There are scenes that we want to show the character value of traced
arguments other than a decimal or hexadecimal or string value for debug
convinience. Add a new type named 'char' to do it.
For example:
echo 'p:myprobe xxxx $arg1:char' > kprobe_events
echo 'p:myprobe xxxx $arg1:char[2]' > kprobe_events
Signed-off-by: Donglin Peng <[email protected]>
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Reported-by: kernel test robot <[email protected]>
---
Changes in v3:
- update readme_msg
Changes in v2:
- fix build warnings reported by kernel test robot
- modify commit log
---
Documentation/trace/kprobetrace.rst | 3 ++-
kernel/trace/trace.c | 2 +-
kernel/trace/trace_probe.c | 2 ++
kernel/trace/trace_probe.h | 1 +
4 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst
index 4274cc6a2f94..007972a3c5c4 100644
--- a/Documentation/trace/kprobetrace.rst
+++ b/Documentation/trace/kprobetrace.rst
@@ -58,7 +58,7 @@ Synopsis of kprobe_events
NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
(u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types
- (x8/x16/x32/x64), "string", "ustring" and bitfield
+ (x8/x16/x32/x64), "char", "string", "ustring" and bitfield
are supported.
(\*1) only for the probe on function entry (offs == 0).
@@ -80,6 +80,7 @@ E.g. 'x16[4]' means an array of x16 (2bytes hex) with 4 elements.
Note that the array can be applied to memory type fetchargs, you can not
apply it to registers/stack-entries etc. (for example, '$stack1:x8[8]' is
wrong, but '+8($stack):x8[8]' is OK.)
+Char type can be used to show the character value of traced arguments.
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. "ustring" type is an alternative of string for user-space.
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 5cfc95a52bc3..a64e206f94e6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5615,7 +5615,7 @@ static const char readme_msg[] =
"\t $stack<index>, $stack, $retval, $comm,\n"
#endif
"\t +|-[u]<offset>(<fetcharg>), \\imm-value, \\\"imm-string\"\n"
- "\t type: s8/16/32/64, u8/16/32/64, x8/16/32/64, string, symbol,\n"
+ "\t type: s8/16/32/64, u8/16/32/64, x8/16/32/64, char, string, symbol,\n"
"\t b<bit-width>@<bit-offset>/<container-size>, ustring,\n"
"\t <type>\\[<array-size>\\]\n"
#ifdef CONFIG_HIST_TRIGGERS
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 36dff277de46..a4abf7f6c295 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -50,6 +50,7 @@ DEFINE_BASIC_PRINT_TYPE_FUNC(x8, u8, "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x16, u16, "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x32, u32, "0x%x")
DEFINE_BASIC_PRINT_TYPE_FUNC(x64, u64, "0x%Lx")
+DEFINE_BASIC_PRINT_TYPE_FUNC(char, u8, "%c")
int PRINT_TYPE_FUNC_NAME(symbol)(struct trace_seq *s, void *data, void *ent)
{
@@ -93,6 +94,7 @@ static const struct fetch_type probe_fetch_types[] = {
ASSIGN_FETCH_TYPE_ALIAS(x16, u16, u16, 0),
ASSIGN_FETCH_TYPE_ALIAS(x32, u32, u32, 0),
ASSIGN_FETCH_TYPE_ALIAS(x64, u64, u64, 0),
+ ASSIGN_FETCH_TYPE_ALIAS(char, u8, u8, 0),
ASSIGN_FETCH_TYPE_ALIAS(symbol, ADDR_FETCH_TYPE, ADDR_FETCH_TYPE, 0),
ASSIGN_FETCH_TYPE_END
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index de38f1c03776..8c86aaa8b0c9 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -164,6 +164,7 @@ DECLARE_BASIC_PRINT_TYPE_FUNC(x16);
DECLARE_BASIC_PRINT_TYPE_FUNC(x32);
DECLARE_BASIC_PRINT_TYPE_FUNC(x64);
+DECLARE_BASIC_PRINT_TYPE_FUNC(char);
DECLARE_BASIC_PRINT_TYPE_FUNC(string);
DECLARE_BASIC_PRINT_TYPE_FUNC(symbol);
--
2.25.1