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Commit cde66c2d authored by Michael Holzheu's avatar Michael Holzheu Committed by David S. Miller
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s390/bpf: Only clear A and X for converted BPF programs 



Only classic BPF programs that have been converted to eBPF need to clear
the A and X registers. We can check for converted programs with:

  bpf_prog->type == BPF_PROG_TYPE_UNSPEC

So add the check and skip initialization for real eBPF programs.

Signed-off-by: default avatarMichael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ce2b6ad9

arch/s390/net/bpf_jit_comp.c

+11 −9
Original line number Diff line number Diff line
@@ -387,7 +387,7 @@ static void save_restore_regs(struct bpf_jit *jit, int op) 
 * Save registers and create stack frame if necessary.

 * See stack frame layout desription in "bpf_jit.h"!

 */

static void bpf_jit_prologue(struct bpf_jit *jit)

static void bpf_jit_prologue(struct bpf_jit *jit, bool is_classic)

{

	if (jit->seen & SEEN_TAIL_CALL) {

		/* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */
@@ -440,7 +440,8 @@ static void bpf_jit_prologue(struct bpf_jit *jit) 
		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,

			      BPF_REG_1, offsetof(struct sk_buff, data));

	}

	/* BPF compatibility: clear A (%b0) and X (%b7) registers */

	/* Clear A (%b0) and X (%b7) registers for converted BPF programs */

	if (is_classic) {

		if (REG_SEEN(BPF_REG_A))

			/* lghi %ba,0 */

			EMIT4_IMM(0xa7090000, BPF_REG_A, 0);
@@ -448,6 +449,7 @@ static void bpf_jit_prologue(struct bpf_jit *jit) 
			/* lghi %bx,0 */

			EMIT4_IMM(0xa7090000, BPF_REG_X, 0);

	}

}



/*

 * Function epilogue
@@ -1232,7 +1234,7 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp) 
	jit->lit = jit->lit_start;

	jit->prg = 0;



	bpf_jit_prologue(jit);

	bpf_jit_prologue(jit, fp->type == BPF_PROG_TYPE_UNSPEC);

	for (i = 0; i < fp->len; i += insn_count) {

		insn_count = bpf_jit_insn(jit, fp, i);

		if (insn_count < 0)