[src/trunk]: src/sys/arch/aarch64/aarch64 Adjust register usage a bit and unb...

To: source-changes-hg%NetBSD.org@localhost
Subject: [src/trunk]: src/sys/arch/aarch64/aarch64 Adjust register usage a bit and unb...
From: skrll <skrll%NetBSD.org@localhost>
Date: Mon, 08 Nov 2021 06:52:24 +0000

details:   https://anonhg.NetBSD.org/src/rev/b7cddfafd05c
branches:  trunk
changeset: 993320:b7cddfafd05c
user:      skrll <skrll%NetBSD.org@localhost>
date:      Tue Sep 04 15:50:25 2018 +0000

description:
Adjust register usage a bit and unbreak DEBUG_MMU as a result.

The change moves to using callee-saved registers more so that any call
into C will have them preserved (if they're used or not).  It's safe
to use stack as it's setup very early for BP/APs.

Discussed with ryo@

diffstat:

 sys/arch/aarch64/aarch64/locore.S |  130 +++++++++++++++++++++++--------------
 1 files changed, 79 insertions(+), 51 deletions(-)

diffs (232 lines):

diff -r 14d7eec66629 -r b7cddfafd05c sys/arch/aarch64/aarch64/locore.S
--- a/sys/arch/aarch64/aarch64/locore.S Tue Sep 04 15:48:44 2018 +0000
+++ b/sys/arch/aarch64/aarch64/locore.S Tue Sep 04 15:50:25 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore.S,v 1.21 2018/08/30 10:38:01 maxv Exp $ */
+/*     $NetBSD: locore.S,v 1.22 2018/09/04 15:50:25 skrll Exp $        */
 
 /*
  * Copyright (c) 2017 Ryo Shimizu <ryo%nerv.org@localhost>
@@ -35,7 +35,7 @@
 #include <aarch64/hypervisor.h>
 #include "assym.h"
 
-RCSID("$NetBSD: locore.S,v 1.21 2018/08/30 10:38:01 maxv Exp $")
+RCSID("$NetBSD: locore.S,v 1.22 2018/09/04 15:50:25 skrll Exp $")
 
 /* #define DEBUG_LOCORE */
 /* #define DEBUG_MMU */
@@ -496,22 +496,25 @@
  *    .ascii    "Hello\r\n\0" <- wouldn't return here
  *    .align    2
  *    nop                     <- return to here
+ *
+ * x0 is preserved despite being caller saved.
  */
 ENTRY_NP(xprint)
-       mov     x11, lr
-       mov     x12, x0
-       ldrb    w0, [x11], #1
+       stp     x0, x19, [sp, #-16]!
+
+       mov     x19, lr
+       ldrb    w0, [x19], #1
        cbz     w0, 2f
 
 1:
        bl      uartputc
-       ldrb    w0, [x11], #1
+       ldrb    w0, [x19], #1
        cbnz    w0, 1b
 
 2:
-       add     x11, x11, #3
-       bic     lr, x11, #3
-       mov     x0, x12
+       add     x19, x19, #3
+       bic     lr, x19, #3
+       ldp     x0, x19, [sp], #16
        ret
 END(xprint)
 
@@ -527,47 +530,52 @@
        ret
 END(uartputs)
 
+/* x0 is preserved despite being caller saved. */
 ENTRY_NP(_print_x0)
        stp     x0, lr, [sp, #-16]!
-       stp     x4, x5, [sp, #-16]!
-       stp     x6, x7, [sp, #-16]!
+       stp     x20, x21, [sp, #-16]!
 
-       mov     x7, x0          /* number to display */
-       mov     x4, #60         /* num of shift */
-       mov     x5, #0xf        /* mask */
+       mov     x21, x0         /* number to display */
+       mov     x20, #60        /* num of shift */
 1:
-       ror     x0, x7, x4
-       and     x0, x0, x5
+       ror     x0, x21, x20
+       and     x0, x0, #0xf
        cmp     x0, #10
        blt     2f
        add     x0, x0, #('a' - 10 - '0')
 2:     add     x0, x0, #'0'
        bl      uartputc
-       subs    x4, x4, #4
+       subs    x20, x20, #4
        bge     1b
 
-       ldp     x6, x7, [sp], #16
-       ldp     x4, x5, [sp], #16
+       ldp     x20, x21, [sp], #16
        ldp     x0, lr, [sp], #16
        ret
 END(_print_x0)
 
+/* Preserve x{0,1,2} descpite them being caller saved */
 ENTRY_NP(print_x0)
        stp     x0, lr, [sp, #-16]!
+       stp     x1, x2, [sp, #-16]!
        bl      _print_x0
        PRINT("\r\n")
+       ldp     x1, x2, [sp], #16
        ldp     x0, lr, [sp], #16
        ret
 END(print_x0)
 
+/* Preserve x{0,1,2} descpite them being caller saved */
 ENTRY_NP(printn_x1)
        stp     x0, lr, [sp, #-16]!
+       stp     x1, x2, [sp, #-16]!
        mov     x0, x1
        bl      _print_x0
+       ldp     x1, x2, [sp], #16
        ldp     x0, lr, [sp], #16
        ret
 END(printn_x1)
 
+/* Preserve x{0,1,2} descpite them being caller saved */
 ENTRY_NP(print_x2)
        stp     x0, lr, [sp, #-16]!
        mov     x0, x2
@@ -772,32 +780,42 @@
  */
 ENTRY_NP(l1_setblocks)
        stp     x0, lr, [sp, #-16]!
+       stp     x19, x20, [sp, #-16]!
+       stp     x21, x22, [sp, #-16]!
 
-       and     x2, x2, #L1_ADDR_BITS
-       mov     x8, #L1_BLOCK
-       orr     x2, x2, x8
-       orr     x2, x2, x3
-       mov     x8, #(LX_BLKPAG_AF|LX_BLKPAG_AP_RW)
-       orr     x2, x2, x8
+       mov     x19, x0                 /* l1table */
+       mov     x22, x4                 /* N entries */
+
+       and     x21, x2, #L1_ADDR_BITS  /* PA[38:30] */
+       mov     x9, #L1_BLOCK
+       orr     x21, x21, x9
+       orr     x21, x21, x3            /* add in attr */
+       mov     x9, #(LX_BLKPAG_AF|LX_BLKPAG_AP_RW)
+       orr     x21, x21, x9
 #ifdef MULTIPROCESSOR
-       orr     x2, x2, #LX_BLKPAG_SH_IS
+       orr     x21, x21, #LX_BLKPAG_SH_IS
 #endif
-       and     x1, x1, #L1_ADDR_BITS
-       lsr     x1, x1, #L1_SHIFT
+       and     x20, x1, #L1_ADDR_BITS  /* VA[38:30] */
+       lsr     x20, x20, #L1_SHIFT
 1:
-       str     x2, [x0, x1, lsl #3]    /* l1table[x1] = x2 */
+       str     x21, [x19, x20, lsl #3] /* l1table[x20] = x21 */
+
 #ifdef DEBUG_MMU
        PRINT("L1 entry[")
-       bl printn_x1
+       mov     x1, x19
+       bl      printn_x1
        PRINT("]=")
-       bl print_x2
+       mov     x2, x21
+       bl      print_x2
 #endif
-       mov     x3, #L1_SIZE
-       add     x2, x2, x3
-       add     x1, x1, #1
-       subs    x4, x4, #1
+       mov     x9, #L1_SIZE
+       add     x21, x21, x9
+       add     x20, x20, #1
+       subs    x22, x22, #1
        bne     1b
 
+       ldp     x21, x22, [sp], #16
+       ldp     x19, x20, [sp], #16
        ldp     x0, lr, [sp], #16
        ret
 END(l1_setblocks)
@@ -837,32 +855,42 @@
  */
 ENTRY_NP(l2_setblocks)
        stp     x0, lr, [sp, #-16]!
+       stp     x19, x20, [sp, #-16]!
+       stp     x21, x22, [sp, #-16]!
 
-       and     x2, x2, #L2_BLOCK_MASK
-       mov     x8, #L2_BLOCK
-       orr     x2, x2, x8
-       orr     x2, x2, x3
-       mov     x8, #(LX_BLKPAG_AF|LX_BLKPAG_AP_RW)
-       orr     x2, x2, x8
+       mov     x19, x0                 /* l1table */
+       mov     x22, x4                 /* N entries */
+
+       and     x21, x2, #L2_BLOCK_MASK
+       mov     x9, #L2_BLOCK
+       orr     x21, x21, x9
+       orr     x21, x21, x3            /* Add attr bits */
+       mov     x9, #(LX_BLKPAG_AF|LX_BLKPAG_AP_RW)
+       orr     x21, x21, x9
 #ifdef MULTIPROCESSOR
-       orr     x2, x2, #LX_BLKPAG_SH_IS
+       orr     x21, x21, #LX_BLKPAG_SH_IS
 #endif
-       and     x1, x1, #L2_ADDR_BITS
-       lsr     x1, x1, #L2_SHIFT
+       and     x20, x1, #L2_ADDR_BITS
+       lsr     x20, x20, #L2_SHIFT
 1:
-       str     x2, [x0, x1, lsl #3]    /* l2table[x1] = x2 */
+       str     x21, [x19, x20, lsl #3] /* l2table[x20] = x21 */
+
 #ifdef DEBUG_MMU
        PRINT("L2 entry[")
-       bl printn_x1
+       mov     x1, x19
+       bl      printn_x1
        PRINT("]=")
-       bl print_x2
+       mov     x2, x21
+       bl      print_x2
 #endif
-       mov     x3, #L2_SIZE
-       add     x2, x2, x3
-       add     x1, x1, #1
-       subs    x4, x4, #1
+       mov     x9, #L2_SIZE
+       add     x21, x21, x9
+       add     x20, x20, #1
+       subs    x22, x22, #1
        bne     1b
 
+       ldp     x21, x22, [sp], #16
+       ldp     x19, x20, [sp], #16
        ldp     x0, lr, [sp], #16
        ret
 END(l2_setblocks)

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