As suggested by paulus we can simplify the Data Stream Control Register
(DSCR) Facility Status and Control Register (FSCR) handling.
Firstly, we simplify the asm by using a rldimi.
Secondly, we now use the FSCR only to control the DSCR facility, rather
than both the FSCR and HFSCR. Users will see no functional change from
this but will get a minor speedup as they will trap into the kernel only
once (rather than twice) when they first touch the DSCR. Also, this
changes removes a bunch of ugly FTR_SECTION code.
Signed-off-by: Michael Neuling <mi...@neuling.org>
--
arch/powerpc/kernel/entry_64.S | 31 ++++++-------------------------
arch/powerpc/kernel/traps.c | 7 ++-----
2 files changed, 8 insertions(+), 30 deletions(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 2bd0b88..513dc4d 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -575,34 +575,15 @@ BEGIN_FTR_SECTION
ld r7,DSCR_DEFAULT@toc(2)
ld r0,THREAD_DSCR(r4)
cmpwi r6,0
- li r8, FSCR_DSCR
bne 1f
ld r0,0(r7)
- b 3f
1:
- BEGIN_FTR_SECTION_NESTED(70)
- mfspr r6, SPRN_FSCR
- or r6, r6, r8
- mtspr SPRN_FSCR, r6
- BEGIN_FTR_SECTION_NESTED(69)
- mfspr r6, SPRN_HFSCR
- or r6, r6, r8
- mtspr SPRN_HFSCR, r6
- END_FTR_SECTION_NESTED(CPU_FTR_HVMODE, CPU_FTR_HVMODE, 69)
- b 4f
- END_FTR_SECTION_NESTED(CPU_FTR_ARCH_207S, CPU_FTR_ARCH_207S, 70)
-3:
- BEGIN_FTR_SECTION_NESTED(70)
- mfspr r6, SPRN_FSCR
- andc r6, r6, r8
- mtspr SPRN_FSCR, r6
- BEGIN_FTR_SECTION_NESTED(69)
- mfspr r6, SPRN_HFSCR
- andc r6, r6, r8
- mtspr SPRN_HFSCR, r6
- END_FTR_SECTION_NESTED(CPU_FTR_HVMODE, CPU_FTR_HVMODE, 69)
- END_FTR_SECTION_NESTED(CPU_FTR_ARCH_207S, CPU_FTR_ARCH_207S, 70)
-4: cmpd r0,r25
+BEGIN_FTR_SECTION_NESTED(70)
+ mfspr r8, SPRN_FSCR
+ rldimi r8, r6, FSCR_DSCR_LG, (63 - FSCR_DSCR_LG)
+ mtspr SPRN_FSCR, r8
+END_FTR_SECTION_NESTED(CPU_FTR_ARCH_207S, CPU_FTR_ARCH_207S, 70)
+ cmpd r0,r25
beq 2f
mtspr SPRN_DSCR,r0
2:
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index e435bc0..0ba68a2 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1322,13 +1322,10 @@ void facility_unavailable_exception(struct pt_regs
*regs)
if (status == FSCR_DSCR_LG) {
/* User is acessing the DSCR. Set the inherit bit and allow
* the user to set it directly in future by setting via the
- * H/FSCR DSCR bit.
+ * FSCR DSCR bit. We always leave HFSCR DSCR set.
*/
current->thread.dscr_inherit = 1;
- if (hv)
- mtspr(SPRN_HFSCR, value | HFSCR_DSCR);
- else
- mtspr(SPRN_FSCR, value | FSCR_DSCR);
+ mtspr(SPRN_FSCR, value | FSCR_DSCR);
return;
}
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
