| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20191001215249.4157062-21-paul.burton@mips.com>
Date: Tue, 1 Oct 2019 21:53:30 +0000
From: Paul Burton <paul.burton@...s.com>
To: "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>
CC: Huacai Chen <chenhc@...ote.com>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Paul Burton <pburton@...ecomp.com>
Subject: [PATCH v2 20/36] MIPS: bitops: Implement test_and_set_bit() in terms
of _lock variant
The only difference between test_and_set_bit() & test_and_set_bit_lock()
is memory ordering barrier semantics - the former provides a full
barrier whilst the latter only provides acquire semantics.
We can therefore implement test_and_set_bit() in terms of
test_and_set_bit_lock() with the addition of the extra memory barrier.
Do this in order to avoid duplicating logic.
Signed-off-by: Paul Burton <paul.burton@...s.com>
---
Changes in v2: None
arch/mips/include/asm/bitops.h | 66 +++++++---------------------------
arch/mips/lib/bitops.c | 26 --------------
2 files changed, 13 insertions(+), 79 deletions(-)
diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
index 03532ae9f528..ea35a2e87b6d 100644
--- a/arch/mips/include/asm/bitops.h
+++ b/arch/mips/include/asm/bitops.h
@@ -31,8 +31,6 @@
void __mips_set_bit(unsigned long nr, volatile unsigned long *addr);
void __mips_clear_bit(unsigned long nr, volatile unsigned long *addr);
void __mips_change_bit(unsigned long nr, volatile unsigned long *addr);
-int __mips_test_and_set_bit(unsigned long nr,
- volatile unsigned long *addr);
int __mips_test_and_set_bit_lock(unsigned long nr,
volatile unsigned long *addr);
int __mips_test_and_clear_bit(unsigned long nr,
@@ -236,24 +234,22 @@ static inline void change_bit(unsigned long nr, volatile unsigned long *addr)
}
/*
- * test_and_set_bit - Set a bit and return its old value
+ * test_and_set_bit_lock - Set a bit and return its old value
* @nr: Bit to set
* @addr: Address to count from
*
- * This operation is atomic and cannot be reordered.
- * It also implies a memory barrier.
+ * This operation is atomic and implies acquire ordering semantics
+ * after the memory operation.
*/
-static inline int test_and_set_bit(unsigned long nr,
+static inline int test_and_set_bit_lock(unsigned long nr,
volatile unsigned long *addr)
{
unsigned long *m = ((unsigned long *)addr) + (nr >> SZLONG_LOG);
int bit = nr & SZLONG_MASK;
unsigned long res, temp;
- smp_mb__before_llsc();
-
if (!kernel_uses_llsc) {
- res = __mips_test_and_set_bit(nr, addr);
+ res = __mips_test_and_set_bit_lock(nr, addr);
} else if (R10000_LLSC_WAR) {
__asm__ __volatile__(
" .set push \n"
@@ -264,7 +260,7 @@ static inline int test_and_set_bit(unsigned long nr,
" beqzl %2, 1b \n"
" and %2, %0, %3 \n"
" .set pop \n"
- : "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
+ : "=&r" (temp), "+m" (*m), "=&r" (res)
: "r" (1UL << bit)
: __LLSC_CLOBBER);
} else {
@@ -291,56 +287,20 @@ static inline int test_and_set_bit(unsigned long nr,
}
/*
- * test_and_set_bit_lock - Set a bit and return its old value
+ * test_and_set_bit - Set a bit and return its old value
* @nr: Bit to set
* @addr: Address to count from
*
- * This operation is atomic and implies acquire ordering semantics
- * after the memory operation.
+ * This operation is atomic and cannot be reordered.
+ * It also implies a memory barrier.
*/
-static inline int test_and_set_bit_lock(unsigned long nr,
+static inline int test_and_set_bit(unsigned long nr,
volatile unsigned long *addr)
{
- unsigned long *m = ((unsigned long *)addr) + (nr >> SZLONG_LOG);
- int bit = nr & SZLONG_MASK;
- unsigned long res, temp;
-
- if (!kernel_uses_llsc) {
- res = __mips_test_and_set_bit_lock(nr, addr);
- } else if (R10000_LLSC_WAR) {
- __asm__ __volatile__(
- " .set push \n"
- " .set arch=r4000 \n"
- "1: " __LL "%0, %1 # test_and_set_bit \n"
- " or %2, %0, %3 \n"
- " " __SC "%2, %1 \n"
- " beqzl %2, 1b \n"
- " and %2, %0, %3 \n"
- " .set pop \n"
- : "=&r" (temp), "+m" (*m), "=&r" (res)
- : "r" (1UL << bit)
- : __LLSC_CLOBBER);
- } else {
- do {
- __asm__ __volatile__(
- " .set push \n"
- " .set "MIPS_ISA_ARCH_LEVEL" \n"
- " " __LL "%0, %1 # test_and_set_bit \n"
- " or %2, %0, %3 \n"
- " " __SC "%2, %1 \n"
- " .set pop \n"
- : "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
- : "r" (1UL << bit)
- : __LLSC_CLOBBER);
- } while (unlikely(!res));
-
- res = temp & (1UL << bit);
- }
-
- smp_llsc_mb();
-
- return res != 0;
+ smp_mb__before_llsc();
+ return test_and_set_bit_lock(nr, addr);
}
+
/*
* test_and_clear_bit - Clear a bit and return its old value
* @nr: Bit to clear
diff --git a/arch/mips/lib/bitops.c b/arch/mips/lib/bitops.c
index 3b2a1e78a543..fba402c0879d 100644
--- a/arch/mips/lib/bitops.c
+++ b/arch/mips/lib/bitops.c
@@ -77,32 +77,6 @@ void __mips_change_bit(unsigned long nr, volatile unsigned long *addr)
EXPORT_SYMBOL(__mips_change_bit);
-/**
- * __mips_test_and_set_bit - Set a bit and return its old value. This is
- * called by test_and_set_bit() if it cannot find a faster solution.
- * @nr: Bit to set
- * @addr: Address to count from
- */
-int __mips_test_and_set_bit(unsigned long nr,
- volatile unsigned long *addr)
-{
- unsigned long *a = (unsigned long *)addr;
- unsigned bit = nr & SZLONG_MASK;
- unsigned long mask;
- unsigned long flags;
- int res;
-
- a += nr >> SZLONG_LOG;
- mask = 1UL << bit;
- raw_local_irq_save(flags);
- res = (mask & *a) != 0;
- *a |= mask;
- raw_local_irq_restore(flags);
- return res;
-}
-EXPORT_SYMBOL(__mips_test_and_set_bit);
-
-
/**
* __mips_test_and_set_bit_lock - Set a bit and return its old value. This is
* called by test_and_set_bit_lock() if it cannot find a faster solution.
--
2.23.0
Powered by blists - more mailing lists