[ Upstream commit 07aee94394547721ac168cbf4e1c09c14a5fe671 ]
When LD_ABS/IND is used in the program, and we have a BPF helper call that changes packet data (bpf_helper_changes_pkt_data() returns true), then in case of sparc JIT, we try to reload cached skb data from bpf2sparc[BPF_REG_6]. However, there is no such guarantee or assumption that skb sits in R6 at this point, all helpers changing skb data only have a guarantee that skb sits in R1. Therefore, store BPF R1 in L7 temporarily and after procedure call use L7 to reload cached skb data. skb sitting in R6 is only true at the time when LD_ABS/IND is executed.
Fixes: 7a12b5031c6b ("sparc64: Add eBPF JIT.") Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: David S. Miller davem@davemloft.net Acked-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Alexei Starovoitov ast@kernel.org --- arch/sparc/net/bpf_jit_comp_64.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/sparc/net/bpf_jit_comp_64.c b/arch/sparc/net/bpf_jit_comp_64.c index 5765e7e..ff5f9cb 100644 --- a/arch/sparc/net/bpf_jit_comp_64.c +++ b/arch/sparc/net/bpf_jit_comp_64.c @@ -1245,14 +1245,16 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) u8 *func = ((u8 *)__bpf_call_base) + imm;
ctx->saw_call = true; + if (ctx->saw_ld_abs_ind && bpf_helper_changes_pkt_data(func)) + emit_reg_move(bpf2sparc[BPF_REG_1], L7, ctx);
emit_call((u32 *)func, ctx); emit_nop(ctx);
emit_reg_move(O0, bpf2sparc[BPF_REG_0], ctx);
- if (bpf_helper_changes_pkt_data(func) && ctx->saw_ld_abs_ind) - load_skb_regs(ctx, bpf2sparc[BPF_REG_6]); + if (ctx->saw_ld_abs_ind && bpf_helper_changes_pkt_data(func)) + load_skb_regs(ctx, L7); break; }