From: Yonghong Song <yhs@fb.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 02/12] libbpf: Permit 64bit relocation value
Date: Tue, 10 May 2022 15:14:22 -0700 [thread overview]
Message-ID: <7246362c-8eca-027e-d43d-8d4955ad5bdd@fb.com> (raw)
In-Reply-To: <CAEf4BzYyUUjVYEcDJ75DWyg4HoOm4YbFSy84OY01WgENdWrh8A@mail.gmail.com>
On 5/9/22 3:37 PM, Andrii Nakryiko wrote:
> On Sun, May 1, 2022 at 12:00 PM Yonghong Song <yhs@fb.com> wrote:
>>
>> 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.
>>
>> Signed-off-by: Yonghong Song <yhs@fb.com>
>> ---
>> tools/lib/bpf/relo_core.c | 24 ++++++++++++------------
>> tools/lib/bpf/relo_core.h | 4 ++--
>> 2 files changed, 14 insertions(+), 14 deletions(-)
>>
>
> [...]
>
>> @@ -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);
>> @@ -954,14 +954,14 @@ 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);
>
> %llu is not valid formatter for __u64 on all architectures, please add
> explicit (unsigned long long) cast
Okay, will do.
>
> but also in general for non-ldimm64 instructions we need to check that
> new value fits in 32 bits
The real 64-bit value can only be retrieved for ldimm64 insn, so I
suppose it should be fine here. But let me double check.
>
> [...]
>
>> @@ -1026,7 +1026,7 @@ 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);
>> @@ -1035,7 +1035,7 @@ int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
>>
>> insn[0].imm = new_val;
>> insn[1].imm = 0; /* currently only 32-bit values are supported */
>
> as Dave mentioned, not anymore, so this should take higher 32-bit of new_val
Will do.
>
>
>> - pr_debug("prog '%s': relo #%d: patched insn #%d (LDIMM64) imm64 %llu -> %u\n",
>> + 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);
>> break;
>> @@ -1261,7 +1261,7 @@ 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);
[...]
next prev parent reply other threads:[~2022-05-10 22:14 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-01 19:00 [PATCH bpf-next 00/12] bpf: Add 64bit enum value support Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 01/12] bpf: Add btf enum64 support Yonghong Song
2022-05-09 0:33 ` Dave Marchevsky
2022-05-09 22:29 ` Andrii Nakryiko
2022-05-10 22:06 ` Yonghong Song
2022-05-10 23:18 ` Andrii Nakryiko
2022-05-11 0:17 ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 02/12] libbpf: Permit 64bit relocation value Yonghong Song
2022-05-09 1:06 ` Dave Marchevsky
2022-05-10 19:35 ` Yonghong Song
2022-05-09 22:37 ` Andrii Nakryiko
2022-05-10 22:14 ` Yonghong Song [this message]
2022-05-10 23:19 ` Andrii Nakryiko
2022-05-01 19:00 ` [PATCH bpf-next 03/12] libbpf: Fix an error in 64bit relocation value computation Yonghong Song
2022-05-09 0:55 ` Dave Marchevsky
2022-05-09 0:56 ` Dave Marchevsky
2022-05-09 22:37 ` Andrii Nakryiko
2022-05-10 22:11 ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 04/12] libbpf: Add btf enum64 support Yonghong Song
2022-05-03 17:22 ` kernel test robot
2022-05-05 22:44 ` Yonghong Song
2022-05-09 23:25 ` Andrii Nakryiko
2022-05-10 22:40 ` Yonghong Song
2022-05-10 23:02 ` Yonghong Song
2022-05-10 23:40 ` Andrii Nakryiko
2022-05-10 23:38 ` Andrii Nakryiko
2022-05-11 0:39 ` Yonghong Song
2022-05-11 17:43 ` Andrii Nakryiko
2022-05-11 18:56 ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 05/12] bpftool: " Yonghong Song
2022-05-09 23:31 ` Andrii Nakryiko
2022-05-10 22:43 ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 06/12] selftests/bpf: Fix selftests failure Yonghong Song
2022-05-09 2:21 ` Dave Marchevsky
2022-05-10 19:40 ` Yonghong Song
2022-05-09 23:34 ` Andrii Nakryiko
2022-05-10 22:44 ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 07/12] selftests/bpf: Test new libbpf enum32/enum64 API functions Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 08/12] selftests/bpf: Add BTF_KIND_ENUM64 unit tests Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 09/12] selftests/bpf: Test BTF_KIND_ENUM64 for deduplication Yonghong Song
2022-05-09 23:37 ` Andrii Nakryiko
2022-05-10 22:44 ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 10/12] selftests/bpf: add a test for enum64 value relocation Yonghong Song
2022-05-09 23:38 ` Andrii Nakryiko
2022-05-10 22:45 ` Yonghong Song
2022-05-01 19:00 ` [PATCH bpf-next 11/12] selftests/bpf: Clarify llvm dependency with possible selftest failures Yonghong Song
2022-05-01 19:01 ` [PATCH bpf-next 12/12] docs/bpf: Update documentation for BTF_KIND_ENUM64 support Yonghong Song
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