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selftests/bpf: Don't cast a pointer to .bss in arena_htab_asm

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arena_htab_asm is arena_htab.c with BPF_ARENA_FORCE_ASM. In this variant
__arena has no address space, so arr1 is in .bss, and cast_kern() is a real
insn. cast_kern(arr) turns the pointer to .bss into an offset in the arena.
Each of the 100000 stores to arr[i] faults, and the fault handler of the
arena skips it.

Remove the cast. In the other variant it is a nop. The prog takes 67 ms in
place of 950 ms on a kernel with lockdep.

With one time slice for all may_goto of a prog, may_goto stops the loops of
the old prog after 250 ms. The test does not see that, because it looks at
the first keys only.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261031215543.682284-3-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2026-10-31 21:55:36 +00:00
parent 1ddffb57b3
commit fcda8096dc
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tools/testing/selftests/bpf/progs/arena_htab.c
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@ -34,8 +34,6 @@ int arena_htab_llvm(void *ctx)
cast_kern(htab);
htab_init(htab);
cast_kern(arr);
/* first run. No old elems in the table */
for (i = zero; i < 100000 && can_loop; i++) {
htab_update_elem(htab, i, i);