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Add a new type named 'char' to do it. For example: echo 'p:myprobe xxxx $arg1:char' > kprobe_events echo 'p:myprobe xxxx $arg1:char[2]' > kprobe_events Signed-off-by: Donglin Peng Acked-by: Masami Hiramatsu (Google) Reported-by: kernel test robot --- Changes in v3:  - update readme_msg Changes in v2:  - fix build warnings reported by kernel test robot  - modify commit log --- Documentation/trace/kprobetrace.rst | 3 ++- kernel/trace/trace.c | 2 +- kernel/trace/trace_probe.c | 2 ++ kernel/trace/trace_probe.h | 1 + 4 files changed, 6 insertions(+), 2 deletions(-) diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst index 4274cc6a2f94..007972a3c5c4 100644 --- a/Documentation/trace/kprobetrace.rst +++ b/Documentation/trace/kprobetrace.rst @@ -58,7 +58,7 @@ Synopsis of kprobe_events NAME=FETCHARG : Set NAME as the argument name of FETCHARG. FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal types - (x8/x16/x32/x64), "string", "ustring" and bitfield + (x8/x16/x32/x64), "char", "string", "ustring" and bitfield are supported. (\*1) only for the probe on function entry (offs == 0). @@ -80,6 +80,7 @@ E.g. 'x16[4]' means an array of x16 (2bytes hex) with 4 elements. Note that the array can be applied to memory type fetchargs, you can not apply it to registers/stack-entries etc. (for example, '$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, $stack, $retval, $comm,\n" #endif "\t +|-[u](), \\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@/, ustring,\n" "\t \\[\\]\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);