[PATCH 3.17 37/47] mips: bpf: Fix broken BPF_MOD

[Greg Kroah-Hartman]

3.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Denis Kirjanov <kda@xxxxxxxxxxxxxxxxx>

[ Upstream commit 2e46477a12f6fd273e31a220b155d66e8352198c ]

Remove optimize_div() from BPF_MOD | BPF_K case
since we don't know the dividend and fix the
emit_mod() by reading the mod operation result from HI register

Signed-off-by: Denis Kirjanov <kda@xxxxxxxxxxxxxxxxx>
Reviewed-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/mips/net/bpf_jit.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/mips/net/bpf_jit.c
+++ b/arch/mips/net/bpf_jit.c
@@ -430,7 +430,7 @@ static inline void emit_mod(unsigned int
 		u32 *p = &ctx->target[ctx->idx];
 		uasm_i_divu(&p, dst, src);
 		p = &ctx->target[ctx->idx + 1];
-		uasm_i_mflo(&p, dst);
+		uasm_i_mfhi(&p, dst);
 	}
 	ctx->idx += 2; /* 2 insts */
 }
@@ -1006,7 +1006,7 @@ load_ind:
 			break;
 		case BPF_ALU | BPF_MOD | BPF_K:
 			/* A %= k */
-			if (k == 1 || optimize_div(&k)) {
+			if (k == 1) {
 				ctx->flags |= SEEN_A;
 				emit_jit_reg_move(r_A, r_zero, ctx);
 			} else {


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