sh: Function graph tracer support
Add both dynamic and static function graph tracer support for sh.
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c
index 4f62ece..6647dfc 100644
--- a/arch/sh/kernel/ftrace.c
+++ b/arch/sh/kernel/ftrace.c
@@ -16,11 +16,13 @@
#include <linux/string.h>
#include <linux/init.h>
#include <linux/io.h>
+#include <linux/kernel.h>
#include <asm/ftrace.h>
#include <asm/cacheflush.h>
#include <asm/unistd.h>
#include <trace/syscall.h>
+#ifdef CONFIG_DYNAMIC_FTRACE
static unsigned char ftrace_replaced_code[MCOUNT_INSN_SIZE];
static unsigned char ftrace_nop[4];
@@ -133,6 +135,126 @@
return 0;
}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern void ftrace_graph_call(void);
+
+static int ftrace_mod(unsigned long ip, unsigned long old_addr,
+ unsigned long new_addr)
+{
+ unsigned char code[MCOUNT_INSN_SIZE];
+
+ if (probe_kernel_read(code, (void *)ip, MCOUNT_INSN_SIZE))
+ return -EFAULT;
+
+ if (old_addr != __raw_readl((unsigned long *)code))
+ return -EINVAL;
+
+ __raw_writel(new_addr, ip);
+ return 0;
+}
+
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ unsigned long ip, old_addr, new_addr;
+
+ ip = (unsigned long)(&ftrace_graph_call) + GRAPH_INSN_OFFSET;
+ old_addr = (unsigned long)(&skip_trace);
+ new_addr = (unsigned long)(&ftrace_graph_caller);
+
+ return ftrace_mod(ip, old_addr, new_addr);
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ unsigned long ip, old_addr, new_addr;
+
+ ip = (unsigned long)(&ftrace_graph_call) + GRAPH_INSN_OFFSET;
+ old_addr = (unsigned long)(&ftrace_graph_caller);
+ new_addr = (unsigned long)(&skip_trace);
+
+ return ftrace_mod(ip, old_addr, new_addr);
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in the current thread info.
+ *
+ * This is the main routine for the function graph tracer. The function
+ * graph tracer essentially works like this:
+ *
+ * parent is the stack address containing self_addr's return address.
+ * We pull the real return address out of parent and store it in
+ * current's ret_stack. Then, we replace the return address on the stack
+ * with the address of return_to_handler. self_addr is the function that
+ * called mcount.
+ *
+ * When self_addr returns, it will jump to return_to_handler which calls
+ * ftrace_return_to_handler. ftrace_return_to_handler will pull the real
+ * return address off of current's ret_stack and jump to it.
+ */
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
+{
+ unsigned long old;
+ int faulted, err;
+ struct ftrace_graph_ent trace;
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ /*
+ * Protect against fault, even if it shouldn't
+ * happen. This tool is too much intrusive to
+ * ignore such a protection.
+ */
+ __asm__ __volatile__(
+ "1: \n\t"
+ "mov.l @%2, %0 \n\t"
+ "2: \n\t"
+ "mov.l %3, @%2 \n\t"
+ "mov #0, %1 \n\t"
+ "3: \n\t"
+ ".section .fixup, \"ax\" \n\t"
+ "4: \n\t"
+ "mov.l 5f, %0 \n\t"
+ "jmp @%0 \n\t"
+ " mov #1, %1 \n\t"
+ ".balign 4 \n\t"
+ "5: .long 3b \n\t"
+ ".previous \n\t"
+ ".section __ex_table,\"a\" \n\t"
+ ".long 1b, 4b \n\t"
+ ".long 2b, 4b \n\t"
+ ".previous \n\t"
+ : "=&r" (old), "=r" (faulted)
+ : "r" (parent), "r" (return_hooker)
+ );
+
+ if (unlikely(faulted)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ return;
+ }
+
+ err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);
+ if (err == -EBUSY) {
+ __raw_writel(old, parent);
+ return;
+ }
+
+ trace.func = self_addr;
+
+ /* Only trace if the calling function expects to */
+ if (!ftrace_graph_entry(&trace)) {
+ current->curr_ret_stack--;
+ __raw_writel(old, parent);
+ }
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
#ifdef CONFIG_FTRACE_SYSCALLS