parisc: Avoid trashing sr2 and sr3 in LWS code

There is no need to trash sr2 and sr3 in the Light-weight syscall (LWS).  sr2
already points to kernel space (it's zero in userspace, otherwise syscalls
wouldn't work), and since the LWS code is executed in userspace, we can simply
ignore to preload sr3.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index d03422e5f188368f8df5283cedfd4e32845e64df..40190dbecdc08e23747fdf827f0a2bcb5a2a631b 100644 (file)
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -474,11 +474,6 @@ lws_start:
        comiclr,>>      __NR_lws_entries, %r20, %r0
        b,n     lws_exit_nosys
 
-       /* WARNING: Trashing sr2 and sr3 */
-       mfsp    %sr7,%r1                        /* get userspace into sr3 */
-       mtsp    %r1,%sr3
-       mtsp    %r0,%sr2                        /* get kernel space into sr2 */
-
        /* Load table start */
        ldil    L%lws_table, %r1
        ldo     R%lws_table(%r1), %r28  /* Scratch use of r28 */
@@ -627,9 +622,9 @@ cas_action:
        stw     %r1, 4(%sr2,%r20)
 #endif
        /* The load and store could fail */
-1:     ldw,ma  0(%sr3,%r26), %r28
+1:     ldw,ma  0(%r26), %r28
        sub,<>  %r28, %r25, %r0
-2:     stw,ma  %r24, 0(%sr3,%r26)
+2:     stw,ma  %r24, 0(%r26)
        /* Free lock */
        stw,ma  %r20, 0(%sr2,%r20)
 #if ENABLE_LWS_DEBUG
@@ -706,9 +701,9 @@ lws_compare_and_swap_2:
        nop
 
        /* 8bit load */
-4:     ldb     0(%sr3,%r25), %r25
+4:     ldb     0(%r25), %r25
        b       cas2_lock_start
-5:     ldb     0(%sr3,%r24), %r24
+5:     ldb     0(%r24), %r24
        nop
        nop
        nop
@@ -716,9 +711,9 @@ lws_compare_and_swap_2:
        nop
 
        /* 16bit load */
-6:     ldh     0(%sr3,%r25), %r25
+6:     ldh     0(%r25), %r25
        b       cas2_lock_start
-7:     ldh     0(%sr3,%r24), %r24
+7:     ldh     0(%r24), %r24
        nop
        nop
        nop
@@ -726,9 +721,9 @@ lws_compare_and_swap_2:
        nop
 
        /* 32bit load */
-8:     ldw     0(%sr3,%r25), %r25
+8:     ldw     0(%r25), %r25
        b       cas2_lock_start
-9:     ldw     0(%sr3,%r24), %r24
+9:     ldw     0(%r24), %r24
        nop
        nop
        nop
@@ -737,14 +732,14 @@ lws_compare_and_swap_2:
 
        /* 64bit load */
 #ifdef CONFIG_64BIT
-10:    ldd     0(%sr3,%r25), %r25
-11:    ldd     0(%sr3,%r24), %r24
+10:    ldd     0(%r25), %r25
+11:    ldd     0(%r24), %r24
 #else
        /* Load new value into r22/r23 - high/low */
-10:    ldw     0(%sr3,%r25), %r22
-11:    ldw     4(%sr3,%r25), %r23
+10:    ldw     0(%r25), %r22
+11:    ldw     4(%r25), %r23
        /* Load new value into fr4 for atomic store later */
-12:    flddx   0(%sr3,%r24), %fr4
+12:    flddx   0(%r24), %fr4
 #endif
 
 cas2_lock_start:
@@ -794,30 +789,30 @@ cas2_action:
        ldo     1(%r0),%r28
 
        /* 8bit CAS */
-13:    ldb,ma  0(%sr3,%r26), %r29
+13:    ldb,ma  0(%r26), %r29
        sub,=   %r29, %r25, %r0
        b,n     cas2_end
-14:    stb,ma  %r24, 0(%sr3,%r26)
+14:    stb,ma  %r24, 0(%r26)
        b       cas2_end
        copy    %r0, %r28
        nop
        nop
 
        /* 16bit CAS */
-15:    ldh,ma  0(%sr3,%r26), %r29
+15:    ldh,ma  0(%r26), %r29
        sub,=   %r29, %r25, %r0
        b,n     cas2_end
-16:    sth,ma  %r24, 0(%sr3,%r26)
+16:    sth,ma  %r24, 0(%r26)
        b       cas2_end
        copy    %r0, %r28
        nop
        nop
 
        /* 32bit CAS */
-17:    ldw,ma  0(%sr3,%r26), %r29
+17:    ldw,ma  0(%r26), %r29
        sub,=   %r29, %r25, %r0
        b,n     cas2_end
-18:    stw,ma  %r24, 0(%sr3,%r26)
+18:    stw,ma  %r24, 0(%r26)
        b       cas2_end
        copy    %r0, %r28
        nop
@@ -825,22 +820,22 @@ cas2_action:
 
        /* 64bit CAS */
 #ifdef CONFIG_64BIT
-19:    ldd,ma  0(%sr3,%r26), %r29
+19:    ldd,ma  0(%r26), %r29
        sub,*=  %r29, %r25, %r0
        b,n     cas2_end
-20:    std,ma  %r24, 0(%sr3,%r26)
+20:    std,ma  %r24, 0(%r26)
        copy    %r0, %r28
 #else
        /* Compare first word */
-19:    ldw,ma  0(%sr3,%r26), %r29
+19:    ldw,ma  0(%r26), %r29
        sub,=   %r29, %r22, %r0
        b,n     cas2_end
        /* Compare second word */
-20:    ldw,ma  4(%sr3,%r26), %r29
+20:    ldw,ma  4(%r26), %r29
        sub,=   %r29, %r23, %r0
        b,n     cas2_end
        /* Perform the store */
-21:    fstdx   %fr4, 0(%sr3,%r26)
+21:    fstdx   %fr4, 0(%r26)
        copy    %r0, %r28
 #endif