Re: [GIT PULL] tracing: Fixes for 7.1

[Nathan Chancellor <nathan@kernel.org>]

On Thu, Jun 04, 2026 at 08:47:55AM -0400, Steven Rostedt wrote:
> commit 0652a3daa78723f955b1ebeb621665ce72bec53e
> Author: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
> Date:   Wed Jun 3 18:31:42 2026 +0300
> 
>     tracing: Fix CFI violation in probestub being called by tprobes
>     
>     The probestub is a function to allow tprobes to hook to a tracepoint to
>     gain access to its parameters. The function itself is only referenced by
>     the tracepoint structure which lives in the __tracepoint section. objtool
>     explicitly ignores that section and when processing functions in the
>     kernel, if it detects one that has no references it will seal it to have
>     its ENDBR stripped on boot up.
>     
>     This means when a tprobe is attached to the sched_wakeup tracepoint, when it
>     is triggered it will call __probestub_sched_wakeup and due to the missing
>     ENDBR on a CFI-enabled machine it will take a #CP exception.
>     
>     Fix this by adding CFI_NOSEAL annotation to probestub declaration.
>     
>     Cc: stable@vger.kernel.org
>     Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>     Link: https://patch.msgid.link/20260603153147.573589-1-eva.kurchatova@virtuozzo.com
>     Fixes: d5173f753750 ("objtool: Exclude __tracepoints data from ENDBR checks")
>     Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
>     [ Updated change log ]
>     Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> 
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 763eea4d80d8..2d2b9f8cdda4 100644
> --- a/include/linux/tracepoint.h
> +++ b/include/linux/tracepoint.h
> @@ -20,6 +20,7 @@
>  #include <linux/rcupdate_trace.h>
>  #include <linux/tracepoint-defs.h>
>  #include <linux/static_call.h>
> +#include <linux/cfi.h>
>  
>  struct module;
>  struct tracepoint;
> @@ -389,6 +390,13 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
>  	void __probestub_##_name(void *__data, proto)			\
>  	{								\
>  	}								\
> +	/*								\
> +	 * Annotate the probestub 'CFI_NOSEAL' to stop objtool from	\
> +	 * requesting the kernel remove the ENDBR, because the only	\
> +	 * references to the function are in the __tracepoint section,	\
> +	 * that objtool doesn't scan.					\
> +	 */								\
> +	CFI_NOSEAL(__probestub_##_name);				\
>  	DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name);	\
>  	DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args))
>  

This needs a build fix, as ARCH=arm allmodconfig is now broken with
Clang.

  https://lore.kernel.org/20260604-tracing-fix-cfi-h-build-error-v1-1-b27015390901@kernel.org/

-- 
Cheers,
Nathan