[POWERPC] Lazy interrupt disabling for 64-bit machines
This implements a lazy strategy for disabling interrupts. This means
that local_irq_disable() et al. just clear the 'interrupts are
enabled' flag in the paca. If an interrupt comes along, the interrupt
entry code notices that interrupts are supposed to be disabled, and
clears the EE bit in SRR1, clears the 'interrupts are hard-enabled'
flag in the paca, and returns. This means that interrupts only
actually get disabled in the processor when an interrupt comes along.
When interrupts are enabled by local_irq_enable() et al., the code
sets the interrupts-enabled flag in the paca, and then checks whether
interrupts got hard-disabled. If so, it also sets the EE bit in the
MSR to hard-enable the interrupts.
This has the potential to improve performance, and also makes it
easier to make a kernel that can boot on iSeries and on other 64-bit
machines, since this lazy-disable strategy is very similar to the
soft-disable strategy that iSeries already uses.
This version renames paca->proc_enabled to paca->soft_enabled, and
changes a couple of soft-disables in the kexec code to hard-disables,
which should fix the crash that Michael Ellerman saw. This doesn't
yet use a reserved CR field for the soft_enabled and hard_enabled
flags. This applies on top of Stephen Rothwell's patches to make it
possible to build a combined iSeries/other kernel.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 645c7f1..c93d9f3 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -35,9 +35,7 @@
#include <asm/thread_info.h>
#include <asm/firmware.h>
-#ifdef CONFIG_PPC_ISERIES
#define DO_SOFT_DISABLE
-#endif
/*
* We layout physical memory as follows:
@@ -308,7 +306,9 @@
std r9,_LINK(r1); \
mfctr r10; /* save CTR in stackframe */ \
std r10,_CTR(r1); \
+ lbz r10,PACASOFTIRQEN(r13); \
mfspr r11,SPRN_XER; /* save XER in stackframe */ \
+ std r10,SOFTE(r1); \
std r11,_XER(r1); \
li r9,(n)+1; \
std r9,_TRAP(r1); /* set trap number */ \
@@ -343,6 +343,34 @@
EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label##_common)
+#define MASKABLE_EXCEPTION_PSERIES(n, label) \
+ . = n; \
+ .globl label##_pSeries; \
+label##_pSeries: \
+ HMT_MEDIUM; \
+ mtspr SPRN_SPRG1,r13; /* save r13 */ \
+ mfspr r13,SPRN_SPRG3; /* get paca address into r13 */ \
+ std r9,PACA_EXGEN+EX_R9(r13); /* save r9, r10 */ \
+ std r10,PACA_EXGEN+EX_R10(r13); \
+ lbz r10,PACASOFTIRQEN(r13); \
+ mfcr r9; \
+ cmpwi r10,0; \
+ beq masked_interrupt; \
+ mfspr r10,SPRN_SPRG1; \
+ std r10,PACA_EXGEN+EX_R13(r13); \
+ std r11,PACA_EXGEN+EX_R11(r13); \
+ std r12,PACA_EXGEN+EX_R12(r13); \
+ clrrdi r12,r13,32; /* get high part of &label */ \
+ mfmsr r10; \
+ mfspr r11,SPRN_SRR0; /* save SRR0 */ \
+ LOAD_HANDLER(r12,label##_common) \
+ ori r10,r10,MSR_IR|MSR_DR|MSR_RI; \
+ mtspr SPRN_SRR0,r12; \
+ mfspr r12,SPRN_SRR1; /* and SRR1 */ \
+ mtspr SPRN_SRR1,r10; \
+ rfid; \
+ b . /* prevent speculative execution */
+
#define STD_EXCEPTION_ISERIES(n, label, area) \
.globl label##_iSeries; \
label##_iSeries: \
@@ -358,40 +386,32 @@
HMT_MEDIUM; \
mtspr SPRN_SPRG1,r13; /* save r13 */ \
EXCEPTION_PROLOG_ISERIES_1(PACA_EXGEN); \
- lbz r10,PACAPROCENABLED(r13); \
+ lbz r10,PACASOFTIRQEN(r13); \
cmpwi 0,r10,0; \
beq- label##_iSeries_masked; \
EXCEPTION_PROLOG_ISERIES_2; \
b label##_common; \
-#ifdef DO_SOFT_DISABLE
+#ifdef CONFIG_PPC_ISERIES
#define DISABLE_INTS \
-BEGIN_FW_FTR_SECTION; \
- lbz r10,PACAPROCENABLED(r13); \
li r11,0; \
- std r10,SOFTE(r1); \
+ stb r11,PACASOFTIRQEN(r13); \
+BEGIN_FW_FTR_SECTION; \
+ stb r11,PACAHARDIRQEN(r13); \
+END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES); \
+BEGIN_FW_FTR_SECTION; \
mfmsr r10; \
- stb r11,PACAPROCENABLED(r13); \
ori r10,r10,MSR_EE; \
mtmsrd r10,1; \
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
-#define ENABLE_INTS \
-BEGIN_FW_FTR_SECTION; \
- lbz r10,PACAPROCENABLED(r13); \
- mfmsr r11; \
- std r10,SOFTE(r1); \
- ori r11,r11,MSR_EE; \
-END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES); \
-BEGIN_FW_FTR_SECTION; \
- ld r12,_MSR(r1); \
- mfmsr r11; \
- rlwimi r11,r12,0,MSR_EE; \
-END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES); \
- mtmsrd r11,1
+#else
+#define DISABLE_INTS \
+ li r11,0; \
+ stb r11,PACASOFTIRQEN(r13); \
+ stb r11,PACAHARDIRQEN(r13)
-#else /* hard enable/disable interrupts */
-#define DISABLE_INTS
+#endif /* CONFIG_PPC_ISERIES */
#define ENABLE_INTS \
ld r12,_MSR(r1); \
@@ -399,8 +419,6 @@
rlwimi r11,r12,0,MSR_EE; \
mtmsrd r11,1
-#endif
-
#define STD_EXCEPTION_COMMON(trap, label, hdlr) \
.align 7; \
.globl label##_common; \
@@ -541,11 +559,11 @@
mfspr r12,SPRN_SRR1 /* and SRR1 */
b .slb_miss_realmode /* Rel. branch works in real mode */
- STD_EXCEPTION_PSERIES(0x500, hardware_interrupt)
+ MASKABLE_EXCEPTION_PSERIES(0x500, hardware_interrupt)
STD_EXCEPTION_PSERIES(0x600, alignment)
STD_EXCEPTION_PSERIES(0x700, program_check)
STD_EXCEPTION_PSERIES(0x800, fp_unavailable)
- STD_EXCEPTION_PSERIES(0x900, decrementer)
+ MASKABLE_EXCEPTION_PSERIES(0x900, decrementer)
STD_EXCEPTION_PSERIES(0xa00, trap_0a)
STD_EXCEPTION_PSERIES(0xb00, trap_0b)
@@ -597,7 +615,24 @@
/*** pSeries interrupt support ***/
/* moved from 0xf00 */
- STD_EXCEPTION_PSERIES(., performance_monitor)
+ MASKABLE_EXCEPTION_PSERIES(., performance_monitor)
+
+/*
+ * An interrupt came in while soft-disabled; clear EE in SRR1,
+ * clear paca->hard_enabled and return.
+ */
+masked_interrupt:
+ stb r10,PACAHARDIRQEN(r13)
+ mtcrf 0x80,r9
+ ld r9,PACA_EXGEN+EX_R9(r13)
+ mfspr r10,SPRN_SRR1
+ rldicl r10,r10,48,1 /* clear MSR_EE */
+ rotldi r10,r10,16
+ mtspr SPRN_SRR1,r10
+ ld r10,PACA_EXGEN+EX_R10(r13)
+ mfspr r13,SPRN_SPRG1
+ rfid
+ b .
.align 7
_GLOBAL(do_stab_bolted_pSeries)
@@ -952,7 +987,8 @@
REST_8GPRS(2, r1)
mfmsr r10
- clrrdi r10,r10,2 /* clear RI (LE is 0 already) */
+ rldicl r10,r10,48,1 /* clear EE */
+ rldicr r10,r10,16,61 /* clear RI (LE is 0 already) */
mtmsrd r10,1
mtspr SPRN_SRR1,r12
@@ -1877,11 +1913,16 @@
/* enable MMU and jump to start_secondary */
LOAD_REG_ADDR(r3, .start_secondary_prolog)
LOAD_REG_IMMEDIATE(r4, MSR_KERNEL)
-#ifdef DO_SOFT_DISABLE
+#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
ori r4,r4,MSR_EE
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
+BEGIN_FW_FTR_SECTION
+ stb r7,PACASOFTIRQEN(r13)
+ stb r7,PACAHARDIRQEN(r13)
+END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
+
mtspr SPRN_SRR0,r3
mtspr SPRN_SRR1,r4
rfid
@@ -2019,15 +2060,18 @@
/* Load up the kernel context */
5:
-#ifdef DO_SOFT_DISABLE
-BEGIN_FW_FTR_SECTION
li r5,0
- stb r5,PACAPROCENABLED(r13) /* Soft Disabled */
+ stb r5,PACASOFTIRQEN(r13) /* Soft Disabled */
+#ifdef CONFIG_PPC_ISERIES
+BEGIN_FW_FTR_SECTION
mfmsr r5
ori r5,r5,MSR_EE /* Hard Enabled */
mtmsrd r5
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
+BEGIN_FW_FTR_SECTION
+ stb r5,PACAHARDIRQEN(r13)
+END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
bl .start_kernel