On Thu, 2025-09-11 at 14:58 +0000, Puranjay Mohan wrote:
> Add selftests for testing the reporting of arena page faults through BPF
> streams. Two new bpf programs are added that read and write to an
> unmapped arena address and the fault reporting is verified in the
> userspace through streams.
>
> The added bpf programs need to access the user_vm_start in struct
> bpf_arena, this is done by casting &arena to struct bpf_arena *, but
> barrier_var() is used on this ptr before accessing ptr->user_vm_start;
> to stop GCC from issuing an out-of-bound access due to the cast from
> smaller map struct to larger "struct bpf_arena"
>
> Signed-off-by: Puranjay Mohan <puranjay@xxxxxxxxxx>
> ---
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
[...]
> +SEC("syscall")
> +__arch_x86_64
> +__arch_arm64
> +__success __retval(0)
> +__stderr("ERROR: Arena WRITE access at unmapped address 0x{{.*}}")
> +__stderr("CPU: {{[0-9]+}} UID: 0 PID: {{[0-9]+}} Comm: {{.*}}")
> +__stderr("Call trace:\n"
> +"{{([a-zA-Z_][a-zA-Z0-9_]*\\+0x[0-9a-fA-F]+/0x[0-9a-fA-F]+\n"
> +"|[ \t]+[^\n]+\n)*}}")
Nit: here and in other tests, the regex is a bit hard to read.
How wrong would it be to write it down as follows:
__stderr("Call trace:")
__stderr("bpf_stream_stage_dump_stack+0x{{.*}}/0x{{.*}}")
?
(or at-least add a comment).
[...]
