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selftests/bpf: Mark uprobe trigger functions with nocf_check attribute

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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: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240322134936.1075395-1-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2024-03-22 14:49:36 +01:00 committed by Andrii Nakryiko
parent 1684d6eb99
commit af8d27bf15
2 changed files with 9 additions and 3 deletions
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4
tools/include/linux/compiler.h
View File

@ -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))

8
tools/testing/selftests/bpf/benchs/bench_trigger.c
View File

@ -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 ("");
}