From: Suchit Karunakaran <suchitkarunakaran@gmail.com>
To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
namhyung@kernel.org, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@kernel.org,
irogers@google.com, adrian.hunter@intel.com,
james.clark@linaro.org
Cc: linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org,
Suchit Karunakaran <suchitkarunakaran@gmail.com>
Subject: [PATCH v2 2/2] perf build: compile BPF skeletons with -mcpu=v3
Date: Sun, 31 May 2026 01:25:10 +0530 [thread overview]
Message-ID: <20260530195511.71452-1-suchitkarunakaran@gmail.com> (raw)
The lock_contention BPF program uses __sync_val_compare_and_swap()
to atomically update the max_time and min_time fields in
contention_data. This builtin lowers to the BPF_CMPXCHG instruction,
which is only available in BPF ISA v3. Without an explicit -mcpu flag,
Clang targets BPF v1/v2 by default on older toolchains (Clang < 18),
causing build errors when v3 instructions are emitted.
Add -mcpu=v3 to CLANG_OPTIONS, which is used exclusively in the BPF
skeleton compilation rule.
Signed-off-by: Suchit Karunakaran <suchitkarunakaran@gmail.com>
Changes since v1:
- Moved the -mcpu=v3 addition from tools/perf/Makefile.perf to
tools/perf/bpf_skel.mak, following the refactoring of BPF skeleton
build logic into that file.
---
tools/perf/bpf_skel.mak | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/bpf_skel.mak b/tools/perf/bpf_skel.mak
index 7704e7e635d8..f2559de39f96 100644
--- a/tools/perf/bpf_skel.mak
+++ b/tools/perf/bpf_skel.mak
@@ -29,7 +29,7 @@ ifneq ($(CROSS_COMPILE),)
CLANG_TARGET_ARCH = --target=$(notdir $(CROSS_COMPILE:%-=%))
endif
-CLANG_OPTIONS = -Wall
+CLANG_OPTIONS = -Wall -mcpu=v3
CLANG_SYS_INCLUDES = $(call get_sys_includes,$(CLANG),$(CLANG_TARGET_ARCH))
LIBBPF_INCLUDE := $(abspath $(or $(OUTPUT),.))/libbpf/include
BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. -I$(SKEL_TOOL_OUT) -I$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES)
--
2.54.0
next reply other threads:[~2026-05-30 19:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-30 19:55 Suchit Karunakaran [this message]
2026-05-30 22:39 ` [PATCH v2 2/2] perf build: compile BPF skeletons with -mcpu=v3 Ian Rogers
2026-06-04 13:34 ` Arnaldo Carvalho de Melo
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