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[POWERPC] Lazy interrupt disabling for 64-bit machines

Browse source 
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>
This commit is contained in:
Paul Mackerras 2006-10-04 16:47:49 +10:00
parent 284a940675
commit d04c56f73c
12 changed files with 160 additions and 111 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
arch/powerpc/kernel/asm-offsets.c
View file

@ -118,7 +118,8 @@ int main(void)
DEFINE(PACASTABRR, offsetof(struct paca_struct, stab_rr));
DEFINE(PACAR1, offsetof(struct paca_struct, saved_r1));
DEFINE(PACATOC, offsetof(struct paca_struct, kernel_toc));
DEFINE(PACAPROCENABLED, offsetof(struct paca_struct, proc_enabled));
DEFINE(PACASOFTIRQEN, offsetof(struct paca_struct, soft_enabled));
DEFINE(PACAHARDIRQEN, offsetof(struct paca_struct, hard_enabled));
DEFINE(PACASLBCACHE, offsetof(struct paca_struct, slb_cache));
DEFINE(PACASLBCACHEPTR, offsetof(struct paca_struct, slb_cache_ptr));
DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id));

4
arch/powerpc/kernel/crash.c
View file

@ -111,7 +111,7 @@ void crash_ipi_callback(struct pt_regs *regs)
if (!cpu_online(cpu))
return;
local_irq_disable();
hard_irq_disable();
if (!cpu_isset(cpu, cpus_in_crash))
crash_save_this_cpu(regs, cpu);
cpu_set(cpu, cpus_in_crash);
@ -289,7 +289,7 @@ void default_machine_crash_shutdown(struct pt_regs *regs)
* an SMP system.
* The kernel is broken so disable interrupts.
*/
local_irq_disable();
hard_irq_disable();
for_each_irq(irq) {
struct irq_desc *desc = irq_desc + irq;

39
arch/powerpc/kernel/entry_64.S
View file

@ -87,6 +87,10 @@ system_call_common:
addi r9,r1,STACK_FRAME_OVERHEAD
ld r11,exception_marker@toc(r2)
std r11,-16(r9) /* "regshere" marker */
li r10,1
stb r10,PACASOFTIRQEN(r13)
stb r10,PACAHARDIRQEN(r13)
std r10,SOFTE(r1)
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
/* Hack for handling interrupts when soft-enabling on iSeries */
@ -94,8 +98,6 @@ BEGIN_FW_FTR_SECTION
andi. r10,r12,MSR_PR /* from kernel */
crand 4*cr0+eq,4*cr1+eq,4*cr0+eq
beq hardware_interrupt_entry
lbz r10,PACAPROCENABLED(r13)
std r10,SOFTE(r1)
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
mfmsr r11
@ -460,9 +462,9 @@ _GLOBAL(ret_from_except_lite)
#endif
restore:
ld r5,SOFTE(r1)
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
ld r5,SOFTE(r1)
cmpdi 0,r5,0
beq 4f
/* Check for pending interrupts (iSeries) */
@ -472,16 +474,16 @@ BEGIN_FW_FTR_SECTION
beq+ 4f /* skip do_IRQ if no interrupts */
li r3,0
stb r3,PACAPROCENABLED(r13) /* ensure we are soft-disabled */
stb r3,PACASOFTIRQEN(r13) /* ensure we are soft-disabled */
ori r10,r10,MSR_EE
mtmsrd r10 /* hard-enable again */
addi r3,r1,STACK_FRAME_OVERHEAD
bl .do_IRQ
b .ret_from_except_lite /* loop back and handle more */
4: stb r5,PACAPROCENABLED(r13)
4:
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
stb r5,PACASOFTIRQEN(r13)
ld r3,_MSR(r1)
andi. r0,r3,MSR_RI
@ -538,25 +540,15 @@ do_work:
/* Check that preempt_count() == 0 and interrupts are enabled */
lwz r8,TI_PREEMPT(r9)
cmpwi cr1,r8,0
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
ld r0,SOFTE(r1)
cmpdi r0,0
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
BEGIN_FW_FTR_SECTION
andi. r0,r3,MSR_EE
END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES)
crandc eq,cr1*4+eq,eq
bne restore
/* here we are preempting the current task */
1:
#ifdef CONFIG_PPC_ISERIES
BEGIN_FW_FTR_SECTION
li r0,1
stb r0,PACAPROCENABLED(r13)
END_FW_FTR_SECTION_IFSET(FW_FEATURE_ISERIES)
#endif
stb r0,PACASOFTIRQEN(r13)
stb r0,PACAHARDIRQEN(r13)
ori r10,r10,MSR_EE
mtmsrd r10,1 /* reenable interrupts */
bl .preempt_schedule
@ -639,8 +631,7 @@ _GLOBAL(enter_rtas)
/* There is no way it is acceptable to get here with interrupts enabled,
* check it with the asm equivalent of WARN_ON
*/
mfmsr r6
andi. r0,r6,MSR_EE
lbz r0,PACASOFTIRQEN(r13)
1: tdnei r0,0
.section __bug_table,"a"
.llong 1b,__LINE__ + 0x1000000, 1f, 2f
@ -649,7 +640,13 @@ _GLOBAL(enter_rtas)
1: .asciz __FILE__
2: .asciz "enter_rtas"
.previous
/* Hard-disable interrupts */
mfmsr r6
rldicl r7,r6,48,1
rotldi r7,r7,16
mtmsrd r7,1
/* Unfortunately, the stack pointer and the MSR are also clobbered,
* so they are saved in the PACA which allows us to restore
* our original state after RTAS returns.

110
arch/powerpc/kernel/head_64.S
View file

@ -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 @@ exception_marker:
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 @@ label##_pSeries: \
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 @@ label##_iSeries: \
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 @@ END_FW_FTR_SECTION_IFCLR(FW_FEATURE_ISERIES); \
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 @@ instruction_access_slb_pSeries:
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 @@ system_call_pSeries:
/*** 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 @@ fast_exception_return:
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 @@ _GLOBAL(__secondary_start)
/* 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 @@ _STATIC(start_here_common)
/* 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

8
arch/powerpc/kernel/idle_power4.S
View file

@ -30,6 +30,13 @@ END_FTR_SECTION_IFCLR(CPU_FTR_CAN_NAP)
beqlr
/* Go to NAP now */
mfmsr r7
rldicl r0,r7,48,1
rotldi r0,r0,16
mtmsrd r0,1 /* hard-disable interrupts */
li r0,1
stb r0,PACASOFTIRQEN(r13) /* we'll hard-enable shortly */
stb r0,PACAHARDIRQEN(r13)
BEGIN_FTR_SECTION
DSSALL
sync
@ -38,7 +45,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
ld r8,TI_LOCAL_FLAGS(r9) /* set napping bit */
ori r8,r8,_TLF_NAPPING /* so when we take an exception */
std r8,TI_LOCAL_FLAGS(r9) /* it will return to our caller */
mfmsr r7
ori r7,r7,MSR_EE
oris r7,r7,MSR_POW@h
1: sync

24
arch/powerpc/kernel/irq.c
View file

@ -64,8 +64,9 @@
#include <asm/ptrace.h>
#include <asm/machdep.h>
#include <asm/udbg.h>
#ifdef CONFIG_PPC_ISERIES
#ifdef CONFIG_PPC64
#include <asm/paca.h>
#include <asm/firmware.h>
#endif
int __irq_offset_value;
@ -95,6 +96,27 @@ extern atomic_t ipi_sent;
EXPORT_SYMBOL(irq_desc);
int distribute_irqs = 1;
void local_irq_restore(unsigned long en)
{
get_paca()->soft_enabled = en;
if (!en)
return;
if (firmware_has_feature(FW_FEATURE_ISERIES)) {
if (get_paca()->lppaca_ptr->int_dword.any_int)
iseries_handle_interrupts();
return;
}
if (get_paca()->hard_enabled)
return;
/* need to hard-enable interrupts here */
get_paca()->hard_enabled = en;
if ((int)mfspr(SPRN_DEC) < 0)
mtspr(SPRN_DEC, 1);
hard_irq_enable();
}
#endif /* CONFIG_PPC64 */
int show_interrupts(struct seq_file *p, void *v)

4
arch/powerpc/kernel/ppc_ksyms.c
View file

@ -49,6 +49,10 @@
#include <asm/commproc.h>
#endif
#ifdef CONFIG_PPC64
EXPORT_SYMBOL(local_irq_restore);
#endif
#ifdef CONFIG_PPC32
extern void transfer_to_handler(void);
extern void do_IRQ(struct pt_regs *regs);

4
arch/powerpc/kernel/setup_64.c
View file

@ -223,8 +223,8 @@ void early_setup_secondary(void)
{
struct paca_struct *lpaca = get_paca();
/* Mark enabled in PACA */
lpaca->proc_enabled = 0;
/* Mark interrupts enabled in PACA */
lpaca->soft_enabled = 0;
/* Initialize hash table for that CPU */
htab_initialize_secondary();

6
arch/powerpc/platforms/iseries/ksyms.c
View file

@ -19,9 +19,3 @@ EXPORT_SYMBOL(HvCall4);
EXPORT_SYMBOL(HvCall5);
EXPORT_SYMBOL(HvCall6);
EXPORT_SYMBOL(HvCall7);
#ifdef CONFIG_SMP
EXPORT_SYMBOL(local_get_flags);
EXPORT_SYMBOL(local_irq_disable);
EXPORT_SYMBOL(local_irq_restore);
#endif

35
arch/powerpc/platforms/iseries/misc.S
View file

@ -19,39 +19,8 @@
.text
/* unsigned long local_save_flags(void) */
_GLOBAL(local_get_flags)
lbz r3,PACAPROCENABLED(r13)
blr
/* unsigned long local_irq_disable(void) */
_GLOBAL(local_irq_disable)
lbz r3,PACAPROCENABLED(r13)
li r4,0
stb r4,PACAPROCENABLED(r13)
blr /* Done */
/* void local_irq_restore(unsigned long flags) */
_GLOBAL(local_irq_restore)
lbz r5,PACAPROCENABLED(r13)
/* Check if things are setup the way we want _already_. */
cmpw 0,r3,r5
beqlr
/* are we enabling interrupts? */
cmpdi 0,r3,0
stb r3,PACAPROCENABLED(r13)
beqlr
/* Check pending interrupts */
/* A decrementer, IPI or PMC interrupt may have occurred
* while we were in the hypervisor (which enables) */
ld r4,PACALPPACAPTR(r13)
ld r4,LPPACAANYINT(r4)
cmpdi r4,0
beqlr
/*
* Handle pending interrupts in interrupt context
*/
/* Handle pending interrupts in interrupt context */
_GLOBAL(iseries_handle_interrupts)
li r0,0x5555
sc
blr

31
include/asm-powerpc/hw_irq.h
View file

@ -7,16 +7,30 @@
#ifdef __KERNEL__
#include <linux/errno.h>
#include <linux/compiler.h>
#include <asm/ptrace.h>
#include <asm/processor.h>
extern void timer_interrupt(struct pt_regs *);
#ifdef CONFIG_PPC_ISERIES
#ifdef CONFIG_PPC64
#include <asm/paca.h>
static inline unsigned long local_get_flags(void)
{
return get_paca()->soft_enabled;
}
static inline unsigned long local_irq_disable(void)
{
unsigned long flag = get_paca()->soft_enabled;
get_paca()->soft_enabled = 0;
barrier();
return flag;
}
extern unsigned long local_get_flags(void);
extern unsigned long local_irq_disable(void);
extern void local_irq_restore(unsigned long);
extern void iseries_handle_interrupts(void);
#define local_irq_enable() local_irq_restore(1)
#define local_save_flags(flags) ((flags) = local_get_flags())
@ -24,17 +38,14 @@ extern void local_irq_restore(unsigned long);
#define irqs_disabled() (local_get_flags() == 0)
#define hard_irq_enable() __mtmsrd(mfmsr() | MSR_EE, 1)
#define hard_irq_disable() __mtmsrd(mfmsr() & ~MSR_EE, 1)
#else
#if defined(CONFIG_BOOKE)
#define SET_MSR_EE(x) mtmsr(x)
#define local_irq_restore(flags) __asm__ __volatile__("wrtee %0" : : "r" (flags) : "memory")
#elif defined(__powerpc64__)
#define SET_MSR_EE(x) __mtmsrd(x, 1)
#define local_irq_restore(flags) do { \
__asm__ __volatile__("": : :"memory"); \
__mtmsrd((flags), 1); \
} while(0)
#else
#define SET_MSR_EE(x) mtmsr(x)
#define local_irq_restore(flags) mtmsr(flags)
@ -81,7 +92,7 @@ static inline void local_irq_save_ptr(unsigned long *flags)
#define local_irq_save(flags) local_irq_save_ptr(&flags)
#define irqs_disabled() ((mfmsr() & MSR_EE) == 0)
#endif /* CONFIG_PPC_ISERIES */
#endif /* CONFIG_PPC64 */
#define mask_irq(irq) \
({ \

3
include/asm-powerpc/paca.h
View file

@ -93,7 +93,8 @@ struct paca_struct {
u64 stab_rr; /* stab/slb round-robin counter */
u64 saved_r1; /* r1 save for RTAS calls */
u64 saved_msr; /* MSR saved here by enter_rtas */
u8 proc_enabled; /* irq soft-enable flag */
u8 soft_enabled; /* irq soft-enable flag */
u8 hard_enabled; /* set if irqs are enabled in MSR */
u8 io_sync; /* writel() needs spin_unlock sync */
/* Stuff for accurate time accounting */