percpu: add raw_cpu_ops

The kernel has never been audited to ensure that this_cpu operations are
consistently used throughout the kernel.  The code generated in many
places can be improved through the use of this_cpu operations (which
uses a segment register for relocation of per cpu offsets instead of
performing address calculations).

The patch set also addresses various consistency issues in general with
the per cpu macros.

A. The semantics of __this_cpu_ptr() differs from this_cpu_ptr only
   because checks are skipped. This is typically shown through a raw_
   prefix. So this patch set changes the places where __this_cpu_ptr()
   is used to raw_cpu_ptr().

B. There has been the long term wish by some that __this_cpu operations
   would check for preemption. However, there are cases where preemption
   checks need to be skipped. This patch set adds raw_cpu operations that
   do not check for preemption and then adds preemption checks to the
   __this_cpu operations.

C. The use of __get_cpu_var is always a reference to a percpu variable
   that can also be handled via a this_cpu operation. This patch set
   replaces all uses of __get_cpu_var with this_cpu operations.

D. We can then use this_cpu RMW operations in various places replacing
   sequences of instructions by a single one.

E. The use of this_cpu operations throughout will allow other arches than
   x86 to implement optimized references and RMV operations to work with
   per cpu local data.

F. The use of this_cpu operations opens up the possibility to
   further optimize code that relies on synchronization through
   per cpu data.

The patch set works in a couple of stages:

I. Patch 1 adds the additional raw_cpu operations and raw_cpu_ptr().
    Also converts the existing __this_cpu_xx_# primitive in the x86
    code to raw_cpu_xx_#.

II. Patch 2-4 use the raw_cpu operations in places that would give
     us false positives once they are enabled.

III. Patch 5 adds preemption checks to __this_cpu operations to allow
    checking if preemption is properly disabled when these functions
    are used.

IV. Patches 6-20 are patches that simply replace uses of __get_cpu_var
   with this_cpu_ptr. They do not depend on any changes to the percpu
   code. No preemption tests are skipped if they are applied.

V. Patches 21-46 are conversion patches that use this_cpu operations
   in various kernel subsystems/drivers or arch code.

VI.  Patches 47/48 (not included in this series) remove no longer used
    functions (__this_cpu_ptr and __get_cpu_var).  These should only be
    applied after all the conversion patches have made it and after we
    have done additional passes through the kernel to ensure that none of
    the uses of these functions remain.

This patch (of 46):

The patches following this one will add preemption checks to __this_cpu
ops so we need to have an alternative way to use this_cpu operations
without preemption checks.

raw_cpu_ops will be the basis for all other ops since these will be the
operations that do not implement any checks.

Primitive operations are renamed by this patch from __this_cpu_xxx to
raw_cpu_xxxx.

Also change the uses of the x86 percpu primitives in preempt.h.
These depend directly on asm/percpu.h (header #include nesting issue).

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Alex Shi <alex.shi@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Bryan Wu <cooloney@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: David Daney <david.daney@cavium.com>
Cc: David Miller <davem@davemloft.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dimitri Sivanich <sivanich@sgi.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Hedi Berriche <hedi@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Mike Travis <travis@sgi.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Robert Richter <rric@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 57 insertions, 57 deletions

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 94220d14d5c..851bcdc5db0 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -52,7 +52,7 @@
  * Compared to the generic __my_cpu_offset version, the following
  * saves one instruction and avoids clobbering a temp register.
  */
-#define __this_cpu_ptr(ptr)				\
+#define raw_cpu_ptr(ptr)				\
 ({							\
 	unsigned long tcp_ptr__;			\
 	__verify_pcpu_ptr(ptr);				\
@@ -362,25 +362,25 @@ do {									\
  */
 #define this_cpu_read_stable(var)	percpu_from_op("mov", var, "p" (&(var)))
 
-#define __this_cpu_read_1(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
-#define __this_cpu_read_2(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
-#define __this_cpu_read_4(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
-
-#define __this_cpu_write_1(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define __this_cpu_write_2(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define __this_cpu_write_4(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define __this_cpu_add_1(pcp, val)	percpu_add_op((pcp), val)
-#define __this_cpu_add_2(pcp, val)	percpu_add_op((pcp), val)
-#define __this_cpu_add_4(pcp, val)	percpu_add_op((pcp), val)
-#define __this_cpu_and_1(pcp, val)	percpu_to_op("and", (pcp), val)
-#define __this_cpu_and_2(pcp, val)	percpu_to_op("and", (pcp), val)
-#define __this_cpu_and_4(pcp, val)	percpu_to_op("and", (pcp), val)
-#define __this_cpu_or_1(pcp, val)	percpu_to_op("or", (pcp), val)
-#define __this_cpu_or_2(pcp, val)	percpu_to_op("or", (pcp), val)
-#define __this_cpu_or_4(pcp, val)	percpu_to_op("or", (pcp), val)
-#define __this_cpu_xchg_1(pcp, val)	percpu_xchg_op(pcp, val)
-#define __this_cpu_xchg_2(pcp, val)	percpu_xchg_op(pcp, val)
-#define __this_cpu_xchg_4(pcp, val)	percpu_xchg_op(pcp, val)
+#define raw_cpu_read_1(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
+#define raw_cpu_read_2(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
+#define raw_cpu_read_4(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
+
+#define raw_cpu_write_1(pcp, val)	percpu_to_op("mov", (pcp), val)
+#define raw_cpu_write_2(pcp, val)	percpu_to_op("mov", (pcp), val)
+#define raw_cpu_write_4(pcp, val)	percpu_to_op("mov", (pcp), val)
+#define raw_cpu_add_1(pcp, val)		percpu_add_op((pcp), val)
+#define raw_cpu_add_2(pcp, val)		percpu_add_op((pcp), val)
+#define raw_cpu_add_4(pcp, val)		percpu_add_op((pcp), val)
+#define raw_cpu_and_1(pcp, val)		percpu_to_op("and", (pcp), val)
+#define raw_cpu_and_2(pcp, val)		percpu_to_op("and", (pcp), val)
+#define raw_cpu_and_4(pcp, val)		percpu_to_op("and", (pcp), val)
+#define raw_cpu_or_1(pcp, val)		percpu_to_op("or", (pcp), val)
+#define raw_cpu_or_2(pcp, val)		percpu_to_op("or", (pcp), val)
+#define raw_cpu_or_4(pcp, val)		percpu_to_op("or", (pcp), val)
+#define raw_cpu_xchg_1(pcp, val)	percpu_xchg_op(pcp, val)
+#define raw_cpu_xchg_2(pcp, val)	percpu_xchg_op(pcp, val)
+#define raw_cpu_xchg_4(pcp, val)	percpu_xchg_op(pcp, val)
 
 #define this_cpu_read_1(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
 #define this_cpu_read_2(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
@@ -401,16 +401,16 @@ do {									\
 #define this_cpu_xchg_2(pcp, nval)	percpu_xchg_op(pcp, nval)
 #define this_cpu_xchg_4(pcp, nval)	percpu_xchg_op(pcp, nval)
 
-#define __this_cpu_add_return_1(pcp, val) percpu_add_return_op(pcp, val)
-#define __this_cpu_add_return_2(pcp, val) percpu_add_return_op(pcp, val)
-#define __this_cpu_add_return_4(pcp, val) percpu_add_return_op(pcp, val)
-#define __this_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
-#define __this_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
-#define __this_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
+#define raw_cpu_add_return_1(pcp, val)		percpu_add_return_op(pcp, val)
+#define raw_cpu_add_return_2(pcp, val)		percpu_add_return_op(pcp, val)
+#define raw_cpu_add_return_4(pcp, val)		percpu_add_return_op(pcp, val)
+#define raw_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
+#define raw_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
+#define raw_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
 
-#define this_cpu_add_return_1(pcp, val)	percpu_add_return_op(pcp, val)
-#define this_cpu_add_return_2(pcp, val)	percpu_add_return_op(pcp, val)
-#define this_cpu_add_return_4(pcp, val)	percpu_add_return_op(pcp, val)
+#define this_cpu_add_return_1(pcp, val)		percpu_add_return_op(pcp, val)
+#define this_cpu_add_return_2(pcp, val)		percpu_add_return_op(pcp, val)
+#define this_cpu_add_return_4(pcp, val)		percpu_add_return_op(pcp, val)
 #define this_cpu_cmpxchg_1(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
 #define this_cpu_cmpxchg_2(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
 #define this_cpu_cmpxchg_4(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
@@ -427,7 +427,7 @@ do {									\
 	__ret;								\
 })
 
-#define __this_cpu_cmpxchg_double_4	percpu_cmpxchg8b_double
+#define raw_cpu_cmpxchg_double_4	percpu_cmpxchg8b_double
 #define this_cpu_cmpxchg_double_4	percpu_cmpxchg8b_double
 #endif /* CONFIG_X86_CMPXCHG64 */
 
@@ -436,22 +436,22 @@ do {									\
  * 32 bit must fall back to generic operations.
  */
 #ifdef CONFIG_X86_64
-#define __this_cpu_read_8(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
-#define __this_cpu_write_8(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define __this_cpu_add_8(pcp, val)	percpu_add_op((pcp), val)
-#define __this_cpu_and_8(pcp, val)	percpu_to_op("and", (pcp), val)
-#define __this_cpu_or_8(pcp, val)	percpu_to_op("or", (pcp), val)
-#define __this_cpu_add_return_8(pcp, val) percpu_add_return_op(pcp, val)
-#define __this_cpu_xchg_8(pcp, nval)	percpu_xchg_op(pcp, nval)
-#define __this_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
-
-#define this_cpu_read_8(pcp)		percpu_from_op("mov", (pcp), "m"(pcp))
-#define this_cpu_write_8(pcp, val)	percpu_to_op("mov", (pcp), val)
-#define this_cpu_add_8(pcp, val)	percpu_add_op((pcp), val)
-#define this_cpu_and_8(pcp, val)	percpu_to_op("and", (pcp), val)
-#define this_cpu_or_8(pcp, val)		percpu_to_op("or", (pcp), val)
-#define this_cpu_add_return_8(pcp, val)	percpu_add_return_op(pcp, val)
-#define this_cpu_xchg_8(pcp, nval)	percpu_xchg_op(pcp, nval)
+#define raw_cpu_read_8(pcp)			percpu_from_op("mov", (pcp), "m"(pcp))
+#define raw_cpu_write_8(pcp, val)		percpu_to_op("mov", (pcp), val)
+#define raw_cpu_add_8(pcp, val)			percpu_add_op((pcp), val)
+#define raw_cpu_and_8(pcp, val)			percpu_to_op("and", (pcp), val)
+#define raw_cpu_or_8(pcp, val)			percpu_to_op("or", (pcp), val)
+#define raw_cpu_add_return_8(pcp, val)		percpu_add_return_op(pcp, val)
+#define raw_cpu_xchg_8(pcp, nval)		percpu_xchg_op(pcp, nval)
+#define raw_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
+
+#define this_cpu_read_8(pcp)			percpu_from_op("mov", (pcp), "m"(pcp))
+#define this_cpu_write_8(pcp, val)		percpu_to_op("mov", (pcp), val)
+#define this_cpu_add_8(pcp, val)		percpu_add_op((pcp), val)
+#define this_cpu_and_8(pcp, val)		percpu_to_op("and", (pcp), val)
+#define this_cpu_or_8(pcp, val)			percpu_to_op("or", (pcp), val)
+#define this_cpu_add_return_8(pcp, val)		percpu_add_return_op(pcp, val)
+#define this_cpu_xchg_8(pcp, nval)		percpu_xchg_op(pcp, nval)
 #define this_cpu_cmpxchg_8(pcp, oval, nval)	percpu_cmpxchg_op(pcp, oval, nval)
 
 /*
@@ -474,7 +474,7 @@ do {									\
 	__ret;								\
 })
 
-#define __this_cpu_cmpxchg_double_8	percpu_cmpxchg16b_double
+#define raw_cpu_cmpxchg_double_8	percpu_cmpxchg16b_double
 #define this_cpu_cmpxchg_double_8	percpu_cmpxchg16b_double
 
 #endif
@@ -495,9 +495,9 @@ static __always_inline int x86_this_cpu_constant_test_bit(unsigned int nr,
 	unsigned long __percpu *a = (unsigned long *)addr + nr / BITS_PER_LONG;
 
 #ifdef CONFIG_X86_64
-	return ((1UL << (nr % BITS_PER_LONG)) & __this_cpu_read_8(*a)) != 0;
+	return ((1UL << (nr % BITS_PER_LONG)) & raw_cpu_read_8(*a)) != 0;
 #else
-	return ((1UL << (nr % BITS_PER_LONG)) & __this_cpu_read_4(*a)) != 0;
+	return ((1UL << (nr % BITS_PER_LONG)) & raw_cpu_read_4(*a)) != 0;
 #endif
 }
 
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h
index c8b051933b1..7024c12f7bf 100644
--- a/arch/x86/include/asm/preempt.h
+++ b/arch/x86/include/asm/preempt.h
@@ -19,12 +19,12 @@ DECLARE_PER_CPU(int, __preempt_count);
  */
 static __always_inline int preempt_count(void)
 {
-	return __this_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED;
+	return raw_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED;
 }
 
 static __always_inline void preempt_count_set(int pc)
 {
-	__this_cpu_write_4(__preempt_count, pc);
+	raw_cpu_write_4(__preempt_count, pc);
 }
 
 /*
@@ -53,17 +53,17 @@ static __always_inline void preempt_count_set(int pc)
 
 static __always_inline void set_preempt_need_resched(void)
 {
-	__this_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED);
+	raw_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED);
 }
 
 static __always_inline void clear_preempt_need_resched(void)
 {
-	__this_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED);
+	raw_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED);
 }
 
 static __always_inline bool test_preempt_need_resched(void)
 {
-	return !(__this_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED);
+	return !(raw_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED);
 }
 
 /*
@@ -72,12 +72,12 @@ static __always_inline bool test_preempt_need_resched(void)
 
 static __always_inline void __preempt_count_add(int val)
 {
-	__this_cpu_add_4(__preempt_count, val);
+	raw_cpu_add_4(__preempt_count, val);
 }
 
 static __always_inline void __preempt_count_sub(int val)
 {
-	__this_cpu_add_4(__preempt_count, -val);
+	raw_cpu_add_4(__preempt_count, -val);
 }
 
 /*
@@ -95,7 +95,7 @@ static __always_inline bool __preempt_count_dec_and_test(void)
  */
 static __always_inline bool should_resched(void)
 {
-	return unlikely(!__this_cpu_read_4(__preempt_count));
+	return unlikely(!raw_cpu_read_4(__preempt_count));
 }
 
 #ifdef CONFIG_PREEMPT