s390/ftrace: Add -mfentry and -mnop-mcount support

Utilize -mfentry and -mnop-mcount gcc options together with
-mrecord-mcount to get compiler generated calls to the profiling functions
as nops which are compatible with current -mhotpatch=0,3 approach.  At the
same time -mrecord-mcount enables __mcount_loc section generation by
the compiler which allows to avoid using scripts/recordmcount.pl script.

Link: http://lkml.kernel.org/r/patch-4.thread-aa7b8d.git-aa7b8dbf236f.your-ad-here.call-01533557518-ext-9465@work.hours
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index e44bb2b..4e91444 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -136,6 +136,7 @@ config S390
        select HAVE_DYNAMIC_FTRACE
        select HAVE_DYNAMIC_FTRACE_WITH_REGS
        select HAVE_EFFICIENT_UNALIGNED_ACCESS
+       select HAVE_FENTRY
        select HAVE_FTRACE_MCOUNT_RECORD
        select HAVE_FUNCTION_GRAPH_TRACER
        select HAVE_FUNCTION_TRACER
@@ -157,6 +158,7 @@ config S390
        select HAVE_MEMBLOCK_NODE_MAP
        select HAVE_MEMBLOCK_PHYS_MAP
        select HAVE_MOD_ARCH_SPECIFIC
+       select HAVE_NOP_MCOUNT
        select HAVE_OPROFILE
        select HAVE_PERF_EVENTS
        select HAVE_REGS_AND_STACK_ACCESS_API

diff --git a/arch/s390/Makefile b/arch/s390/Makefile
index 68a6904..8498bab 100644 (file)
--- a/arch/s390/Makefile
+++ b/arch/s390/Makefile
@@ -86,13 +86,15 @@ ifdef CONFIG_EXPOLINE
 endif
 
 ifdef CONFIG_FUNCTION_TRACER
-# make use of hotpatch feature if the compiler supports it
-cc_hotpatch    := -mhotpatch=0,3
-ifeq ($(call cc-option-yn,$(cc_hotpatch)),y)
-CC_FLAGS_FTRACE := $(cc_hotpatch)
-KBUILD_AFLAGS  += -DCC_USING_HOTPATCH
-KBUILD_CFLAGS  += -DCC_USING_HOTPATCH
-endif
+  ifeq ($(call cc-option-yn,-mfentry -mnop-mcount),n)
+    # make use of hotpatch feature if the compiler supports it
+    cc_hotpatch        := -mhotpatch=0,3
+    ifeq ($(call cc-option-yn,$(cc_hotpatch)),y)
+      CC_FLAGS_FTRACE := $(cc_hotpatch)
+      KBUILD_AFLAGS    += -DCC_USING_HOTPATCH
+      KBUILD_CFLAGS    += -DCC_USING_HOTPATCH
+    endif
+  endif
 endif
 
 # Test CFI features of binutils

diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index cfccc0e..8ea270f 100644 (file)
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -4,7 +4,7 @@
 
 #define ARCH_SUPPORTS_FTRACE_OPS 1
 
-#ifdef CC_USING_HOTPATCH
+#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
 #define MCOUNT_INSN_SIZE       6
 #else
 #define MCOUNT_INSN_SIZE       24
@@ -42,7 +42,7 @@ struct ftrace_insn {
 static inline void ftrace_generate_nop_insn(struct ftrace_insn *insn)
 {
 #ifdef CONFIG_FUNCTION_TRACER
-#ifdef CC_USING_HOTPATCH
+#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
        /* brcl 0,0 */
        insn->opc = 0xc004;
        insn->disp = 0;
@@ -57,7 +57,7 @@ static inline void ftrace_generate_nop_insn(struct ftrace_insn *insn)
 static inline int is_ftrace_nop(struct ftrace_insn *insn)
 {
 #ifdef CONFIG_FUNCTION_TRACER
-#ifdef CC_USING_HOTPATCH
+#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
        if (insn->disp == 0)
                return 1;
 #else

diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index dc76d81..84be7f0 100644 (file)
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -61,7 +61,7 @@ unsigned long ftrace_plt;
 
 static inline void ftrace_generate_orig_insn(struct ftrace_insn *insn)
 {
-#ifdef CC_USING_HOTPATCH
+#if defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT)
        /* brcl 0,0 */
        insn->opc = 0xc004;
        insn->disp = 0;

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 27110f3..e93fbf0 100644 (file)
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -35,7 +35,7 @@ ENTRY(ftrace_caller)
        .globl  ftrace_regs_caller
        .set    ftrace_regs_caller,ftrace_caller
        lgr     %r1,%r15
-#ifndef CC_USING_HOTPATCH
+#if !(defined(CC_USING_HOTPATCH) || defined(CC_USING_NOP_MCOUNT))
        aghi    %r0,MCOUNT_RETURN_FIXUP
 #endif
        aghi    %r15,-STACK_FRAME_SIZE