[src/trunk]: src/sys/arch/sh3 _cpu_exception_suspend - return old SR

To: source-changes-hg%NetBSD.org@localhost
Subject: [src/trunk]: src/sys/arch/sh3 _cpu_exception_suspend - return old SR
From: uwe <uwe%NetBSD.org@localhost>
Date: Mon, 08 Nov 2021 11:52:31 +0000

details:   https://anonhg.NetBSD.org/src/rev/08d255286508
branches:  trunk
changeset: 1012606:08d255286508
user:      uwe <uwe%NetBSD.org@localhost>
date:      Mon Aug 03 16:43:44 2020 +0000

description:
_cpu_exception_suspend - return old SR

In a typical use case we do a very short code sequence with PSL_BL set
and restore the old PSL_BL value with _cpu_exception_resume that does
the full read/mask/set dance.  In reality we are just restoring SR to
its old state as no other modifications to SR can possibly happen.  So
return old SR and let the caller restore it in one instruction.

diffstat:

 sys/arch/sh3/include/psl.h     |   8 +++++++-
 sys/arch/sh3/sh3/clock.c       |  14 +++++++-------
 sys/arch/sh3/sh3/locore_subr.S |   8 ++++----
 sys/arch/sh3/sh3/mmu_sh4.c     |  28 ++++++++++++++--------------
 4 files changed, 32 insertions(+), 26 deletions(-)

diffs (211 lines):

diff -r aadb0df6e2e7 -r 08d255286508 sys/arch/sh3/include/psl.h
--- a/sys/arch/sh3/include/psl.h        Mon Aug 03 15:43:31 2020 +0000
+++ b/sys/arch/sh3/include/psl.h        Mon Aug 03 16:43:44 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: psl.h,v 1.11 2011/01/26 19:07:42 uwe Exp $     */
+/*     $NetBSD: psl.h,v 1.12 2020/08/03 16:43:44 uwe Exp $     */
 
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
@@ -62,6 +62,12 @@
 #ifdef _KERNEL
 #ifndef _LOCORE
 
+static inline __always_inline void
+_cpu_set_sr(uint32_t sr)
+{
+    __asm volatile("ldc %0, sr" :: "r"(sr));
+}
+
 /* SR.IMASK */
 int _cpu_intr_raise(int);
 int _cpu_intr_suspend(void);
diff -r aadb0df6e2e7 -r 08d255286508 sys/arch/sh3/sh3/clock.c
--- a/sys/arch/sh3/sh3/clock.c  Mon Aug 03 15:43:31 2020 +0000
+++ b/sys/arch/sh3/sh3/clock.c  Mon Aug 03 16:43:44 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: clock.c,v 1.40 2009/03/18 10:22:36 cegger Exp $        */
+/*     $NetBSD: clock.c,v 1.41 2020/08/03 16:43:44 uwe Exp $   */
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.40 2009/03/18 10:22:36 cegger Exp $");
+__KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.41 2020/08/03 16:43:44 uwe Exp $");
 
 #include "opt_pclock.h"
 #include "opt_hz.h"
@@ -111,7 +111,7 @@
 void
 sh_clock_init(int flags)
 {
-       uint32_t s, t0, cnt_1s;
+       uint32_t sr, t0, cnt_1s;
 
        sh_clock.flags = flags;
 
@@ -143,12 +143,12 @@
                _reg_bset_1(SH_(RCR2), SH_RCR2_ENABLE);
        }
 
-       s = _cpu_exception_suspend();
+       sr = _cpu_exception_suspend();
        _cpu_spin(1);   /* load function on cache. */
        TMU_START(0);
        _cpu_spin(10000000);
        t0 = TMU_ELAPSED(0);
-       _cpu_exception_resume(s);
+       _cpu_set_sr(sr);
 
        sh_clock.cpucycle_1us = (sh_clock.tmuclk * 10) / t0;
 
@@ -166,14 +166,14 @@
 
                /* set TMU channel 1 source to PCLOCK / 4 */
                _reg_write_2(SH_(TCR1), TCR_TPSC_P4);
-               s = _cpu_exception_suspend();
+               sr = _cpu_exception_suspend();
                _cpu_spin(1);   /* load function on cache. */
                TMU_START(0);
                TMU_START(1);
                _cpu_spin(cnt_1s); /* 1 sec. */
                t0 = TMU_ELAPSED(0);
                t1 = TMU_ELAPSED(1);
-               _cpu_exception_resume(s);
+               _cpu_set_sr(sr);
 
                sh_clock.pclock
                    = ((uint64_t)t1 * 4 * SH_RTC_CLOCK + t0/2) / t0;
diff -r aadb0df6e2e7 -r 08d255286508 sys/arch/sh3/sh3/locore_subr.S
--- a/sys/arch/sh3/sh3/locore_subr.S    Mon Aug 03 15:43:31 2020 +0000
+++ b/sys/arch/sh3/sh3/locore_subr.S    Mon Aug 03 16:43:44 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore_subr.S,v 1.59 2020/08/03 03:34:11 uwe Exp $     */
+/*     $NetBSD: locore_subr.S,v 1.60 2020/08/03 16:43:44 uwe Exp $     */
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -40,7 +40,7 @@
 #include <sh3/mmu_sh3.h>
 #include <sh3/mmu_sh4.h>
 
-__KERNEL_RCSID(0, "$NetBSD: locore_subr.S,v 1.59 2020/08/03 03:34:11 uwe Exp $")
+__KERNEL_RCSID(0, "$NetBSD: locore_subr.S,v 1.60 2020/08/03 16:43:44 uwe Exp $")
 
 
 /*
@@ -305,8 +305,8 @@
        swap.w  r1, r1          /* r1 = PSL_BL */
        or      r1, r2          /* r2 |= PSL_BL */
        ldc     r2, sr          /* SR = r2 */
-       rts
-        and    r1, r0          /* r0 &= 0x10000000 */
+       rts                     /* return old SR */
+        nop
        SET_ENTRY_SIZE(_cpu_exception_suspend)
 
 
diff -r aadb0df6e2e7 -r 08d255286508 sys/arch/sh3/sh3/mmu_sh4.c
--- a/sys/arch/sh3/sh3/mmu_sh4.c        Mon Aug 03 15:43:31 2020 +0000
+++ b/sys/arch/sh3/sh3/mmu_sh4.c        Mon Aug 03 16:43:44 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: mmu_sh4.c,v 1.14 2012/02/12 16:34:10 matt Exp $        */
+/*     $NetBSD: mmu_sh4.c,v 1.15 2020/08/03 16:43:44 uwe Exp $ */
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: mmu_sh4.c,v 1.14 2012/02/12 16:34:10 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: mmu_sh4.c,v 1.15 2020/08/03 16:43:44 uwe Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -81,10 +81,10 @@
 sh4_tlb_invalidate_addr(int asid, vaddr_t va)
 {
        uint32_t pteh;
-       int s;
+       int sr;
 
        va &= SH4_PTEH_VPN_MASK;
-       s = _cpu_exception_suspend();
+       sr = _cpu_exception_suspend();
 
        /* Save current ASID */
        pteh = _reg_read_4(SH4_PTEH);
@@ -98,16 +98,16 @@
        /* Restore ASID */
        _reg_write_4(SH4_PTEH, pteh);
 
-       _cpu_exception_resume(s);
+       _cpu_set_sr(sr);
 }
 
 void
 sh4_tlb_invalidate_asid(int asid)
 {
        uint32_t a;
-       int e, s;
+       int e, sr;
 
-       s = _cpu_exception_suspend();
+       sr = _cpu_exception_suspend();
        /* Invalidate entry attribute to ASID */
        RUN_P2;
        for (e = 0; e < SH4_UTLB_ENTRY; e++) {
@@ -118,16 +118,16 @@
 
        __sh4_itlb_invalidate_all();
        RUN_P1;
-       _cpu_exception_resume(s);
+       _cpu_set_sr(sr);
 }
 
 void
 sh4_tlb_invalidate_all(void)
 {
        uint32_t a;
-       int e, eend, s;
+       int e, eend, sr;
 
-       s = _cpu_exception_suspend();
+       sr = _cpu_exception_suspend();
        /* If non-wired entry limit is zero, clear all entry. */
        a = _reg_read_4(SH4_MMUCR) & SH4_MMUCR_URB_MASK;
        eend = a ? (a >> SH4_MMUCR_URB_SHIFT) : SH4_UTLB_ENTRY;
@@ -145,7 +145,7 @@
        _reg_write_4(SH4_ITLB_DA1 | (2 << SH4_ITLB_E_SHIFT), 0);
        _reg_write_4(SH4_ITLB_DA1 | (3 << SH4_ITLB_E_SHIFT), 0);
        RUN_P1;
-       _cpu_exception_resume(s);
+       _cpu_set_sr(sr);
 }
 
 void
@@ -153,11 +153,11 @@
 {
        uint32_t oasid;
        uint32_t ptel;
-       int s;
+       int sr;
 
        KDASSERT(asid < 0x100 && (pte & ~PGOFSET) != 0 && va != 0);
 
-       s = _cpu_exception_suspend();
+       sr = _cpu_exception_suspend();
        /* Save old ASID */
        oasid = _reg_read_4(SH4_PTEH) & SH4_PTEH_ASID_MASK;
 
@@ -180,5 +180,5 @@
        /* Restore old ASID */
        if (asid != oasid)
                _reg_write_4(SH4_PTEH, oasid);
-       _cpu_exception_resume(s);
+       _cpu_set_sr(sr);
 }

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