ftrace: support for PowerPC
This patch adds full support for ftrace for PowerPC (both 64 and 32 bit).
This includes dynamic tracing and function filtering.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
new file mode 100644
index 0000000..5a4993f
--- /dev/null
+++ b/arch/powerpc/kernel/ftrace.c
@@ -0,0 +1,165 @@
+/*
+ * Code for replacing ftrace calls with jumps.
+ *
+ * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
+ *
+ * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
+ *
+ */
+
+#include <linux/spinlock.h>
+#include <linux/hardirq.h>
+#include <linux/ftrace.h>
+#include <linux/percpu.h>
+#include <linux/init.h>
+#include <linux/list.h>
+
+#include <asm/cacheflush.h>
+
+#define CALL_BACK 4
+
+static unsigned int ftrace_nop = 0x60000000;
+
+#ifdef CONFIG_PPC32
+# define GET_ADDR(addr) addr
+#else
+/* PowerPC64's functions are data that points to the functions */
+# define GET_ADDR(addr) *(unsigned long *)addr
+#endif
+
+notrace int ftrace_ip_converted(unsigned long ip)
+{
+ unsigned int save;
+
+ ip -= CALL_BACK;
+ save = *(unsigned int *)ip;
+
+ return save == ftrace_nop;
+}
+
+static unsigned int notrace ftrace_calc_offset(long ip, long addr)
+{
+ return (int)((addr + CALL_BACK) - ip);
+}
+
+notrace unsigned char *ftrace_nop_replace(void)
+{
+ return (char *)&ftrace_nop;
+}
+
+notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
+{
+ static unsigned int op;
+
+ addr = GET_ADDR(addr);
+
+ /* Set to "bl addr" */
+ op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffe);
+
+ /*
+ * No locking needed, this must be called via kstop_machine
+ * which in essence is like running on a uniprocessor machine.
+ */
+ return (unsigned char *)&op;
+}
+
+#ifdef CONFIG_PPC64
+# define _ASM_ALIGN " .align 3 "
+# define _ASM_PTR " .llong "
+#else
+# define _ASM_ALIGN " .align 2 "
+# define _ASM_PTR " .long "
+#endif
+
+notrace int
+ftrace_modify_code(unsigned long ip, unsigned char *old_code,
+ unsigned char *new_code)
+{
+ unsigned replaced;
+ unsigned old = *(unsigned *)old_code;
+ unsigned new = *(unsigned *)new_code;
+ int faulted = 0;
+
+ /* move the IP back to the start of the call */
+ ip -= CALL_BACK;
+
+ /*
+ * 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.
+ */
+ asm volatile (
+ "1: lwz %1, 0(%2)\n"
+ " cmpw %1, %5\n"
+ " bne 2f\n"
+ " stwu %3, 0(%2)\n"
+ "2:\n"
+ ".section .fixup, \"ax\"\n"
+ "3: li %0, 1\n"
+ " b 2b\n"
+ ".previous\n"
+ ".section __ex_table,\"a\"\n"
+ _ASM_ALIGN "\n"
+ _ASM_PTR "1b, 3b\n"
+ ".previous"
+ : "=r"(faulted), "=r"(replaced)
+ : "r"(ip), "r"(new),
+ "0"(faulted), "r"(old)
+ : "memory");
+
+ if (replaced != old && replaced != new)
+ faulted = 2;
+
+ if (!faulted)
+ flush_icache_range(ip, ip + 8);
+
+ return faulted;
+}
+
+notrace int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ unsigned long ip = (unsigned long)(&ftrace_call);
+ unsigned char old[4], *new;
+ int ret;
+
+ ip += CALL_BACK;
+
+ memcpy(old, &ftrace_call, 4);
+ new = ftrace_call_replace(ip, (unsigned long)func);
+ ret = ftrace_modify_code(ip, old, new);
+
+ return ret;
+}
+
+notrace int ftrace_mcount_set(unsigned long *data)
+{
+ unsigned long ip = (long)(&mcount_call);
+ unsigned long *addr = data;
+ unsigned char old[4], *new;
+
+ /* ip is at the location, but modify code will subtact this */
+ ip += CALL_BACK;
+
+ /*
+ * Replace the mcount stub with a pointer to the
+ * ip recorder function.
+ */
+ memcpy(old, &mcount_call, 4);
+ new = ftrace_call_replace(ip, *addr);
+ *addr = ftrace_modify_code(ip, old, new);
+
+ return 0;
+}
+
+int __init ftrace_dyn_arch_init(void *data)
+{
+ /* This is running in kstop_machine */
+
+ ftrace_mcount_set(data);
+
+ return 0;
+}
+