[src/trunk]: src/sys/arch/alpha/alpha Provide a BWX version of alpha_copystr(...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/39480b42bc4d
branches:  trunk
changeset: 1022174:39480b42bc4d
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Wed Jul 07 03:30:35 2021 +0000

description:
Provide a BWX version of alpha_copystr() and patch it into place if
the system supports the BWX extension.  The inner loop of the BWX
version is 42% shorter than the non-BWX version (7 vs 12 insns).

diffstat:

 sys/arch/alpha/alpha/locore.s |  43 +++++++++++++++++++++++++++++++++++++++++--
 sys/arch/alpha/alpha/patch.c  |  12 ++++++++++--
 2 files changed, 51 insertions(+), 4 deletions(-)

diffs (111 lines):

diff -r bd40cf0dccf7 -r 39480b42bc4d sys/arch/alpha/alpha/locore.s
--- a/sys/arch/alpha/alpha/locore.s     Wed Jul 07 03:24:26 2021 +0000
+++ b/sys/arch/alpha/alpha/locore.s     Wed Jul 07 03:30:35 2021 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.s,v 1.138 2021/07/07 02:44:04 thorpej Exp $ */
+/* $NetBSD: locore.s,v 1.139 2021/07/07 03:30:35 thorpej Exp $ */
 
 /*-
  * Copyright (c) 1999, 2000, 2019 The NetBSD Foundation, Inc.
@@ -67,7 +67,7 @@
 
 #include <machine/asm.h>
 
-__KERNEL_RCSID(0, "$NetBSD: locore.s,v 1.138 2021/07/07 02:44:04 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: locore.s,v 1.139 2021/07/07 03:30:35 thorpej Exp $");
 
 #include "assym.h"
 
@@ -902,6 +902,44 @@
 /*
  * alpha_copystr(const void *from, void *to, size_t len, size_t *donep)
  */
+       .arch   ev56
+LEAF(alpha_copystr_bwx, 4)
+       LDGP(pv)
+
+       mov     a2, t0                  /* t0 = i = len */
+       beq     a2, 5f                  /* if (len == 0), bail */
+
+1:     ldbu    t1, 0(a0)               /* t1 = *from */
+       subl    a2, 1, a2               /* len-- */
+       addq    a0, 1, a0               /* from++ */
+       stb     t1, 0(a1)               /* *to = t1 */
+       beq     t1, 2f                  /* if (t1 == '\0'), bail out */
+       addq    a1, 1, a1               /* to++ */
+       bne     a2, 1b                  /* if (len != 0), copy more */
+
+2:     beq     a3, 3f                  /* if (lenp != NULL) */
+       subl    t0, a2, t0              /* *lenp = (i - len) */
+       stq     t0, 0(a3)
+3:     bne     t1, 4f                  /* *from != '\0'; leave in a huff */
+
+       mov     zero, v0                /* return 0. */
+       RET
+
+4:     ldiq    v0, ENAMETOOLONG
+       RET
+
+5:     ldiq    t1, 1                   /* fool the test above... */
+       br      zero, 2b
+
+       nop                             /* pad to same length as... */
+       nop                             /* non-BWX version. */
+       nop
+       nop
+       nop
+       EXPORT(alpha_copystr_bwx_end)
+       END(alpha_copystr_bwx)
+       .arch   ev4
+
 LEAF(alpha_copystr, 4)
        LDGP(pv)
 
@@ -935,6 +973,7 @@
 
 5:     ldiq    t1, 1                   /* fool the test above... */
        br      zero, 2b
+       EXPORT(alpha_copystr_end)
        END(alpha_copystr)
 
 NESTED(copyinstr, 4, 16, ra, IM_RA|IM_S0, 0)
diff -r bd40cf0dccf7 -r 39480b42bc4d sys/arch/alpha/alpha/patch.c
--- a/sys/arch/alpha/alpha/patch.c      Wed Jul 07 03:24:26 2021 +0000
+++ b/sys/arch/alpha/alpha/patch.c      Wed Jul 07 03:30:35 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: patch.c,v 1.5 2020/09/04 03:41:49 thorpej Exp $        */
+/*     $NetBSD: patch.c,v 1.6 2021/07/07 03:30:35 thorpej Exp $        */
 
 /*-
  * Copyright (c) 2007 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: patch.c,v 1.5 2020/09/04 03:41:49 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: patch.c,v 1.6 2021/07/07 03:30:35 thorpej Exp $");
 
 #include "opt_multiprocessor.h"
 
@@ -57,6 +57,9 @@
 void   _membar_sync_mp(void);
 void   _membar_sync_mp_end(void);
 
+extern char alpha_copystr_bwx[], alpha_copystr_bwx_end[];
+extern char alpha_copystr[], alpha_copystr_end[];
+
 static void __attribute__((__unused__))
 patchfunc(void *from_s, void *from_e, void *to_s, void *to_e)
 {
@@ -85,6 +88,11 @@
         * kernel code.
         */
 
+       if (cpu_amask & ALPHA_AMASK_BWX) {
+               patchfunc(alpha_copystr_bwx, alpha_copystr_bwx_end,
+                   alpha_copystr, alpha_copystr_end);
+       }
+
 #if defined(MULTIPROCESSOR)
        if (is_mp) {
                KASSERT(curcpu()->ci_flags & CPUF_PRIMARY);