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Commit 9a06927e authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Alexei Starovoitov
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nfp: bpf: support removing dead code 



Add a verifier callback to the nfp JIT to remove the instructions
the verifier deemed to be dead.

Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent a32014b3

drivers/net/ethernet/netronome/nfp/bpf/main.h

+5 −1
Original line number Diff line number Diff line
@@ -247,9 +247,12 @@ struct nfp_bpf_reg_state { 
#define FLAG_INSN_SKIP_NOOP			BIT(3)

/* Instruction is optimized out based on preceding instructions */

#define FLAG_INSN_SKIP_PREC_DEPENDENT		BIT(4)

/* Instruction is optimized by the verifier */

#define FLAG_INSN_SKIP_VERIFIER_OPT		BIT(5)



#define FLAG_INSN_SKIP_MASK		(FLAG_INSN_SKIP_NOOP | \

					 FLAG_INSN_SKIP_PREC_DEPENDENT)

					 FLAG_INSN_SKIP_PREC_DEPENDENT | \

					 FLAG_INSN_SKIP_VERIFIER_OPT)



/**

 * struct nfp_insn_meta - BPF instruction wrapper
@@ -533,6 +536,7 @@ int nfp_bpf_finalize(struct bpf_verifier_env *env); 


int nfp_bpf_opt_replace_insn(struct bpf_verifier_env *env, u32 off,

			     struct bpf_insn *insn);

int nfp_bpf_opt_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt);



extern const struct bpf_prog_offload_ops nfp_bpf_dev_ops;

drivers/net/ethernet/netronome/nfp/bpf/offload.c

+5 −0
Original line number Diff line number Diff line
@@ -220,6 +220,10 @@ static int nfp_bpf_translate(struct bpf_prog *prog) 
	unsigned int max_instr;

	int err;



	/* We depend on dead code elimination succeeding */

	if (prog->aux->offload->opt_failed)

		return -EINVAL;



	max_instr = nn_readw(nn, NFP_NET_CFG_BPF_MAX_LEN);

	nfp_prog->__prog_alloc_len = max_instr * sizeof(u64);
@@ -593,6 +597,7 @@ const struct bpf_prog_offload_ops nfp_bpf_dev_ops = { 
	.insn_hook	= nfp_verify_insn,

	.finalize	= nfp_bpf_finalize,

	.replace_insn	= nfp_bpf_opt_replace_insn,

	.remove_insns	= nfp_bpf_opt_remove_insns,

	.prepare	= nfp_bpf_verifier_prep,

	.translate	= nfp_bpf_translate,

	.destroy	= nfp_bpf_destroy,

drivers/net/ethernet/netronome/nfp/bpf/verifier.c

+24 −0
Original line number Diff line number Diff line
@@ -820,3 +820,27 @@ int nfp_bpf_opt_replace_insn(struct bpf_verifier_env *env, u32 off, 
		meta->insn.code, insn->code);

	return -EINVAL;

}



int nfp_bpf_opt_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)

{

	struct nfp_prog *nfp_prog = env->prog->aux->offload->dev_priv;

	struct bpf_insn_aux_data *aux_data = env->insn_aux_data;

	struct nfp_insn_meta *meta = nfp_prog->verifier_meta;

	unsigned int i;



	meta = nfp_bpf_goto_meta(nfp_prog, meta, aux_data[off].orig_idx);



	for (i = 0; i < cnt; i++) {

		if (WARN_ON_ONCE(&meta->l == &nfp_prog->insns))

			return -EINVAL;



		/* doesn't count if it already has the flag */

		if (meta->flags & FLAG_INSN_SKIP_VERIFIER_OPT)

			i--;



		meta->flags |= FLAG_INSN_SKIP_VERIFIER_OPT;

		meta = list_next_entry(meta, l);

	}



	return 0;

}