Commit e30c8fd3 authored by Andrii Nakryiko's avatar Andrii Nakryiko
Browse files

Merge branch 'Apply suggestions for typeless/weak ksym series' 



Kumar Kartikeya says:

====================

Three commits addressing comments for the typeless/weak ksym set. No functional
change intended. Hopefully this is simpler to read for kfunc as well.
====================

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
parents b98057ef d995816b

kernel/bpf/syscall.c

+1 −1
Original line number Diff line number Diff line
@@ -4804,7 +4804,7 @@ const struct bpf_func_proto bpf_kallsyms_lookup_name_proto = { 
	.gpl_only	= false,

	.ret_type	= RET_INTEGER,

	.arg1_type	= ARG_PTR_TO_MEM,

	.arg2_type	= ARG_CONST_SIZE,

	.arg2_type	= ARG_CONST_SIZE_OR_ZERO,

	.arg3_type	= ARG_ANYTHING,

	.arg4_type	= ARG_PTR_TO_LONG,

};

tools/lib/bpf/gen_loader.c

+23 −19
Original line number Diff line number Diff line
@@ -674,27 +674,29 @@ static void emit_relo_kfunc_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo 
		return;

	}

	kdesc->off = btf_fd_idx;

	/* set a default value for imm */

	/* jump to success case */

	emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));

	/* set value for imm, off as 0 */

	emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));

	/* skip success case store if ret < 0 */

	emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 1));

	emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));

	/* skip success case for ret < 0 */

	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 10));

	/* store btf_id into insn[insn_idx].imm */

	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));

	/* obtain fd in BPF_REG_9 */

	emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_7));

	emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));

	/* jump to fd_array store if fd denotes module BTF */

	emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 2));

	/* set the default value for off */

	emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));

	/* skip BTF fd store for vmlinux BTF */

	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 4));

	/* load fd_array slot pointer */

	emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,

					 0, 0, 0, blob_fd_array_off(gen, btf_fd_idx)));

	/* skip store of BTF fd if ret < 0 */

	emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 3));

	/* store BTF fd in slot */

	emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_7));

	emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));

	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_9, 0));

	/* set a default value for off */

	emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));

	/* skip insn->off store if ret < 0 */

	emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 2));

	/* skip if vmlinux BTF */

	emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_9, 0, 1));

	/* store index into insn[insn_idx].off */

	emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), btf_fd_idx));

log:
@@ -793,9 +795,8 @@ static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, 
			       kdesc->insn + offsetof(struct bpf_insn, imm));

		move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,

			       kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));

		emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_8, offsetof(struct bpf_insn, imm)));

		/* jump over src_reg adjustment if imm is not 0 */

		emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_9, 0, 3));

		/* jump over src_reg adjustment if imm is not 0, reuse BPF_REG_0 from move_blob2blob */

		emit(gen, BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 3));

		goto clear_src_reg;

	}

	/* remember insn offset, so we can copy BTF ID and FD later */
@@ -803,17 +804,20 @@ static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, 
	emit_bpf_find_by_name_kind(gen, relo);

	if (!relo->is_weak)

		emit_check_err(gen);

	/* set default values as 0 */

	/* jump to success case */

	emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));

	/* set values for insn[insn_idx].imm, insn[insn_idx + 1].imm as 0 */

	emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));

	emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 0));

	/* skip success case stores if ret < 0 */

	emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 4));

	/* skip success case for ret < 0 */

	emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 4));

	/* store btf_id into insn[insn_idx].imm */

	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));

	/* store btf_obj_fd into insn[insn_idx + 1].imm */

	emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));

	emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7,

			      sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm)));

	/* skip src_reg adjustment */

	emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 3));

clear_src_reg:

	/* clear bpf_object__relocate_data's src_reg assignment, otherwise we get a verifier failure */