From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: [PATCH v2 08/10] arm64: barrier: Use '__unqual_scalar_typeof' for acquire/release macros Date: Thu, 23 Jan 2020 15:33:39 +0000 Message-ID: <20200123153341.19947-9-will@kernel.org> References: <20200123153341.19947-1-will@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200123153341.19947-1-will@kernel.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, kernel-team@android.com, Will Deacon , Michael Ellerman , Peter Zijlstra , Linus Torvalds , Segher Boessenkool , Christian Borntraeger , Luc Van Oostenryck , Arnd Bergmann , Peter Oberparleiter , Masahiro Yamada , Nick Desaulniers , Mark Rutland List-Id: linux-arch.vger.kernel.org Passing volatile-qualified pointers to the arm64 implementations of the load-acquire/store-release macros results in a re-load from the stack and a bunch of associated stack-protector churn due to the temporary result variable inheriting the volatile semantics thanks to the use of 'typeof()'. Define these temporary variables using 'unqual_scalar_typeof' to drop the volatile qualifier in the case that they are scalar types. Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Arnd Bergmann Acked-by: Mark Rutland Signed-off-by: Will Deacon --- arch/arm64/include/asm/barrier.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h index 7d9cc5ec4971..fb4c27506ef4 100644 --- a/arch/arm64/include/asm/barrier.h +++ b/arch/arm64/include/asm/barrier.h @@ -76,8 +76,8 @@ static inline unsigned long array_index_mask_nospec(unsigned long idx, #define __smp_store_release(p, v) \ do { \ typeof(p) __p = (p); \ - union { typeof(*p) __val; char __c[1]; } __u = \ - { .__val = (__force typeof(*p)) (v) }; \ + union { __unqual_scalar_typeof(*p) __val; char __c[1]; } __u = \ + { .__val = (__force __unqual_scalar_typeof(*p)) (v) }; \ compiletime_assert_atomic_type(*p); \ kasan_check_write(__p, sizeof(*p)); \ switch (sizeof(*p)) { \ @@ -110,7 +110,7 @@ do { \ #define __smp_load_acquire(p) \ ({ \ - union { typeof(*p) __val; char __c[1]; } __u; \ + union { __unqual_scalar_typeof(*p) __val; char __c[1]; } __u; \ typeof(p) __p = (p); \ compiletime_assert_atomic_type(*p); \ kasan_check_read(__p, sizeof(*p)); \ @@ -136,33 +136,33 @@ do { \ : "Q" (*__p) : "memory"); \ break; \ } \ - __u.__val; \ + (typeof(*p))__u.__val; \ }) #define smp_cond_load_relaxed(ptr, cond_expr) \ ({ \ typeof(ptr) __PTR = (ptr); \ - typeof(*ptr) VAL; \ + __unqual_scalar_typeof(*ptr) VAL; \ for (;;) { \ VAL = READ_ONCE(*__PTR); \ if (cond_expr) \ break; \ __cmpwait_relaxed(__PTR, VAL); \ } \ - VAL; \ + (typeof(*ptr))VAL; \ }) #define smp_cond_load_acquire(ptr, cond_expr) \ ({ \ typeof(ptr) __PTR = (ptr); \ - typeof(*ptr) VAL; \ + __unqual_scalar_typeof(*ptr) VAL; \ for (;;) { \ VAL = smp_load_acquire(__PTR); \ if (cond_expr) \ break; \ __cmpwait_relaxed(__PTR, VAL); \ } \ - VAL; \ + (typeof(*ptr))VAL; \ }) #include -- 2.25.0.341.g760bfbb309-goog From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:51954 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729159AbgAWPeP (ORCPT ); Thu, 23 Jan 2020 10:34:15 -0500 From: Will Deacon Subject: [PATCH v2 08/10] arm64: barrier: Use '__unqual_scalar_typeof' for acquire/release macros Date: Thu, 23 Jan 2020 15:33:39 +0000 Message-ID: <20200123153341.19947-9-will@kernel.org> In-Reply-To: <20200123153341.19947-1-will@kernel.org> References: <20200123153341.19947-1-will@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-arch@vger.kernel.org, kernel-team@android.com, Will Deacon , Michael Ellerman , Peter Zijlstra , Linus Torvalds , Segher Boessenkool , Christian Borntraeger , Luc Van Oostenryck , Arnd Bergmann , Peter Oberparleiter , Masahiro Yamada , Nick Desaulniers , Mark Rutland Message-ID: <20200123153339.yddSGx1_1SGk6AcjpNMVLeZ9KWvmSvK7Y6VZc3ADgEw@z> Passing volatile-qualified pointers to the arm64 implementations of the load-acquire/store-release macros results in a re-load from the stack and a bunch of associated stack-protector churn due to the temporary result variable inheriting the volatile semantics thanks to the use of 'typeof()'. Define these temporary variables using 'unqual_scalar_typeof' to drop the volatile qualifier in the case that they are scalar types. Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Arnd Bergmann Acked-by: Mark Rutland Signed-off-by: Will Deacon --- arch/arm64/include/asm/barrier.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h index 7d9cc5ec4971..fb4c27506ef4 100644 --- a/arch/arm64/include/asm/barrier.h +++ b/arch/arm64/include/asm/barrier.h @@ -76,8 +76,8 @@ static inline unsigned long array_index_mask_nospec(unsigned long idx, #define __smp_store_release(p, v) \ do { \ typeof(p) __p = (p); \ - union { typeof(*p) __val; char __c[1]; } __u = \ - { .__val = (__force typeof(*p)) (v) }; \ + union { __unqual_scalar_typeof(*p) __val; char __c[1]; } __u = \ + { .__val = (__force __unqual_scalar_typeof(*p)) (v) }; \ compiletime_assert_atomic_type(*p); \ kasan_check_write(__p, sizeof(*p)); \ switch (sizeof(*p)) { \ @@ -110,7 +110,7 @@ do { \ #define __smp_load_acquire(p) \ ({ \ - union { typeof(*p) __val; char __c[1]; } __u; \ + union { __unqual_scalar_typeof(*p) __val; char __c[1]; } __u; \ typeof(p) __p = (p); \ compiletime_assert_atomic_type(*p); \ kasan_check_read(__p, sizeof(*p)); \ @@ -136,33 +136,33 @@ do { \ : "Q" (*__p) : "memory"); \ break; \ } \ - __u.__val; \ + (typeof(*p))__u.__val; \ }) #define smp_cond_load_relaxed(ptr, cond_expr) \ ({ \ typeof(ptr) __PTR = (ptr); \ - typeof(*ptr) VAL; \ + __unqual_scalar_typeof(*ptr) VAL; \ for (;;) { \ VAL = READ_ONCE(*__PTR); \ if (cond_expr) \ break; \ __cmpwait_relaxed(__PTR, VAL); \ } \ - VAL; \ + (typeof(*ptr))VAL; \ }) #define smp_cond_load_acquire(ptr, cond_expr) \ ({ \ typeof(ptr) __PTR = (ptr); \ - typeof(*ptr) VAL; \ + __unqual_scalar_typeof(*ptr) VAL; \ for (;;) { \ VAL = smp_load_acquire(__PTR); \ if (cond_expr) \ break; \ __cmpwait_relaxed(__PTR, VAL); \ } \ - VAL; \ + (typeof(*ptr))VAL; \ }) #include -- 2.25.0.341.g760bfbb309-goog