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Subject[RFC PATCH] x86-64: software IRQ masking and handling
Hello,

This is something suggested by Rusty Russell a while ago. It makes
IRQ masking a software switch like preemption or softirq
enable/disable. Hardware interrupt masking (cli/sti) and delivery are
decoupled from actual IRQ handling. IRQ disabling is done by single
instruction moving 1 to a percpu variable. Enabling is similar but it
should check whether there's any pending interrupt to handle.

This change greatly reduces the number of hardware IRQ masking
manipulations. cli/sti still being somewhat costly operations (I hear
nehalem is better tho), this should be able to improve overall
performance, especially on paravirts.

I just got it working and it behaves pretty good on qemu. Actual
machines can't idle but seem to work otherwise. I'll fix up idle, get
paravirt working and try to get some perf measurements but I'll be
mostly off next week, so it will take some time. In the meantime,
what do you guys think?

Thanks.

HIGHLY_EXPERIMENTAL_DONT_APPLY
---
arch/x86/ia32/ia32entry.S | 12 +--
arch/x86/include/asm/irqflags.h | 103 ++++++++++++++++++++++------
arch/x86/include/asm/paravirt.h | 21 +----
arch/x86/include/asm/system.h | 4 -
arch/x86/kernel/cpu/common.c | 10 ++
arch/x86/kernel/entry_64.S | 143 +++++++++++++++++++++++++---------------
arch/x86/kernel/irq.c | 21 +++++
arch/x86/kernel/process.c | 21 ++---
arch/x86/kernel/process_64.c | 2
arch/x86/kernel/smpboot.c | 2
arch/x86/kernel/traps.c | 16 ++--
arch/x86/mm/fault.c | 6 -
drivers/acpi/processor_idle.c | 24 +++---
drivers/cpuidle/cpuidle.c | 6 -
include/linux/irqflags.h | 31 ++++++++
init/main.c | 2
lib/smp_processor_id.c | 2
17 files changed, 283 insertions(+), 143 deletions(-)
Index: work/drivers/acpi/processor_idle.c
===================================================================
--- work.orig/drivers/acpi/processor_idle.c
+++ work/drivers/acpi/processor_idle.c
@@ -137,7 +137,7 @@ static void acpi_safe_halt(void)
smp_mb();
if (!need_resched()) {
safe_halt();
- local_irq_disable();
+ hw_irq_disable();
}
current_thread_info()->status |= TS_POLLING;
}
@@ -826,11 +826,11 @@ static int acpi_idle_enter_c1(struct cpu
if (unlikely(!pr))
return 0;

- local_irq_disable();
+ hw_irq_disable();

/* Do not access any ACPI IO ports in suspend path */
if (acpi_idle_suspend) {
- local_irq_enable();
+ hw_irq_enable();
cpu_relax();
return 0;
}
@@ -841,7 +841,7 @@ static int acpi_idle_enter_c1(struct cpu
kt2 = ktime_get_real();
idle_time = ktime_to_us(ktime_sub(kt2, kt1));

- local_irq_enable();
+ hw_irq_enable();
cx->usage++;
lapic_timer_state_broadcast(pr, cx, 0);

@@ -870,7 +870,7 @@ static int acpi_idle_enter_simple(struct
if (acpi_idle_suspend)
return(acpi_idle_enter_c1(dev, state));

- local_irq_disable();
+ hw_irq_disable();

if (cx->entry_method != ACPI_CSTATE_FFH) {
current_thread_info()->status &= ~TS_POLLING;
@@ -882,7 +882,7 @@ static int acpi_idle_enter_simple(struct

if (unlikely(need_resched())) {
current_thread_info()->status |= TS_POLLING;
- local_irq_enable();
+ hw_irq_enable();
return 0;
}
}
@@ -908,7 +908,7 @@ static int acpi_idle_enter_simple(struct
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(idle_time_ns);

- local_irq_enable();
+ hw_irq_enable();
if (cx->entry_method != ACPI_CSTATE_FFH)
current_thread_info()->status |= TS_POLLING;

@@ -952,14 +952,14 @@ static int acpi_idle_enter_bm(struct cpu
dev->last_state = dev->safe_state;
return dev->safe_state->enter(dev, dev->safe_state);
} else {
- local_irq_disable();
+ hw_irq_disable();
acpi_safe_halt();
- local_irq_enable();
+ hw_irq_enable();
return 0;
}
}

- local_irq_disable();
+ hw_irq_disable();

if (cx->entry_method != ACPI_CSTATE_FFH) {
current_thread_info()->status &= ~TS_POLLING;
@@ -971,7 +971,7 @@ static int acpi_idle_enter_bm(struct cpu

if (unlikely(need_resched())) {
current_thread_info()->status |= TS_POLLING;
- local_irq_enable();
+ hw_irq_enable();
return 0;
}
}
@@ -1025,7 +1025,7 @@ static int acpi_idle_enter_bm(struct cpu
/* Tell the scheduler how much we idled: */
sched_clock_idle_wakeup_event(idle_time_ns);

- local_irq_enable();
+ hw_irq_enable();
if (cx->entry_method != ACPI_CSTATE_FFH)
current_thread_info()->status |= TS_POLLING;

Index: work/drivers/cpuidle/cpuidle.c
===================================================================
--- work.orig/drivers/cpuidle/cpuidle.c
+++ work/drivers/cpuidle/cpuidle.c
@@ -61,7 +61,7 @@ static void cpuidle_idle_call(void)
#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
default_idle();
#else
- local_irq_enable();
+ hw_irq_enable();
#endif
return;
}
@@ -77,7 +77,7 @@ static void cpuidle_idle_call(void)
/* ask the governor for the next state */
next_state = cpuidle_curr_governor->select(dev);
if (need_resched()) {
- local_irq_enable();
+ hw_irq_enable();
return;
}

@@ -229,7 +229,7 @@ static int poll_idle(struct cpuidle_devi
int ret;

t1 = ktime_get();
- local_irq_enable();
+ hw_irq_enable();
while (!need_resched())
cpu_relax();

Index: work/include/linux/irqflags.h
===================================================================
--- work.orig/include/linux/irqflags.h
+++ work/include/linux/irqflags.h
@@ -79,6 +79,17 @@
raw_local_irq_restore(flags); \
} \
} while (0)
+
+#ifndef __ARCH_HAS_HW_IRQ
+#define raw_hw_irq_enable() raw_local_irq_enable()
+#define raw_hw_irq_disable() raw_local_irq_disable()
+#endif
+
+#define hw_irq_enable() \
+ do { trace_hardirqs_on(); raw_hw_irq_enable(); } while (0)
+#define hw_irq_disable() \
+ do { raw_hw_irq_disable(); trace_hardirqs_off(); } while (0)
+
#else /* !CONFIG_TRACE_IRQFLAGS_SUPPORT */
/*
* The local_irq_*() APIs are equal to the raw_local_irq*()
@@ -96,6 +107,10 @@
typecheck(unsigned long, flags); \
local_irq_restore(flags); \
} while (0)
+# define raw_hw_irq_enable() raw_local_irq_enable()
+# define raw_hw_irq_disable() raw_local_irq_disable()
+# define hw_irq_enable() raw_hw_irq_enable()
+# define hw_irq_disable() raw_hw_irq_disable()
#endif /* CONFIG_TRACE_IRQFLAGS_SUPPORT */

#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
@@ -124,6 +139,22 @@
typecheck(unsigned long, flags); \
raw_irqs_disabled_flags(flags); \
})
+
+#ifdef __ARCH_HAS_HW_IRQ
+static inline bool hw_irqs_disabled(void)
+{
+ unsigned long flags;
+
+ if (irqs_disabled())
+ return true;
+
+ raw_hw_irq_save_flags(flags);
+ return raw_hw_irqs_disabled_flags(flags);
+}
+#else /* __ARCH_HAS_HW_IRQ */
+#define hw_irqs_disabled() irqs_disabled()
+#endif /* __ARCH_HAS_HW_IRQ */
+
#endif /* CONFIG_TRACE_IRQFLAGS_SUPPORT */

#endif
Index: work/init/main.c
===================================================================
--- work.orig/init/main.c
+++ work/init/main.c
@@ -626,7 +626,7 @@ asmlinkage void __init start_kernel(void
printk(KERN_CRIT "start_kernel(): bug: interrupts were "
"enabled early\n");
early_boot_irqs_on();
- local_irq_enable();
+ hw_irq_enable();

/* Interrupts are enabled now so all GFP allocations are safe. */
gfp_allowed_mask = __GFP_BITS_MASK;
Index: work/arch/x86/include/asm/system.h
===================================================================
--- work.orig/arch/x86/include/asm/system.h
+++ work/arch/x86/include/asm/system.h
@@ -102,8 +102,8 @@ do { \
#define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"

/* frame pointer must be last for get_wchan */
-#define SAVE_CONTEXT "pushf ; pushq %%rbp ; movq %%rsi,%%rbp\n\t"
-#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp ; popf\t"
+#define SAVE_CONTEXT "pushq %%rbp ; movq %%rsi,%%rbp\n\t"
+#define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp\t"

#define __EXTRA_CLOBBER \
, "rcx", "rbx", "rdx", "r8", "r9", "r10", "r11", \
Index: work/arch/x86/ia32/ia32entry.S
===================================================================
--- work.orig/arch/x86/ia32/ia32entry.S
+++ work/arch/x86/ia32/ia32entry.S
@@ -162,7 +162,7 @@ sysenter_dispatch:
movq %rax,RAX-ARGOFFSET(%rsp)
GET_THREAD_INFO(%r10)
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
testl $_TIF_ALLWORK_MASK,TI_flags(%r10)
jnz sysexit_audit
sysexit_from_sys_call:
@@ -182,7 +182,7 @@ sysexit_from_sys_call:
popq %rcx /* User %esp */
CFI_ADJUST_CFA_OFFSET -8
CFI_REGISTER rsp,rcx
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS_SYSEXIT32

#ifdef CONFIG_AUDITSYSCALL
@@ -207,7 +207,7 @@ sysexit_from_sys_call:
.macro auditsys_exit exit
testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags(%r10)
jnz ia32_ret_from_sys_call
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
sti
movl %eax,%esi /* second arg, syscall return value */
cmpl $0,%eax /* is it < 0? */
@@ -219,7 +219,7 @@ sysexit_from_sys_call:
movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall return value */
movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi
cli
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
testl %edi,TI_flags(%r10)
jz \exit
CLEAR_RREGS -ARGOFFSET
@@ -323,7 +323,7 @@ cstar_dispatch:
movq %rax,RAX-ARGOFFSET(%rsp)
GET_THREAD_INFO(%r10)
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
testl $_TIF_ALLWORK_MASK,TI_flags(%r10)
jnz sysretl_audit
sysretl_from_sys_call:
@@ -336,7 +336,7 @@ sysretl_from_sys_call:
xorq %r10,%r10
xorq %r9,%r9
xorq %r8,%r8
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
movl RSP-ARGOFFSET(%rsp),%esp
CFI_RESTORE rsp
USERGS_SYSRET32
Index: work/arch/x86/kernel/cpu/common.c
===================================================================
--- work.orig/arch/x86/kernel/cpu/common.c
+++ work/arch/x86/kernel/cpu/common.c
@@ -1005,6 +1005,14 @@ DEFINE_PER_CPU(char *, irq_stack_ptr) =

DEFINE_PER_CPU(unsigned int, irq_count) = -1;

+DEFINE_PER_CPU(unsigned int, x86_irq_enable) = 0;
+EXPORT_PER_CPU_SYMBOL(x86_irq_enable);
+
+DEFINE_PER_CPU(unsigned long, x86_irq_pending) = 0;
+EXPORT_PER_CPU_SYMBOL(x86_irq_pending);
+
+DEFINE_PER_CPU(void (*)(struct pt_regs *), x86_irq_pending_handler) = NULL;
+
/*
* Special IST stacks which the CPU switches to when it calls
* an IST-marked descriptor entry. Up to 7 stacks (hardware
@@ -1211,7 +1219,7 @@ void __cpuinit cpu_init(void)
if (cpumask_test_and_set_cpu(cpu, cpu_initialized_mask)) {
printk(KERN_WARNING "CPU#%d already initialized!\n", cpu);
for (;;)
- local_irq_enable();
+ hw_irq_enable();
}

printk(KERN_INFO "Initializing CPU#%d\n", cpu);
Index: work/arch/x86/kernel/entry_64.S
===================================================================
--- work.orig/arch/x86/kernel/entry_64.S
+++ work/arch/x86/kernel/entry_64.S
@@ -175,11 +175,11 @@ ENDPROC(native_usergs_sysret64)
#endif /* CONFIG_PARAVIRT */


-.macro TRACE_IRQS_IRETQ offset=ARGOFFSET
+.macro TRACE_HW_IRQS_IRETQ offset=ARGOFFSET
#ifdef CONFIG_TRACE_IRQFLAGS
bt $9,EFLAGS-\offset(%rsp) /* interrupts off? */
jnc 1f
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
1:
#endif
.endm
@@ -317,17 +317,14 @@ ENTRY(save_args)
leaq -ARGOFFSET+16(%rsp),%rdi /* arg1 for handler */
movq_cfi rbp, 8 /* push %rbp */
leaq 8(%rsp), %rbp /* mov %rsp, %ebp */
- testl $3, CS(%rdi)
- je 1f
- SWAPGS
/*
* irq_count is used to check if a CPU is already on an interrupt stack
* or not. While this is essentially redundant with preempt_count it is
* a little cheaper to use a separate counter in the PDA (short of
* moving irq_enter into assembly, which would be too much work)
*/
-1: incl PER_CPU_VAR(irq_count)
- jne 2f
+ incl PER_CPU_VAR(irq_count)
+ jne 1f
popq_cfi %rax /* move return address... */
mov PER_CPU_VAR(irq_stack_ptr),%rsp
EMPTY_FRAME 0
@@ -336,7 +333,7 @@ ENTRY(save_args)
/*
* We entered an interrupt context - irqs are off:
*/
-2: TRACE_IRQS_OFF
+1: TRACE_HW_IRQS_OFF
ret
CFI_ENDPROC
END(save_args)
@@ -497,7 +494,7 @@ sysret_check:
LOCKDEP_SYS_EXIT
GET_THREAD_INFO(%rcx)
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
movl TI_flags(%rcx),%edx
andl %edi,%edx
jnz sysret_careful
@@ -505,7 +502,7 @@ sysret_check:
/*
* sysretq will re-enable interrupts:
*/
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
movq RIP-ARGOFFSET(%rsp),%rcx
CFI_REGISTER rip,rcx
RESTORE_ARGS 0,-ARG_SKIP,1
@@ -519,7 +516,7 @@ sysret_check:
sysret_careful:
bt $TIF_NEED_RESCHED,%edx
jnc sysret_signal
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
@@ -530,7 +527,7 @@ sysret_careful:

/* Handle a signal */
sysret_signal:
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
#ifdef CONFIG_AUDITSYSCALL
bt $TIF_SYSCALL_AUDIT,%edx
@@ -612,7 +609,7 @@ tracesys:
*/
GLOBAL(int_ret_from_sys_call)
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
testl $3,CS-ARGOFFSET(%rsp)
je retint_restore_args
movl $_TIF_ALLWORK_MASK,%edi
@@ -632,7 +629,7 @@ GLOBAL(int_with_check)
int_careful:
bt $TIF_NEED_RESCHED,%edx
jnc int_very_careful
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
@@ -640,12 +637,12 @@ int_careful:
popq %rdi
CFI_ADJUST_CFA_OFFSET -8
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
jmp int_with_check

/* handle signals and tracing -- both require a full stack frame */
int_very_careful:
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
int_check_syscall_exit_work:
SAVE_REST
@@ -671,7 +668,7 @@ int_signal:
int_restore_rest:
RESTORE_REST
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
jmp int_with_check
CFI_ENDPROC
END(system_call)
@@ -796,11 +793,22 @@ END(interrupt)

/* 0(%rsp): ~(interrupt number) */
.macro interrupt func
+ testl $3, CS-ORIG_RAX(%rsp)
+ je 1f
+ SWAPGS
+1: btrl $0, PER_CPU_VAR(x86_irq_enable)
+ jc 2f
+ pushq $\func
+ CFI_ADJUST_CFA_OFFSET 8
+ jmp mark_irq_pending
+2: TRACE_IRQS_OFF
subq $10*8, %rsp
CFI_ADJUST_CFA_OFFSET 10*8
call save_args
PARTIAL_FRAME 0
call \func
+ TRACE_IRQS_ON
+ movl $1, PER_CPU_VAR(x86_irq_enable)
.endm

/*
@@ -818,8 +826,6 @@ common_interrupt:
interrupt do_IRQ
/* 0(%rsp): old_rsp-ARGOFFSET */
ret_from_intr:
- DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
decl PER_CPU_VAR(irq_count)
leaveq
CFI_DEF_CFA_REGISTER rsp
@@ -844,21 +850,8 @@ retint_check:
jnz retint_careful

retint_swapgs: /* return to user-space */
- /*
- * The iretq could re-enable interrupts:
- */
- DISABLE_INTERRUPTS(CLBR_ANY)
- TRACE_IRQS_IRETQ
SWAPGS
- jmp restore_args
-
retint_restore_args: /* return to kernel space */
- DISABLE_INTERRUPTS(CLBR_ANY)
- /*
- * The iretq could re-enable interrupts:
- */
- TRACE_IRQS_IRETQ
-restore_args:
RESTORE_ARGS 0,8,0

irq_return:
@@ -901,7 +894,7 @@ retint_careful:
CFI_RESTORE_STATE
bt $TIF_NEED_RESCHED,%edx
jnc retint_signal
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
@@ -910,13 +903,13 @@ retint_careful:
CFI_ADJUST_CFA_OFFSET -8
GET_THREAD_INFO(%rcx)
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
jmp retint_check

retint_signal:
testl $_TIF_DO_NOTIFY_MASK,%edx
jz retint_swapgs
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
SAVE_REST
movq $-1,ORIG_RAX(%rsp)
@@ -925,7 +918,7 @@ retint_signal:
call do_notify_resume
RESTORE_REST
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
GET_THREAD_INFO(%rcx)
jmp retint_with_reschedule

@@ -937,14 +930,62 @@ ENTRY(retint_kernel)
jnz retint_restore_args
bt $TIF_NEED_RESCHED,TI_flags(%rcx)
jnc retint_restore_args
- bt $9,EFLAGS-ARGOFFSET(%rsp) /* interrupts off? */
+ bt $0, PER_CPU_VAR(x86_irq_enable) /* interrupts off? */
jnc retint_restore_args
+ bt $9, EFLAGS-ARGOFFSET(%rsp) /* hw interrupts off? */
+ jnc retint_restore_args
+ movl $0, PER_CPU_VAR(x86_irq_enable)
+ TRACE_IRQS_OFF
+ TRACE_HW_IRQS_ON
+ ENABLE_INTERRUPTS(CLBR_NONE)
call preempt_schedule_irq
+ DISABLE_INTERRUPTS(CLBR_NONE)
+ TRACE_HW_IRQS_OFF
+ TRACE_IRQS_ON
+ movl $1, PER_CPU_VAR(x86_irq_enable)
jmp exit_intr
#endif

CFI_ENDPROC
END(common_interrupt)
+
+mark_irq_pending:
+ XCPT_FRAME 1 8
+ btl $31, PER_CPU_VAR(x86_irq_pending) /* negative if pending */
+ jc 1f
+ popq PER_CPU_VAR(x86_irq_pending_handler)
+ CFI_ADJUST_CFA_OFFSET -8
+ popq PER_CPU_VAR(x86_irq_pending)
+ CFI_ADJUST_CFA_OFFSET -8
+ andl $~X86_EFLAGS_IF, EFLAGS-RIP(%rsp)
+ testl $3, CS-RIP(%rsp)
+ je irq_return
+ SWAPGS
+ jmp irq_return
+1: ud2
+ CFI_ENDPROC
+
+/* void call_on_irq_stack(void *fn, void *arg) */
+ENTRY(call_on_irq_stack)
+ CFI_STARTPROC
+ pushq_cfi %rbp
+ CFI_REL_OFFSET rbp, 0
+ movq %rsp, %rbp
+ CFI_DEF_CFA_REGISTER %rbp
+ incl PER_CPU_VAR(irq_count)
+ cmove PER_CPU_VAR(irq_stack_ptr),%rsp
+ pushq %rbp # backlink for old unwinder
+ movq %rdi, %rcx
+ movq %rsi, %rdi
+ call *%rcx
+ leaveq
+ CFI_DEF_CFA_REGISTER %rsp
+ CFI_ADJUST_CFA_OFFSET -8
+ decl PER_CPU_VAR(irq_count)
+ ret
+ CFI_ENDPROC
+END(cal_irq_handler)
+
/*
* End of kprobes section
*/
@@ -1056,7 +1097,7 @@ ENTRY(\sym)
CFI_ADJUST_CFA_OFFSET 8
subq $15*8, %rsp
call save_paranoid
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
movq %rsp,%rdi /* pt_regs pointer */
xorl %esi,%esi /* no error code */
call \do_sym
@@ -1073,7 +1114,7 @@ ENTRY(\sym)
CFI_ADJUST_CFA_OFFSET 8
subq $15*8, %rsp
call save_paranoid
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
movq %rsp,%rdi /* pt_regs pointer */
xorl %esi,%esi /* no error code */
PER_CPU(init_tss, %r12)
@@ -1111,7 +1152,7 @@ ENTRY(\sym)
CFI_ADJUST_CFA_OFFSET 15*8
call save_paranoid
DEFAULT_FRAME 0
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
movq %rsp,%rdi /* pt_regs pointer */
movq ORIG_RAX(%rsp),%rsi /* get error code */
movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
@@ -1367,18 +1408,18 @@ paranoidzeroentry machine_check *machine
ENTRY(paranoid_exit)
INTR_FRAME
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
testl %ebx,%ebx /* swapgs needed? */
jnz paranoid_restore
testl $3,CS(%rsp)
jnz paranoid_userspace
paranoid_swapgs:
- TRACE_IRQS_IRETQ 0
+ TRACE_HW_IRQS_IRETQ 0
SWAPGS_UNSAFE_STACK
RESTORE_ALL 8
jmp irq_return
paranoid_restore:
- TRACE_IRQS_IRETQ 0
+ TRACE_HW_IRQS_IRETQ 0
RESTORE_ALL 8
jmp irq_return
paranoid_userspace:
@@ -1392,20 +1433,20 @@ paranoid_userspace:
testl $_TIF_NEED_RESCHED,%ebx
jnz paranoid_schedule
movl %ebx,%edx /* arg3: thread flags */
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_NONE)
xorl %esi,%esi /* arg2: oldset */
movq %rsp,%rdi /* arg1: &pt_regs */
call do_notify_resume
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
jmp paranoid_userspace
paranoid_schedule:
- TRACE_IRQS_ON
+ TRACE_HW_IRQS_ON
ENABLE_INTERRUPTS(CLBR_ANY)
call schedule
DISABLE_INTERRUPTS(CLBR_ANY)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
jmp paranoid_userspace
CFI_ENDPROC
END(paranoid_exit)
@@ -1440,7 +1481,7 @@ ENTRY(error_entry)
error_swapgs:
SWAPGS
error_sti:
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
ret
CFI_ENDPROC

@@ -1476,7 +1517,7 @@ ENTRY(error_exit)
movl %ebx,%eax
RESTORE_REST
DISABLE_INTERRUPTS(CLBR_NONE)
- TRACE_IRQS_OFF
+ TRACE_HW_IRQS_OFF
GET_THREAD_INFO(%rcx)
testl %eax,%eax
jne retint_kernel
@@ -1499,12 +1540,12 @@ ENTRY(nmi)
CFI_ADJUST_CFA_OFFSET 15*8
call save_paranoid
DEFAULT_FRAME 0
- /* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
+ /* paranoidentry do_nmi, 0; without TRACE_HW_IRQS_OFF */
movq %rsp,%rdi
movq $-1,%rsi
call do_nmi
#ifdef CONFIG_TRACE_IRQFLAGS
- /* paranoidexit; without TRACE_IRQS_OFF */
+ /* paranoidexit; without TRACE_HW_IRQS_OFF */
/* ebx: no swapgs flag */
DISABLE_INTERRUPTS(CLBR_NONE)
testl %ebx,%ebx /* swapgs needed? */
Index: work/arch/x86/kernel/process.c
===================================================================
--- work.orig/arch/x86/kernel/process.c
+++ work/arch/x86/kernel/process.c
@@ -381,11 +381,10 @@ void default_idle(void)

if (!need_resched())
safe_halt(); /* enables interrupts racelessly */
- else
- local_irq_enable();
+ hw_irq_enable();
current_thread_info()->status |= TS_POLLING;
} else {
- local_irq_enable();
+ hw_irq_enable();
/* loop is done by the caller */
cpu_relax();
}
@@ -396,7 +395,7 @@ EXPORT_SYMBOL(default_idle);

void stop_this_cpu(void *dummy)
{
- local_irq_disable();
+ hw_irq_disable();
/*
* Remove this CPU:
*/
@@ -465,10 +464,8 @@ static void mwait_idle(void)
smp_mb();
if (!need_resched())
__sti_mwait(0, 0);
- else
- local_irq_enable();
- } else
- local_irq_enable();
+ }
+ hw_irq_enable();
}

/*
@@ -479,7 +476,7 @@ static void mwait_idle(void)
static void poll_idle(void)
{
trace_power_start(POWER_CSTATE, 0);
- local_irq_enable();
+ hw_irq_enable();
while (!need_resched())
cpu_relax();
trace_power_end(0);
@@ -614,9 +611,9 @@ static void c1e_idle(void)
* The switch back from broadcast mode needs to be
* called with interrupts disabled.
*/
- local_irq_disable();
- clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
- local_irq_enable();
+ hw_irq_disable();
+ clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
+ hw_irq_enable();
} else
default_idle();
}
Index: work/arch/x86/include/asm/irqflags.h
===================================================================
--- work.orig/arch/x86/include/asm/irqflags.h
+++ work/arch/x86/include/asm/irqflags.h
@@ -4,6 +4,13 @@
#include <asm/processor-flags.h>

#ifndef __ASSEMBLY__
+
+#include <asm/percpu.h>
+
+DECLARE_PER_CPU(unsigned int, x86_irq_enable); /* boolean switch */
+DECLARE_PER_CPU(unsigned long, x86_irq_pending); /* pending vector */
+DECLARE_PER_CPU(void (*)(struct pt_regs *), x86_irq_pending_handler);
+
/*
* Interrupt control:
*/
@@ -54,6 +61,45 @@ static inline void native_halt(void)
asm volatile("hlt": : :"memory");
}

+extern void __raw_local_irq_enable_slow_path(void);
+
+static inline unsigned long __raw_local_save_flags(void)
+{
+ return percpu_read(x86_irq_enable);
+}
+
+static inline void raw_local_irq_restore(unsigned long flags)
+{
+ barrier();
+ percpu_write(x86_irq_enable, flags);
+ barrier();
+ if (flags && unlikely(percpu_read(x86_irq_pending)))
+ __raw_local_irq_enable_slow_path();
+}
+
+static inline void raw_local_irq_disable(void)
+{
+ percpu_write(x86_irq_enable, 0);
+ barrier();
+}
+
+static inline void raw_local_irq_enable(void)
+{
+ barrier();
+ percpu_write(x86_irq_enable, 1);
+ barrier();
+ if (unlikely(percpu_read(x86_irq_pending)))
+ __raw_local_irq_enable_slow_path();
+}
+
+static inline unsigned long __raw_local_irq_save(void)
+{
+ unsigned long flags = __raw_local_save_flags();
+
+ raw_local_irq_disable();
+
+ return flags;
+}
#endif

#ifdef CONFIG_PARAVIRT
@@ -61,22 +107,17 @@ static inline void native_halt(void)
#else
#ifndef __ASSEMBLY__

-static inline unsigned long __raw_local_save_flags(void)
+static inline unsigned long __raw_hw_save_flags(void)
{
return native_save_fl();
}

-static inline void raw_local_irq_restore(unsigned long flags)
-{
- native_restore_fl(flags);
-}
-
-static inline void raw_local_irq_disable(void)
+static inline void __raw_hw_irq_disable(void)
{
native_irq_disable();
}

-static inline void raw_local_irq_enable(void)
+static inline void __raw_hw_irq_enable(void)
{
native_irq_enable();
}
@@ -87,6 +128,7 @@ static inline void raw_local_irq_enable(
*/
static inline void raw_safe_halt(void)
{
+ percpu_write(x86_irq_enable, 1);
native_safe_halt();
}

@@ -99,17 +141,6 @@ static inline void halt(void)
native_halt();
}

-/*
- * For spinlocks, etc:
- */
-static inline unsigned long __raw_local_irq_save(void)
-{
- unsigned long flags = __raw_local_save_flags();
-
- raw_local_irq_disable();
-
- return flags;
-}
#else

#define ENABLE_INTERRUPTS(x) sti
@@ -161,14 +192,34 @@ static inline unsigned long __raw_local_

static inline int raw_irqs_disabled_flags(unsigned long flags)
{
- return !(flags & X86_EFLAGS_IF);
+ return !flags;
}

static inline int raw_irqs_disabled(void)
{
- unsigned long flags = __raw_local_save_flags();
+ return raw_irqs_disabled_flags(__raw_local_save_flags());
+}
+
+#define __ARCH_HAS_HW_IRQ
+
+#define raw_hw_irq_save_flags(flags) \
+ do { (flags) = __raw_hw_save_flags(); } while (0)
+
+static inline void raw_hw_irq_disable(void)
+{
+ __raw_hw_irq_disable();
+ percpu_write(x86_irq_enable, 0);
+}

- return raw_irqs_disabled_flags(flags);
+static inline void raw_hw_irq_enable(void)
+{
+ raw_local_irq_enable();
+ __raw_hw_irq_enable();
+}
+
+static inline int raw_hw_irqs_disabled_flags(unsigned long flags)
+{
+ return !(flags & X86_EFLAGS_IF);
}

#else
@@ -176,13 +227,13 @@ static inline int raw_irqs_disabled(void
#ifdef CONFIG_X86_64
#define ARCH_LOCKDEP_SYS_EXIT call lockdep_sys_exit_thunk
#define ARCH_LOCKDEP_SYS_EXIT_IRQ \
- TRACE_IRQS_ON; \
+ TRACE_HW_IRQS_ON; \
sti; \
SAVE_REST; \
LOCKDEP_SYS_EXIT; \
RESTORE_REST; \
cli; \
- TRACE_IRQS_OFF;
+ TRACE_HW_IRQS_OFF;

#else
#define ARCH_LOCKDEP_SYS_EXIT \
@@ -212,5 +263,9 @@ static inline int raw_irqs_disabled(void
# define LOCKDEP_SYS_EXIT_IRQ
# endif

+/* HW IRQS tracing isn't implemented yet */
+#define TRACE_HW_IRQS_ON
+#define TRACE_HW_IRQS_OFF
+
#endif /* __ASSEMBLY__ */
#endif
Index: work/arch/x86/kernel/process_64.c
===================================================================
--- work.orig/arch/x86/kernel/process_64.c
+++ work/arch/x86/kernel/process_64.c
@@ -132,7 +132,7 @@ void cpu_idle(void)
* from here on, until they go to idle.
* Otherwise, idle callbacks can misfire.
*/
- local_irq_disable();
+ hw_irq_disable();
enter_idle();
/* Don't trace irqs off for idle */
stop_critical_timings();
Index: work/arch/x86/kernel/smpboot.c
===================================================================
--- work.orig/arch/x86/kernel/smpboot.c
+++ work/arch/x86/kernel/smpboot.c
@@ -1364,7 +1364,7 @@ void play_dead_common(void)
/*
* With physical CPU hotplug, we should halt the cpu
*/
- local_irq_disable();
+ hw_irq_disable();
}

void native_play_dead(void)
Index: work/arch/x86/include/asm/paravirt.h
===================================================================
--- work.orig/arch/x86/include/asm/paravirt.h
+++ work/arch/x86/include/asm/paravirt.h
@@ -107,6 +107,7 @@ static inline void write_cr8(unsigned lo

static inline void raw_safe_halt(void)
{
+ percpu_write(x86_irq_enable, 1);
PVOP_VCALL0(pv_irq_ops.safe_halt);
}

@@ -829,35 +830,21 @@ static __always_inline void arch_spin_un
#define __PV_IS_CALLEE_SAVE(func) \
((struct paravirt_callee_save) { func })

-static inline unsigned long __raw_local_save_flags(void)
+static inline unsigned long __raw_hw_save_flags(void)
{
return PVOP_CALLEE0(unsigned long, pv_irq_ops.save_fl);
}

-static inline void raw_local_irq_restore(unsigned long f)
-{
- PVOP_VCALLEE1(pv_irq_ops.restore_fl, f);
-}
-
-static inline void raw_local_irq_disable(void)
+static inline void __raw_hw_irq_disable(void)
{
PVOP_VCALLEE0(pv_irq_ops.irq_disable);
}

-static inline void raw_local_irq_enable(void)
+static inline void __raw_hw_irq_enable(void)
{
PVOP_VCALLEE0(pv_irq_ops.irq_enable);
}

-static inline unsigned long __raw_local_irq_save(void)
-{
- unsigned long f;
-
- f = __raw_local_save_flags();
- raw_local_irq_disable();
- return f;
-}
-

/* Make sure as little as possible of this mess escapes. */
#undef PARAVIRT_CALL
Index: work/arch/x86/kernel/irq.c
===================================================================
--- work.orig/arch/x86/kernel/irq.c
+++ work/arch/x86/kernel/irq.c
@@ -14,6 +14,7 @@
#include <asm/idle.h>
#include <asm/mce.h>
#include <asm/hw_irq.h>
+#include <asm/desc.h>

atomic_t irq_err_count;

@@ -217,6 +218,26 @@ u64 arch_irq_stat(void)
return sum;
}

+void call_on_irq_stack(void *fn, void *arg);
+
+void __raw_local_irq_enable_slow_path(void)
+{
+ struct pt_regs regs;
+
+ regs.sp = (unsigned long)&regs;
+ regs.orig_ax = percpu_read(x86_irq_pending);
+ regs.flags = 0x2; /* bit 1 is always set */
+
+ percpu_write(x86_irq_enable, 0);
+ percpu_write(x86_irq_pending, 0);
+
+ call_on_irq_stack(percpu_read(x86_irq_pending_handler), &regs);
+
+ trace_hardirqs_on();
+ percpu_write(x86_irq_enable, 1);
+ __raw_hw_irq_enable();
+}
+EXPORT_SYMBOL(__raw_local_irq_enable_slow_path);

/*
* do_IRQ handles all normal device IRQ's (the special
Index: work/arch/x86/kernel/traps.c
===================================================================
--- work.orig/arch/x86/kernel/traps.c
+++ work/arch/x86/kernel/traps.c
@@ -86,26 +86,26 @@ static int ignore_nmis;
static inline void conditional_sti(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
- local_irq_enable();
+ __raw_hw_irq_enable();
}

static inline void preempt_conditional_sti(struct pt_regs *regs)
{
inc_preempt_count();
if (regs->flags & X86_EFLAGS_IF)
- local_irq_enable();
+ __raw_hw_irq_enable();
}

static inline void conditional_cli(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
- local_irq_disable();
+ __raw_hw_irq_disable();
}

static inline void preempt_conditional_cli(struct pt_regs *regs)
{
if (regs->flags & X86_EFLAGS_IF)
- local_irq_disable();
+ __raw_hw_irq_disable();
dec_preempt_count();
}

@@ -283,7 +283,7 @@ do_general_protection(struct pt_regs *re

#ifdef CONFIG_X86_32
gp_in_vm86:
- local_irq_enable();
+ __raw_hw_irq_enable();
handle_vm86_fault((struct kernel_vm86_regs *) regs, error_code);
return;
#endif
@@ -749,7 +749,7 @@ asmlinkage void math_state_restore(void)
struct task_struct *tsk = thread->task;

if (!tsk_used_math(tsk)) {
- local_irq_enable();
+ __raw_hw_irq_enable();
/*
* does a slab alloc which can sleep
*/
@@ -760,7 +760,7 @@ asmlinkage void math_state_restore(void)
do_group_exit(SIGKILL);
return;
}
- local_irq_disable();
+ __raw_hw_irq_disable();
}

clts(); /* Allow maths ops (or we recurse) */
@@ -804,7 +804,7 @@ do_device_not_available(struct pt_regs *
dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
{
siginfo_t info;
- local_irq_enable();
+ __raw_hw_irq_enable();

info.si_signo = SIGILL;
info.si_errno = 0;
Index: work/arch/x86/mm/fault.c
===================================================================
--- work.orig/arch/x86/mm/fault.c
+++ work/arch/x86/mm/fault.c
@@ -711,7 +711,7 @@ __bad_area_nosemaphore(struct pt_regs *r
/*
* It's possible to have interrupts off here:
*/
- local_irq_enable();
+ __raw_hw_irq_enable();

/*
* Valid to do another page fault here because this one came
@@ -1019,11 +1019,11 @@ do_page_fault(struct pt_regs *regs, unsi
* potential system fault or CPU buglet:
*/
if (user_mode_vm(regs)) {
- local_irq_enable();
+ __raw_hw_irq_enable();
error_code |= PF_USER;
} else {
if (regs->flags & X86_EFLAGS_IF)
- local_irq_enable();
+ __raw_hw_irq_enable();
}

if (unlikely(error_code & PF_RSVD))
Index: work/lib/smp_processor_id.c
===================================================================
--- work.orig/lib/smp_processor_id.c
+++ work/lib/smp_processor_id.c
@@ -15,7 +15,7 @@ notrace unsigned int debug_smp_processor
if (likely(preempt_count))
goto out;

- if (irqs_disabled())
+ if (hw_irqs_disabled())
goto out;

/*

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  Last update: 2010-07-11 20:05    [from the cache]
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