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From: Paul Burton <paul.burton@mips.com>
To: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: Huacai Chen <chenhc@lemote.com>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Paul Burton <pburton@wavecomp.com>
Subject: [PATCH 31/37] MIPS: futex: Emit Loongson3 sync workarounds within asm
Date: Mon, 30 Sep 2019 23:08:41 +0000	[thread overview]
Message-ID: <20190930230806.2940505-32-paul.burton@mips.com> (raw)
In-Reply-To: <20190930230806.2940505-1-paul.burton@mips.com>

Generate the sync instructions required to workaround Loongson3 LL/SC
errata within inline asm blocks, which feels a little safer than doing
it from C where strictly speaking the compiler would be well within its
rights to insert a memory access between the separate asm statements we
previously had, containing sync & ll instructions respectively.

Signed-off-by: Paul Burton <paul.burton@mips.com>
---

 arch/mips/include/asm/futex.h | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/mips/include/asm/futex.h b/arch/mips/include/asm/futex.h
index b83b0397462d..45c3e3652f48 100644
--- a/arch/mips/include/asm/futex.h
+++ b/arch/mips/include/asm/futex.h
@@ -16,6 +16,7 @@
 #include <asm/barrier.h>
 #include <asm/compiler.h>
 #include <asm/errno.h>
+#include <asm/sync.h>
 #include <asm/war.h>
 
 #define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)		\
@@ -50,12 +51,12 @@
 		  "i" (-EFAULT)						\
 		: "memory");						\
 	} else if (cpu_has_llsc) {					\
-		loongson_llsc_mb();					\
 		__asm__ __volatile__(					\
 		"	.set	push				\n"	\
 		"	.set	noat				\n"	\
 		"	.set	push				\n"	\
 		"	.set	"MIPS_ISA_ARCH_LEVEL"		\n"	\
+		"	" __SYNC(full, loongson3_war) "		\n"	\
 		"1:	"user_ll("%1", "%4")" # __futex_atomic_op\n"	\
 		"	.set	pop				\n"	\
 		"	" insn	"				\n"	\
@@ -164,13 +165,13 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 		  "i" (-EFAULT)
 		: "memory");
 	} else if (cpu_has_llsc) {
-		loongson_llsc_mb();
 		__asm__ __volatile__(
 		"# futex_atomic_cmpxchg_inatomic			\n"
 		"	.set	push					\n"
 		"	.set	noat					\n"
 		"	.set	push					\n"
 		"	.set	"MIPS_ISA_ARCH_LEVEL"			\n"
+		"	" __SYNC(full, loongson3_war) "			\n"
 		"1:	"user_ll("%1", "%3")"				\n"
 		"	bne	%1, %z4, 3f				\n"
 		"	.set	pop					\n"
@@ -178,8 +179,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 		"	.set	"MIPS_ISA_ARCH_LEVEL"			\n"
 		"2:	"user_sc("$1", "%2")"				\n"
 		"	beqz	$1, 1b					\n"
-		__WEAK_LLSC_MB
-		"3:							\n"
+		"3:	" __SYNC_ELSE(full, loongson3_war, __WEAK_LLSC_MB) "\n"
 		"	.insn						\n"
 		"	.set	pop					\n"
 		"	.section .fixup,\"ax\"				\n"
@@ -194,7 +194,6 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
 		: GCC_OFF_SMALL_ASM() (*uaddr), "Jr" (oldval), "Jr" (newval),
 		  "i" (-EFAULT)
 		: "memory");
-		loongson_llsc_mb();
 	} else
 		return -ENOSYS;
 
-- 
2.23.0


  parent reply	other threads:[~2019-09-30 23:09 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-30 23:08 [PATCH 00/37] MIPS: barriers & atomics cleanups Paul Burton
2019-09-30 23:08 ` [PATCH 01/37] MIPS: Unify sc beqz definition Paul Burton
2019-09-30 23:08 ` [PATCH 02/37] MIPS: Use compact branch for LL/SC loops on MIPSr6+ Paul Burton
2019-09-30 23:08 ` [PATCH 03/37] MIPS: barrier: Add __SYNC() infrastructure Paul Burton
2019-09-30 23:08 ` [PATCH 04/37] MIPS: barrier: Clean up rmb() & wmb() definitions Paul Burton
2019-09-30 23:08 ` [PATCH 05/37] MIPS: barrier: Clean up __smp_mb() definition Paul Burton
2019-09-30 23:08 ` [PATCH 06/37] MIPS: barrier: Remove fast_mb() Octeon #ifdef'ery Paul Burton
2019-09-30 23:08 ` [PATCH 07/37] MIPS: barrier: Clean up __sync() definition Paul Burton
2019-09-30 23:08 ` [PATCH 08/37] MIPS: barrier: Clean up sync_ginv() Paul Burton
2019-09-30 23:08 ` [PATCH 09/37] MIPS: atomic: Fix whitespace in ATOMIC_OP macros Paul Burton
2019-09-30 23:08 ` [PATCH 11/37] MIPS: atomic: Use one macro to generate 32b & 64b functions Paul Burton
2019-09-30 23:08 ` [PATCH 10/37] MIPS: atomic: Handle !kernel_uses_llsc first Paul Burton
2019-09-30 23:08 ` [PATCH 12/37] MIPS: atomic: Emit Loongson3 sync workarounds within asm Paul Burton
2019-09-30 23:08 ` [PATCH 13/37] MIPS: atomic: Use _atomic barriers in atomic_sub_if_positive() Paul Burton
2019-09-30 23:08 ` [PATCH 14/37] MIPS: atomic: Unify 32b & 64b sub_if_positive Paul Burton
2019-09-30 23:08 ` [PATCH 15/37] MIPS: atomic: Deduplicate 32b & 64b read, set, xchg, cmpxchg Paul Burton
2019-09-30 23:08 ` [PATCH 17/37] MIPS: bitops: Handle !kernel_uses_llsc first Paul Burton
2019-09-30 23:08 ` [PATCH 16/37] MIPS: bitops: Use generic builtin ffs/fls; drop cpu_has_clo_clz Paul Burton
2019-09-30 23:08 ` [PATCH 18/37] MIPS: bitops: Only use ins for bit 16 or higher Paul Burton
2019-09-30 23:08 ` [PATCH 19/37] MIPS: bitops: Use MIPS_ISA_REV, not #ifdefs Paul Burton
2019-09-30 23:08 ` [PATCH 20/37] MIPS: bitops: ins start position is always an immediate Paul Burton
2019-09-30 23:08 ` [PATCH 21/37] MIPS: bitops: Implement test_and_set_bit() in terms of _lock variant Paul Burton
2019-09-30 23:08 ` [PATCH 22/37] MIPS: bitops: Allow immediates in test_and_{set,clear,change}_bit Paul Burton
2019-09-30 23:08 ` [PATCH 23/37] MIPS: bitops: Use the BIT() macro Paul Burton
2019-09-30 23:08 ` [PATCH 24/37] MIPS: bitops: Avoid redundant zero-comparison for non-LLSC Paul Burton
2019-09-30 23:08 ` [PATCH 25/37] MIPS: bitops: Abstract LL/SC loops Paul Burton
2019-09-30 23:08 ` [PATCH 26/37] MIPS: bitops: Use BIT_WORD() & BITS_PER_LONG Paul Burton
2019-09-30 23:08 ` [PATCH 27/37] MIPS: bitops: Emit Loongson3 sync workarounds within asm Paul Burton
2019-09-30 23:08 ` [PATCH 28/37] MIPS: bitops: Use smp_mb__before_atomic in test_* ops Paul Burton
2019-09-30 23:08 ` [PATCH 29/37] MIPS: cmpxchg: Emit Loongson3 sync workarounds within asm Paul Burton
2019-09-30 23:08 ` [PATCH 30/37] MIPS: cmpxchg: Omit redundant barriers for Loongson3 Paul Burton
2019-09-30 23:08 ` Paul Burton [this message]
2019-09-30 23:08 ` [PATCH 32/37] MIPS: syscall: Emit Loongson3 sync workarounds within asm Paul Burton
2019-09-30 23:08 ` [PATCH 33/37] MIPS: barrier: Remove loongson_llsc_mb() Paul Burton
2019-09-30 23:08 ` [PATCH 34/37] MIPS: barrier: Make __smp_mb__before_atomic() a no-op for Loongson3 Paul Burton
2019-09-30 23:08 ` [PATCH 35/37] MIPS: genex: Add Loongson3 LL/SC workaround to ejtag_debug_handler Paul Burton
2019-09-30 23:08 ` [PATCH 36/37] MIPS: genex: Don't reload address unnecessarily Paul Burton
2019-09-30 23:08 ` [PATCH 37/37] MIPS: Check Loongson3 LL/SC errata workaround correctness Paul Burton

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