From: Will Deacon <will@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org, kernel-team@android.com,
Will Deacon <will@kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Peter Zijlstra <peterz@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Segher Boessenkool <segher@kernel.crashing.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
Arnd Bergmann <arnd@arndb.de>,
Peter Oberparleiter <oberpar@linux.ibm.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Mark Rutland <mark.rutland@arm.com>
Subject: [PATCH v3 10/12] arm64: barrier: Use '__unqual_scalar_typeof' for acquire/release macros
Date: Wed, 15 Apr 2020 17:52:16 +0100 [thread overview]
Message-ID: <20200415165218.20251-11-will@kernel.org> (raw)
In-Reply-To: <20200415165218.20251-1-will@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 <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
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 <asm-generic/barrier.h>
--
2.26.0.110.g2183baf09c-goog
next prev parent reply other threads:[~2020-04-15 16:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 16:52 [PATCH v3 00/12] Rework READ_ONCE() to improve codegen Will Deacon
2020-04-15 16:52 ` [PATCH v3 01/12] compiler/gcc: Emit build-time warning for GCC prior to version 4.8 Will Deacon
2020-04-15 17:20 ` Masahiro Yamada
2020-04-15 16:52 ` [PATCH v3 02/12] netfilter: Avoid assigning 'const' pointer to non-const pointer Will Deacon
2020-04-15 16:52 ` [PATCH v3 03/12] net: tls: " Will Deacon
2020-04-15 16:52 ` [PATCH v3 04/12] fault_inject: Don't rely on "return value" from WRITE_ONCE() Will Deacon
2020-04-15 16:52 ` [PATCH v3 05/12] arm64: csum: Disable KASAN for do_csum() Will Deacon
2020-04-15 17:28 ` Mark Rutland
2020-04-15 18:42 ` Arnd Bergmann
2020-04-15 19:43 ` Will Deacon
2020-04-15 20:10 ` Will Deacon
2020-04-15 19:26 ` Will Deacon
2020-04-16 9:31 ` Mark Rutland
2020-04-16 11:53 ` Will Deacon
2020-04-16 12:11 ` Mark Rutland
2020-04-15 19:26 ` Robin Murphy
2020-04-15 16:52 ` [PATCH v3 06/12] READ_ONCE: Simplify implementations of {READ,WRITE}_ONCE() Will Deacon
2020-04-15 16:52 ` [PATCH v3 07/12] READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses Will Deacon
2020-04-15 16:52 ` [PATCH v3 08/12] READ_ONCE: Drop pointer qualifiers when reading from scalar types Will Deacon
2020-04-15 16:52 ` [PATCH v3 09/12] locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros Will Deacon
2020-04-15 16:52 ` Will Deacon [this message]
2020-04-15 16:52 ` [PATCH v3 11/12] compiler/gcc: Raise minimum GCC version for kernel builds to 4.8 Will Deacon
2020-04-15 18:37 ` Arnd Bergmann
2020-04-15 16:52 ` [PATCH v3 12/12] gcov: Remove old GCC 3.4 support Will Deacon
2020-04-16 12:30 ` [PATCH v3 00/12] Rework READ_ONCE() to improve codegen Christian Borntraeger
2020-04-16 12:48 ` Will Deacon
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