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/alpha/lib/memset.S | 133 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 133 insertions(+) create mode 100644 arch/alpha/lib/memset.S (limited to 'arch/alpha/lib/memset.S') diff --git a/arch/alpha/lib/memset.S b/arch/alpha/lib/memset.S new file mode 100644 index 000000000..9075d6918 --- /dev/null +++ b/arch/alpha/lib/memset.S @@ -0,0 +1,133 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * linux/arch/alpha/lib/memset.S + * + * This is an efficient (and small) implementation of the C library "memset()" + * function for the alpha. + * + * (C) Copyright 1996 Linus Torvalds + * + * This routine is "moral-ware": you are free to use it any way you wish, and + * the only obligation I put on you is a moral one: if you make any improvements + * to the routine, please send me your improvements for me to use similarly. + * + * The scheduling comments are according to the EV5 documentation (and done by + * hand, so they might well be incorrect, please do tell me about it..) + */ +#include + .set noat + .set noreorder +.text + .globl memset + .globl __memset + .globl ___memset + .globl __memset16 + .globl __constant_c_memset + + .ent ___memset +.align 5 +___memset: + .frame $30,0,$26,0 + .prologue 0 + + and $17,255,$1 /* E1 */ + insbl $17,1,$17 /* .. E0 */ + bis $17,$1,$17 /* E0 (p-c latency, next cycle) */ + sll $17,16,$1 /* E1 (p-c latency, next cycle) */ + + bis $17,$1,$17 /* E0 (p-c latency, next cycle) */ + sll $17,32,$1 /* E1 (p-c latency, next cycle) */ + bis $17,$1,$17 /* E0 (p-c latency, next cycle) */ + ldq_u $31,0($30) /* .. E1 */ + +.align 5 +__constant_c_memset: + addq $18,$16,$6 /* E0 */ + bis $16,$16,$0 /* .. E1 */ + xor $16,$6,$1 /* E0 */ + ble $18,end /* .. E1 */ + + bic $1,7,$1 /* E0 */ + beq $1,within_one_quad /* .. E1 (note EV5 zero-latency forwarding) */ + and $16,7,$3 /* E0 */ + beq $3,aligned /* .. E1 (note EV5 zero-latency forwarding) */ + + ldq_u $4,0($16) /* E0 */ + bis $16,$16,$5 /* .. E1 */ + insql $17,$16,$2 /* E0 */ + subq $3,8,$3 /* .. E1 */ + + addq $18,$3,$18 /* E0 $18 is new count ($3 is negative) */ + mskql $4,$16,$4 /* .. E1 (and possible load stall) */ + subq $16,$3,$16 /* E0 $16 is new aligned destination */ + bis $2,$4,$1 /* .. E1 */ + + bis $31,$31,$31 /* E0 */ + ldq_u $31,0($30) /* .. E1 */ + stq_u $1,0($5) /* E0 */ + bis $31,$31,$31 /* .. E1 */ + +.align 4 +aligned: + sra $18,3,$3 /* E0 */ + and $18,7,$18 /* .. E1 */ + bis $16,$16,$5 /* E0 */ + beq $3,no_quad /* .. E1 */ + +.align 3 +loop: + stq $17,0($5) /* E0 */ + subq $3,1,$3 /* .. E1 */ + addq $5,8,$5 /* E0 */ + bne $3,loop /* .. E1 */ + +no_quad: + bis $31,$31,$31 /* E0 */ + beq $18,end /* .. E1 */ + ldq $7,0($5) /* E0 */ + mskqh $7,$6,$2 /* .. E1 (and load stall) */ + + insqh $17,$6,$4 /* E0 */ + bis $2,$4,$1 /* .. E1 */ + stq $1,0($5) /* E0 */ + ret $31,($26),1 /* .. E1 */ + +.align 3 +within_one_quad: + ldq_u $1,0($16) /* E0 */ + insql $17,$16,$2 /* E1 */ + mskql $1,$16,$4 /* E0 (after load stall) */ + bis $2,$4,$2 /* E0 */ + + mskql $2,$6,$4 /* E0 */ + mskqh $1,$6,$2 /* .. E1 */ + bis $2,$4,$1 /* E0 */ + stq_u $1,0($16) /* E0 */ + +end: + ret $31,($26),1 /* E1 */ + .end ___memset +EXPORT_SYMBOL(___memset) +EXPORT_SYMBOL(__constant_c_memset) + + .align 5 + .ent __memset16 +__memset16: + .prologue 0 + + inswl $17,0,$1 /* E0 */ + inswl $17,2,$2 /* E0 */ + inswl $17,4,$3 /* E0 */ + or $1,$2,$1 /* .. E1 */ + inswl $17,6,$4 /* E0 */ + or $1,$3,$1 /* .. E1 */ + or $1,$4,$17 /* E0 */ + br __constant_c_memset /* .. E1 */ + + .end __memset16 +EXPORT_SYMBOL(__memset16) + +memset = ___memset +__memset = ___memset + EXPORT_SYMBOL(memset) + EXPORT_SYMBOL(__memset) -- cgit v1.3.1