Commit af8d27bf authored by Jiri Olsa's avatar Jiri Olsa Committed by Andrii Nakryiko
Browse files

selftests/bpf: Mark uprobe trigger functions with nocf_check attribute 



Some distros seem to enable the -fcf-protection=branch by default,
which breaks our setup on first instruction of uprobe trigger
functions and place there endbr64 instruction.

Marking them with nocf_check attribute to skip that.

Ignoring unknown attribute warning in gcc for bench objects, because
nocf_check can be used only when -fcf-protection=branch is enabled,
otherwise we get a warning and break compilation.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240322134936.1075395-1-jolsa@kernel.org
parent 1684d6eb

tools/include/linux/compiler.h

+4 −0
Original line number Diff line number Diff line
@@ -58,6 +58,10 @@ 
#define noinline

#endif



#ifndef __nocf_check

#define __nocf_check __attribute__((nocf_check))

#endif



/* Are two types/vars the same type (ignoring qualifiers)? */

#ifndef __same_type

# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))

tools/testing/selftests/bpf/benchs/bench_trigger.c

+5 −3
Original line number Diff line number Diff line
@@ -9,6 +9,8 @@ 
/* adjust slot shift in inc_hits() if changing */

#define MAX_BUCKETS 256



#pragma GCC diagnostic ignored "-Wattributes"



/* BPF triggering benchmarks */

static struct trigger_ctx {

	struct trigger_bench *skel;
@@ -167,7 +169,7 @@ static void trigger_fmodret_setup(void) 
 * GCC doesn't generate stack setup preample for these functions due to them

 * having no input arguments and doing nothing in the body.

 */

__weak void uprobe_target_nop(void)

__nocf_check __weak void uprobe_target_nop(void)

{

	asm volatile ("nop");

}
@@ -176,7 +178,7 @@ __weak void opaque_noop_func(void) 
{

}



__weak int uprobe_target_push(void)

__nocf_check __weak int uprobe_target_push(void)

{

	/* overhead of function call is negligible compared to uprobe

	 * triggering, so this shouldn't affect benchmark results much
@@ -185,7 +187,7 @@ __weak int uprobe_target_push(void) 
	return 1;

}



__weak void uprobe_target_ret(void)

__nocf_check __weak void uprobe_target_ret(void)

{

	asm volatile ("");

}