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Message-ID: <20211210162313.464256797@infradead.org>
Date: Fri, 10 Dec 2021 17:16:21 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: will@...nel.org, boqun.feng@...il.com
Cc: linux-kernel@...r.kernel.org, x86@...nel.org, peterz@...radead.org,
mark.rutland@....com, elver@...gle.com, keescook@...omium.org,
hch@...radead.org, torvalds@...ux-foundation.org, axboe@...nel.dk
Subject: [PATCH v2 3/9] atomic: Introduce atomic_{inc,dec,dec_and_test}_overflow()
In order to facilitate architecture support for refcount_t, introduce
a number of new atomic primitives that have a uaccess style exception
for overflow.
Notably:
atomic_inc_overflow(v, Label):
increment and goto Label when the old value of v is zero or
negative.
atomic_dec_overflow(v, Label):
decrement and goto Label when the new value of v is zero or
negative
atomic_dec_and_test_overflow(v, Label):
decrement and return true when the result is zero and goto
Label when the new value of v is negative
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
include/linux/atomic/atomic-arch-fallback.h | 64 ++++++++++++++++++++++++
include/linux/atomic/atomic-instrumented.h | 65 ++++++++++++++++++++++++-
include/linux/atomic/atomic-long.h | 32 +++++++++++-
scripts/atomic/atomics.tbl | 3 +
scripts/atomic/fallbacks/dec_and_test_overflow | 12 ++++
scripts/atomic/fallbacks/dec_overflow | 8 +++
scripts/atomic/fallbacks/inc_overflow | 8 +++
7 files changed, 189 insertions(+), 3 deletions(-)
--- a/include/linux/atomic/atomic-arch-fallback.h
+++ b/include/linux/atomic/atomic-arch-fallback.h
@@ -1250,6 +1250,37 @@ arch_atomic_dec_if_positive(atomic_t *v)
#define arch_atomic_dec_if_positive arch_atomic_dec_if_positive
#endif
+#ifndef arch_atomic_inc_overflow
+#define arch_atomic_inc_overflow(_v, _label) \
+do { \
+ int __old = arch_atomic_fetch_inc(_v); \
+ if (unlikely(__old <= 0)) \
+ goto _label; \
+} while (0)
+#endif
+
+#ifndef arch_atomic_dec_overflow
+#define arch_atomic_dec_overflow(_v, _label) \
+do { \
+ int __new = arch_atomic_dec_return(_v); \
+ if (unlikely(__new <= 0)) \
+ goto _label; \
+} while (0)
+#endif
+
+#ifndef arch_atomic_dec_and_test_overflow
+#define arch_atomic_dec_and_test_overflow(_v, _label) \
+({ \
+ bool __ret = false; \
+ int __new = arch_atomic_dec_return(_v); \
+ if (unlikely(__new < 0)) \
+ goto _label; \
+ if (unlikely(__new == 0)) \
+ __ret = true; \
+ __ret; \
+})
+#endif
+
#ifdef CONFIG_GENERIC_ATOMIC64
#include <asm-generic/atomic64.h>
#endif
@@ -2357,5 +2388,36 @@ arch_atomic64_dec_if_positive(atomic64_t
#define arch_atomic64_dec_if_positive arch_atomic64_dec_if_positive
#endif
+#ifndef arch_atomic64_inc_overflow
+#define arch_atomic64_inc_overflow(_v, _label) \
+do { \
+ s64 __old = arch_atomic64_fetch_inc(_v); \
+ if (unlikely(__old <= 0)) \
+ goto _label; \
+} while (0)
+#endif
+
+#ifndef arch_atomic64_dec_overflow
+#define arch_atomic64_dec_overflow(_v, _label) \
+do { \
+ s64 __new = arch_atomic64_dec_return(_v); \
+ if (unlikely(__new <= 0)) \
+ goto _label; \
+} while (0)
+#endif
+
+#ifndef arch_atomic64_dec_and_test_overflow
+#define arch_atomic64_dec_and_test_overflow(_v, _label) \
+({ \
+ bool __ret = false; \
+ s64 __new = arch_atomic64_dec_return(_v); \
+ if (unlikely(__new < 0)) \
+ goto _label; \
+ if (unlikely(__new == 0)) \
+ __ret = true; \
+ __ret; \
+})
+#endif
+
#endif /* _LINUX_ATOMIC_FALLBACK_H */
-// cca554917d7ea73d5e3e7397dd70c484cad9b2c4
+// e4c677b23b3fd5e8dc4bce9d6c055103666cfc4a
--- a/include/linux/atomic/atomic-instrumented.h
+++ b/include/linux/atomic/atomic-instrumented.h
@@ -599,6 +599,27 @@ atomic_dec_if_positive(atomic_t *v)
return arch_atomic_dec_if_positive(v);
}
+#define atomic_inc_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic_inc_overflow(__ai_v, L); \
+})
+
+#define atomic_dec_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic_dec_overflow(__ai_v, L); \
+})
+
+#define atomic_dec_and_test_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic_dec_and_test_overflow(__ai_v, L); \
+})
+
static __always_inline s64
atomic64_read(const atomic64_t *v)
{
@@ -1177,6 +1198,27 @@ atomic64_dec_if_positive(atomic64_t *v)
return arch_atomic64_dec_if_positive(v);
}
+#define atomic64_inc_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic64_inc_overflow(__ai_v, L); \
+})
+
+#define atomic64_dec_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic64_dec_overflow(__ai_v, L); \
+})
+
+#define atomic64_dec_and_test_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic64_dec_and_test_overflow(__ai_v, L); \
+})
+
static __always_inline long
atomic_long_read(const atomic_long_t *v)
{
@@ -1755,6 +1797,27 @@ atomic_long_dec_if_positive(atomic_long_
return arch_atomic_long_dec_if_positive(v);
}
+#define atomic_long_inc_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic_long_inc_overflow(__ai_v, L); \
+})
+
+#define atomic_long_dec_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic_long_dec_overflow(__ai_v, L); \
+})
+
+#define atomic_long_dec_and_test_overflow(v, L) \
+({ \
+ typeof(v) __ai_v = (v); \
+ instrument_atomic_read_write(__ai_v, sizeof(*__ai_v)); \
+ arch_atomic_long_dec_and_test_overflow(__ai_v, L); \
+})
+
#define xchg(ptr, ...) \
({ \
typeof(ptr) __ai_ptr = (ptr); \
@@ -1912,4 +1975,4 @@ atomic_long_dec_if_positive(atomic_long_
#endif /* _LINUX_ATOMIC_INSTRUMENTED_H */
-// 66cdf9a0e0a995cba29c61baf018f7ef35974ae5
+// 702806891ef1d01d76767c55088264ab6a1ef77d
--- a/include/linux/atomic/atomic-long.h
+++ b/include/linux/atomic/atomic-long.h
@@ -515,6 +515,21 @@ arch_atomic_long_dec_if_positive(atomic_
return arch_atomic64_dec_if_positive(v);
}
+#define arch_atomic_long_inc_overflow(v, L) \
+({ \
+ arch_atomic64_inc_overflow((v), L) \
+})
+
+#define arch_atomic_long_dec_overflow(v, L) \
+({ \
+ arch_atomic64_dec_overflow((v), L) \
+})
+
+#define arch_atomic_long_dec_and_test_overflow(v, L) \
+({ \
+ arch_atomic64_dec_and_test_overflow((v), L) \
+})
+
#else /* CONFIG_64BIT */
static __always_inline long
@@ -1009,6 +1024,21 @@ arch_atomic_long_dec_if_positive(atomic_
return arch_atomic_dec_if_positive(v);
}
+#define arch_atomic_long_inc_overflow(v, L) \
+({ \
+ arch_atomic_inc_overflow((v), L) \
+})
+
+#define arch_atomic_long_dec_overflow(v, L) \
+({ \
+ arch_atomic_dec_overflow((v), L) \
+})
+
+#define arch_atomic_long_dec_and_test_overflow(v, L) \
+({ \
+ arch_atomic_dec_and_test_overflow((v), L) \
+})
+
#endif /* CONFIG_64BIT */
#endif /* _LINUX_ATOMIC_LONG_H */
-// e8f0e08ff072b74d180eabe2ad001282b38c2c88
+// 487bc4fea91f23f2a4b42af7d5b49ef9172ae792
--- a/scripts/atomic/atomics.tbl
+++ b/scripts/atomic/atomics.tbl
@@ -44,3 +44,6 @@ inc_not_zero b v
inc_unless_negative b v
dec_unless_positive b v
dec_if_positive i v
+inc_overflow n v L
+dec_overflow n v L
+dec_and_test_overflow m v L
--- /dev/null
+++ b/scripts/atomic/fallbacks/dec_and_test_overflow
@@ -0,0 +1,12 @@
+cat << EOF
+#define arch_${atomic}_dec_and_test_overflow(_v, _label) \\
+({ \\
+ bool __ret = false; \\
+ ${int} __new = arch_${atomic}_dec_return(_v); \\
+ if (unlikely(__new < 0)) \\
+ goto _label; \\
+ if (unlikely(__new == 0)) \\
+ __ret = true; \\
+ __ret; \\
+})
+EOF
--- /dev/null
+++ b/scripts/atomic/fallbacks/dec_overflow
@@ -0,0 +1,8 @@
+cat << EOF
+#define arch_${atomic}_dec_overflow(_v, _label) \\
+do { \\
+ ${int} __new = arch_${atomic}_dec_return(_v); \\
+ if (unlikely(__new <= 0)) \\
+ goto _label; \\
+} while (0)
+EOF
--- /dev/null
+++ b/scripts/atomic/fallbacks/inc_overflow
@@ -0,0 +1,8 @@
+cat << EOF
+#define arch_${atomic}_inc_overflow(_v, _label) \\
+do { \\
+ ${int} __old = arch_${atomic}_fetch_inc(_v); \\
+ if (unlikely(__old <= 0)) \\
+ goto _label; \\
+} while (0)
+EOF
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