Commit bdf4c66f authored by Quentin Monnet's avatar Quentin Monnet Committed by Daniel Borkmann
Browse files

nfp: bpf: update fixup function for BPF-to-BPF calls support 



Relocation for targets of BPF-to-BPF calls are required at the end of
translation. Update the nfp_fixup_branches() function in that regard.

When checking that the last instruction of each bloc is a branch, we
must account for the length of the instructions required to pop the
return address from the stack.

Signed-off-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: default avatarJiong Wang <jiong.wang@netronome.com>
Reviewed-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent fb198165

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

+22 −3
Original line number Diff line number Diff line
@@ -3116,7 +3116,7 @@ static int jne_reg(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) 
static int

bpf_to_bpf_call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta)

{

	u32 ret_tgt, stack_depth;

	u32 ret_tgt, stack_depth, offset_br;

	swreg tmp_reg;



	stack_depth = round_up(nfp_prog->stack_frame_depth, STACK_FRAME_ALIGN);
@@ -3160,6 +3160,7 @@ bpf_to_bpf_call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) 
	ret_tgt = nfp_prog_current_offset(nfp_prog) + 3;

	emit_br_relo(nfp_prog, BR_UNC, BR_OFF_RELO, 2,

		     RELO_BR_GO_CALL_PUSH_REGS);

	offset_br = nfp_prog_current_offset(nfp_prog);

	wrp_immed_relo(nfp_prog, imm_b(nfp_prog), 0, RELO_IMMED_REL);

	wrp_immed_relo(nfp_prog, ret_reg(nfp_prog), ret_tgt, RELO_IMMED_REL);
@@ -3176,6 +3177,9 @@ bpf_to_bpf_call(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta) 
		wrp_nops(nfp_prog, 3);

	}



	meta->num_insns_after_br = nfp_prog_current_offset(nfp_prog);

	meta->num_insns_after_br -= offset_br;



	return 0;

}
@@ -3344,21 +3348,36 @@ static int nfp_fixup_branches(struct nfp_prog *nfp_prog) 
	list_for_each_entry(meta, &nfp_prog->insns, l) {

		if (meta->skip)

			continue;

		if (meta->insn.code == (BPF_JMP | BPF_CALL))

			continue;

		if (BPF_CLASS(meta->insn.code) != BPF_JMP)

			continue;

		if (meta->insn.code == (BPF_JMP | BPF_EXIT) &&

		    !nfp_is_main_function(meta))

			continue;

		if (is_mbpf_helper_call(meta))

			continue;



		if (list_is_last(&meta->l, &nfp_prog->insns))

			br_idx = nfp_prog->last_bpf_off;

		else

			br_idx = list_next_entry(meta, l)->off - 1;



		/* For BPF-to-BPF function call, a stack adjustment sequence is

		 * generated after the return instruction. Therefore, we must

		 * withdraw the length of this sequence to have br_idx pointing

		 * to where the "branch" NFP instruction is expected to be.

		 */

		if (is_mbpf_pseudo_call(meta))

			br_idx -= meta->num_insns_after_br;



		if (!nfp_is_br(nfp_prog->prog[br_idx])) {

			pr_err("Fixup found block not ending in branch %d %02x %016llx!!\n",

			       br_idx, meta->insn.code, nfp_prog->prog[br_idx]);

			return -ELOOP;

		}



		if (meta->insn.code == (BPF_JMP | BPF_EXIT))

			continue;



		/* Leave special branches for later */

		if (FIELD_GET(OP_RELO_TYPE, nfp_prog->prog[br_idx]) !=

		    RELO_BR_REL)

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

+2 −0
Original line number Diff line number Diff line
@@ -283,6 +283,7 @@ struct nfp_bpf_reg_state { 
 * @xadd_maybe_16bit: 16bit immediate is possible

 * @jmp_dst: destination info for jump instructions

 * @jump_neg_op: jump instruction has inverted immediate, use ADD instead of SUB

 * @num_insns_after_br: number of insns following a branch jump, used for fixup

 * @func_id: function id for call instructions

 * @arg1: arg1 for call instructions

 * @arg2: arg2 for call instructions
@@ -319,6 +320,7 @@ struct nfp_insn_meta { 
		struct {

			struct nfp_insn_meta *jmp_dst;

			bool jump_neg_op;

			u32 num_insns_after_br; /* only for BPF-to-BPF calls */

		};

		/* function calls */

		struct {

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