On Thu, Sep 11, 2025 at 11:19 AM Eduard Zingerman <eddyz87@xxxxxxxxx> wrote:
>
> 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).
Applied as-is.
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