From c838b580ca9dcf16b07aa72bb61a914e9db0fd2c Mon Sep 17 00:00:00 2001
From: Paul Burton <paul.burton@mips.com>
Date: Fri, 5 Apr 2019 22:50:35 +0000
Subject: [PATCH] MIPS: jump_label: Remove redundant nops
Both arch_static_branch() & arch_static_branch_jump() emit a control
transfer instruction (ie. branch or jump) without disabling assembler
re-ordering. As such the assembler will automatically fill their delay
slots.
Both functions follow their branch or jump with an explicit nop that at
first appears to be there to fill the delay slot, but given that the
assembler will do that the explicit nops serve no purpose & we end up
with our branch or jump followed by 2 nops. Remove the redundant nops.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
---
arch/mips/include/asm/jump_label.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index e4456e450f946..df04449b261b0 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -29,7 +29,7 @@
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
asm_volatile_goto("1:\t" B_INSN " 2f\n\t"
- "2:\tnop\n\t"
+ "2:\t.insn\n\t"
".pushsection __jump_table, \"aw\"\n\t"
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"
@@ -43,7 +43,6 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
asm_volatile_goto("1:\tj %l[l_yes]\n\t"
- "nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"
--
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