powerpc: Implement PPR save/restore
[PATCH 6/6] powerpc: Implement PPR save/restore
When the task enters in to kernel space, the user defined priority (PPR)
will be saved in to PACA at the beginning of first level exception
vector and then copy from PACA to thread_info in second level vector.
PPR will be restored from thread_info before exits the kernel space.
P7/P8 temporarily raises the thread priority to higher level during
exception until the program executes HMT_* calls. But it will not modify
PPR register. So we save PPR value whenever some register is available
to use and then calls HMT_MEDIUM to increase the priority. This feature
supports on P7 or later processors.
We save/ restore PPR for all exception vectors except system call entry.
GLIBC will be saving / restore for system calls. So the default PPR
value (3) will be set for the system call exit when the task returned
to the user space.
Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 391e013..370298a 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -147,8 +147,9 @@
#define __EXCEPTION_PROLOG_1(area, extra, vec) \
GET_PACA(r13); \
- std r9,area+EX_R9(r13); /* save r9 - r12 */ \
- std r10,area+EX_R10(r13); \
+ std r9,area+EX_R9(r13); /* save r9 */ \
+ HMT_MEDIUM_PPR_SAVE(area, r9); \
+ std r10,area+EX_R10(r13); /* save r10 - r12 */ \
BEGIN_FTR_SECTION_NESTED(66); \
mfspr r10,SPRN_CFAR; \
std r10,area+EX_CFAR(r13); \
@@ -264,6 +265,7 @@
std r10,GPR1(r1); /* save r1 in stackframe */ \
beq 4f; /* if from kernel mode */ \
ACCOUNT_CPU_USER_ENTRY(r9, r10); \
+ SAVE_PPR(area, r9, r10); \
4: std r2,GPR2(r1); /* save r2 in stackframe */ \
SAVE_4GPRS(3, r1); /* save r3 - r6 in stackframe */ \
SAVE_2GPRS(7, r1); /* save r7, r8 in stackframe */ \
@@ -305,7 +307,7 @@
. = loc; \
.globl label##_pSeries; \
label##_pSeries: \
- HMT_MEDIUM; \
+ HMT_MEDIUM_PPR_DISCARD; \
SET_SCRATCH0(r13); /* save r13 */ \
EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label##_common, \
EXC_STD, KVMTEST_PR, vec)
@@ -314,7 +316,7 @@
. = loc; \
.globl label##_hv; \
label##_hv: \
- HMT_MEDIUM; \
+ HMT_MEDIUM_PPR_DISCARD; \
SET_SCRATCH0(r13); /* save r13 */ \
EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label##_common, \
EXC_HV, KVMTEST, vec)
@@ -323,7 +325,7 @@
. = loc; \
.globl label##_relon_pSeries; \
label##_relon_pSeries: \
- HMT_MEDIUM; \
+ HMT_MEDIUM_PPR_DISCARD; \
/* No guest interrupts come through here */ \
SET_SCRATCH0(r13); /* save r13 */ \
EXCEPTION_RELON_PROLOG_PSERIES(PACA_EXGEN, label##_common, \
@@ -333,7 +335,7 @@
. = loc; \
.globl label##_relon_hv; \
label##_relon_hv: \
- HMT_MEDIUM; \
+ HMT_MEDIUM_PPR_DISCARD; \
/* No guest interrupts come through here */ \
SET_SCRATCH0(r13); /* save r13 */ \
EXCEPTION_RELON_PROLOG_PSERIES(PACA_EXGEN, label##_common, \
@@ -371,7 +373,7 @@
#define SOFTEN_NOTEST_HV(vec) _SOFTEN_TEST(EXC_HV, vec)
#define __MASKABLE_EXCEPTION_PSERIES(vec, label, h, extra) \
- HMT_MEDIUM; \
+ HMT_MEDIUM_PPR_DISCARD; \
SET_SCRATCH0(r13); /* save r13 */ \
__EXCEPTION_PROLOG_1(PACA_EXGEN, extra, vec); \
EXCEPTION_PROLOG_PSERIES_1(label##_common, h);
@@ -393,7 +395,7 @@
EXC_HV, SOFTEN_TEST_HV)
#define __MASKABLE_RELON_EXCEPTION_PSERIES(vec, label, h, extra) \
- HMT_MEDIUM; \
+ HMT_MEDIUM_PPR_DISCARD; \
SET_SCRATCH0(r13); /* save r13 */ \
__EXCEPTION_PROLOG_1(PACA_EXGEN, extra, vec); \
EXCEPTION_RELON_PROLOG_PSERIES_1(label##_common, h);