[PATCH 14/15] ftrace/x86: mcount offset calculation

[Steven Rostedt]

From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>

Do the mcount offset adjustment in the recordmcount.pl/recordmcount.[ch]
at compile time and not in ftrace_call_adjust at run time.

Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 arch/x86/include/asm/ftrace.h |    7 +++----
 scripts/recordmcount.c        |    2 ++
 scripts/recordmcount.pl       |    2 ++
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index db24c22..268c783 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -38,11 +38,10 @@ extern void mcount(void);
 static inline unsigned long ftrace_call_adjust(unsigned long addr)
 {
 	/*
-	 * call mcount is "e8 <4 byte offset>"
-	 * The addr points to the 4 byte offset and the caller of this
-	 * function wants the pointer to e8. Simply subtract one.
+	 * addr is the address of the mcount call instruction.
+	 * recordmcount does the necessary offset calculation.
 	 */
-	return addr - 1;
+	return addr;
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 0e18975..7648a5d 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -335,6 +335,7 @@ do_file(char const *const fname)
 		reltype = R_386_32;
 		make_nop = make_nop_x86;
 		ideal_nop = ideal_nop5_x86_32;
+		mcount_adjust_32 = -1;
 		break;
 	case EM_ARM:	 reltype = R_ARM_ABS32;
 			 altmcount = "__gnu_mcount_nc";
@@ -350,6 +351,7 @@ do_file(char const *const fname)
 		make_nop = make_nop_x86;
 		ideal_nop = ideal_nop5_x86_64;
 		reltype = R_X86_64_64;
+		mcount_adjust_64 = -1;
 		break;
 	}  /* end switch */
 
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index a871cd4..414e7f5 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -223,6 +223,7 @@ if ($arch eq "x86_64") {
     $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\smcount([+-]0x[0-9a-zA-Z]+)?\$";
     $type = ".quad";
     $alignment = 8;
+    $mcount_adjust = -1;
 
     # force flags for this arch
     $ld .= " -m elf_x86_64";
@@ -232,6 +233,7 @@ if ($arch eq "x86_64") {
 
 } elsif ($arch eq "i386") {
     $alignment = 4;
+    $mcount_adjust = -1;
 
     # force flags for this arch
     $ld .= " -m elf_i386";
-- 
1.7.4.4


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