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 2/2] perf build: compile BPF skeletons with -mcpu=v3
Date: Fri, 8 May 2026 00:12:38 +0530 [thread overview]
Message-ID: <20260507184238.65280-2-suchitkarunakaran@gmail.com> (raw)
In-Reply-To: <20260507184238.65280-1-suchitkarunakaran@gmail.com>
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>
---
tools/perf/Makefile.perf | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index cee19c923c06..a9a8c84b6b00 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -1195,7 +1195,7 @@ 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),$(CLANG_TARGET_ARCH))
BPF_INCLUDE := -I$(SKEL_TMP_OUT)/.. -I$(LIBBPF_INCLUDE) $(CLANG_SYS_INCLUDES)
TOOLS_UAPI_INCLUDE := -I$(srctree)/tools/include/uapi
--
2.54.0
prev parent reply other threads:[~2026-05-07 18:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-07 18:42 [PATCH 1/2] perf/lock: Fix non-atomic max/time and min_time updates in contention_data Suchit Karunakaran
2026-05-07 18:42 ` Suchit Karunakaran [this message]
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