[PATCH] bpf, riscv: fix missing extable entry for arena load_acquire

[Feng Jiang]

emit_atomic_ld_st() returns 1 to have build_body() skip the zext after
a sub-word load_acquire. The caller does "ret = ret ?:
add_exception_handler(...)", which skips add_exception_handler() on any
non-zero ret, so the extable entry is missing and a faulting
PROBE_ATOMIC load_acquire oopses.

Check ret >= 0 before calling add_exception_handler(), and return ret
unchanged so build_body() still skips the zext.

Fixes: fb7cefabae81 ("riscv, bpf: Add support arena atomics for RV64")
Signed-off-by: Feng Jiang <jiangfeng@xxxxxxxxxx>
---
 arch/riscv/net/bpf_jit_comp64.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index f9d5347ba966..4fd4392dd080 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -1986,10 +1986,14 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
 		else
 			ret = emit_atomic_rmw(rd, rs, insn, ctx);
 
-		ret = ret ?: add_exception_handler(insn, REG_DONT_CLEAR_MARKER, ctx);
-		if (ret)
-			return ret;
-		break;
+		/* ret can be 1 (skip-zext); extable entry still needs to be added */
+		if (ret >= 0) {
+			int err = add_exception_handler(insn, REG_DONT_CLEAR_MARKER, ctx);
+
+			if (err)
+				return err;
+		}
+		return ret;
 
 	default:
 		pr_err("bpf-jit: unknown opcode %02x\n", code);

---
base-commit: a13c140cc289c0b7b3770bce5b3ad42ab35074aa
change-id: 20260716-bpf-riscv-fix-extable-399947ca778d

Best regards,
-- 
Feng Jiang <jiangfeng@xxxxxxxxxx>