From c50a184a0e9da662a27532d53bc8298d8ebed0ce Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Sun, 31 Jul 2022 01:59:28 -0400 Subject: [PATCH] tracing: Use a struct alignof to determine trace event field alignment commit 045e997bfe79d55bb8885d0211a89fe1409e5567 upstream. 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) Signed-off-by: Greg Kroah-Hartman --- include/trace/trace_events.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/include/trace/trace_events.h b/include/trace/trace_events.h index 65d927e059d31..c60e10cd07c9f 100644 --- a/include/trace/trace_events.h +++ b/include/trace/trace_events.h @@ -479,16 +479,18 @@ static struct trace_event_functions trace_event_type_funcs_##call = { \ #include TRACE_INCLUDE(TRACE_INCLUDE_FILE) +#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 @@ -500,7 +502,7 @@ static struct trace_event_functions trace_event_type_funcs_##call = { \ #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 -- 2.39.5