On Fri, Nov 15, 2024 at 8:30 AM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:
>
>
>
>
> On 11/15/24 4:20 AM, Jiri Olsa wrote:
> > On Thu, Nov 07, 2024 at 06:56:16PM -0800, Alexei Starovoitov wrote:
> >> From: Alexei Starovoitov <ast@xxxxxxxxxx>
> >>
> >> Add a test that verifies specific behavior of arena range tree
> >> algorithm and just existing bif_alloc1 test due to use
> >> of global data in arena.
> >>
> >> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> >> ---
> >> .../bpf/progs/verifier_arena_large.c | 110 +++++++++++++++++-
> >> 1 file changed, 108 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_large.c b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> >> index 6065f862d964..8a9af79db884 100644
> >> --- a/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> >> +++ b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> >> @@ -29,12 +29,12 @@ int big_alloc1(void *ctx)
> >> if (!page1)
> >> return 1;
> >> *page1 = 1;
> >> - page2 = bpf_arena_alloc_pages(&arena, base + ARENA_SIZE - PAGE_SIZE,
> >> + page2 = bpf_arena_alloc_pages(&arena, base + ARENA_SIZE - PAGE_SIZE * 2,
> >> 1, NUMA_NO_NODE, 0);
> >> if (!page2)
> >> return 2;
> >> *page2 = 2;
> >> - no_page = bpf_arena_alloc_pages(&arena, base + ARENA_SIZE,
> >> + no_page = bpf_arena_alloc_pages(&arena, base + ARENA_SIZE - PAGE_SIZE,
> >> 1, NUMA_NO_NODE, 0);
> >> if (no_page)
> >> return 3;
> >> @@ -66,4 +66,110 @@ int big_alloc1(void *ctx)
> >> #endif
> >> return 0;
> >> }
> >> +
> >> +#if defined(__BPF_FEATURE_ADDR_SPACE_CAST)
> >> +#define PAGE_CNT 100
> >> +__u8 __arena * __arena page[PAGE_CNT]; /* occupies the first page */
> >> +__u8 __arena *base;
> >> +
> >> +/*
> >> + * Check that arena's range_tree algorithm allocates pages sequentially
> >> + * on the first pass and then fills in all gaps on the second pass.
> >> + */
> >> +__noinline int alloc_pages(int page_cnt, int pages_atonce, bool first_pass,
> >> + int max_idx, int step)
> >> +{
> >> + __u8 __arena *pg;
> >> + int i, pg_idx;
> >> +
> >> + for (i = 0; i < page_cnt; i++) {
> >> + pg = bpf_arena_alloc_pages(&arena, NULL, pages_atonce,
> >> + NUMA_NO_NODE, 0);
> >> + if (!pg)
> >> + return step;
> >> + pg_idx = (pg - base) / PAGE_SIZE;
> > hi,
> > I'm getting compile error below with clang 20.0.0:
> >
> > CLNG-BPF [test_progs] verifier_arena_large.bpf.o
> > progs/verifier_arena_large.c:90:24: error: unsupported signed division, please convert to unsigned div/mod.
> > 90 | pg_idx = (pg - base) / PAGE_SIZE;
> >
> > should we just convert it to unsigned div like below?
> >
> > also I saw recent llvm change [1] that might help, I'll give it a try
>
> I am using latest clang 20 and compilation is successful due to the llvm change [1].
>
> >
> > jirka
> >
> >
> > [1] 38a8000f30aa [BPF] Use mul for certain div/mod operations (#110712)
> > ---
> > diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_large.c b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> > index 8a9af79db884..e743d008697e 100644
> > --- a/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> > +++ b/tools/testing/selftests/bpf/progs/verifier_arena_large.c
> > @@ -87,7 +87,7 @@ __noinline int alloc_pages(int page_cnt, int pages_atonce, bool first_pass,
> > NUMA_NO_NODE, 0);
> > if (!pg)
> > return step;
> > - pg_idx = (pg - base) / PAGE_SIZE;
> > + pg_idx = (unsigned int) (pg - base) / PAGE_SIZE;
> > if (first_pass) {
> > /* Pages must be allocated sequentially */
> > if (pg_idx != i)
>
> I think this patch is still good.
> Compiling the current verifier_arena_large.c will be okay for llvm <= 18 and >= 20.
> But llvm19 will have compilation failure as you mentioned in the above.
>
> So once bpf ci upgrades compiler to llvm19 we will see the above compilation failure.
>
> Please verifify it as well. If this is the case in your side, please submit a patch.
The merge window is about to open, so I pushed the fix myself.
