Commit 77628165 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

libbpf: Permit 64bit relocation value 



Currently, the libbpf limits the relocation value to be 32bit
since all current relocations have such a limit. But with
BTF_KIND_ENUM64 support, the enum value could be 64bit.
So let us permit 64bit relocation value in libbpf.

Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220607062605.3716779-1-yhs@fb.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 6089fb32

tools/lib/bpf/relo_core.c

+27 −22
Original line number Diff line number Diff line
@@ -583,7 +583,7 @@ static int bpf_core_spec_match(struct bpf_core_spec *local_spec, 
static int bpf_core_calc_field_relo(const char *prog_name,

				    const struct bpf_core_relo *relo,

				    const struct bpf_core_spec *spec,

				    __u32 *val, __u32 *field_sz, __u32 *type_id,

				    __u64 *val, __u32 *field_sz, __u32 *type_id,

				    bool *validate)

{

	const struct bpf_core_accessor *acc;
@@ -708,7 +708,7 @@ static int bpf_core_calc_field_relo(const char *prog_name, 


static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo,

				   const struct bpf_core_spec *spec,

				   __u32 *val, bool *validate)

				   __u64 *val, bool *validate)

{

	__s64 sz;
@@ -751,7 +751,7 @@ static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo, 


static int bpf_core_calc_enumval_relo(const struct bpf_core_relo *relo,

				      const struct bpf_core_spec *spec,

				      __u32 *val)

				      __u64 *val)

{

	const struct btf_type *t;

	const struct btf_enum *e;
@@ -929,7 +929,7 @@ int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn, 
			int insn_idx, const struct bpf_core_relo *relo,

			int relo_idx, const struct bpf_core_relo_res *res)

{

	__u32 orig_val, new_val;

	__u64 orig_val, new_val;

	__u8 class;



	class = BPF_CLASS(insn->code);
@@ -954,28 +954,30 @@ int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn, 
		if (BPF_SRC(insn->code) != BPF_K)

			return -EINVAL;

		if (res->validate && insn->imm != orig_val) {

			pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %u, exp %u -> %u\n",

			pr_warn("prog '%s': relo #%d: unexpected insn #%d (ALU/ALU64) value: got %u, exp %llu -> %llu\n",

				prog_name, relo_idx,

				insn_idx, insn->imm, orig_val, new_val);

				insn_idx, insn->imm, (unsigned long long)orig_val,

				(unsigned long long)new_val);

			return -EINVAL;

		}

		orig_val = insn->imm;

		insn->imm = new_val;

		pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %u -> %u\n",

		pr_debug("prog '%s': relo #%d: patched insn #%d (ALU/ALU64) imm %llu -> %llu\n",

			 prog_name, relo_idx, insn_idx,

			 orig_val, new_val);

			 (unsigned long long)orig_val, (unsigned long long)new_val);

		break;

	case BPF_LDX:

	case BPF_ST:

	case BPF_STX:

		if (res->validate && insn->off != orig_val) {

			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %u, exp %u -> %u\n",

				prog_name, relo_idx, insn_idx, insn->off, orig_val, new_val);

			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDX/ST/STX) value: got %u, exp %llu -> %llu\n",

				prog_name, relo_idx, insn_idx, insn->off, (unsigned long long)orig_val,

				(unsigned long long)new_val);

			return -EINVAL;

		}

		if (new_val > SHRT_MAX) {

			pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %u\n",

				prog_name, relo_idx, insn_idx, new_val);

			pr_warn("prog '%s': relo #%d: insn #%d (LDX/ST/STX) value too big: %llu\n",

				prog_name, relo_idx, insn_idx, (unsigned long long)new_val);

			return -ERANGE;

		}

		if (res->fail_memsz_adjust) {
@@ -987,8 +989,9 @@ int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn, 


		orig_val = insn->off;

		insn->off = new_val;

		pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %u -> %u\n",

			 prog_name, relo_idx, insn_idx, orig_val, new_val);

		pr_debug("prog '%s': relo #%d: patched insn #%d (LDX/ST/STX) off %llu -> %llu\n",

			 prog_name, relo_idx, insn_idx, (unsigned long long)orig_val,

			 (unsigned long long)new_val);



		if (res->new_sz != res->orig_sz) {

			int insn_bytes_sz, insn_bpf_sz;
@@ -1026,18 +1029,18 @@ int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn, 


		imm = insn[0].imm + ((__u64)insn[1].imm << 32);

		if (res->validate && imm != orig_val) {

			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %u -> %u\n",

			pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %llu -> %llu\n",

				prog_name, relo_idx,

				insn_idx, (unsigned long long)imm,

				orig_val, new_val);

				(unsigned long long)orig_val, (unsigned long long)new_val);

			return -EINVAL;

		}



		insn[0].imm = new_val;

		insn[1].imm = 0; /* currently only 32-bit values are supported */

		pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %u\n",

		insn[1].imm = new_val >> 32;

		pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %llu\n",

			 prog_name, relo_idx, insn_idx,

			 (unsigned long long)imm, new_val);

			 (unsigned long long)imm, (unsigned long long)new_val);

		break;

	}

	default:
@@ -1261,10 +1264,12 @@ int bpf_core_calc_relo_insn(const char *prog_name, 
			 * decision and value, otherwise it's dangerous to

			 * proceed due to ambiguity

			 */

			pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %u != %s %u\n",

			pr_warn("prog '%s': relo #%d: relocation decision ambiguity: %s %llu != %s %llu\n",

				prog_name, relo_idx,

				cand_res.poison ? "failure" : "success", cand_res.new_val,

				targ_res->poison ? "failure" : "success", targ_res->new_val);

				cand_res.poison ? "failure" : "success",

				(unsigned long long)cand_res.new_val,

				targ_res->poison ? "failure" : "success",

				(unsigned long long)targ_res->new_val);

			return -EINVAL;

		}

tools/lib/bpf/relo_core.h

+2 −2
Original line number Diff line number Diff line
@@ -46,9 +46,9 @@ struct bpf_core_spec { 


struct bpf_core_relo_res {

	/* expected value in the instruction, unless validate == false */

	__u32 orig_val;

	__u64 orig_val;

	/* new value that needs to be patched up to */

	__u32 new_val;

	__u64 new_val;

	/* relocation unsuccessful, poison instruction, but don't fail load */

	bool poison;

	/* some relocations can't be validated against orig_val */