[src/trunk]: src/sys/arch/arm/arm32 Rearrange the exit path so that we don't ...

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

details:   https://anonhg.NetBSD.org/src/rev/ff5fa0b426cf
branches:  trunk
changeset: 534929:ff5fa0b426cf
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Tue Aug 06 19:20:29 2002 +0000

description:
Rearrange the exit path so that we don't do a idcache_wbinv_all *twice*
when a process exits.

diffstat:

 sys/arch/arm/arm32/cpuswitch.S |  56 ++++++++++++++++++++++++++++++-----------
 1 files changed, 41 insertions(+), 15 deletions(-)

diffs (118 lines):

diff -r 2b67cef2610a -r ff5fa0b426cf sys/arch/arm/arm32/cpuswitch.S
--- a/sys/arch/arm/arm32/cpuswitch.S    Tue Aug 06 17:44:35 2002 +0000
+++ b/sys/arch/arm/arm32/cpuswitch.S    Tue Aug 06 19:20:29 2002 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: cpuswitch.S,v 1.8 2002/08/06 17:44:35 thorpej Exp $    */
+/*     $NetBSD: cpuswitch.S,v 1.9 2002/08/06 19:20:29 thorpej Exp $    */
 
 /*
  * Copyright (c) 1994-1998 Mark Brinicombe.
@@ -467,26 +467,26 @@
        teq     r1, r6
        beq     switch_return
 
+       /* Remember the old process in r0 */
+       mov     r0, r1
+
        /*
         * If the curproc on entry to cpu_switch was zero then the
         * process that called it was exiting. This means that we do
         * not need to save the current context. Instead we can jump
         * straight to restoring the context for the new process.
         */
-       teq     r1, #0x00000000
+       teq     r0, #0x00000000
        beq     switch_exited
 
-       /* rem: r1 = old proc */
+       /* rem: r0 = old proc */
        /* rem: r6 = new process */
        /* rem: interrupts are enabled */
 
        /* Stage two : Save old context */
 
-       /* Remember the old process in r0 */
-       mov     r0, r1
-
        /* Get the user structure for the old process. */
-       ldr     r1, [r1, #(P_ADDR)]
+       ldr     r1, [r0, #(P_ADDR)]
 
        /* Save all the registers in the old process's pcb */
        add     r7, r1, #(PCB_R8)
@@ -512,27 +512,36 @@
 
        /* What else needs to be saved  Only FPA stuff when that is supported */
 
+       /* r1 now free! */
+
        /* Third phase : restore saved context */
 
-switch_exited:
-       /* Don't allow user space access beween the purge and the switch */
+       /* rem: r0 = old proc */
+       /* rem: r6 = new process */
+       /* rem: interrupts are enabled */
+
+       /*
+        * Don't allow user space access between the purge and the switch.
+        */
        ldr     r3, Lblock_userspace_access
-       ldr     r2, [r3]
-       orr     r0, r2, #1
-       str     r0, [r3]
+       mov     r1, #0x00000001
+       mov     r2, #0x00000000
+       str     r1, [r3]
 
        stmfd   sp!, {r0-r3}
-       ldr     r0, Lcpufuncs
+       ldr     r1, Lcpufuncs
        add     lr, pc, #Lcs_cache_purged - . - 8
-       ldr     pc, [r0, #CF_IDCACHE_WBINV_ALL]
+       ldr     pc, [r1, #CF_IDCACHE_WBINV_ALL]
 
 Lcs_cache_purged:
        ldmfd   sp!, {r0-r3}
 
+Lcs_cache_purge_skipped:
        /* At this point we need to kill IRQ's again. */
        IRQdisable
 
-       /* Interrupts are disabled so we can allow user space accesses again
+       /*
+        * Interrupts are disabled so we can allow user space accesses again
         * as none will occur until interrupts are re-enabled after the
         * switch.
         */
@@ -591,6 +600,16 @@
         */
        ldmfd   sp!, {r4-r7, pc}
 
+switch_exited:
+       /*
+        * We skip the cache purge because switch_exit() already did
+        * it.  Load up registers the way Lcs_cache_purge_skipped
+        * expects.  Userspace access already blocked in switch_exit().
+        */
+       ldr     r3, Lblock_userspace_access
+       mov     r2, #0x00000000
+       b       Lcs_cache_purge_skipped
+
 Lproc0:
        .word   _C_LABEL(proc0)
 
@@ -620,6 +639,13 @@
 /*     ldr     r0, Lcurpcb
        str     r2, [r0]*/
 
+       /*
+        * Don't allow user space access between the purge and the switch.
+        */
+       ldr     r0, Lblock_userspace_access
+       mov     r2, #0x00000001
+       str     r2, [r0]
+
        /* Switch to proc0 context */
 
        stmfd   sp!, {r0-r3}