[RFC PATCH bpf-next v1 07/14] MIPS: eBPF: fix MOD64 insn on R6 ISA
From: Tony Ambardar <hidden>
Date: 2021-07-12 00:35:43
Also in:
bpf, linux-mips
Subsystem:
bpf jit for mips (32-bit and 64-bit), bpf [general] (safe dynamic programs and tools), mips, the rest · Maintainers:
Johan Almbladh, Paul Burton, Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Thomas Bogendoerfer, Linus Torvalds
The BPF_ALU64 | BPF_MOD implementation is broken on MIPS64R6 due to use of
a 32-bit "modu" insn, as shown by the test_verifier failures:
455/p MOD64 overflow, check 1 FAIL retval 0 != 1 (run 1/1)
456/p MOD64 overflow, check 2 FAIL retval 0 != 1 (run 1/1)
Resolve by using the 64-bit "dmodu" instead.
Fixes: 6c2c8a188868 ("MIPS: eBPF: Provide eBPF support for MIPS64R6")
Signed-off-by: Tony Ambardar <redacted>
---
arch/mips/net/ebpf_jit.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 4f641dcb2031..e8c403c6cfa3 100644
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c@@ -800,7 +800,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, if (bpf_op == BPF_DIV) emit_instr(ctx, ddivu_r6, dst, dst, MIPS_R_AT); else - emit_instr(ctx, modu, dst, dst, MIPS_R_AT); + emit_instr(ctx, dmodu, dst, dst, MIPS_R_AT); break; } emit_instr(ctx, ddivu, dst, MIPS_R_AT);
@@ -882,7 +882,7 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, emit_instr(ctx, ddivu_r6, dst, dst, src); else - emit_instr(ctx, modu, dst, dst, src); + emit_instr(ctx, dmodu, dst, dst, src); break; } emit_instr(ctx, ddivu, dst, src);
--
2.25.1