From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- arch/arc/lib/strcpy-700.S | 67 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 arch/arc/lib/strcpy-700.S (limited to 'arch/arc/lib/strcpy-700.S') diff --git a/arch/arc/lib/strcpy-700.S b/arch/arc/lib/strcpy-700.S new file mode 100644 index 000000000..6e2294d13 --- /dev/null +++ b/arch/arc/lib/strcpy-700.S @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +/* If dst and src are 4 byte aligned, copy 8 bytes at a time. + If the src is 4, but not 8 byte aligned, we first read 4 bytes to get + it 8 byte aligned. Thus, we can do a little read-ahead, without + dereferencing a cache line that we should not touch. + Note that short and long instructions have been scheduled to avoid + branch stalls. + The beq_s to r3z could be made unaligned & long to avoid a stall + there, but the it is not likely to be taken often, and it + would also be likey to cost an unaligned mispredict at the next call. */ + +#include + +ENTRY_CFI(strcpy) + or r2,r0,r1 + bmsk_s r2,r2,1 + brne.d r2,0,charloop + mov_s r10,r0 + ld_s r3,[r1,0] + mov r8,0x01010101 + bbit0.d r1,2,loop_start + ror r12,r8 + sub r2,r3,r8 + bic_s r2,r2,r3 + tst_s r2,r12 + bne r3z + mov_s r4,r3 + .balign 4 +loop: + ld.a r3,[r1,4] + st.ab r4,[r10,4] +loop_start: + ld.a r4,[r1,4] + sub r2,r3,r8 + bic_s r2,r2,r3 + tst_s r2,r12 + bne_s r3z + st.ab r3,[r10,4] + sub r2,r4,r8 + bic r2,r2,r4 + tst r2,r12 + beq loop + mov_s r3,r4 +#ifdef __LITTLE_ENDIAN__ +r3z: bmsk.f r1,r3,7 + lsr_s r3,r3,8 +#else +r3z: lsr.f r1,r3,24 + asl_s r3,r3,8 +#endif + bne.d r3z + stb.ab r1,[r10,1] + j_s [blink] + + .balign 4 +charloop: + ldb.ab r3,[r1,1] + + + brne.d r3,0,charloop + stb.ab r3,[r10,1] + j [blink] +END_CFI(strcpy) -- cgit v1.3.1