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libbpf: Permit 64bit relocation value
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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: Andrii Nakryiko <[email protected]>
Signed-off-by: Yonghong Song <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>
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@yonghong-song
yonghong-song authored and Alexei Starovoitov committed Jun 7, 2022
1 parent 6089fb3 commit 7762816
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Showing 2 changed files with 29 additions and 24 deletions.
49 changes: 27 additions & 22 deletions tools/lib/bpf/relo_core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -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) {
Expand All @@ -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;
Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -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;
}

Expand Down
4 changes: 2 additions & 2 deletions tools/lib/bpf/relo_core.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down

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