1 files changed, 30 insertions, 113 deletions

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 231bdd3c5b1c..a85da1764b1c 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -18,6 +18,7 @@
 #include <linux/init.h>
 #include <linux/list.h>
 
+#include <asm/cacheflush.h>
 #include <asm/ftrace.h>
 #include <linux/ftrace.h>
 #include <asm/nops.h>
@@ -26,6 +27,18 @@
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
+int ftrace_arch_code_modify_prepare(void)
+{
+        set_kernel_text_rw();
+        return 0;
+}
+
+int ftrace_arch_code_modify_post_process(void)
+{
+        set_kernel_text_ro();
+        return 0;
+}
+
 union ftrace_code_union {
         char code[MCOUNT_INSN_SIZE];
         struct {
@@ -82,7 +95,7 @@ static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
  * are the same as what exists.
  */
 
-static atomic_t in_nmi = ATOMIC_INIT(0);
+static atomic_t nmi_running = ATOMIC_INIT(0);
 static int mod_code_status;             /* holds return value of text write */
 static int mod_code_write;              /* set when NMI should do the write */
 static void *mod_code_ip;               /* holds the IP to write to */
@@ -111,12 +124,16 @@ static void ftrace_mod_code(void)
          */
         mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
                                              MCOUNT_INSN_SIZE);
+
+        /* if we fail, then kill any new writers */
+        if (mod_code_status)
+                mod_code_write = 0;
 }
 
 void ftrace_nmi_enter(void)
 {
-        atomic_inc(&in_nmi);
-        /* Must have in_nmi seen before reading write flag */
+        atomic_inc(&nmi_running);
+        /* Must have nmi_running seen before reading write flag */
         smp_mb();
         if (mod_code_write) {
                 ftrace_mod_code();
@@ -126,22 +143,21 @@ void ftrace_nmi_enter(void)
 
 void ftrace_nmi_exit(void)
 {
-        /* Finish all executions before clearing in_nmi */
+        /* Finish all executions before clearing nmi_running */
         smp_wmb();
-        atomic_dec(&in_nmi);
+        atomic_dec(&nmi_running);
 }
 
 static void wait_for_nmi(void)
 {
-        int waited = 0;
+        if (!atomic_read(&nmi_running))
+                return;
 
-        while (atomic_read(&in_nmi)) {
-                waited = 1;
+        do {
                 cpu_relax();
-        }
+        } while (atomic_read(&nmi_running));
 
-        if (waited)
-                nmi_wait_count++;
+        nmi_wait_count++;
 }
 
 static int
@@ -368,100 +384,8 @@ int ftrace_disable_ftrace_graph_caller(void)
         return ftrace_mod_jmp(ip, old_offset, new_offset);
 }
 
-#else /* CONFIG_DYNAMIC_FTRACE */
-
-/*
- * These functions are picked from those used on
- * this page for dynamic ftrace. They have been
- * simplified to ignore all traces in NMI context.
- */
-static atomic_t in_nmi;
-
-void ftrace_nmi_enter(void)
-{
-        atomic_inc(&in_nmi);
-}
-
-void ftrace_nmi_exit(void)
-{
-        atomic_dec(&in_nmi);
-}
-
 #endif /* !CONFIG_DYNAMIC_FTRACE */
 
-/* Add a function return address to the trace stack on thread info.*/
-static int push_return_trace(unsigned long ret, unsigned long long time,
-                                unsigned long func, int *depth)
-{
-        int index;
-
-        if (!current->ret_stack)
-                return -EBUSY;
-
-        /* The return trace stack is full */
-        if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
-                atomic_inc(&current->trace_overrun);
-                return -EBUSY;
-        }
-
-        index = ++current->curr_ret_stack;
-        barrier();
-        current->ret_stack[index].ret = ret;
-        current->ret_stack[index].func = func;
-        current->ret_stack[index].calltime = time;
-        *depth = index;
-
-        return 0;
-}
-
-/* Retrieve a function return address to the trace stack on thread info.*/
-static void pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret)
-{
-        int index;
-
-        index = current->curr_ret_stack;
-
-        if (unlikely(index < 0)) {
-                ftrace_graph_stop();
-                WARN_ON(1);
-                /* Might as well panic, otherwise we have no where to go */
-                *ret = (unsigned long)panic;
-                return;
-        }
-
-        *ret = current->ret_stack[index].ret;
-        trace->func = current->ret_stack[index].func;
-        trace->calltime = current->ret_stack[index].calltime;
-        trace->overrun = atomic_read(&current->trace_overrun);
-        trace->depth = index;
-        barrier();
-        current->curr_ret_stack--;
-
-}
-
-/*
- * Send the trace to the ring-buffer.
- * @return the original return address.
- */
-unsigned long ftrace_return_to_handler(void)
-{
-        struct ftrace_graph_ret trace;
-        unsigned long ret;
-
-        pop_return_trace(&trace, &ret);
-        trace.rettime = cpu_clock(raw_smp_processor_id());
-        ftrace_graph_return(&trace);
-
-        if (unlikely(!ret)) {
-                ftrace_graph_stop();
-                WARN_ON(1);
-                /* Might as well panic. What else to do? */
-                ret = (unsigned long)panic;
-        }
-
-        return ret;
-}
-
 /*
  * Hook the return address and push it in the stack of return addrs
  * in current thread info.
@@ -476,7 +400,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
                                 &return_to_handler;
 
         /* Nmi's are currently unsupported */
-        if (unlikely(atomic_read(&in_nmi)))
+        if (unlikely(in_nmi()))
                 return;
 
         if (unlikely(atomic_read(&current->tracing_graph_pause)))
@@ -512,16 +436,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
                 return;
         }
 
-        if (unlikely(!__kernel_text_address(old))) {
-                ftrace_graph_stop();
-                *parent = old;
-                WARN_ON(1);
-                return;
-        }
-
-        calltime = cpu_clock(raw_smp_processor_id());
+        calltime = trace_clock_local();
 
-        if (push_return_trace(old, calltime,
+        if (ftrace_push_return_trace(old, calltime,
                                 self_addr, &trace.depth) == -EBUSY) {
                 *parent = old;
                 return;