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

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

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 582fa38307725ab76adb8278b7c46ec2e81142bc..ecd53f8f0602c0a43d6ee9505df9962d9e1f193e 100644 (file)
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -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;