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Diffstat (limited to '')
| -rw-r--r-- | Documentation/trace/kprobetrace.txt | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt index 5f77d94598dd..c83bd6b4e6e8 100644 --- a/Documentation/trace/kprobetrace.txt +++ b/Documentation/trace/kprobetrace.txt @@ -42,11 +42,25 @@ 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) and string are supported. + (u8/u16/u32/u64/s8/s16/s32/s64), "string" and bitfield + are supported. (*) only for return probe. (**) this is useful for fetching a field of data structures. +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. +Bitfield is another special type, which takes 3 parameters, bit-width, bit- +offset, and container-size (usually 32). The syntax is; + + b<bit-width>@<bit-offset>/<container-size> + Per-Probe Event Filtering ------------------------- @@ -106,7 +120,6 @@ format: field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1;signed:0; field:int common_pid; offset:4; size:4; signed:1; - field:int common_lock_depth; offset:8; size:4; signed:1; field:unsigned long __probe_ip; offset:12; size:4; signed:0; field:int __probe_nargs; offset:16; size:4; signed:1; |