[Devel] [PATCH 1/2] ms/tracing: Introduce tracepoint extended structure

[Konstantin Khorenko]

On 5/17/26 21:28, Eva Kurchatova wrote:
> From: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> 
> Commit 1d562f197d01a ("ms/objtool: Exclude __tracepoints data from
> ENDBR checks") was backported from mainstream, which excludes the
> __tracepoints section from objtool's IBT validation. This causes
> regfunc/unregfunc function pointers stored directly in struct tracepoint
> to have their ENDBR instructions incorrectly sealed at boot, resulting
> in a kernel crash when called indirectly with CONFIG_X86_KERNEL_IBT=y.
> 
> In mainstream, this commit amends the crash by moving regfunc/unregfunc
> into a separate struct tracepoint_ext outside the __tracepoints section,
> and should be backported alongside it.

When you backport a commit from mainstream (or from any place),
please do not change the original commit message at all and post the full original commit message.

Your add-ons to the commit message should go under the original commit message.

> 
> Tested-by: Jordan Rife <jrife at google.com>
> Cc: Michael Jeanson <mjeanson at efficios.com>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: Masami Hiramatsu <mhiramat at kernel.org>
> Cc: Peter Zijlstra <peterz at infradead.org>
> Cc: Alexei Starovoitov <ast at kernel.org>
> Cc: Yonghong Song <yhs at fb.com>
> Cc: Paul E. McKenney <paulmck at kernel.org>
> Cc: Ingo Molnar <mingo at redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme at kernel.org>
> Cc: Mark Rutland <mark.rutland at arm.com>
> Cc: Alexander Shishkin <alexander.shishkin at linux.intel.com>
> Cc: Namhyung Kim <namhyung at kernel.org>
> Cc: Andrii Nakryiko <andrii.nakryiko at gmail.com>
> Cc: bpf at vger.kernel.org
> Cc: Joel Fernandes <joel at joelfernandes.org>
> Cc: Jordan Rife <jrife at google.com>
> Cc: linux-trace-kernel at vger.kernel.org
> Link: https://lore.kernel.org/20241031152056.744137-2-mathieu.desnoyers@efficios.com
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> Signed-off-by: Steven Rostedt (Google) <rostedt at goodmis.org>
> 
> (cherry picked from commit a9cfb8778c43fc473ae16cddb6e9611705721b31)
> Signed-off-by: Eva Kurchatova <eva.kurchatova at virtuozzo.com>
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-131560
> Feature: fix tracepoint
> ---
>   include/linux/tracepoint-defs.h |  8 ++++++--
>   include/linux/tracepoint.h      | 19 +++++++++++++------
>   kernel/tracepoint.c             |  8 ++++----
>   3 files changed, 23 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/tracepoint-defs.h b/include/linux/tracepoint-defs.h
> index 4dc4955f0fbf..e1af02e375d6 100644
> --- a/include/linux/tracepoint-defs.h
> +++ b/include/linux/tracepoint-defs.h
> @@ -29,6 +29,11 @@ struct tracepoint_func {
>   	int prio;
>   };
>   
> +struct tracepoint_ext {
> +	int (*regfunc)(void);
> +	void (*unregfunc)(void);
> +};
> +
>   struct tracepoint {
>   	const char *name;		/* Tracepoint name */
>   	struct static_key key;
> @@ -36,9 +41,8 @@ struct tracepoint {
>   	void *static_call_tramp;
>   	void *iterator;
>   	void *probestub;
> -	int (*regfunc)(void);
> -	void (*unregfunc)(void);
>   	struct tracepoint_func __rcu *funcs;
> +	struct tracepoint_ext *ext;
>   };
>   
>   #ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 93a9f3070b48..583d962abcc3 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -319,7 +319,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
>    * structures, so we create an array of pointers that will be used for iteration
>    * on the tracepoints.
>    */
> -#define DEFINE_TRACE_FN(_name, _reg, _unreg, proto, args)		\
> +#define __DEFINE_TRACE_EXT(_name, _ext, proto, args)			\
>   	static const char __tpstrtab_##_name[]				\
>   	__section("__tracepoints_strings") = #_name;			\
>   	extern struct static_call_key STATIC_CALL_KEY(tp_func_##_name);	\
> @@ -333,9 +333,9 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
>   		.static_call_tramp = STATIC_CALL_TRAMP_ADDR(tp_func_##_name), \
>   		.iterator = &__traceiter_##_name,			\
>   		.probestub = &__probestub_##_name,			\
> -		.regfunc = _reg,					\
> -		.unregfunc = _unreg,					\
> -		.funcs = NULL };					\
> +		.funcs = NULL,						\
> +		.ext = _ext,						\
> +	};								\
>   	__TRACEPOINT_ENTRY(_name);					\
>   	int __traceiter_##_name(void *__data, proto)			\
>   	{								\
> @@ -358,8 +358,15 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
>   	}								\
>   	DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name);
>   
> -#define DEFINE_TRACE(name, proto, args)		\
> -	DEFINE_TRACE_FN(name, NULL, NULL, PARAMS(proto), PARAMS(args));
> +#define DEFINE_TRACE_FN(_name, _reg, _unreg, _proto, _args)		\
> +	static struct tracepoint_ext __tracepoint_ext_##_name = {	\
> +		.regfunc = _reg,					\
> +		.unregfunc = _unreg,					\
> +	};								\
> +	__DEFINE_TRACE_EXT(_name, &__tracepoint_ext_##_name, PARAMS(_proto), PARAMS(_args));
> +
> +#define DEFINE_TRACE(_name, _proto, _args)				\
> +	__DEFINE_TRACE_EXT(_name, NULL, PARAMS(_proto), PARAMS(_args));
>   
>   #define EXPORT_TRACEPOINT_SYMBOL_GPL(name)				\
>   	EXPORT_SYMBOL_GPL(__tracepoint_##name);				\
> diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
> index 8879da16ef4d..ebab4290d486 100644
> --- a/kernel/tracepoint.c
> +++ b/kernel/tracepoint.c
> @@ -327,8 +327,8 @@ static int tracepoint_add_func(struct tracepoint *tp,
>   	struct tracepoint_func *old, *tp_funcs;
>   	int ret;
>   
> -	if (tp->regfunc && !static_key_enabled(&tp->key)) {
> -		ret = tp->regfunc();
> +	if (tp->ext && tp->ext->regfunc && !static_key_enabled(&tp->key)) {
> +		ret = tp->ext->regfunc();
>   		if (ret < 0)
>   			return ret;
>   	}
> @@ -411,8 +411,8 @@ static int tracepoint_remove_func(struct tracepoint *tp,
>   	switch (nr_func_state(tp_funcs)) {
>   	case TP_FUNC_0:		/* 1->0 */
>   		/* Removed last function */
> -		if (tp->unregfunc && static_key_enabled(&tp->key))
> -			tp->unregfunc();
> +		if (tp->ext && tp->ext->unregfunc && static_key_enabled(&tp->key))
> +			tp->ext->unregfunc();
>   
>   		static_key_disable(&tp->key);
>   		/* Set iterator static call */