On Wed, 15 Jul 2026 02:32:06 +0800
Jinchao Wang <[email protected]> wrote:
> --- /dev/null
> +++ b/include/trace/events/kwatch.h
> @@ -0,0 +1,57 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM kwatch
> +
> +#if !defined(_TRACE_KWATCH_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_KWATCH_H
> +
> +#include <linux/tracepoint.h>
> +#include <linux/ptrace.h>
> +
> +#define KWATCH_STACK_DEPTH 8
> +
> +struct trace_seq;
> +const char *kwatch_trace_print_stack(struct trace_seq *p,
> + const unsigned long *stack,
> + unsigned int nr);
> +
> +TRACE_EVENT(kwatch_hit,
> + TP_PROTO(unsigned long ip, unsigned long sp, unsigned long addr,
> + u64 time_ns,
> + unsigned long *stack_entries, unsigned int stack_nr),
> + TP_ARGS(ip, sp, addr, time_ns, stack_entries, stack_nr),
> +
> + TP_STRUCT__entry(
> + __field(unsigned long, ip)
> + __field(unsigned long, sp)
> + __field(unsigned long, addr)
> + __field(u64, time_ns)
Move the time_ns to the first field, as unsigned long on 32 bit
architectures is 4 bytes, and this will make 4 byte "hole" in the event.
> + __field(unsigned int, stack_nr)
Make stack_nr the last element for the same reason.
> + __array(unsigned long, stack, KWATCH_STACK_DEPTH)
Make the above a dynamic array based on stack entries.
__dynamic_array(unsigned long, stack, min_t(unsigned int,
stack_nr,
KWATCH_STACK_DEPTH);
> + ),
> +
> + TP_fast_assign(
> + unsigned int i;
unsigned long *stack = __get_dynamic_array(stack);
> +
> + __entry->ip = ip;
> + __entry->sp = sp;
> + __entry->addr = addr;
> + __entry->time_ns = time_ns;
> + __entry->stack_nr = min_t(unsigned int, stack_nr,
> + KWATCH_STACK_DEPTH);
> + for (i = 0; i < __entry->stack_nr; i++)
> + __entry->stack[i] = stack_entries[i];
stack[i] = stack_entries[i];
> + ),
> +
> + TP_printk("KWatch HIT: time=%llu.%06lu ip=%pS addr=0x%lx%s",
> + __entry->time_ns / 1000000000ULL,
> + (unsigned long)((__entry->time_ns / 1000ULL) % 1000000ULL),
> + (void *)__entry->ip, __entry->addr,
> + kwatch_trace_print_stack(p, __entry->stack,
kwatch_trace_print_stack(p, __get_dynamic_array(stack),
> + __entry->stack_nr))
> +);
> +
-- Steve
