parisc: Avoid trashing sr2 and sr3 in LWS code From: John David Anglin <dave.anglin@xxxxxxxx> There is no need to trash sr2 and sr3 in the Leight-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@xxxxxxxx> Signed-off-by: Helge Deller <deller@xxxxxx> diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S index d03422e..f13836b 100644 --- a/arch/parisc/kernel/syscall.S +++ b/arch/parisc/kernel/syscall.S @@ -474,10 +478,8 @@ 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 */ + /* Note: %sr2 is zero when called from userspace, + else syscalls wouldn't work. */ /* Load table start */ ldil L%lws_table, %r1 @@ -627,9 +629,9 @@ 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 +708,9 @@ 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 +718,9 @@ 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 +728,9 @@ 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 +739,14 @@ 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 +796,30 @@ 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 +827,22 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
