From 2aa93695081d4bd62350b41d58684d802be4563f Mon Sep 17 00:00:00 2001 From: Cupertino Miranda Date: Mon, 19 Aug 2024 16:11:27 +0100 Subject: selftests/bpf: Disable strict aliasing for verifier_nocsr.c verfifier_nocsr.c fails to compile in GCC. The reason behind it was initially explained in commit 27a90b14b93d3b2e1efd10764e456af7e2a42991. "A few BPF selftests perform type punning and they may break strict aliasing rules, which are exploited by both GCC and clang by default while optimizing. This can lead to broken compiled programs." Signed-off-by: Cupertino Miranda Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240819151129.1366484-2-cupertino.miranda@oracle.com --- tools/testing/selftests/bpf/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 4eceb491a8ae..7bca9a2b8bc0 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -58,6 +58,7 @@ progs/test_pkt_md_access.c-CFLAGS := -fno-strict-aliasing progs/test_sk_lookup.c-CFLAGS := -fno-strict-aliasing progs/timer_crash.c-CFLAGS := -fno-strict-aliasing progs/test_global_func9.c-CFLAGS := -fno-strict-aliasing +progs/verifier_nocsr.c-CFLAGS := -fno-strict-aliasing ifneq ($(LLVM),) # Silence some warnings when compiled with clang -- cgit v1.2.3 From d9075ac631ce0c5c2c17aa6221282a7c4ba8fa70 Mon Sep 17 00:00:00 2001 From: Cupertino Miranda Date: Mon, 19 Aug 2024 16:11:29 +0100 Subject: selftest/bpf: Adapt inline asm operand constraint for GCC support GCC errors when compiling tailcall_bpf2bpf_hierarchy2.c and tailcall_bpf2bpf_hierarchy3.c with the following error: progs/tailcall_bpf2bpf_hierarchy2.c: In function 'tailcall_bpf2bpf_hierarchy_2': progs/tailcall_bpf2bpf_hierarchy2.c:66:9: error: input operand constraint contains '+' 66 | asm volatile (""::"r+"(ret)); | ^~~ Changed implementation to make use of __sink macro that abstracts the desired behaviour. The proposed change seems valid for both GCC and CLANG. Signed-off-by: Cupertino Miranda Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240819151129.1366484-4-cupertino.miranda@oracle.com --- tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy2.c | 4 ++-- tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy3.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy2.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy2.c index 37604b0b97af..72fd0d577506 100644 --- a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy2.c +++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy2.c @@ -58,12 +58,12 @@ __retval(33) SEC("tc") int tailcall_bpf2bpf_hierarchy_2(struct __sk_buff *skb) { - volatile int ret = 0; + int ret = 0; subprog_tail0(skb); subprog_tail1(skb); - asm volatile (""::"r+"(ret)); + __sink(ret); return (count1 << 16) | count0; } diff --git a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy3.c b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy3.c index 0cdbb781fcbc..a7fb91cb05b7 100644 --- a/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy3.c +++ b/tools/testing/selftests/bpf/progs/tailcall_bpf2bpf_hierarchy3.c @@ -51,11 +51,11 @@ __retval(33) SEC("tc") int tailcall_bpf2bpf_hierarchy_3(struct __sk_buff *skb) { - volatile int ret = 0; + int ret = 0; bpf_tail_call_static(skb, &jmp_table0, 0); - asm volatile (""::"r+"(ret)); + __sink(ret); return ret; } -- cgit v1.2.3