2024-01-23 09:21:18

by yebin (H)

Subject: [PATCH v4 6/7] Documentation: tracing: add new type '%pd' and '%pD' for kprobe

Similar to printk() '%pd' is for fetch dentry's name from struct dentry's
pointer, and '%pD' is for fetch file's name from struct file's pointer.

Signed-off-by: Ye Bin <[email protected]>
---
Documentation/trace/kprobetrace.rst | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
index bf9cecb69fc9..a1d12d65a8dc 100644
--- a/Documentation/trace/kprobetrace.rst
+++ b/Documentation/trace/kprobetrace.rst
@@ -58,7 +58,8 @@ Synopsis of kprobe_events
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), hexadecimal types
- (x8/x16/x32/x64), "char", "string", "ustring", "symbol", "symstr"
+ (x8/x16/x32/x64), VFS layer common type(%pd/%pD) for print
+ file name, "char", "string", "ustring", "symbol", "symstr"
and bitfield are supported.

(\*1) only for the probe on function entry (offs == 0). Note, this argument access
@@ -113,6 +114,9 @@ With 'symstr' type, you can filter the event with wildcard pattern of the
symbols, and you don't need to solve symbol name by yourself.
For $comm, the default type is "string"; any other type is invalid.

+VFS layer common type(%pd/%pD) is a special type, which fetches dentry's or
+file's name from struct dentry's pointer or struct file's pointer.
+
.. _user_mem_access:

User Memory Access
--
2.31.1

2024-01-23 13:09:29

by Masami Hiramatsu

Subject: Re: [PATCH v4 6/7] Documentation: tracing: add new type '%pd' and '%pD' for kprobe

On Tue, 23 Jan 2024 17:21:38 +0800
Ye Bin <[email protected]> wrote:

> Similar to printk() '%pd' is for fetch dentry's name from struct dentry's
> pointer, and '%pD' is for fetch file's name from struct file's pointer.
>
> Signed-off-by: Ye Bin <[email protected]>
> ---
> Documentation/trace/kprobetrace.rst | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
> index bf9cecb69fc9..a1d12d65a8dc 100644
> --- a/Documentation/trace/kprobetrace.rst
> +++ b/Documentation/trace/kprobetrace.rst
> @@ -58,7 +58,8 @@ Synopsis of kprobe_events
> 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), hexadecimal types
> - (x8/x16/x32/x64), "char", "string", "ustring", "symbol", "symstr"
> + (x8/x16/x32/x64), VFS layer common type(%pd/%pD) for print
> + file name, "char", "string", "ustring", "symbol", "symstr"

Could you remove the "for print file name" here? Since this is not the place
where such precise information describes. I think following hunk is enough to
explain it.

Thank you,

> and bitfield are supported.
>
> (\*1) only for the probe on function entry (offs == 0). Note, this argument access
> @@ -113,6 +114,9 @@ With 'symstr' type, you can filter the event with wildcard pattern of the
> symbols, and you don't need to solve symbol name by yourself.
> For $comm, the default type is "string"; any other type is invalid.
>
> +VFS layer common type(%pd/%pD) is a special type, which fetches dentry's or
> +file's name from struct dentry's pointer or struct file's pointer.
> +
> .. _user_mem_access:
>
> User Memory Access
> --
> 2.31.1
>
>


--
Masami Hiramatsu (Google) <[email protected]>