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    SubjectRe: [PATCH v2 1/3] tracing: document "string_size" [ku]probe type
    On Thu,  2 Jun 2016 18:11:01 -0700
    Omar Sandoval <osandov@osandov.com> wrote:

    > From: Omar Sandoval <osandov@fb.com>
    >
    > It has been undocumented since it was introduced in commit e09c8614b329
    > ("tracing/kprobes: Support "string" type").

    Ah, actually, string_size is a support fetch function for string.
    So please ignore it. Or would you have any idea to use it?

    Thank you,

    >
    > Signed-off-by: Omar Sandoval <osandov@fb.com>
    > ---
    > Documentation/trace/kprobetrace.txt | 11 ++++++-----
    > Documentation/trace/uprobetracer.txt | 9 +++++----
    > 2 files changed, 11 insertions(+), 9 deletions(-)
    >
    > diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt
    > index d68ea5fc812b..4b3f5293b7bf 100644
    > --- a/Documentation/trace/kprobetrace.txt
    > +++ b/Documentation/trace/kprobetrace.txt
    > @@ -43,8 +43,8 @@ Synopsis of kprobe_events
    > +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
    > NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
    > FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
    > - (u8/u16/u32/u64/s8/s16/s32/s64), "string" and bitfield
    > - are supported.
    > + (u8/u16/u32/u64/s8/s16/s32/s64), "string", "string_size", and
    > + bitfield are supported.
    >
    > (*) only for return probe.
    > (**) this is useful for fetching a field of data structures.
    > @@ -54,9 +54,10 @@ Types
    > Several types are supported for fetch-args. Kprobe tracer will access memory
    > by given type. Prefix 's' and 'u' means those types are signed and unsigned
    > respectively. Traced arguments are shown in decimal (signed) or hex (unsigned).
    > -String type is a special type, which fetches a "null-terminated" string from
    > -kernel space. This means it will fail and store NULL if the string container
    > -has been paged out.
    > +"string" is a special type which fetches a null-terminated string from kernel
    > +space. This means it will fail and store NULL if the string container has been
    > +paged out. "string_size" is the length of a null-terminated string including
    > +the NUL byte.
    > Bitfield is another special type, which takes 3 parameters, bit-width, bit-
    > offset, and container-size (usually 32). The syntax is;
    >
    > diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt
    > index f1cf9a34ad9d..7e0480263c2f 100644
    > --- a/Documentation/trace/uprobetracer.txt
    > +++ b/Documentation/trace/uprobetracer.txt
    > @@ -39,8 +39,8 @@ Synopsis of uprobe_tracer
    > +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
    > NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
    > FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
    > - (u8/u16/u32/u64/s8/s16/s32/s64), "string" and bitfield
    > - are supported.
    > + (u8/u16/u32/u64/s8/s16/s32/s64), "string",
    > + "string_size", and bitfield are supported.
    >
    > (*) only for return probe.
    > (**) this is useful for fetching a field of data structures.
    > @@ -50,8 +50,9 @@ Types
    > Several types are supported for fetch-args. Uprobe tracer will access memory
    > by given type. Prefix 's' and 'u' means those types are signed and unsigned
    > respectively. Traced arguments are shown in decimal (signed) or hex (unsigned).
    > -String type is a special type, which fetches a "null-terminated" string from
    > -user space.
    > +"string" is a special type which fetches a null-terminated string from user
    > +space. "string_size" is the length of a null-terminated string including the
    > +NUL byte.
    > Bitfield is another special type, which takes 3 parameters, bit-width, bit-
    > offset, and container-size (usually 32). The syntax is;
    >
    > --
    > 2.8.3
    >


    --
    Masami Hiramatsu <mhiramat@kernel.org>

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