metag: ftrace support

Add ftrace support for metag.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>

6 files changed, 235 insertions, 1 deletions

diff --git a/arch/metag/Kconfig b/arch/metag/Kconfig
index 47972025818f..f6846ad5d3a8 100644
--- a/arch/metag/Kconfig
+++ b/arch/metag/Kconfig
@@ -12,7 +12,12 @@ config METAG
 	select GENERIC_SMP_IDLE_THREAD
 	select HAVE_64BIT_ALIGNED_ACCESS
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_KMEMLEAK
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_FUNCTION_TRACER
+	select HAVE_FUNCTION_TRACE_MCOUNT_TEST
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_IRQ_WORK
 	select HAVE_KERNEL_BZIP2
diff --git a/arch/metag/include/asm/Kbuild b/arch/metag/include/asm/Kbuild
index 3a139810559e..6ae0ccb632cb 100644
--- a/arch/metag/include/asm/Kbuild
+++ b/arch/metag/include/asm/Kbuild
@@ -11,7 +11,6 @@ generic-y += errno.h
 generic-y += exec.h
 generic-y += fb.h
 generic-y += fcntl.h
-generic-y += ftrace.h
 generic-y += futex.h
 generic-y += hardirq.h
 generic-y += hw_irq.h
diff --git a/arch/metag/include/asm/ftrace.h b/arch/metag/include/asm/ftrace.h
new file mode 100644
index 000000000000..2901f0f7d944
--- /dev/null
+++ b/arch/metag/include/asm/ftrace.h
@@ -0,0 +1,23 @@
+#ifndef _ASM_METAG_FTRACE
+#define _ASM_METAG_FTRACE
+
+#ifdef CONFIG_FUNCTION_TRACER
+#define MCOUNT_INSN_SIZE	8 /* sizeof mcount call */
+
+#ifndef __ASSEMBLY__
+extern void mcount_wrapper(void);
+#define MCOUNT_ADDR		((long)(mcount_wrapper))
+
+static inline unsigned long ftrace_call_adjust(unsigned long addr)
+{
+	return addr;
+}
+
+struct dyn_arch_ftrace {
+	/* No extra data needed on metag */
+};
+#endif /* __ASSEMBLY__ */
+
+#endif /* CONFIG_FUNCTION_TRACER */
+
+#endif /* _ASM_METAG_FTRACE */
diff --git a/arch/metag/kernel/ftrace.c b/arch/metag/kernel/ftrace.c
new file mode 100644
index 000000000000..a774f321643f
--- /dev/null
+++ b/arch/metag/kernel/ftrace.c
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2008 Imagination Technologies Ltd.
+ * Licensed under the GPL
+ *
+ * Dynamic ftrace support.
+ */
+
+#include <linux/ftrace.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#include <asm/cacheflush.h>
+
+#define D04_MOVT_TEMPLATE	0x02200005
+#define D04_CALL_TEMPLATE	0xAC200005
+#define D1RTP_MOVT_TEMPLATE	0x03200005
+#define D1RTP_CALL_TEMPLATE	0xAC200006
+
+static const unsigned long NOP[2] = {0xa0fffffe, 0xa0fffffe};
+static unsigned long movt_and_call_insn[2];
+
+static unsigned char *ftrace_nop_replace(void)
+{
+	return (char *)&NOP[0];
+}
+
+static unsigned char *ftrace_call_replace(unsigned long pc, unsigned long addr)
+{
+	unsigned long hi16, low16;
+
+	hi16 = (addr & 0xffff0000) >> 13;
+	low16 = (addr & 0x0000ffff) << 3;
+
+	/*
+	 * The compiler makes the call to mcount_wrapper()
+	 * (Meta's wrapper around mcount()) through the register
+	 * D0.4. So whenever we're patching one of those compiler-generated
+	 * calls we also need to go through D0.4. Otherwise use D1RtP.
+	 */
+	if (pc == (unsigned long)&ftrace_call) {
+		writel(D1RTP_MOVT_TEMPLATE | hi16, &movt_and_call_insn[0]);
+		writel(D1RTP_CALL_TEMPLATE | low16, &movt_and_call_insn[1]);
+	} else {
+		writel(D04_MOVT_TEMPLATE | hi16, &movt_and_call_insn[0]);
+		writel(D04_CALL_TEMPLATE | low16, &movt_and_call_insn[1]);
+	}
+
+	return (unsigned char *)&movt_and_call_insn[0];
+}
+
+static int ftrace_modify_code(unsigned long pc, unsigned char *old_code,
+			      unsigned char *new_code)
+{
+	unsigned char replaced[MCOUNT_INSN_SIZE];
+
+	/*
+	 * Note: Due to modules and __init, code can
+	 *  disappear and change, we need to protect against faulting
+	 *  as well as code changing.
+	 *
+	 * No real locking needed, this code is run through
+	 * kstop_machine.
+	 */
+
+	/* read the text we want to modify */
+	if (probe_kernel_read(replaced, (void *)pc, MCOUNT_INSN_SIZE))
+		return -EFAULT;
+
+	/* Make sure it is what we expect it to be */
+	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
+		return -EINVAL;
+
+	/* replace the text with the new text */
+	if (probe_kernel_write((void *)pc, new_code, MCOUNT_INSN_SIZE))
+		return -EPERM;
+
+	flush_icache_range(pc, pc + MCOUNT_INSN_SIZE);
+
+	return 0;
+}
+
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+	int ret;
+	unsigned long pc;
+	unsigned char old[MCOUNT_INSN_SIZE], *new;
+
+	pc = (unsigned long)&ftrace_call;
+	memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
+	new = ftrace_call_replace(pc, (unsigned long)func);
+	ret = ftrace_modify_code(pc, old, new);
+
+	return ret;
+}
+
+int ftrace_make_nop(struct module *mod,
+		    struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned char *new, *old;
+	unsigned long ip = rec->ip;
+
+	old = ftrace_call_replace(ip, addr);
+	new = ftrace_nop_replace();
+
+	return ftrace_modify_code(ip, old, new);
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+	unsigned char *new, *old;
+	unsigned long ip = rec->ip;
+
+	old = ftrace_nop_replace();
+	new = ftrace_call_replace(ip, addr);
+
+	return ftrace_modify_code(ip, old, new);
+}
+
+/* run from kstop_machine */
+int __init ftrace_dyn_arch_init(void *data)
+{
+	/* The return code is returned via data */
+	writel(0, data);
+
+	return 0;
+}
diff --git a/arch/metag/kernel/ftrace_stub.S b/arch/metag/kernel/ftrace_stub.S
new file mode 100644
index 000000000000..e70bff745bdd
--- /dev/null
+++ b/arch/metag/kernel/ftrace_stub.S
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2008 Imagination Technologies Ltd.
+ * Licensed under the GPL
+ *
+ */
+
+#include <asm/ftrace.h>
+
+	.text
+#ifdef CONFIG_DYNAMIC_FTRACE
+	.global	_mcount_wrapper
+	.type	_mcount_wrapper,function
+_mcount_wrapper:
+	MOV	PC,D0.4
+
+	.global _ftrace_caller
+	.type	_ftrace_caller,function
+_ftrace_caller:
+	MOVT    D0Re0,#HI(_function_trace_stop)
+	ADD	D0Re0,D0Re0,#LO(_function_trace_stop)
+	GETD	D0Re0,[D0Re0]
+	CMP	D0Re0,#0
+	BEQ	$Lcall_stub
+	MOV	PC,D0.4
+$Lcall_stub:
+	MSETL   [A0StP], D0Ar6, D0Ar4, D0Ar2, D0.4
+	MOV     D1Ar1, D0.4
+	MOV     D0Ar2, D1RtP
+	SUB	D1Ar1,D1Ar1,#MCOUNT_INSN_SIZE
+
+	.global _ftrace_call
+_ftrace_call:
+	MOVT	D1RtP,#HI(_ftrace_stub)
+	CALL	D1RtP,#LO(_ftrace_stub)
+	GETL    D0.4,  D1RtP, [A0StP++#(-8)]
+	GETL    D0Ar2, D1Ar1, [A0StP++#(-8)]
+	GETL    D0Ar4, D1Ar3, [A0StP++#(-8)]
+	GETL    D0Ar6, D1Ar5, [A0StP++#(-8)]
+	MOV     PC, D0.4
+#else
+
+	.global	_mcount_wrapper
+	.type	_mcount_wrapper,function
+_mcount_wrapper:
+	MOVT    D0Re0,#HI(_function_trace_stop)
+	ADD	D0Re0,D0Re0,#LO(_function_trace_stop)
+	GETD	D0Re0,[D0Re0]
+	CMP	D0Re0,#0
+	BEQ	$Lcall_mcount
+	MOV	PC,D0.4
+$Lcall_mcount:
+	MSETL   [A0StP], D0Ar6, D0Ar4, D0Ar2, D0.4
+	MOV     D1Ar1, D0.4
+	MOV     D0Ar2, D1RtP
+	MOVT    D0Re0,#HI(_ftrace_trace_function)
+	ADD	D0Re0,D0Re0,#LO(_ftrace_trace_function)
+	GET	D1Ar3,[D0Re0]
+	MOVT	D1Re0,#HI(_ftrace_stub)
+	ADD	D1Re0,D1Re0,#LO(_ftrace_stub)
+	CMP	D1Ar3,D1Re0
+	BEQ	$Ltrace_exit
+	MOV	D1RtP,D1Ar3
+	SUB	D1Ar1,D1Ar1,#MCOUNT_INSN_SIZE
+	SWAP	PC,D1RtP
+$Ltrace_exit:
+	GETL    D0.4,  D1RtP, [A0StP++#(-8)]
+	GETL    D0Ar2, D1Ar1, [A0StP++#(-8)]
+	GETL    D0Ar4, D1Ar3, [A0StP++#(-8)]
+	GETL    D0Ar6, D1Ar5, [A0StP++#(-8)]
+	MOV     PC, D0.4
+
+#endif	/* CONFIG_DYNAMIC_FTRACE */
+
+	.global _ftrace_stub
+_ftrace_stub:
+	MOV 	PC,D1RtP
diff --git a/arch/metag/kernel/metag_ksyms.c b/arch/metag/kernel/metag_ksyms.c
index c73ebd3db417..3cc4d1d4b322 100644
--- a/arch/metag/kernel/metag_ksyms.c
+++ b/arch/metag/kernel/metag_ksyms.c
@@ -10,6 +10,7 @@
 #include <asm/checksum.h>
 #include <asm/uaccess.h>
 #include <asm/traps.h>
+#include <asm/ftrace.h>
 #include <asm/tbx.h>
 
 /* uaccess symbols */
@@ -73,3 +74,7 @@ EXPORT_SYMBOL(div_s64);
 EXPORT_SYMBOL(memcpy);
 EXPORT_SYMBOL(memset);
 EXPORT_SYMBOL(memmove);
+
+#ifdef CONFIG_FUNCTION_TRACER
+EXPORT_SYMBOL(mcount_wrapper);
+#endif