On Fri, 2025-02-07 at 02:06 +0000, Peilin Ye wrote:
> Add several ./test_progs tests:
>
> - arena_atomics/load_acquire
> - arena_atomics/store_release
> - verifier_load_acquire/*
> - verifier_store_release/*
> - verifier_precision/bpf_load_acquire
> - verifier_precision/bpf_store_release
>
> The last two tests are added to check if backtrack_insn() handles the
> new instructions correctly.
>
> Additionally, the last test also makes sure that the verifier
> "remembers" the value (in src_reg) we store-release into e.g. a stack
> slot. For example, if we take a look at the test program:
>
> #0: r1 = 8;
> /* store_release((u64 *)(r10 - 8), r1); */
> #1: .8byte %[store_release];
> #2: r1 = *(u64 *)(r10 - 8);
> #3: r2 = r10;
> #4: r2 += r1;
> #5: r0 = 0;
> #6: exit;
>
> At #1, if the verifier doesn't remember that we wrote 8 to the stack,
> then later at #4 we would be adding an unbounded scalar value to the
> stack pointer, which would cause the program to be rejected:
>
> VERIFIER LOG:
> =============
> ...
> math between fp pointer and register with unbounded min value is not allowed
>
> All new tests depend on #ifdef ENABLE_ATOMICS_TESTS. Currently they
> only run for arm64.
>
> Signed-off-by: Peilin Ye <yepeilin@xxxxxxxxxx>
> ---
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
[...]
> +++ b/tools/testing/selftests/bpf/progs/verifier_load_acquire.c
> @@ -0,0 +1,190 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/bpf.h>
> +#include <bpf/bpf_helpers.h>
> +#include "../../../include/linux/filter.h"
> +#include "bpf_misc.h"
> +
> +#if defined(ENABLE_ATOMICS_TESTS) && defined(__TARGET_ARCH_arm64)
[...]
> +#else
> +
> +SEC("socket")
> +__description("load-acquire is not supported by compiler or jit, use a dummy test")
> +__success
> +int dummy_test(void)
> +{
> + return 0;
> +}
Nit: why is dummy_test() necessary?
> +
> +#endif
> +
> +char _license[] SEC("license") = "GPL";
[...]
