From: Steven Rostedt (Google) Date: Sun, 31 Jul 2022 05:59:28 +0000 (-0400) Subject: tracing: Use a struct alignof to determine trace event field alignment X-Git-Tag: baikal/mips/sdk6.1~5122^2~6 X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=045e997bfe79d55bb8885d0211a89fe1409e5567;p=kernel.git tracing: Use a struct alignof to determine trace event field alignment alignof() gives an alignment of types as they would be as standalone variables. But alignment in structures might be different, and when building the fields of events, the alignment must be the actual alignment otherwise the field offsets may not match what they actually are. This caused trace-cmd to crash, as libtraceevent did not check if the field offset was bigger than the event. The write_msr and read_msr events on 32 bit had their fields incorrect, because it had a u64 field between two ints. alignof(u64) would give 8, but the u64 field was at a 4 byte alignment. Define a macro as: ALIGN_STRUCTFIELD(type) ((int)(offsetof(struct {char a; type b;}, b))) which gives the actual alignment of types in a structure. Link: https://lkml.kernel.org/r/20220731015928.7ab3a154@rorschach.local.home Cc: Ingo Molnar Cc: Andrew Morton Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Masami Hiramatsu Cc: stable@vger.kernel.org Fixes: 45de884aa7537 ("ftrace: Rework event_create_dir()") Signed-off-by: Steven Rostedt (Google) --- diff --git a/include/trace/stages/stage4_event_fields.h b/include/trace/stages/stage4_event_fields.h index c3790ec7a4530..80d34f3965555 100644 --- a/include/trace/stages/stage4_event_fields.h +++ b/include/trace/stages/stage4_event_fields.h @@ -2,16 +2,18 @@ /* Stage 4 definitions for creating trace events */ +#define ALIGN_STRUCTFIELD(type) ((int)(offsetof(struct {char a; type b;}, b))) + #undef __field_ext #define __field_ext(_type, _item, _filter_type) { \ .type = #_type, .name = #_item, \ - .size = sizeof(_type), .align = __alignof__(_type), \ + .size = sizeof(_type), .align = ALIGN_STRUCTFIELD(_type), \ .is_signed = is_signed_type(_type), .filter_type = _filter_type }, #undef __field_struct_ext #define __field_struct_ext(_type, _item, _filter_type) { \ .type = #_type, .name = #_item, \ - .size = sizeof(_type), .align = __alignof__(_type), \ + .size = sizeof(_type), .align = ALIGN_STRUCTFIELD(_type), \ 0, .filter_type = _filter_type }, #undef __field @@ -23,7 +25,7 @@ #undef __array #define __array(_type, _item, _len) { \ .type = #_type"["__stringify(_len)"]", .name = #_item, \ - .size = sizeof(_type[_len]), .align = __alignof__(_type), \ + .size = sizeof(_type[_len]), .align = ALIGN_STRUCTFIELD(_type), \ .is_signed = is_signed_type(_type), .filter_type = FILTER_OTHER }, #undef __dynamic_array