[src/trunk]: src/sys/arch/hppa/hppa Comment improvements.

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

details:   https://anonhg.NetBSD.org/src/rev/f711956f8f06
branches:  trunk
changeset: 752898:f711956f8f06
user:      skrll <skrll%NetBSD.org@localhost>
date:      Wed Mar 10 18:17:42 2010 +0000

description:
Comment improvements.

diffstat:

 sys/arch/hppa/hppa/trap.S |  34 +++++++++-------------------------
 1 files changed, 9 insertions(+), 25 deletions(-)

diffs (76 lines):

diff -r 4299406d9844 -r f711956f8f06 sys/arch/hppa/hppa/trap.S
--- a/sys/arch/hppa/hppa/trap.S Wed Mar 10 18:06:57 2010 +0000
+++ b/sys/arch/hppa/hppa/trap.S Wed Mar 10 18:17:42 2010 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: trap.S,v 1.41 2010/03/08 07:42:47 skrll Exp $  */
+/*     $NetBSD: trap.S,v 1.42 2010/03/10 18:17:42 skrll Exp $  */
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -205,14 +205,6 @@
         * %sr0, %r31:  return address
         * %sp:         user stack
         *
-        * N.B. we are trying to rely on the fact that bottom of kernel
-        *      stack contains a print of some past trapframe, so
-        *      we do not save hard to get information, but do restore
-        *      the whole context later on return anyway.
-        * XXXXXX this is very bad. everything must be saved
-        *
-        * WHAT ARE WE RELYING ON?
-        *
         */
 
        /* t2 = curlwp PCB */
@@ -259,7 +251,6 @@
        stw     %r1, TF_CR15-TRAPFRAME_SIZEOF(%sr1, %t3)        /* eiem ,bc */
        stw     %t1, TF_CR22-TRAPFRAME_SIZEOF(%sr1, %t3)        /* ipsw */
  
-       /* XXX moved here to be protected from interrupts - why? */
        mfsp    %sr3, %t1
        stw     %t1, TF_SR3-TRAPFRAME_SIZEOF(%sr1, %t3)
        stw     %ret0, TF_CR8-TRAPFRAME_SIZEOF(%sr1, %t3)       /* pidr1 */
@@ -2012,17 +2003,12 @@
         * the user's stack, and we must move to the kernel stack.
         */
        mfctl   %pcoq, %t1
-       ldil    L%SYSCALLGATE, %t2
-       /* Start aligning the assumed kernel sp. */
-       ldo     HPPA_FRAME_SIZE-1(%sp), %sp
-       /* This dep leaves t2 with SYSCALLGATE | (pcoqh & PAGE_MASK). */
-       dep     %t1, 31, PGSHIFT, %t2
-       /* Nullify if pcoqh & HPPA_PC_PRIV_MASK != 0. */
-       dep,<>  %t1, 31, 2, %r0
-       /* Branch if (pcoqh & ~PAGE_MASK) != SYSCALLGATE */
-       comb,<> %t1, %t2, L$trap_from_kernel
-       /* Finish aligning the assumed kernel sp. */
-       dep     %r0, 31, 6, %sp
+       ldil    L%SYSCALLGATE, %t2              /* t2 = SYSCALLGATE */
+       ldo     HPPA_FRAME_SIZE-1(%sp), %sp     /* Assumed stack align step 1 */
+       dep     %t1, 31, PGSHIFT, %t2           /* t2 |= (pcoqh & PAGE_MASK) */
+       dep,<>  %t1, 31, 2, %r0                 /* Nullify if user mode (!0) */
+       comb,<>,n %t1, %t2, L$trap_from_kernel  /* if %t1 != %t2 => kernel */
+       dep     %r0, 31, 6, %sp                 /* Assumed stack align step 2 */
 
        mfctl   CR_UPADDR, %t2
        depi    1, T_USER_POS, 1, %r1
@@ -2088,8 +2074,6 @@
        /* save the trap type and flags */
        stw     %r1, TF_FLAGS(%t3)
 
-       /* XXX not in use... yet */
-       /* XXX save %ccr here w/ rctr */
        mfctl   %rctr, %t1              /* gotta get it before R is up */
 
        copy    %sp, %t3
@@ -2106,8 +2090,8 @@
        nop ! nop ! nop ! nop ! nop ! nop ! nop ! nop
 trapnowvirt:
        /*
-        * t3 contains the virtual address of the trapframe
-        * sp is loaded w/ the right VA (we did not need it being physical)
+        * %t3 contains the virtual address of the trapframe
+        * %sp is loaded w/ the right VA (we did not need it being physical)
         */
 
        mfctl   %ccr, %t2