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Subject[patch 18/61] lock validator: irqtrace: core
From: Ingo Molnar <mingo@elte.hu>

accurate hard-IRQ-flags state tracing. This allows us to attach
extra functionality to IRQ flags on/off events (such as trace-on/off).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
---
arch/i386/kernel/entry.S | 25 ++++++-
arch/i386/kernel/irq.c | 6 +
arch/x86_64/ia32/ia32entry.S | 19 +++++
arch/x86_64/kernel/entry.S | 54 +++++++++++++++-
arch/x86_64/kernel/irq.c | 4 -
include/asm-i386/irqflags.h | 56 ++++++++++++++++
include/asm-i386/spinlock.h | 5 +
include/asm-i386/system.h | 20 -----
include/asm-powerpc/irqflags.h | 31 +++++++++
include/asm-x86_64/irqflags.h | 54 ++++++++++++++++
include/asm-x86_64/system.h | 38 -----------
include/linux/hardirq.h | 13 +++
include/linux/init_task.h | 1
include/linux/interrupt.h | 11 +--
include/linux/sched.h | 15 ++++
include/linux/trace_irqflags.h | 87 ++++++++++++++++++++++++++
kernel/fork.c | 20 +++++
kernel/sched.c | 4 -
kernel/softirq.c | 137 +++++++++++++++++++++++++++++++++++------
lib/locking-selftest.c | 3
20 files changed, 513 insertions(+), 90 deletions(-)

Index: linux/arch/i386/kernel/entry.S
===================================================================
--- linux.orig/arch/i386/kernel/entry.S
+++ linux/arch/i386/kernel/entry.S
@@ -43,6 +43,7 @@
#include <linux/config.h>
#include <linux/linkage.h>
#include <asm/thread_info.h>
+#include <asm/irqflags.h>
#include <asm/errno.h>
#include <asm/segment.h>
#include <asm/smp.h>
@@ -76,7 +77,7 @@ NT_MASK = 0x00004000
VM_MASK = 0x00020000

#ifdef CONFIG_PREEMPT
-#define preempt_stop cli
+#define preempt_stop cli; TRACE_IRQS_OFF
#else
#define preempt_stop
#define resume_kernel restore_nocheck
@@ -186,6 +187,10 @@ need_resched:
ENTRY(sysenter_entry)
movl TSS_sysenter_esp0(%esp),%esp
sysenter_past_esp:
+ /*
+ * No need to follow this irqs on/off section: the syscall
+ * disabled irqs and here we enable it straight after entry:
+ */
sti
pushl $(__USER_DS)
pushl %ebp
@@ -217,6 +222,7 @@ sysenter_past_esp:
call *sys_call_table(,%eax,4)
movl %eax,EAX(%esp)
cli
+ TRACE_IRQS_OFF
movl TI_flags(%ebp), %ecx
testw $_TIF_ALLWORK_MASK, %cx
jne syscall_exit_work
@@ -224,6 +230,7 @@ sysenter_past_esp:
movl EIP(%esp), %edx
movl OLDESP(%esp), %ecx
xorl %ebp,%ebp
+ TRACE_IRQS_ON
sti
sysexit

@@ -250,6 +257,7 @@ syscall_exit:
cli # make sure we don't miss an interrupt
# setting need_resched or sigpending
# between sampling and the iret
+ TRACE_IRQS_OFF
movl TI_flags(%ebp), %ecx
testw $_TIF_ALLWORK_MASK, %cx # current->work
jne syscall_exit_work
@@ -265,11 +273,14 @@ restore_all:
cmpl $((4 << 8) | 3), %eax
je ldt_ss # returning to user-space with LDT SS
restore_nocheck:
+ TRACE_IRQS_ON
+restore_nocheck_notrace:
RESTORE_REGS
addl $4, %esp
1: iret
.section .fixup,"ax"
iret_exc:
+ TRACE_IRQS_ON
sti
pushl $0 # no error code
pushl $do_iret_error
@@ -293,10 +304,12 @@ ldt_ss:
* dosemu and wine happy. */
subl $8, %esp # reserve space for switch16 pointer
cli
+ TRACE_IRQS_OFF
movl %esp, %eax
/* Set up the 16bit stack frame with switch32 pointer on top,
* and a switch16 pointer on top of the current frame. */
call setup_x86_bogus_stack
+ TRACE_IRQS_ON
RESTORE_REGS
lss 20+4(%esp), %esp # switch to 16bit stack
1: iret
@@ -315,6 +328,7 @@ work_resched:
cli # make sure we don't miss an interrupt
# setting need_resched or sigpending
# between sampling and the iret
+ TRACE_IRQS_OFF
movl TI_flags(%ebp), %ecx
andl $_TIF_WORK_MASK, %ecx # is there any work to be done other
# than syscall tracing?
@@ -364,6 +378,7 @@ syscall_trace_entry:
syscall_exit_work:
testb $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP), %cl
jz work_pending
+ TRACE_IRQS_ON
sti # could let do_syscall_trace() call
# schedule() instead
movl %esp, %eax
@@ -425,9 +440,14 @@ ENTRY(irq_entries_start)
vector=vector+1
.endr

+/*
+ * the CPU automatically disables interrupts when executing an IRQ vector,
+ * so IRQ-flags tracing has to follow that:
+ */
ALIGN
common_interrupt:
SAVE_ALL
+ TRACE_IRQS_OFF
movl %esp,%eax
call do_IRQ
jmp ret_from_intr
@@ -436,6 +456,7 @@ common_interrupt:
ENTRY(name) \
pushl $~(nr); \
SAVE_ALL \
+ TRACE_IRQS_OFF \
movl %esp,%eax; \
call smp_/**/name; \
jmp ret_from_intr;
@@ -565,7 +586,7 @@ nmi_stack_correct:
xorl %edx,%edx # zero error code
movl %esp,%eax # pt_regs pointer
call do_nmi
- jmp restore_all
+ jmp restore_nocheck_notrace

nmi_stack_fixup:
FIX_STACK(12,nmi_stack_correct, 1)
Index: linux/arch/i386/kernel/irq.c
===================================================================
--- linux.orig/arch/i386/kernel/irq.c
+++ linux/arch/i386/kernel/irq.c
@@ -147,7 +147,7 @@ void irq_ctx_init(int cpu)
irqctx->tinfo.task = NULL;
irqctx->tinfo.exec_domain = NULL;
irqctx->tinfo.cpu = cpu;
- irqctx->tinfo.preempt_count = SOFTIRQ_OFFSET;
+ irqctx->tinfo.preempt_count = 0;
irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);

softirq_ctx[cpu] = irqctx;
@@ -192,6 +192,10 @@ asmlinkage void do_softirq(void)
: "0"(isp)
: "memory", "cc", "edx", "ecx", "eax"
);
+ /*
+ * Shouldnt happen, we returned above if in_interrupt():
+ */
+ WARN_ON_ONCE(softirq_count());
}

local_irq_restore(flags);
Index: linux/arch/x86_64/ia32/ia32entry.S
===================================================================
--- linux.orig/arch/x86_64/ia32/ia32entry.S
+++ linux/arch/x86_64/ia32/ia32entry.S
@@ -13,6 +13,7 @@
#include <asm/thread_info.h>
#include <asm/segment.h>
#include <asm/vsyscall32.h>
+#include <asm/irqflags.h>
#include <linux/linkage.h>

#define IA32_NR_syscalls ((ia32_syscall_end - ia32_sys_call_table)/8)
@@ -75,6 +76,10 @@ ENTRY(ia32_sysenter_target)
swapgs
movq %gs:pda_kernelstack, %rsp
addq $(PDA_STACKOFFSET),%rsp
+ /*
+ * No need to follow this irqs on/off section: the syscall
+ * disabled irqs, here we enable it straight after entry:
+ */
sti
movl %ebp,%ebp /* zero extension */
pushq $__USER32_DS
@@ -118,6 +123,7 @@ sysenter_do_call:
movq %rax,RAX-ARGOFFSET(%rsp)
GET_THREAD_INFO(%r10)
cli
+ TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK,threadinfo_flags(%r10)
jnz int_ret_from_sys_call
andl $~TS_COMPAT,threadinfo_status(%r10)
@@ -132,6 +138,7 @@ sysenter_do_call:
CFI_REGISTER rsp,rcx
movl $VSYSCALL32_SYSEXIT,%edx /* User %eip */
CFI_REGISTER rip,rdx
+ TRACE_IRQS_ON
swapgs
sti /* sti only takes effect after the next instruction */
/* sysexit */
@@ -186,6 +193,10 @@ ENTRY(ia32_cstar_target)
movl %esp,%r8d
CFI_REGISTER rsp,r8
movq %gs:pda_kernelstack,%rsp
+ /*
+ * No need to follow this irqs on/off section: the syscall
+ * disabled irqs and here we enable it straight after entry:
+ */
sti
SAVE_ARGS 8,1,1
movl %eax,%eax /* zero extension */
@@ -220,6 +231,7 @@ cstar_do_call:
movq %rax,RAX-ARGOFFSET(%rsp)
GET_THREAD_INFO(%r10)
cli
+ TRACE_IRQS_OFF
testl $_TIF_ALLWORK_MASK,threadinfo_flags(%r10)
jnz int_ret_from_sys_call
andl $~TS_COMPAT,threadinfo_status(%r10)
@@ -228,6 +240,7 @@ cstar_do_call:
CFI_REGISTER rip,rcx
movl EFLAGS-ARGOFFSET(%rsp),%r11d
/*CFI_REGISTER rflags,r11*/
+ TRACE_IRQS_ON
movl RSP-ARGOFFSET(%rsp),%esp
CFI_RESTORE rsp
swapgs
@@ -286,7 +299,11 @@ ENTRY(ia32_syscall)
/*CFI_REL_OFFSET rflags,EFLAGS-RIP*/
/*CFI_REL_OFFSET cs,CS-RIP*/
CFI_REL_OFFSET rip,RIP-RIP
- swapgs
+ swapgs
+ /*
+ * No need to follow this irqs on/off section: the syscall
+ * disabled irqs and here we enable it straight after entry:
+ */
sti
movl %eax,%eax
pushq %rax
Index: linux/arch/x86_64/kernel/entry.S
===================================================================
--- linux.orig/arch/x86_64/kernel/entry.S
+++ linux/arch/x86_64/kernel/entry.S
@@ -42,13 +42,14 @@
#include <asm/thread_info.h>
#include <asm/hw_irq.h>
#include <asm/page.h>
+#include <asm/irqflags.h>

.code64

#ifndef CONFIG_PREEMPT
#define retint_kernel retint_restore_args
#endif
-
+
/*
* C code is not supposed to know about undefined top of stack. Every time
* a C function with an pt_regs argument is called from the SYSCALL based
@@ -195,6 +196,10 @@ ENTRY(system_call)
swapgs
movq %rsp,%gs:pda_oldrsp
movq %gs:pda_kernelstack,%rsp
+ /*
+ * No need to follow this irqs off/on section - it's straight
+ * and short:
+ */
sti
SAVE_ARGS 8,1
movq %rax,ORIG_RAX-ARGOFFSET(%rsp)
@@ -220,10 +225,15 @@ ret_from_sys_call:
sysret_check:
GET_THREAD_INFO(%rcx)
cli
+ TRACE_IRQS_OFF
movl threadinfo_flags(%rcx),%edx
andl %edi,%edx
CFI_REMEMBER_STATE
jnz sysret_careful
+ /*
+ * sysretq will re-enable interrupts:
+ */
+ TRACE_IRQS_ON
movq RIP-ARGOFFSET(%rsp),%rcx
CFI_REGISTER rip,rcx
RESTORE_ARGS 0,-ARG_SKIP,1
@@ -238,6 +248,7 @@ sysret_careful:
CFI_RESTORE_STATE
bt $TIF_NEED_RESCHED,%edx
jnc sysret_signal
+ TRACE_IRQS_ON
sti
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
@@ -248,6 +259,7 @@ sysret_careful:

/* Handle a signal */
sysret_signal:
+ TRACE_IRQS_ON
sti
testl $(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SINGLESTEP),%edx
jz 1f
@@ -262,6 +274,7 @@ sysret_signal:
/* Use IRET because user could have changed frame. This
works because ptregscall_common has called FIXUP_TOP_OF_STACK. */
cli
+ TRACE_IRQS_OFF
jmp int_with_check

badsys:
@@ -315,6 +328,7 @@ ENTRY(int_ret_from_sys_call)
CFI_REL_OFFSET r10,R10-ARGOFFSET
CFI_REL_OFFSET r11,R11-ARGOFFSET
cli
+ TRACE_IRQS_OFF
testl $3,CS-ARGOFFSET(%rsp)
je retint_restore_args
movl $_TIF_ALLWORK_MASK,%edi
@@ -333,6 +347,7 @@ int_with_check:
int_careful:
bt $TIF_NEED_RESCHED,%edx
jnc int_very_careful
+ TRACE_IRQS_ON
sti
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
@@ -340,10 +355,12 @@ int_careful:
popq %rdi
CFI_ADJUST_CFA_OFFSET -8
cli
+ TRACE_IRQS_OFF
jmp int_with_check

/* handle signals and tracing -- both require a full stack frame */
int_very_careful:
+ TRACE_IRQS_ON
sti
SAVE_REST
/* Check for syscall exit trace */
@@ -357,6 +374,7 @@ int_very_careful:
CFI_ADJUST_CFA_OFFSET -8
andl $~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edi
cli
+ TRACE_IRQS_OFF
jmp int_restore_rest

int_signal:
@@ -369,6 +387,7 @@ int_signal:
int_restore_rest:
RESTORE_REST
cli
+ TRACE_IRQS_OFF
jmp int_with_check
CFI_ENDPROC
END(int_ret_from_sys_call)
@@ -501,6 +520,11 @@ END(stub_rt_sigreturn)
#ifndef CONFIG_DEBUG_INFO
CFI_ADJUST_CFA_OFFSET 8
#endif
+ /*
+ * We entered an interrupt context - irqs are off:
+ */
+ TRACE_IRQS_OFF
+
call \func
.endm

@@ -514,6 +538,7 @@ ret_from_intr:
CFI_ADJUST_CFA_OFFSET -8
#endif
cli
+ TRACE_IRQS_OFF
decl %gs:pda_irqcount
#ifdef CONFIG_DEBUG_INFO
movq RBP(%rdi),%rbp
@@ -538,9 +563,21 @@ retint_check:
CFI_REMEMBER_STATE
jnz retint_careful
retint_swapgs:
+ /*
+ * The iretq will re-enable interrupts:
+ */
+ cli
+ TRACE_IRQS_ON
swapgs
+ jmp restore_args
+
retint_restore_args:
cli
+ /*
+ * The iretq will re-enable interrupts:
+ */
+ TRACE_IRQS_ON
+restore_args:
RESTORE_ARGS 0,8,0
iret_label:
iretq
@@ -553,6 +590,7 @@ iret_label:
/* running with kernel gs */
bad_iret:
movq $11,%rdi /* SIGSEGV */
+ TRACE_IRQS_ON
sti
jmp do_exit
.previous
@@ -562,6 +600,7 @@ retint_careful:
CFI_RESTORE_STATE
bt $TIF_NEED_RESCHED,%edx
jnc retint_signal
+ TRACE_IRQS_ON
sti
pushq %rdi
CFI_ADJUST_CFA_OFFSET 8
@@ -570,11 +609,13 @@ retint_careful:
CFI_ADJUST_CFA_OFFSET -8
GET_THREAD_INFO(%rcx)
cli
+ TRACE_IRQS_OFF
jmp retint_check

retint_signal:
testl $(_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SINGLESTEP),%edx
jz retint_swapgs
+ TRACE_IRQS_ON
sti
SAVE_REST
movq $-1,ORIG_RAX(%rsp)
@@ -583,6 +624,7 @@ retint_signal:
call do_notify_resume
RESTORE_REST
cli
+ TRACE_IRQS_OFF
movl $_TIF_NEED_RESCHED,%edi
GET_THREAD_INFO(%rcx)
jmp retint_check
@@ -714,6 +756,7 @@ END(spurious_interrupt)
addq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp)
.endif
cli
+ TRACE_IRQS_OFF
.endm

/*
@@ -771,6 +814,7 @@ error_exit:
movl %ebx,%eax
RESTORE_REST
cli
+ TRACE_IRQS_OFF
GET_THREAD_INFO(%rcx)
testl %eax,%eax
jne retint_kernel
@@ -778,6 +822,10 @@ error_exit:
movl $_TIF_WORK_MASK,%edi
andl %edi,%edx
jnz retint_careful
+ /*
+ * The iret will restore flags:
+ */
+ TRACE_IRQS_ON
swapgs
RESTORE_ARGS 0,8,0
jmp iret_label
@@ -980,16 +1028,20 @@ paranoid_userspace:
testl $_TIF_NEED_RESCHED,%ebx
jnz paranoid_schedule
movl %ebx,%edx /* arg3: thread flags */
+ TRACE_IRQS_ON
sti
xorl %esi,%esi /* arg2: oldset */
movq %rsp,%rdi /* arg1: &pt_regs */
call do_notify_resume
cli
+ TRACE_IRQS_OFF
jmp paranoid_userspace
paranoid_schedule:
+ TRACE_IRQS_ON
sti
call schedule
cli
+ TRACE_IRQS_OFF
jmp paranoid_userspace
CFI_ENDPROC
END(nmi)
Index: linux/arch/x86_64/kernel/irq.c
===================================================================
--- linux.orig/arch/x86_64/kernel/irq.c
+++ linux/arch/x86_64/kernel/irq.c
@@ -145,8 +145,10 @@ asmlinkage void do_softirq(void)
local_irq_save(flags);
pending = local_softirq_pending();
/* Switch to interrupt stack */
- if (pending)
+ if (pending) {
call_softirq();
+ WARN_ON_ONCE(softirq_count());
+ }
local_irq_restore(flags);
}
EXPORT_SYMBOL(do_softirq);
Index: linux/include/asm-i386/irqflags.h
===================================================================
--- /dev/null
+++ linux/include/asm-i386/irqflags.h
@@ -0,0 +1,56 @@
+/*
+ * include/asm-i386/irqflags.h
+ *
+ * IRQ flags handling
+ *
+ * This file gets included from lowlevel asm headers too, to provide
+ * wrapped versions of the local_irq_*() APIs, based on the
+ * raw_local_irq_*() macros from the lowlevel headers.
+ */
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+#define raw_local_save_flags(x) do { typecheck(unsigned long,x); __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */); } while (0)
+#define raw_local_irq_restore(x) do { typecheck(unsigned long,x); __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc"); } while (0)
+#define raw_local_irq_disable() __asm__ __volatile__("cli": : :"memory")
+#define raw_local_irq_enable() __asm__ __volatile__("sti": : :"memory")
+/* used in the idle loop; sti takes one instruction cycle to complete */
+#define raw_safe_halt() __asm__ __volatile__("sti; hlt": : :"memory")
+/* used when interrupts are already enabled or to shutdown the processor */
+#define halt() __asm__ __volatile__("hlt": : :"memory")
+
+#define raw_irqs_disabled_flags(flags) (!((flags) & (1<<9)))
+
+/* For spinlocks etc */
+#define raw_local_irq_save(x) __asm__ __volatile__("pushfl ; popl %0 ; cli":"=g" (x): /* no input */ :"memory")
+
+/*
+ * Do the CPU's IRQ-state tracing from assembly code. We call a
+ * C function, so save all the C-clobbered registers:
+ */
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+# define TRACE_IRQS_ON \
+ pushl %eax; \
+ pushl %ecx; \
+ pushl %edx; \
+ call trace_hardirqs_on; \
+ popl %edx; \
+ popl %ecx; \
+ popl %eax;
+
+# define TRACE_IRQS_OFF \
+ pushl %eax; \
+ pushl %ecx; \
+ pushl %edx; \
+ call trace_hardirqs_off; \
+ popl %edx; \
+ popl %ecx; \
+ popl %eax;
+
+#else
+# define TRACE_IRQS_ON
+# define TRACE_IRQS_OFF
+#endif
+
+#endif
Index: linux/include/asm-i386/spinlock.h
===================================================================
--- linux.orig/include/asm-i386/spinlock.h
+++ linux/include/asm-i386/spinlock.h
@@ -31,6 +31,11 @@
"jmp 1b\n" \
"3:\n\t"

+/*
+ * NOTE: there's an irqs-on section here, which normally would have to be
+ * irq-traced, but on CONFIG_TRACE_IRQFLAGS we never use
+ * __raw_spin_lock_string_flags().
+ */
#define __raw_spin_lock_string_flags \
"\n1:\t" \
"lock ; decb %0\n\t" \
Index: linux/include/asm-i386/system.h
===================================================================
--- linux.orig/include/asm-i386/system.h
+++ linux/include/asm-i386/system.h
@@ -456,25 +456,7 @@ static inline unsigned long long __cmpxc

#define set_wmb(var, value) do { var = value; wmb(); } while (0)

-/* interrupt control.. */
-#define local_save_flags(x) do { typecheck(unsigned long,x); __asm__ __volatile__("pushfl ; popl %0":"=g" (x): /* no input */); } while (0)
-#define local_irq_restore(x) do { typecheck(unsigned long,x); __asm__ __volatile__("pushl %0 ; popfl": /* no output */ :"g" (x):"memory", "cc"); } while (0)
-#define local_irq_disable() __asm__ __volatile__("cli": : :"memory")
-#define local_irq_enable() __asm__ __volatile__("sti": : :"memory")
-/* used in the idle loop; sti takes one instruction cycle to complete */
-#define safe_halt() __asm__ __volatile__("sti; hlt": : :"memory")
-/* used when interrupts are already enabled or to shutdown the processor */
-#define halt() __asm__ __volatile__("hlt": : :"memory")
-
-#define irqs_disabled() \
-({ \
- unsigned long flags; \
- local_save_flags(flags); \
- !(flags & (1<<9)); \
-})
-
-/* For spinlocks etc */
-#define local_irq_save(x) __asm__ __volatile__("pushfl ; popl %0 ; cli":"=g" (x): /* no input */ :"memory")
+#include <linux/trace_irqflags.h>

/*
* disable hlt during certain critical i/o operations
Index: linux/include/asm-powerpc/irqflags.h
===================================================================
--- /dev/null
+++ linux/include/asm-powerpc/irqflags.h
@@ -0,0 +1,31 @@
+/*
+ * include/asm-powerpc/irqflags.h
+ *
+ * IRQ flags handling
+ *
+ * This file gets included from lowlevel asm headers too, to provide
+ * wrapped versions of the local_irq_*() APIs, based on the
+ * raw_local_irq_*() macros from the lowlevel headers.
+ */
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+/*
+ * Get definitions for raw_local_save_flags(x), etc.
+ */
+#include <asm-powerpc/hw_irq.h>
+
+/*
+ * Do the CPU's IRQ-state tracing from assembly code. We call a
+ * C function, so save all the C-clobbered registers:
+ */
+#ifdef CONFIG_TRACE_IRQFLAGS
+
+#error No support on PowerPC yet for CONFIG_TRACE_IRQFLAGS
+
+#else
+# define TRACE_IRQS_ON
+# define TRACE_IRQS_OFF
+#endif
+
+#endif
Index: linux/include/asm-x86_64/irqflags.h
===================================================================
--- /dev/null
+++ linux/include/asm-x86_64/irqflags.h
@@ -0,0 +1,54 @@
+/*
+ * include/asm-x86_64/irqflags.h
+ *
+ * IRQ flags handling
+ *
+ * This file gets included from lowlevel asm headers too, to provide
+ * wrapped versions of the local_irq_*() APIs, based on the
+ * raw_local_irq_*() macros from the lowlevel headers.
+ */
+#ifndef _ASM_IRQFLAGS_H
+#define _ASM_IRQFLAGS_H
+
+/* interrupt control.. */
+#define raw_local_save_flags(x) do { warn_if_not_ulong(x); __asm__ __volatile__("# save_flags \n\t pushfq ; popq %q0":"=g" (x): /* no input */ :"memory"); } while (0)
+#define raw_local_irq_restore(x) __asm__ __volatile__("# restore_flags \n\t pushq %0 ; popfq": /* no output */ :"g" (x):"memory", "cc")
+
+#ifdef CONFIG_X86_VSMP
+/* Interrupt control for VSMP architecture */
+#define raw_local_irq_disable() do { unsigned long flags; raw_local_save_flags(flags); raw_local_irq_restore((flags & ~(1 << 9)) | (1 << 18)); } while (0)
+#define raw_local_irq_enable() do { unsigned long flags; raw_local_save_flags(flags); raw_local_irq_restore((flags | (1 << 9)) & ~(1 << 18)); } while (0)
+
+#define raw_irqs_disabled_flags(flags) \
+({ \
+ (flags & (1<<18)) || !(flags & (1<<9)); \
+})
+
+/* For spinlocks etc */
+#define raw_local_irq_save(x) do { raw_local_save_flags(x); raw_local_irq_restore((x & ~(1 << 9)) | (1 << 18)); } while (0)
+#else /* CONFIG_X86_VSMP */
+#define raw_local_irq_disable() __asm__ __volatile__("cli": : :"memory")
+#define raw_local_irq_enable() __asm__ __volatile__("sti": : :"memory")
+
+#define raw_irqs_disabled_flags(flags) \
+({ \
+ !(flags & (1<<9)); \
+})
+
+/* For spinlocks etc */
+#define raw_local_irq_save(x) do { warn_if_not_ulong(x); __asm__ __volatile__("# raw_local_irq_save \n\t pushfq ; popq %0 ; cli":"=g" (x): /* no input */ :"memory"); } while (0)
+#endif
+
+#define raw_irqs_disabled() \
+({ \
+ unsigned long flags; \
+ raw_local_save_flags(flags); \
+ raw_irqs_disabled_flags(flags); \
+})
+
+/* used in the idle loop; sti takes one instruction cycle to complete */
+#define raw_safe_halt() __asm__ __volatile__("sti; hlt": : :"memory")
+/* used when interrupts are already enabled or to shutdown the processor */
+#define halt() __asm__ __volatile__("hlt": : :"memory")
+
+#endif
Index: linux/include/asm-x86_64/system.h
===================================================================
--- linux.orig/include/asm-x86_64/system.h
+++ linux/include/asm-x86_64/system.h
@@ -244,43 +244,7 @@ static inline unsigned long __cmpxchg(vo

#define warn_if_not_ulong(x) do { unsigned long foo; (void) (&(x) == &foo); } while (0)

-/* interrupt control.. */
-#define local_save_flags(x) do { warn_if_not_ulong(x); __asm__ __volatile__("# save_flags \n\t pushfq ; popq %q0":"=g" (x): /* no input */ :"memory"); } while (0)
-#define local_irq_restore(x) __asm__ __volatile__("# restore_flags \n\t pushq %0 ; popfq": /* no output */ :"g" (x):"memory", "cc")
-
-#ifdef CONFIG_X86_VSMP
-/* Interrupt control for VSMP architecture */
-#define local_irq_disable() do { unsigned long flags; local_save_flags(flags); local_irq_restore((flags & ~(1 << 9)) | (1 << 18)); } while (0)
-#define local_irq_enable() do { unsigned long flags; local_save_flags(flags); local_irq_restore((flags | (1 << 9)) & ~(1 << 18)); } while (0)
-
-#define irqs_disabled() \
-({ \
- unsigned long flags; \
- local_save_flags(flags); \
- (flags & (1<<18)) || !(flags & (1<<9)); \
-})
-
-/* For spinlocks etc */
-#define local_irq_save(x) do { local_save_flags(x); local_irq_restore((x & ~(1 << 9)) | (1 << 18)); } while (0)
-#else /* CONFIG_X86_VSMP */
-#define local_irq_disable() __asm__ __volatile__("cli": : :"memory")
-#define local_irq_enable() __asm__ __volatile__("sti": : :"memory")
-
-#define irqs_disabled() \
-({ \
- unsigned long flags; \
- local_save_flags(flags); \
- !(flags & (1<<9)); \
-})
-
-/* For spinlocks etc */
-#define local_irq_save(x) do { warn_if_not_ulong(x); __asm__ __volatile__("# local_irq_save \n\t pushfq ; popq %0 ; cli":"=g" (x): /* no input */ :"memory"); } while (0)
-#endif
-
-/* used in the idle loop; sti takes one instruction cycle to complete */
-#define safe_halt() __asm__ __volatile__("sti; hlt": : :"memory")
-/* used when interrupts are already enabled or to shutdown the processor */
-#define halt() __asm__ __volatile__("hlt": : :"memory")
+#include <linux/trace_irqflags.h>

void cpu_idle_wait(void);

Index: linux/include/linux/hardirq.h
===================================================================
--- linux.orig/include/linux/hardirq.h
+++ linux/include/linux/hardirq.h
@@ -87,7 +87,11 @@ extern void synchronize_irq(unsigned int
#endif

#define nmi_enter() irq_enter()
-#define nmi_exit() sub_preempt_count(HARDIRQ_OFFSET)
+#define nmi_exit() \
+ do { \
+ sub_preempt_count(HARDIRQ_OFFSET); \
+ trace_hardirq_exit(); \
+ } while (0)

struct task_struct;

@@ -97,10 +101,17 @@ static inline void account_system_vtime(
}
#endif

+/*
+ * It is safe to do non-atomic ops on ->hardirq_context,
+ * because NMI handlers may not preempt and the ops are
+ * always balanced, so the interrupted value of ->hardirq_context
+ * will always be restored.
+ */
#define irq_enter() \
do { \
account_system_vtime(current); \
add_preempt_count(HARDIRQ_OFFSET); \
+ trace_hardirq_enter(); \
} while (0)

extern void irq_exit(void);
Index: linux/include/linux/init_task.h
===================================================================
--- linux.orig/include/linux/init_task.h
+++ linux/include/linux/init_task.h
@@ -133,6 +133,7 @@ extern struct group_info init_groups;
.journal_info = NULL, \
.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
.fs_excl = ATOMIC_INIT(0), \
+ INIT_TRACE_IRQFLAGS \
}


Index: linux/include/linux/interrupt.h
===================================================================
--- linux.orig/include/linux/interrupt.h
+++ linux/include/linux/interrupt.h
@@ -10,6 +10,7 @@
#include <linux/irqreturn.h>
#include <linux/hardirq.h>
#include <linux/sched.h>
+#include <linux/trace_irqflags.h>
#include <asm/atomic.h>
#include <asm/ptrace.h>
#include <asm/system.h>
@@ -72,13 +73,11 @@ static inline void __deprecated save_and
#define save_and_cli(x) save_and_cli(&x)
#endif /* CONFIG_SMP */

-/* SoftIRQ primitives. */
-#define local_bh_disable() \
- do { add_preempt_count(SOFTIRQ_OFFSET); barrier(); } while (0)
-#define __local_bh_enable() \
- do { barrier(); sub_preempt_count(SOFTIRQ_OFFSET); } while (0)
-
+extern void local_bh_disable(void);
+extern void __local_bh_enable(void);
+extern void _local_bh_enable(void);
extern void local_bh_enable(void);
+extern void local_bh_enable_ip(unsigned long ip);

/* PLEASE, avoid to allocate new softirqs, if you need not _really_ high
frequency threaded job scheduling. For almost all the purposes
Index: linux/include/linux/sched.h
===================================================================
--- linux.orig/include/linux/sched.h
+++ linux/include/linux/sched.h
@@ -916,6 +916,21 @@ struct task_struct {
/* mutex deadlock detection */
struct mutex_waiter *blocked_on;
#endif
+#ifdef CONFIG_TRACE_IRQFLAGS
+ unsigned int irq_events;
+ int hardirqs_enabled;
+ unsigned long hardirq_enable_ip;
+ unsigned int hardirq_enable_event;
+ unsigned long hardirq_disable_ip;
+ unsigned int hardirq_disable_event;
+ int softirqs_enabled;
+ unsigned long softirq_disable_ip;
+ unsigned int softirq_disable_event;
+ unsigned long softirq_enable_ip;
+ unsigned int softirq_enable_event;
+ int hardirq_context;
+ int softirq_context;
+#endif

/* journalling filesystem info */
void *journal_info;
Index: linux/include/linux/trace_irqflags.h
===================================================================
--- /dev/null
+++ linux/include/linux/trace_irqflags.h
@@ -0,0 +1,87 @@
+/*
+ * include/linux/trace_irqflags.h
+ *
+ * IRQ flags tracing: follow the state of the hardirq and softirq flags and
+ * provide callbacks for transitions between ON and OFF states.
+ *
+ * This file gets included from lowlevel asm headers too, to provide
+ * wrapped versions of the local_irq_*() APIs, based on the
+ * raw_local_irq_*() macros from the lowlevel headers.
+ */
+#ifndef _LINUX_TRACE_IRQFLAGS_H
+#define _LINUX_TRACE_IRQFLAGS_H
+
+#include <asm/irqflags.h>
+
+/*
+ * The local_irq_*() APIs are equal to the raw_local_irq*()
+ * if !TRACE_IRQFLAGS.
+ */
+#ifdef CONFIG_TRACE_IRQFLAGS
+ extern void trace_hardirqs_on(void);
+ extern void trace_hardirqs_off(void);
+ extern void trace_softirqs_on(unsigned long ip);
+ extern void trace_softirqs_off(unsigned long ip);
+# define trace_hardirq_context(p) ((p)->hardirq_context)
+# define trace_softirq_context(p) ((p)->softirq_context)
+# define trace_hardirqs_enabled(p) ((p)->hardirqs_enabled)
+# define trace_softirqs_enabled(p) ((p)->softirqs_enabled)
+# define trace_hardirq_enter() do { current->hardirq_context++; } while (0)
+# define trace_hardirq_exit() do { current->hardirq_context--; } while (0)
+# define trace_softirq_enter() do { current->softirq_context++; } while (0)
+# define trace_softirq_exit() do { current->softirq_context--; } while (0)
+# define INIT_TRACE_IRQFLAGS .softirqs_enabled = 1,
+
+#else
+# define trace_hardirqs_on() do { } while (0)
+# define trace_hardirqs_off() do { } while (0)
+# define trace_softirqs_on(ip) do { } while (0)
+# define trace_softirqs_off(ip) do { } while (0)
+# define trace_hardirq_context(p) 0
+# define trace_softirq_context(p) 0
+# define trace_hardirqs_enabled(p) 0
+# define trace_softirqs_enabled(p) 0
+# define trace_hardirq_enter() do { } while (0)
+# define trace_hardirq_exit() do { } while (0)
+# define trace_softirq_enter() do { } while (0)
+# define trace_softirq_exit() do { } while (0)
+# define INIT_TRACE_IRQFLAGS
+#endif
+
+#define local_irq_enable() \
+ do { trace_hardirqs_on(); raw_local_irq_enable(); } while (0)
+#define local_irq_disable() \
+ do { raw_local_irq_disable(); trace_hardirqs_off(); } while (0)
+#define local_irq_save(flags) \
+ do { raw_local_irq_save(flags); trace_hardirqs_off(); } while (0)
+
+#define local_irq_restore(flags) \
+ do { \
+ if (raw_irqs_disabled_flags(flags)) { \
+ raw_local_irq_restore(flags); \
+ trace_hardirqs_off(); \
+ } else { \
+ trace_hardirqs_on(); \
+ raw_local_irq_restore(flags); \
+ } \
+ } while (0)
+
+#define safe_halt() \
+ do { \
+ trace_hardirqs_on(); \
+ raw_safe_halt(); \
+ } while (0)
+
+#define local_save_flags(flags) raw_local_save_flags(flags)
+
+#define irqs_disabled() \
+({ \
+ unsigned long flags; \
+ \
+ raw_local_save_flags(flags); \
+ raw_irqs_disabled_flags(flags); \
+})
+
+#define irqs_disabled_flags(flags) raw_irqs_disabled_flags(flags)
+
+#endif
Index: linux/kernel/fork.c
===================================================================
--- linux.orig/kernel/fork.c
+++ linux/kernel/fork.c
@@ -970,6 +970,10 @@ static task_t *copy_process(unsigned lon
if (!p)
goto fork_out;

+#ifdef CONFIG_TRACE_IRQFLAGS
+ DEBUG_WARN_ON(!p->hardirqs_enabled);
+ DEBUG_WARN_ON(!p->softirqs_enabled);
+#endif
retval = -EAGAIN;
if (atomic_read(&p->user->processes) >=
p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
@@ -1051,7 +1055,21 @@ static task_t *copy_process(unsigned lon
#ifdef CONFIG_DEBUG_MUTEXES
p->blocked_on = NULL; /* not blocked yet */
#endif
-
+#ifdef CONFIG_TRACE_IRQFLAGS
+ p->irq_events = 0;
+ p->hardirqs_enabled = 0;
+ p->hardirq_enable_ip = 0;
+ p->hardirq_enable_event = 0;
+ p->hardirq_disable_ip = _THIS_IP_;
+ p->hardirq_disable_event = 0;
+ p->softirqs_enabled = 1;
+ p->softirq_enable_ip = _THIS_IP_;
+ p->softirq_enable_event = 0;
+ p->softirq_disable_ip = 0;
+ p->softirq_disable_event = 0;
+ p->hardirq_context = 0;
+ p->softirq_context = 0;
+#endif
p->tgid = p->pid;
if (clone_flags & CLONE_THREAD)
p->tgid = current->tgid;
Index: linux/kernel/sched.c
===================================================================
--- linux.orig/kernel/sched.c
+++ linux/kernel/sched.c
@@ -4481,7 +4481,9 @@ int __sched cond_resched_softirq(void)
BUG_ON(!in_softirq());

if (need_resched()) {
- __local_bh_enable();
+ raw_local_irq_disable();
+ _local_bh_enable();
+ raw_local_irq_enable();
__cond_resched();
local_bh_disable();
return 1;
Index: linux/kernel/softirq.c
===================================================================
--- linux.orig/kernel/softirq.c
+++ linux/kernel/softirq.c
@@ -62,6 +62,119 @@ static inline void wakeup_softirqd(void)
}

/*
+ * This one is for softirq.c-internal use,
+ * where hardirqs are disabled legitimately:
+ */
+static void __local_bh_disable(unsigned long ip)
+{
+ unsigned long flags;
+
+ WARN_ON_ONCE(in_irq());
+
+ raw_local_irq_save(flags);
+ add_preempt_count(SOFTIRQ_OFFSET);
+ /*
+ * Were softirqs turned off above:
+ */
+ if (softirq_count() == SOFTIRQ_OFFSET)
+ trace_softirqs_off(ip);
+ raw_local_irq_restore(flags);
+}
+
+void local_bh_disable(void)
+{
+ WARN_ON_ONCE(irqs_disabled());
+ __local_bh_disable((unsigned long)__builtin_return_address(0));
+}
+
+EXPORT_SYMBOL(local_bh_disable);
+
+void __local_bh_enable(void)
+{
+ WARN_ON_ONCE(in_irq());
+
+ /*
+ * softirqs should never be enabled by __local_bh_enable(),
+ * it always nests inside local_bh_enable() sections:
+ */
+ WARN_ON_ONCE(softirq_count() == SOFTIRQ_OFFSET);
+
+ sub_preempt_count(SOFTIRQ_OFFSET);
+}
+
+EXPORT_SYMBOL(__local_bh_enable);
+
+/*
+ * Special-case - softirqs can safely be enabled in
+ * cond_resched_softirq(), or by __do_softirq(),
+ * without processing still-pending softirqs:
+ */
+void _local_bh_enable(void)
+{
+ WARN_ON_ONCE(in_irq());
+ WARN_ON_ONCE(!irqs_disabled());
+
+ if (softirq_count() == SOFTIRQ_OFFSET)
+ trace_softirqs_on((unsigned long)__builtin_return_address(0));
+ sub_preempt_count(SOFTIRQ_OFFSET);
+}
+
+void local_bh_enable(void)
+{
+ unsigned long flags;
+
+ WARN_ON_ONCE(in_irq());
+ WARN_ON_ONCE(irqs_disabled());
+
+ local_irq_save(flags);
+ /*
+ * Are softirqs going to be turned on now:
+ */
+ if (softirq_count() == SOFTIRQ_OFFSET)
+ trace_softirqs_on((unsigned long)__builtin_return_address(0));
+ /*
+ * Keep preemption disabled until we are done with
+ * softirq processing:
+ */
+ sub_preempt_count(SOFTIRQ_OFFSET - 1);
+
+ if (unlikely(!in_interrupt() && local_softirq_pending()))
+ do_softirq();
+
+ dec_preempt_count();
+ local_irq_restore(flags);
+ preempt_check_resched();
+}
+EXPORT_SYMBOL(local_bh_enable);
+
+void local_bh_enable_ip(unsigned long ip)
+{
+ unsigned long flags;
+
+ WARN_ON_ONCE(in_irq());
+
+ local_irq_save(flags);
+ /*
+ * Are softirqs going to be turned on now:
+ */
+ if (softirq_count() == SOFTIRQ_OFFSET)
+ trace_softirqs_on(ip);
+ /*
+ * Keep preemption disabled until we are done with
+ * softirq processing:
+ */
+ sub_preempt_count(SOFTIRQ_OFFSET - 1);
+
+ if (unlikely(!in_interrupt() && local_softirq_pending()))
+ do_softirq();
+
+ dec_preempt_count();
+ local_irq_restore(flags);
+ preempt_check_resched();
+}
+EXPORT_SYMBOL(local_bh_enable_ip);
+
+/*
* We restart softirq processing MAX_SOFTIRQ_RESTART times,
* and we fall back to softirqd after that.
*
@@ -80,8 +193,9 @@ asmlinkage void __do_softirq(void)
int cpu;

pending = local_softirq_pending();
+ __local_bh_disable((unsigned long)__builtin_return_address(0));
+ trace_softirq_enter();

- local_bh_disable();
cpu = smp_processor_id();
restart:
/* Reset the pending bitmask before enabling irqs */
@@ -109,7 +223,8 @@ restart:
if (pending)
wakeup_softirqd();

- __local_bh_enable();
+ trace_softirq_exit();
+ _local_bh_enable();
}

#ifndef __ARCH_HAS_DO_SOFTIRQ
@@ -136,23 +251,6 @@ EXPORT_SYMBOL(do_softirq);

#endif

-void local_bh_enable(void)
-{
- WARN_ON(irqs_disabled());
- /*
- * Keep preemption disabled until we are done with
- * softirq processing:
- */
- sub_preempt_count(SOFTIRQ_OFFSET - 1);
-
- if (unlikely(!in_interrupt() && local_softirq_pending()))
- do_softirq();
-
- dec_preempt_count();
- preempt_check_resched();
-}
-EXPORT_SYMBOL(local_bh_enable);
-
#ifdef __ARCH_IRQ_EXIT_IRQS_DISABLED
# define invoke_softirq() __do_softirq()
#else
@@ -165,6 +263,7 @@ EXPORT_SYMBOL(local_bh_enable);
void irq_exit(void)
{
account_system_vtime(current);
+ trace_hardirq_exit();
sub_preempt_count(IRQ_EXIT_OFFSET);
if (!in_interrupt() && local_softirq_pending())
invoke_softirq();
Index: linux/lib/locking-selftest.c
===================================================================
--- linux.orig/lib/locking-selftest.c
+++ linux/lib/locking-selftest.c
@@ -19,6 +19,7 @@
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/debug_locks.h>
+#include <linux/trace_irqflags.h>

/*
* Change this to 1 if you want to see the failure printouts:
@@ -157,9 +158,11 @@ static void init_shared_types(void)
#define SOFTIRQ_ENTER() \
local_bh_disable(); \
local_irq_disable(); \
+ trace_softirq_enter(); \
WARN_ON(!in_softirq());

#define SOFTIRQ_EXIT() \
+ trace_softirq_exit(); \
local_irq_enable(); \
local_bh_enable();

-
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