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Subject[PATCH 4/4] 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.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
---
arch/s390/Kconfig | 2 ++
arch/s390/Makefile | 16 +++++++++-------
arch/s390/include/asm/ftrace.h | 6 +++---
arch/s390/kernel/ftrace.c | 2 +-
arch/s390/kernel/mcount.S | 2 +-
5 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 8a1863d9ed53..71c2d9de379f 100644
--- 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 68a690442be0..8498babb5dad 100644
--- 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 cfccc0edd00d..8ea270fdc7fb 100644
--- 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 dc76d813e420..84be7f02d0c2 100644
--- 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 27110f3294ed..e93fbf02490c 100644
--- 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
--
2.18.0.13.gd42ae10
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