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arm64: lse: convert lse alternatives NOP padding to use __nops

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The LSE atomics are implemented using alternative code sequences of
different lengths, and explicit NOP padding is used to ensure the
patching works correctly.

This patch converts the bulk of the LSE code over to using the __nops
macro, which makes it slightly clearer as to what is going on and also
consolidates all of the padding at the end of the various sequences.

Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon
2016-09-06 16:42:58 +01:00
parent f99a250cb6
commit 05492f2fd8
3 changed files with 39 additions and 56 deletions
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27
arch/arm64/include/asm/spinlock.h
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@@ -66,8 +66,7 @@ static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
ARM64_LSE_ATOMIC_INSN(
/* LL/SC */
" stxr %w1, %w0, %2\n"
" nop\n"
" nop\n",
__nops(2),
/* LSE atomics */
" mov %w1, %w0\n"
" cas %w0, %w0, %2\n"
@@ -99,9 +98,7 @@ static inline void arch_spin_lock(arch_spinlock_t *lock)
/* LSE atomics */
" mov %w2, %w5\n"
" ldadda %w2, %w0, %3\n"
" nop\n"
" nop\n"
" nop\n"
__nops(3)
)
/* Did we get the lock? */
@@ -165,8 +162,8 @@ static inline void arch_spin_unlock(arch_spinlock_t *lock)
" stlrh %w1, %0",
/* LSE atomics */
" mov %w1, #1\n"
" nop\n"
" staddlh %w1, %0")
" staddlh %w1, %0\n"
__nops(1))
: "=Q" (lock->owner), "=&r" (tmp)
:
: "memory");
@@ -212,7 +209,7 @@ static inline void arch_write_lock(arch_rwlock_t *rw)
" cbnz %w0, 1b\n"
" stxr %w0, %w2, %1\n"
" cbnz %w0, 2b\n"
" nop",
__nops(1),
/* LSE atomics */
"1: mov %w0, wzr\n"
"2: casa %w0, %w2, %1\n"
@@ -241,8 +238,7 @@ static inline int arch_write_trylock(arch_rwlock_t *rw)
/* LSE atomics */
" mov %w0, wzr\n"
" casa %w0, %w2, %1\n"
" nop\n"
" nop")
__nops(2))
: "=&r" (tmp), "+Q" (rw->lock)
: "r" (0x80000000)
: "memory");
@@ -290,8 +286,8 @@ static inline void arch_read_lock(arch_rwlock_t *rw)
" add %w0, %w0, #1\n"
" tbnz %w0, #31, 1b\n"
" stxr %w1, %w0, %2\n"
" nop\n"
" cbnz %w1, 2b",
" cbnz %w1, 2b\n"
__nops(1),
/* LSE atomics */
"1: wfe\n"
"2: ldxr %w0, %2\n"
@@ -317,9 +313,8 @@ static inline void arch_read_unlock(arch_rwlock_t *rw)
" cbnz %w1, 1b",
/* LSE atomics */
" movn %w0, #0\n"
" nop\n"
" nop\n"
" staddl %w0, %2")
" staddl %w0, %2\n"
__nops(2))
: "=&r" (tmp), "=&r" (tmp2), "+Q" (rw->lock)
:
: "memory");
@@ -344,7 +339,7 @@ static inline int arch_read_trylock(arch_rwlock_t *rw)
" tbnz %w1, #31, 1f\n"
" casa %w0, %w1, %2\n"
" sbc %w1, %w1, %w0\n"
" nop\n"
__nops(1)
"1:")
: "=&r" (tmp), "=&r" (tmp2), "+Q" (rw->lock)
: