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s390/bpf: Land on the next JITed instruction after exception

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Currently we land on the nop, which is unnecessary: we can just as well
begin executing the next instruction. Furthermore, the upcoming arena
support for the loop-based BPF_XCHG implementation will require landing
on an instruction that comes after the loop.

So land on the next JITed instruction, which covers both cases.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240701234304.14336-6-iii@linux.ibm.com
This commit is contained in:
Ilya Leoshkevich 2024-07-02 01:40:23 +02:00 committed by Daniel Borkmann
parent 89b933a201
commit a1c04bcc41
1 changed files with 4 additions and 3 deletions
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7
arch/s390/net/bpf_jit_comp.c
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@ -747,10 +747,11 @@ static int bpf_jit_probe_post(struct bpf_jit *jit, struct bpf_prog *fp,
return -1;
ex->insn = delta;
/*
* Always land on the nop. Note that extable infrastructure
* ignores fixup field, it is handled by ex_handler_bpf().
* Land on the current instruction. Note that the extable
* infrastructure ignores the fixup field; it is handled by
* ex_handler_bpf().
*/
delta = jit->prg_buf + probe->nop_prg - (u8 *)&ex->fixup;
delta = jit->prg_buf + jit->prg - (u8 *)&ex->fixup;
if (WARN_ON_ONCE(delta < INT_MIN || delta > INT_MAX))
/* JIT bug - landing pad and extable must be close. */
return -1;