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SubjectRe: [tip:x86/trace] x86, trace: Add page fault tracepoints

* tip-bot for Seiji Aguchi <tipbot@zytor.com> wrote:

> Commit-ID: d34603b07c4255b2b00a546d34f297ccd50ae4c6
> Gitweb: http://git.kernel.org/tip/d34603b07c4255b2b00a546d34f297ccd50ae4c6
> Author: Seiji Aguchi <seiji.aguchi@hds.com>
> AuthorDate: Wed, 30 Oct 2013 16:39:03 -0400
> Committer: H. Peter Anvin <hpa@linux.intel.com>
> CommitDate: Fri, 8 Nov 2013 14:15:49 -0800
>
> x86, trace: Add page fault tracepoints
>
> This patch introduces page fault tracepoints to x86 architecture
> by switching IDT.
>
> Two events, for user and kernel spaces, are introduced at the beginning
> of page fault handler for tracing.
>
> - User space event
> There is a request of page fault event for user space as below.
>
> https://lkml.kernel.org/r/1368079520-11015-2-git-send-email-fdeslaur+()+gmail+!+com
> https://lkml.kernel.org/r/1368079520-11015-1-git-send-email-fdeslaur+()+gmail+!+com
>
> - Kernel space event:
> When we measure an overhead in kernel space for investigating performance
> issues, we can check if it comes from the page fault events.
>
> Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
> Link: http://lkml.kernel.org/r/52716E67.6090705@hds.com
> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
> ---
> arch/x86/include/asm/trace/exceptions.h | 52 +++++++++++++++++++++++++++++++++
> arch/x86/mm/Makefile | 2 ++
> arch/x86/mm/fault.c | 13 +++++++++
> 3 files changed, 67 insertions(+)
>
> diff --git a/arch/x86/include/asm/trace/exceptions.h b/arch/x86/include/asm/trace/exceptions.h
> new file mode 100644
> index 0000000..86540c0
> --- /dev/null
> +++ b/arch/x86/include/asm/trace/exceptions.h
> @@ -0,0 +1,52 @@
> +#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( unsigned long, ip )
> + __field( unsigned long, error_code )
> + ),
> +
> + TP_fast_assign(
> + __entry->address = address;
> + __entry->ip = regs->ip;
> + __entry->error_code = error_code;
> + ),
> +
> + TP_printk("address=%pf ip=%pf error_code=0x%lx",
> + (void *)__entry->address, (void *)__entry->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);

Nice!

It would be nice to change this to hierarchical naming:

page_fault_user
page_fault_kernel

I.e. the higher level concept named first and go to the left, details go
to the right.

(That way x86_exceptions.page_fault_user has the names ordered correctly
as well.)

Thanks,

Ingo


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