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* [PATCH v2 00/10] x86: use gcc 6+ asm flag output feature
@ 2016-06-08 19:38 H. Peter Anvin
  2016-06-08 19:38 ` [PATCH v2 01/10] x86, bitops: remove use of "sbb" to return CF H. Peter Anvin
                   ` (10 more replies)
  0 siblings, 11 replies; 24+ messages in thread
From: H. Peter Anvin @ 2016-06-08 19:38 UTC (permalink / raw)
  To: Ingo Molnar, Thomas Gleixner, H. Peter Anvin, Linux Kernel Mailing List
  Cc: Andy Lutomirski, Borislav Petkov

From: "H. Peter Anvin" <hpa@zytor.com>

gcc 6+ has the ability to let flags (actually, conditions, which are
specific combinations of flags) to be used directly as asm() outputs.
The syntax for that is "=@cc<cc>" where <cc> is the same set of
letters that would be used in a j<cc> or set<cc> instruction
(e.g. "=@ccz" to test the ZF flag.)

This patchset by itself reduces the size of the x86-64 kernel by
0.12%, from a baseline of 4.7-rc2 built with gcc 6.1 (first line is
with the patchset, the second one is without):

     text       data       bss        dec       hex filename

 68245656   41004339  20533248  129783243   7bc55cb o.i386-allconfig/vmlinux
 68355716   41008499  20533248  129897463   7be13f7 o.i386-allconfig/vmlinux

127384005  129742359  38150144  295276508  11998fdc o.x86_64-allconfig/vmlinux
127538765  129742295  38150144  295431204  119bec24 o.x86_64-allconfig/vmlinux

v2: fix a conflict between <linux/random.h> and <asm/archrandom.h>
    discovered by Ingo Molnar.  There are a few places in x86-specific
    code where we need all of <arch/archrandom.h> even when
    xCONFIG_ARCH_RANDOM is disabled, so <linux/random.h> does not
    suffice.  Only the <asm/archrandom.h> patch has been changed;
    since it is a little bit different from the others I have moved it
    to the end.

^ permalink raw reply	[flat|nested] 24+ messages in thread
* [PATCH 03/10] x86, asm: change the GEN_*_RMWcc() macros to not quote the condition
@ 2016-06-07 23:31 H. Peter Anvin
  2016-06-07 23:40 ` [tip:x86/asm] " tip-bot for H. Peter Anvin
  0 siblings, 1 reply; 24+ messages in thread
From: H. Peter Anvin @ 2016-06-07 23:31 UTC (permalink / raw)
  To: Ingo Molnar, Thomas Gleixner, H. Peter Anvin, Linux Kernel Mailing List
  Cc: Peter Zijlstra, Andy Lutomirski, Borislav Petkov

From: "H. Peter Anvin" <hpa@zytor.com>

Change the lexical defintion of the GEN_*_RMWcc() macros to not take
the condition code as a quoted string.  This will help support
changing them to use the new __GCC_ASM_FLAG_OUTPUTS__ feature in a
subsequent patch.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 arch/x86/include/asm/atomic.h      | 8 ++++----
 arch/x86/include/asm/atomic64_64.h | 8 ++++----
 arch/x86/include/asm/bitops.h      | 6 +++---
 arch/x86/include/asm/local.h       | 8 ++++----
 arch/x86/include/asm/preempt.h     | 2 +-
 arch/x86/include/asm/rmwcc.h       | 4 ++--
 6 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h
index 17d8812..7322c15 100644
--- a/arch/x86/include/asm/atomic.h
+++ b/arch/x86/include/asm/atomic.h
@@ -77,7 +77,7 @@ static __always_inline void atomic_sub(int i, atomic_t *v)
  */
 static __always_inline bool atomic_sub_and_test(int i, atomic_t *v)
 {
-	GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", "e");
+	GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", e);
 }
 
 /**
@@ -114,7 +114,7 @@ static __always_inline void atomic_dec(atomic_t *v)
  */
 static __always_inline bool atomic_dec_and_test(atomic_t *v)
 {
-	GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
+	GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", e);
 }
 
 /**
@@ -127,7 +127,7 @@ static __always_inline bool atomic_dec_and_test(atomic_t *v)
  */
 static __always_inline bool atomic_inc_and_test(atomic_t *v)
 {
-	GEN_UNARY_RMWcc(LOCK_PREFIX "incl", v->counter, "%0", "e");
+	GEN_UNARY_RMWcc(LOCK_PREFIX "incl", v->counter, "%0", e);
 }
 
 /**
@@ -141,7 +141,7 @@ static __always_inline bool atomic_inc_and_test(atomic_t *v)
  */
 static __always_inline bool atomic_add_negative(int i, atomic_t *v)
 {
-	GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", "s");
+	GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", s);
 }
 
 /**
diff --git a/arch/x86/include/asm/atomic64_64.h b/arch/x86/include/asm/atomic64_64.h
index 4f881d7..57bf925 100644
--- a/arch/x86/include/asm/atomic64_64.h
+++ b/arch/x86/include/asm/atomic64_64.h
@@ -72,7 +72,7 @@ static inline void atomic64_sub(long i, atomic64_t *v)
  */
 static inline bool atomic64_sub_and_test(long i, atomic64_t *v)
 {
-	GEN_BINARY_RMWcc(LOCK_PREFIX "subq", v->counter, "er", i, "%0", "e");
+	GEN_BINARY_RMWcc(LOCK_PREFIX "subq", v->counter, "er", i, "%0", e);
 }
 
 /**
@@ -111,7 +111,7 @@ static __always_inline void atomic64_dec(atomic64_t *v)
  */
 static inline bool atomic64_dec_and_test(atomic64_t *v)
 {
-	GEN_UNARY_RMWcc(LOCK_PREFIX "decq", v->counter, "%0", "e");
+	GEN_UNARY_RMWcc(LOCK_PREFIX "decq", v->counter, "%0", e);
 }
 
 /**
@@ -124,7 +124,7 @@ static inline bool atomic64_dec_and_test(atomic64_t *v)
  */
 static inline bool atomic64_inc_and_test(atomic64_t *v)
 {
-	GEN_UNARY_RMWcc(LOCK_PREFIX "incq", v->counter, "%0", "e");
+	GEN_UNARY_RMWcc(LOCK_PREFIX "incq", v->counter, "%0", e);
 }
 
 /**
@@ -138,7 +138,7 @@ static inline bool atomic64_inc_and_test(atomic64_t *v)
  */
 static inline bool atomic64_add_negative(long i, atomic64_t *v)
 {
-	GEN_BINARY_RMWcc(LOCK_PREFIX "addq", v->counter, "er", i, "%0", "s");
+	GEN_BINARY_RMWcc(LOCK_PREFIX "addq", v->counter, "er", i, "%0", s);
 }
 
 /**
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index 8cbb7f4..ed8f485 100644
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -203,7 +203,7 @@ static __always_inline void change_bit(long nr, volatile unsigned long *addr)
  */
 static __always_inline bool test_and_set_bit(long nr, volatile unsigned long *addr)
 {
-	GEN_BINARY_RMWcc(LOCK_PREFIX "bts", *addr, "Ir", nr, "%0", "c");
+	GEN_BINARY_RMWcc(LOCK_PREFIX "bts", *addr, "Ir", nr, "%0", c);
 }
 
 /**
@@ -249,7 +249,7 @@ static __always_inline bool __test_and_set_bit(long nr, volatile unsigned long *
  */
 static __always_inline bool test_and_clear_bit(long nr, volatile unsigned long *addr)
 {
-	GEN_BINARY_RMWcc(LOCK_PREFIX "btr", *addr, "Ir", nr, "%0", "c");
+	GEN_BINARY_RMWcc(LOCK_PREFIX "btr", *addr, "Ir", nr, "%0", c);
 }
 
 /**
@@ -302,7 +302,7 @@ static __always_inline bool __test_and_change_bit(long nr, volatile unsigned lon
  */
 static __always_inline bool test_and_change_bit(long nr, volatile unsigned long *addr)
 {
-	GEN_BINARY_RMWcc(LOCK_PREFIX "btc", *addr, "Ir", nr, "%0", "c");
+	GEN_BINARY_RMWcc(LOCK_PREFIX "btc", *addr, "Ir", nr, "%0", c);
 }
 
 static __always_inline bool constant_test_bit(long nr, const volatile unsigned long *addr)
diff --git a/arch/x86/include/asm/local.h b/arch/x86/include/asm/local.h
index 0cdc65b..7511978 100644
--- a/arch/x86/include/asm/local.h
+++ b/arch/x86/include/asm/local.h
@@ -52,7 +52,7 @@ static inline void local_sub(long i, local_t *l)
  */
 static inline bool local_sub_and_test(long i, local_t *l)
 {
-	GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, "er", i, "%0", "e");
+	GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, "er", i, "%0", e);
 }
 
 /**
@@ -65,7 +65,7 @@ static inline bool local_sub_and_test(long i, local_t *l)
  */
 static inline bool local_dec_and_test(local_t *l)
 {
-	GEN_UNARY_RMWcc(_ASM_DEC, l->a.counter, "%0", "e");
+	GEN_UNARY_RMWcc(_ASM_DEC, l->a.counter, "%0", e);
 }
 
 /**
@@ -78,7 +78,7 @@ static inline bool local_dec_and_test(local_t *l)
  */
 static inline bool local_inc_and_test(local_t *l)
 {
-	GEN_UNARY_RMWcc(_ASM_INC, l->a.counter, "%0", "e");
+	GEN_UNARY_RMWcc(_ASM_INC, l->a.counter, "%0", e);
 }
 
 /**
@@ -92,7 +92,7 @@ static inline bool local_inc_and_test(local_t *l)
  */
 static inline bool local_add_negative(long i, local_t *l)
 {
-	GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, "er", i, "%0", "s");
+	GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, "er", i, "%0", s);
 }
 
 /**
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index d397deb..17f2186 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -81,7 +81,7 @@ static __always_inline void __preempt_count_sub(int val)
  */
 static __always_inline bool __preempt_count_dec_and_test(void)
 {
-	GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), "e");
+	GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), e);
 }
 
 /*
diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h
index a15b73d..e3264c4 100644
--- a/arch/x86/include/asm/rmwcc.h
+++ b/arch/x86/include/asm/rmwcc.h
@@ -5,7 +5,7 @@
 
 #define __GEN_RMWcc(fullop, var, cc, ...)				\
 do {									\
-	asm_volatile_goto (fullop "; j" cc " %l[cc_label]"		\
+	asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"		\
 			: : "m" (var), ## __VA_ARGS__ 			\
 			: "memory" : cc_label);				\
 	return 0;							\
@@ -24,7 +24,7 @@ cc_label:								\
 #define __GEN_RMWcc(fullop, var, cc, ...)				\
 do {									\
 	bool c;								\
-	asm volatile (fullop "; set" cc " %1"				\
+	asm volatile (fullop "; set" #cc " %1"				\
 			: "+m" (var), "=qm" (c)				\
 			: __VA_ARGS__ : "memory");			\
 	return c;							\
-- 
2.7.3.0.11.gd79db92

^ permalink raw reply related	[flat|nested] 24+ messages in thread

end of thread, other threads:[~2016-06-09 15:49 UTC | newest]

Thread overview: 24+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-06-08 19:38 [PATCH v2 00/10] x86: use gcc 6+ asm flag output feature H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 01/10] x86, bitops: remove use of "sbb" to return CF H. Peter Anvin
2016-06-08 19:45   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 02/10] x86, asm: use bool for bitops and other assembly outputs H. Peter Anvin
2016-06-08 19:46   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 03/10] x86, asm: change the GEN_*_RMWcc() macros to not quote the condition H. Peter Anvin
2016-06-08 19:46   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 04/10] x86, asm: define CC_SET() and CC_OUT() macros H. Peter Anvin
2016-06-08 19:47   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 05/10] x86, asm: change GEN_*_RMWcc() to use CC_SET()/CC_OUT() H. Peter Anvin
2016-06-08 19:47   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 06/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/bitops.h> H. Peter Anvin
2016-06-08 19:48   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 07/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/percpu.h> H. Peter Anvin
2016-06-08 19:48   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 08/10] x86, asm: Use CC_SET()/CC_OUT() in <asm/rwsem.h> H. Peter Anvin
2016-06-08 19:49   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 09/10] x86, asm, boot: Use CC_SET()/CC_OUT() in arch/x86/boot/boot.h H. Peter Anvin
2016-06-08 19:49   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-08 19:38 ` [PATCH v2 10/10] x86, asm: Use CC_SET()/CC_OUT() and static_cpu_has() in archrandom.h H. Peter Anvin
2016-06-08 19:49   ` [tip:x86/asm] " tip-bot for H. Peter Anvin
2016-06-09 15:49   ` [PATCH v2 10/10] " Borislav Petkov
2016-06-08 21:30 ` [PATCH v2 00/10] x86: use gcc 6+ asm flag output feature H. Peter Anvin
  -- strict thread matches above, loose matches on Subject: below --
2016-06-07 23:31 [PATCH 03/10] x86, asm: change the GEN_*_RMWcc() macros to not quote the condition H. Peter Anvin
2016-06-07 23:40 ` [tip:x86/asm] " tip-bot for H. Peter Anvin

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