[PARISC] Make sure use of RFI conforms to PA 2.0 and 1.1 arch docs

2.6.12-rc4-pa3 : first pass at making sure use of RFI conforms to
PA 2.0 arch pages F-4 and F-5, PA 1.1 Arch page 3-19 and 3-20.

The discussion revolves around all the rules for clearing PSW Q-bit.
The hard part is meeting all the rules for "relied upon translation".

.align directive is used to guarantee the critical sequence ends more than
8 instructions (32 bytes) from the end of page.

Signed-off-by: Grant Grundler <grundler@parisc-linux.org>

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

1 files changed, 24 insertions, 27 deletions

diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index be0f07f2fa58..65a82c2645a7 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -30,9 +30,9 @@
  *  - save registers to kernel stack and handle in assembly or C */
 
 
+#include <asm/psw.h>
 #include <asm/assembly.h>       /* for LDREG/STREG defines */
 #include <asm/pgtable.h>
-#include <asm/psw.h>
 #include <asm/signal.h>
 #include <asm/unistd.h>
 #include <asm/thread_info.h>
@@ -67,19 +67,22 @@
 
         /* Switch to virtual mapping, trashing only %r1 */
         .macro  virt_map
-        rsm     PSW_SM_Q,%r0
-        tovirt_r1 %r29
-        mfsp    %sr7, %r1
-        or,=    %r0,%r1,%r0 /* Only save sr7 in sr3 if sr7 != 0 */
-        mtsp    %r1, %sr3
+        /* pcxt_ssm_bug */
+        rsm     PSW_SM_I, %r0   /* barrier for "Relied upon Translation */
         mtsp    %r0, %sr4
         mtsp    %r0, %sr5
+        mfsp    %sr7, %r1
+        or,=    %r0,%r1,%r0     /* Only save sr7 in sr3 if sr7 != 0 */
+        mtsp    %r1, %sr3
+        tovirt_r1 %r29
+        load32  KERNEL_PSW, %r1
+
+        rsm     PSW_SM_QUIET,%r0        /* second "heavy weight" ctl op */
         mtsp    %r0, %sr6
         mtsp    %r0, %sr7
-        load32  KERNEL_PSW, %r1
-        mtctl   %r1, %cr22
         mtctl   %r0, %cr17      /* Clear IIASQ tail */
         mtctl   %r0, %cr17      /* Clear IIASQ head */
+        mtctl   %r1, %ipsw
         load32  4f, %r1
         mtctl   %r1, %cr18      /* Set IIAOQ tail */
         ldo     4(%r1), %r1
@@ -888,9 +891,6 @@ _switch_to_ret:
          * this way, then we will need to copy %sr3 in to PT_SR[3..7], and
          * adjust IASQ[0..1].
          *
-         * Note that the following code uses a "relied upon translation".
-         * See the parisc ACD for details. The ssm is necessary due to a
-         * PCXT bug.
          */
 
         .align 4096
@@ -985,24 +985,19 @@ intr_restore:
         rest_fp         %r1
         rest_general    %r29
 
-        /* Create a "relied upon translation" PA 2.0 Arch. F-5 */
-        ssm             0,%r0
-        nop
-        nop
-        nop
-        nop
-        nop
-        nop
-        nop
+        /* inverse of virt_map */
+        pcxt_ssm_bug
+        rsm             PSW_SM_QUIET,%r0        /* prepare for rfi */
         tophys_r1       %r29
-        rsm             (PSW_SM_Q|PSW_SM_P|PSW_SM_D|PSW_SM_I),%r0
 
         /* Restore space id's and special cr's from PT_REGS
-         * structure pointed to by r29 */
+         * structure pointed to by r29
+         */
         rest_specials   %r29
 
-        /* Important: Note that rest_stack restores r29
-         * last (we are using it)! It also restores r1 and r30. */
+        /* IMPORTANT: rest_stack restores r29 last (we are using it)!
+         * It also restores r1 and r30.
+         */
         rest_stack
 
         rfi
@@ -1153,15 +1148,17 @@ intr_save:
 
         CMPIB=,n        6,%r26,skip_save_ior
 
-        /* save_specials left ipsw value in r8 for us to test */
 
         mfctl           %cr20, %r16 /* isr */
+        nop             /* serialize mfctl on PA 2.0 to avoid 4 cycle penalty */
         mfctl           %cr21, %r17 /* ior */
 
+
 #ifdef __LP64__
         /*
          * If the interrupted code was running with W bit off (32 bit),
          * clear the b bits (bits 0 & 1) in the ior.
+         * save_specials left ipsw value in r8 for us to test.
          */
         extrd,u,*<>     %r8,PSW_W_BIT,1,%r0
         depdi           0,1,2,%r17
@@ -1487,10 +1484,10 @@ nadtlb_emulate:
         add,l           %r1,%r24,%r1           /* doesn't affect c/b bits */
 
 nadtlb_nullify:
-        mfctl           %cr22,%r8              /* Get ipsw */
+        mfctl           %ipsw,%r8
         ldil            L%PSW_N,%r9
         or              %r8,%r9,%r8            /* Set PSW_N */
-        mtctl           %r8,%cr22
+        mtctl           %r8,%ipsw
 
         rfir
         nop