RE: [PATCH v2] Introduce page fault tracepoint

From: Seiji Aguchi
Date: Fri Sep 06 2013 - 10:48:06 EST

Any comment?

> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] On Behalf Of Seiji Aguchi
> Sent: Friday, August 23, 2013 11:38 AM
> To: linux-kernel@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx
> Cc: hpa@xxxxxxxxx; rostedt@xxxxxxxxxxx; mingo@xxxxxxx; bp@xxxxxxxxx; tglx@xxxxxxxxxxxxx; fdeslaur@xxxxxxxxx;
> raphael.beamonte@xxxxxxxxx; dle-develop@xxxxxxxxxxxxxxxxxxxxx; Tomoki Sekiyama
> Subject: [PATCH v2] Introduce page fault tracepoint
>
> Change from v1
> - Print regs->ip instead of regs to know where the page fault event happened
> (Suggested by Steven Rostedt)
>
>
> This patch introduces page fault tracepoints to x86 architecture
> by switching IDT.
>
> [Use case of page fault events]
>
> Two events, for user and kernel spaces, are introduced at the beginning of
> page fault handler.
>
> - User space event
> There is a request of page fault event for user space as below.
>
> http://marc.info/?l=linux-mm&m=136807959830182&w=2
> http://marc.info/?l=linux-mm&m=136807959130175&w=2
>
> - Kernel space event:
> Overhead in kernel space is measurable by enabling it.
>
> [Creating IDT]
>
> A way to create IDT is as below.
>
> - Introduce set_intr_gate_raw() to register just non-trace handler to IDT.
> This is used at boot time which tracing is disabled.
> - Make set_intr_gate() macro so that it can register trace handler to
> trace IDT and non-trace handler to normal IDT.
>
> Signed-off-by: Seiji Aguchi <seiji.aguchi@xxxxxxx>
> ---
> arch/x86/include/asm/desc.h | 33 +++++++++++++++++----
> arch/x86/include/asm/hw_irq.h | 14 ++++++++-
> arch/x86/include/asm/trace/exceptions.h | 51 +++++++++++++++++++++++++++++++++
> arch/x86/include/asm/traps.h | 22 ++++++++++++++
> arch/x86/kernel/entry_32.S | 10 +++++++
> arch/x86/kernel/entry_64.S | 13 ++++++++-
> arch/x86/kernel/head64.c | 2 +-
> arch/x86/kernel/irqinit.c | 2 +-
> arch/x86/kernel/kvm.c | 2 +-
> arch/x86/kernel/traps.c | 28 +++++++++---------
> arch/x86/mm/Makefile | 2 ++
> arch/x86/mm/fault.c | 22 ++++++++++++++
> 12 files changed, 177 insertions(+), 24 deletions(-)
> create mode 100644 arch/x86/include/asm/trace/exceptions.h
>
> diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
> index b90e5df..c04302b 100644
> --- a/arch/x86/include/asm/desc.h
> +++ b/arch/x86/include/asm/desc.h
> @@ -327,10 +327,28 @@ static inline void write_trace_idt_entry(int entry, const gate_desc *gate)
> {
> write_idt_entry(trace_idt_table, entry, gate);
> }
> +
> +static inline void _trace_set_gate(int gate, unsigned type, void *addr,
> + unsigned dpl, unsigned ist, unsigned seg)
> +{
> + gate_desc s;
> +
> + pack_gate(&s, type, (unsigned long)addr, dpl, ist, seg);
> + /*
> + * does not need to be atomic because it is only done once at
> + * setup time
> + */
> + write_trace_idt_entry(gate, &s);
> +}
> #else
> static inline void write_trace_idt_entry(int entry, const gate_desc *gate)
> {
> }
> +
> +static inline void _trace_set_gate(int gate, unsigned type, void *addr,
> + unsigned dpl, unsigned ist, unsigned seg)
> +{
> +}
> #endif
>
> static inline void _set_gate(int gate, unsigned type, void *addr,
> @@ -353,12 +371,20 @@ static inline void _set_gate(int gate, unsigned type, void *addr,
> * Pentium F0 0F bugfix can have resulted in the mapped
> * IDT being write-protected.
> */
> -static inline void set_intr_gate(unsigned int n, void *addr)
> +static inline void set_intr_gate_raw(unsigned int n, void *addr)
> {
> BUG_ON((unsigned)n > 0xFF);
> _set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS);
> }
>
> +#define set_intr_gate(n, addr) \
> + do { \
> + BUG_ON((unsigned)n > 0xFF); \
> + _set_gate(n, GATE_INTERRUPT, addr, 0, 0, __KERNEL_CS); \
> + _trace_set_gate(n, GATE_INTERRUPT, trace_##addr, 0, 0, \
> + __KERNEL_CS); \
> + } while (0)
> +
> extern int first_system_vector;
> /* used_vectors is BITMAP for irq is not managed by percpu vector_irq */
> extern unsigned long used_vectors[];
> @@ -395,10 +421,7 @@ static inline void trace_set_intr_gate(unsigned int gate, void *addr)
> #define __trace_alloc_intr_gate(n, addr)
> #endif
>
> -static inline void __alloc_intr_gate(unsigned int n, void *addr)
> -{
> - set_intr_gate(n, addr);
> -}
> +#define __alloc_intr_gate(n, addr) set_intr_gate(n, addr)
>
> #define alloc_intr_gate(n, addr) \
> do { \
> diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
> index e4ac559..fbd73b7 100644
> --- a/arch/x86/include/asm/hw_irq.h
> +++ b/arch/x86/include/asm/hw_irq.h
> @@ -89,10 +89,22 @@ extern void trace_reschedule_interrupt(void);
> extern void trace_threshold_interrupt(void);
> extern void trace_call_function_interrupt(void);
> extern void trace_call_function_single_interrupt(void);
> +#else /* CONFIG_TRACING */
> +#define trace_apic_timer_interrupt apic_timer_interrupt
> +#define trace_x86_platform_ipi x86_platform_ipi
> +#define trace_error_interrupt error_interrupt
> +#define trace_irq_work_interrupt irq_work_interrupt
> +#define trace_spurious_interrupt spurious_interrupt
> +#define trace_thermal_interrupt thermal_interrupt
> +#define trace_reschedule_interrupt reschedule_interrupt
> +#define trace_threshold_interrupt threshold_interrupt
> +#define trace_call_function_interrupt call_function_interrupt
> +#define trace_call_function_single_interrupt call_function_single_interrupt
> +#endif
> +
> #define trace_irq_move_cleanup_interrupt irq_move_cleanup_interrupt
> #define trace_reboot_interrupt reboot_interrupt
> #define trace_kvm_posted_intr_ipi kvm_posted_intr_ipi
> -#endif /* CONFIG_TRACING */
>
> /* IOAPIC */
> #define IO_APIC_IRQ(x) (((x) >= NR_IRQS_LEGACY) || ((1<<(x)) & io_apic_irqs))
> diff --git a/arch/x86/include/asm/trace/exceptions.h b/arch/x86/include/asm/trace/exceptions.h
> new file mode 100644
> index 0000000..a379a49
> --- /dev/null
> +++ b/arch/x86/include/asm/trace/exceptions.h
> @@ -0,0 +1,51 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM exceptions
> +
> +#if !defined(_TRACE_PAGE_FAULT_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_PAGE_FAULT_H
> +
> +#include <linux/tracepoint.h>
> +
> +extern void trace_irq_vector_regfunc(void);
> +extern void trace_irq_vector_unregfunc(void);
> +
> +DECLARE_EVENT_CLASS(x86_exceptions,
> +
> + TP_PROTO(unsigned long address, struct pt_regs *regs,
> + unsigned long error_code),
> +
> + TP_ARGS(address, regs, error_code),
> +
> + TP_STRUCT__entry(
> + __field( unsigned long, address )
> + __field( struct pt_regs *, regs )
> + __field( unsigned long, error_code )
> + ),
> +
> + TP_fast_assign(
> + __entry->address = address;
> + __entry->regs = regs;
> + __entry->error_code = error_code;
> + ),
> +
> + TP_printk("address=0x%lx ip=0x%lx error_code=0x%lx",
> + __entry->address, __entry->regs->ip, __entry->error_code) );
> +
> +#define DEFINE_PAGE_FAULT_EVENT(name) \
> +DEFINE_EVENT_FN(x86_exceptions, name, \
> + TP_PROTO(unsigned long address, struct pt_regs *regs, \
> + unsigned long error_code), \
> + TP_ARGS(address, regs, error_code), \
> + trace_irq_vector_regfunc, \
> + trace_irq_vector_unregfunc);
> +
> +DEFINE_PAGE_FAULT_EVENT(user_page_fault);
> +DEFINE_PAGE_FAULT_EVENT(kernel_page_fault);
> +
> +#undef TRACE_INCLUDE_PATH
> +#define TRACE_INCLUDE_PATH .
> +#define TRACE_INCLUDE_FILE exceptions
> +#endif /* _TRACE_PAGE_FAULT_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
> index 88eae2a..adf9258 100644
> --- a/arch/x86/include/asm/traps.h
> +++ b/arch/x86/include/asm/traps.h
> @@ -41,6 +41,25 @@ asmlinkage void machine_check(void);
> #endif /* CONFIG_X86_MCE */
> asmlinkage void simd_coprocessor_error(void);
>
> +#ifdef CONFIG_TRACING
> +asmlinkage void trace_page_fault(void);
> +#else
> +#define trace_page_fault page_fault
> +#endif
> +#define trace_divide_error divide_error
> +#define trace_bounds bounds
> +#define trace_invalid_op invalid_op
> +#define trace_device_not_available device_not_available
> +#define trace_coprocessor_segment_overrun coprocessor_segment_overrun
> +#define trace_invalid_TSS invalid_TSS
> +#define trace_segment_not_present segment_not_present
> +#define trace_general_protection general_protection
> +#define trace_spurious_interrupt_bug spurious_interrupt_bug
> +#define trace_coprocessor_error coprocessor_error
> +#define trace_alignment_check alignment_check
> +#define trace_simd_coprocessor_error simd_coprocessor_error
> +#define trace_async_page_fault async_page_fault
> +
> dotraplinkage void do_divide_error(struct pt_regs *, long);
> dotraplinkage void do_debug(struct pt_regs *, long);
> dotraplinkage void do_nmi(struct pt_regs *, long);
> @@ -59,6 +78,9 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *);
> #endif
> dotraplinkage void do_general_protection(struct pt_regs *, long);
> dotraplinkage void do_page_fault(struct pt_regs *, unsigned long);
> +#ifdef CONFIG_TRACING
> +dotraplinkage void trace_do_page_fault(struct pt_regs *, unsigned long);
> +#endif
> dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *, long);
> dotraplinkage void do_coprocessor_error(struct pt_regs *, long);
> dotraplinkage void do_alignment_check(struct pt_regs *, long);
> diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
> index 2cfbc3a..c9eb4e2 100644
> --- a/arch/x86/kernel/entry_32.S
> +++ b/arch/x86/kernel/entry_32.S
> @@ -1244,6 +1244,16 @@ return_to_handler:
> */
> .pushsection .kprobes.text, "ax"
>
> +#ifdef CONFIG_TRACING
> +ENTRY(trace_page_fault)
> + RING0_EC_FRAME
> + ASM_CLAC
> + pushl_cfi $trace_do_page_fault
> + jmp error_code
> + CFI_ENDPROC
> +END(trace_page_fault)
> +#endif
> +
> ENTRY(page_fault)
> RING0_EC_FRAME
> ASM_CLAC
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index 1b69951..5136404 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -1295,6 +1295,17 @@ ENTRY(\sym)
> END(\sym)
> .endm
>
> +#ifdef CONFIG_TRACING
> +.macro trace_errorentry sym do_sym
> +errorentry trace(\sym) trace(\do_sym)
> +errorentry \sym \do_sym
> +.endm
> +#else
> +.macro trace_errorentry sym do_sym
> +errorentry \sym \do_sym
> +.endm
> +#endif
> +
> /* error code is on the stack already */
> .macro paranoiderrorentry sym do_sym
> ENTRY(\sym)
> @@ -1497,7 +1508,7 @@ zeroentry xen_int3 do_int3
> errorentry xen_stack_segment do_stack_segment
> #endif
> errorentry general_protection do_general_protection
> -errorentry page_fault do_page_fault
> +trace_errorentry page_fault do_page_fault
> #ifdef CONFIG_KVM_GUEST
> errorentry async_page_fault do_async_page_fault
> #endif
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index 55b6761..67a0649 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -162,7 +162,7 @@ void __init x86_64_start_kernel(char * real_mode_data)
> clear_bss();
>
> for (i = 0; i < NUM_EXCEPTION_VECTORS; i++)
> - set_intr_gate(i, &early_idt_handlers[i]);
> + set_intr_gate_raw(i, &early_idt_handlers[i]);
> load_idt((const struct desc_ptr *)&idt_descr);
>
> copy_bootdata(__va(real_mode_data));
> diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
> index a2a1fbc..2ca2354 100644
> --- a/arch/x86/kernel/irqinit.c
> +++ b/arch/x86/kernel/irqinit.c
> @@ -206,7 +206,7 @@ void __init native_init_IRQ(void)
> i = FIRST_EXTERNAL_VECTOR;
> for_each_clear_bit_from(i, used_vectors, NR_VECTORS) {
> /* IA32_SYSCALL_VECTOR could be used in trap_init already. */
> - set_intr_gate(i, interrupt[i - FIRST_EXTERNAL_VECTOR]);
> + set_intr_gate_raw(i, interrupt[i - FIRST_EXTERNAL_VECTOR]);
> }
>
> if (!acpi_ioapic && !of_ioapic)
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index a96d32c..12b384e 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -462,7 +462,7 @@ static struct notifier_block kvm_cpu_notifier = {
>
> static void __init kvm_apf_trap_init(void)
> {
> - set_intr_gate(14, &async_page_fault);
> + set_intr_gate(14, async_page_fault);
> }
>
> void __init kvm_guest_init(void)
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 1b23a1c..eadd251 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -709,7 +709,7 @@ void __init early_trap_init(void)
> /* int3 can be called from all */
> set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
> #ifdef CONFIG_X86_32
> - set_intr_gate(X86_TRAP_PF, &page_fault);
> + set_intr_gate(X86_TRAP_PF, page_fault);
> #endif
> load_idt(&idt_descr);
> }
> @@ -717,7 +717,7 @@ void __init early_trap_init(void)
> void __init early_trap_pf_init(void)
> {
> #ifdef CONFIG_X86_64
> - set_intr_gate(X86_TRAP_PF, &page_fault);
> + set_intr_gate(X86_TRAP_PF, page_fault);
> #endif
> }
>
> @@ -733,30 +733,30 @@ void __init trap_init(void)
> early_iounmap(p, 4);
> #endif
>
> - set_intr_gate(X86_TRAP_DE, &divide_error);
> + set_intr_gate(X86_TRAP_DE, divide_error);
> set_intr_gate_ist(X86_TRAP_NMI, &nmi, NMI_STACK);
> /* int4 can be called from all */
> set_system_intr_gate(X86_TRAP_OF, &overflow);
> - set_intr_gate(X86_TRAP_BR, &bounds);
> - set_intr_gate(X86_TRAP_UD, &invalid_op);
> - set_intr_gate(X86_TRAP_NM, &device_not_available);
> + set_intr_gate(X86_TRAP_BR, bounds);
> + set_intr_gate(X86_TRAP_UD, invalid_op);
> + set_intr_gate(X86_TRAP_NM, device_not_available);
> #ifdef CONFIG_X86_32
> set_task_gate(X86_TRAP_DF, GDT_ENTRY_DOUBLEFAULT_TSS);
> #else
> set_intr_gate_ist(X86_TRAP_DF, &double_fault, DOUBLEFAULT_STACK);
> #endif
> - set_intr_gate(X86_TRAP_OLD_MF, &coprocessor_segment_overrun);
> - set_intr_gate(X86_TRAP_TS, &invalid_TSS);
> - set_intr_gate(X86_TRAP_NP, &segment_not_present);
> + set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
> + set_intr_gate(X86_TRAP_TS, invalid_TSS);
> + set_intr_gate(X86_TRAP_NP, segment_not_present);
> set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
> - set_intr_gate(X86_TRAP_GP, &general_protection);
> - set_intr_gate(X86_TRAP_SPURIOUS, &spurious_interrupt_bug);
> - set_intr_gate(X86_TRAP_MF, &coprocessor_error);
> - set_intr_gate(X86_TRAP_AC, &alignment_check);
> + set_intr_gate(X86_TRAP_GP, general_protection);
> + set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
> + set_intr_gate(X86_TRAP_MF, coprocessor_error);
> + set_intr_gate(X86_TRAP_AC, alignment_check);
> #ifdef CONFIG_X86_MCE
> set_intr_gate_ist(X86_TRAP_MC, &machine_check, MCE_STACK);
> #endif
> - set_intr_gate(X86_TRAP_XF, &simd_coprocessor_error);
> + set_intr_gate(X86_TRAP_XF, simd_coprocessor_error);
>
> /* Reserve all the builtin and the syscall vector: */
> for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++)
> diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile
> index 23d8e5f..6a19ad9 100644
> --- a/arch/x86/mm/Makefile
> +++ b/arch/x86/mm/Makefile
> @@ -6,6 +6,8 @@ nostackp := $(call cc-option, -fno-stack-protector)
> CFLAGS_physaddr.o := $(nostackp)
> CFLAGS_setup_nx.o := $(nostackp)
>
> +CFLAGS_fault.o := -I$(src)/../include/asm/trace
> +
> obj-$(CONFIG_X86_PAT) += pat_rbtree.o
> obj-$(CONFIG_SMP) += tlb.o
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 654be4a..f515154 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -20,6 +20,9 @@
> #include <asm/kmemcheck.h> /* kmemcheck_*(), ... */
> #include <asm/fixmap.h> /* VSYSCALL_START */
>
> +#define CREATE_TRACE_POINTS
> +#include <asm/trace/exceptions.h>
> +
> /*
> * Page fault error code bits:
> *
> @@ -1230,3 +1233,22 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code)
> __do_page_fault(regs, error_code);
> exception_exit(prev_state);
> }
> +
> +static void trace_page_fault_entries(struct pt_regs *regs,
> + unsigned long error_code)
> +{
> + if (user_mode(regs))
> + trace_user_page_fault(read_cr2(), regs, error_code);
> + else
> + trace_kernel_page_fault(read_cr2(), regs, error_code);
> +}
> +
> +dotraplinkage void __kprobes
> +trace_do_page_fault(struct pt_regs *regs, unsigned long error_code)
> +{
> + enum ctx_state prev_state;
> + prev_state = exception_enter();
> + trace_page_fault_entries(regs, error_code);
> + __do_page_fault(regs, error_code);
> + exception_exit(prev_state);
> +}
> --
> 1.8.2.1
>
> --
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