry(&trace)) {
+		current->curr_ret_stack--;
+		*parent = old;
+	}
+	return;
+out:
+	ftrace_graph_stop();
+	WARN_ON(1);
+}
+#endif				/* CONFIG_FUNCTION_GRAPH_TRACER */