4 files changed, 39 insertions, 7 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a2d19ee750ca..28dd891a0a16 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -36,6 +36,7 @@ config X86
         select HAVE_KRETPROBES
         select HAVE_OPTPROBES
         select HAVE_FTRACE_MCOUNT_RECORD
+        select HAVE_FENTRY if X86_64
         select HAVE_C_RECORDMCOUNT
         select HAVE_DYNAMIC_FTRACE
         select HAVE_FUNCTION_TRACER
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index a6cae0c1720c..9a25b522d377 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -35,7 +35,11 @@
 #endif
 
 #ifdef CONFIG_FUNCTION_TRACER
-#define MCOUNT_ADDR             ((long)(mcount))
+#ifdef CC_USING_FENTRY
+# define MCOUNT_ADDR            ((long)(__fentry__))
+#else
+# define MCOUNT_ADDR            ((long)(mcount))
+#endif
 #define MCOUNT_INSN_SIZE        5 /* sizeof mcount call */
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -46,6 +50,7 @@
 #ifndef __ASSEMBLY__
 extern void mcount(void);
 extern atomic_t modifying_ftrace_code;
+extern void __fentry__(void);
 
 static inline unsigned long ftrace_call_adjust(unsigned long addr)
 {
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index b7a81dcb7366..ed767b747fe5 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -68,10 +68,18 @@
         .section .entry.text, "ax"
 
 #ifdef CONFIG_FUNCTION_TRACER
+
+#ifdef CC_USING_FENTRY
+# define function_hook  __fentry__
+#else
+# define function_hook  mcount
+#endif
+
 #ifdef CONFIG_DYNAMIC_FTRACE
-ENTRY(mcount)
+
+ENTRY(function_hook)
         retq
-END(mcount)
+END(function_hook)
 
 /* skip is set if stack has been adjusted */
 .macro ftrace_caller_setup skip=0
@@ -84,7 +92,11 @@ END(mcount)
         movq RIP(%rsp), %rdi
         subq $MCOUNT_INSN_SIZE, %rdi
         /* Load the parent_ip into the second parameter */
+#ifdef CC_USING_FENTRY
+        movq SS+16(%rsp), %rsi
+#else
         movq 8(%rbp), %rsi
+#endif
 .endm
 
 ENTRY(ftrace_caller)
@@ -177,7 +189,8 @@ END(ftrace_regs_caller)
 
 
 #else /* ! CONFIG_DYNAMIC_FTRACE */
-ENTRY(mcount)
+
+ENTRY(function_hook)
         cmpl $0, function_trace_stop
         jne  ftrace_stub
 
@@ -199,7 +212,11 @@ trace:
         MCOUNT_SAVE_FRAME
 
         movq RIP(%rsp), %rdi
+#ifdef CC_USING_FENTRY
+        movq SS+16(%rsp), %rsi
+#else
         movq 8(%rbp), %rsi
+#endif
         subq $MCOUNT_INSN_SIZE, %rdi
 
         call   *ftrace_trace_function
@@ -207,7 +224,7 @@ trace:
         MCOUNT_RESTORE_FRAME
 
         jmp ftrace_stub
-END(mcount)
+END(function_hook)
 #endif /* CONFIG_DYNAMIC_FTRACE */
 #endif /* CONFIG_FUNCTION_TRACER */
 
@@ -215,9 +232,14 @@ END(mcount)
 ENTRY(ftrace_graph_caller)
         MCOUNT_SAVE_FRAME
 
+#ifdef CC_USING_FENTRY
+        leaq SS+16(%rsp), %rdi
+        movq $0, %rdx   /* No framepointers needed */
+#else
         leaq 8(%rbp), %rdi
-        movq RIP(%rsp), %rsi
         movq (%rbp), %rdx
+#endif
+        movq RIP(%rsp), %rsi
         subq $MCOUNT_INSN_SIZE, %rsi
 
         call    prepare_ftrace_return
diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
index 6020f6f5927c..1330dd102950 100644
--- a/arch/x86/kernel/x8664_ksyms_64.c
+++ b/arch/x86/kernel/x8664_ksyms_64.c
@@ -13,9 +13,13 @@
 #include <asm/ftrace.h>
 
 #ifdef CONFIG_FUNCTION_TRACER
-/* mcount is defined in assembly */
+/* mcount and __fentry__ are defined in assembly */
+#ifdef CC_USING_FENTRY
+EXPORT_SYMBOL(__fentry__);
+#else
 EXPORT_SYMBOL(mcount);
 #endif
+#endif
 
 EXPORT_SYMBOL(__get_user_1);
 EXPORT_SYMBOL(__get_user_2);