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/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 32fc04f..3425aba 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -104,7 +104,7 @@
.globl system_reset_pSeries;
system_reset_pSeries:
- HMT_MEDIUM;
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13)
#ifdef CONFIG_PPC_P7_NAP
BEGIN_FTR_SECTION
@@ -158,7 +158,7 @@
. = 0x300
.globl data_access_pSeries
data_access_pSeries:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13)
BEGIN_FTR_SECTION
b data_access_check_stab
@@ -170,7 +170,7 @@
. = 0x380
.globl data_access_slb_pSeries
data_access_slb_pSeries:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13)
EXCEPTION_PROLOG_1(PACA_EXSLB, KVMTEST, 0x380)
std r3,PACA_EXSLB+EX_R3(r13)
@@ -201,7 +201,7 @@
. = 0x480
.globl instruction_access_slb_pSeries
instruction_access_slb_pSeries:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13)
EXCEPTION_PROLOG_1(PACA_EXSLB, KVMTEST_PR, 0x480)
std r3,PACA_EXSLB+EX_R3(r13)
@@ -324,10 +324,11 @@
. = 0x1500
.global denorm_exception_hv
denorm_exception_hv:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
mtspr SPRN_SPRG_HSCRATCH0,r13
mfspr r13,SPRN_SPRG_HPACA
std r9,PACA_EXGEN+EX_R9(r13)
+ HMT_MEDIUM_PPR_SAVE(PACA_EXGEN, r9)
std r10,PACA_EXGEN+EX_R10(r13)
std r11,PACA_EXGEN+EX_R11(r13)
std r12,PACA_EXGEN+EX_R12(r13)
@@ -369,7 +370,7 @@
machine_check_pSeries:
.globl machine_check_fwnmi
machine_check_fwnmi:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13) /* save r13 */
EXCEPTION_PROLOG_PSERIES(PACA_EXMC, machine_check_common,
EXC_STD, KVMTEST, 0x200)
@@ -498,6 +499,7 @@
mtspr SPRN_HSRR0,r11
mtcrf 0x80,r9
ld r9,PACA_EXGEN+EX_R9(r13)
+ RESTORE_PPR_PACA(PACA_EXGEN, r10)
ld r10,PACA_EXGEN+EX_R10(r13)
ld r11,PACA_EXGEN+EX_R11(r13)
ld r12,PACA_EXGEN+EX_R12(r13)
@@ -603,7 +605,7 @@
.globl system_reset_fwnmi
.align 7
system_reset_fwnmi:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13) /* save r13 */
EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, system_reset_common, EXC_STD,
NOTEST, 0x100)
@@ -716,7 +718,7 @@
. = 0x4380
.globl data_access_slb_relon_pSeries
data_access_slb_relon_pSeries:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13)
EXCEPTION_PROLOG_1(PACA_EXSLB, NOTEST, 0x380)
std r3,PACA_EXSLB+EX_R3(r13)
@@ -741,7 +743,7 @@
. = 0x4480
.globl instruction_access_slb_relon_pSeries
instruction_access_slb_relon_pSeries:
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13)
EXCEPTION_PROLOG_1(PACA_EXSLB, NOTEST, 0x480)
std r3,PACA_EXSLB+EX_R3(r13)
@@ -1062,6 +1064,7 @@
mtcrf 0x01,r9 /* slb_allocate uses cr0 and cr7 */
.machine pop
+ RESTORE_PPR_PACA(PACA_EXSLB, r9)
ld r9,PACA_EXSLB+EX_R9(r13)
ld r10,PACA_EXSLB+EX_R10(r13)
ld r11,PACA_EXSLB+EX_R11(r13)
@@ -1411,7 +1414,7 @@
#ifdef CONFIG_PPC_POWERNV
_GLOBAL(opal_mc_secondary_handler)
- HMT_MEDIUM
+ HMT_MEDIUM_PPR_DISCARD
SET_SCRATCH0(r13)
GET_PACA(r13)
clrldi r3,r3,2