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authorDaniel Borkmann <daniel@iogearbox.net>2017-12-14 21:07:26 +0100
committerAlexei Starovoitov <ast@kernel.org>2017-12-15 09:19:35 -0800
commit07aee94394547721ac168cbf4e1c09c14a5fe671 (patch)
treefa31f2226634b8f83f00f99bfffd377eb59c270f /arch
parent04514d13222f2c4c91adf0ecb21004cec3388795 (diff)
bpf, sparc: fix usage of wrong reg for load_skb_regs after call
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/sparc/net/bpf_jit_comp_64.c6
1 files 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 5765e7e711f7..ff5f9cb3039a 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;
}

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