[PATCH bpf-next 0/2] add btf_dedup() support for VAR and DATASEC

[PATCH bpf-next 0/2] add btf_dedup() support for VAR and DATASEC

[andrii.nakryiko]

From: Andrii Nakryiko <andriin@fb.com>

This patchset adds support for new BTF_KIND_VAR and BTF_KIND_DATASEC BTF types
in btf_dedup() algorithm. VAR and DATASEC are not deduplicated and are always
considered to be unique, but they require referenced type IDs adjustment.

Patch #1 adds VAR/DATASEC pass-through support to btf_dedup().
Patch #2 adds a test validating all the type ID adjustments are correct.

Andrii Nakryiko (2):
  btf: add support for VAR and DATASEC in btf_dedup()
  selftests/btf: add VAR and DATASEC case for dedup tests

 tools/lib/bpf/btf.c                    | 29 +++++++++++++--
 tools/testing/selftests/bpf/test_btf.c | 49 ++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 2 deletions(-)

-- 
2.17.1

[PATCH bpf-next 1/2] btf: add support for VAR and DATASEC in btf_dedup()

[andrii.nakryiko]

From: Andrii Nakryiko <andriin@fb.com>

This patch adds support for VAR and DATASEC in btf_dedup(). VAR/DATASEC
are never deduplicated, but they need to be processed anyway as types
they refer to might need to be remapped due to deduplication and
compaction.

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 tools/lib/bpf/btf.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 701e7e28ada3..75eaf10b9e1a 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1354,8 +1354,16 @@ static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
 	}
 	/* special BTF "void" type is made canonical immediately */
 	d->map[0] = 0;
-	for (i = 1; i <= btf->nr_types; i++)
-		d->map[i] = BTF_UNPROCESSED_ID;
+	for (i = 1; i <= btf->nr_types; i++) {
+		struct btf_type *t = d->btf->types[i];
+		__u16 kind = BTF_INFO_KIND(t->info);
+
+		/* VAR and DATASEC are never deduped and are self-canonical */
+		if (kind == BTF_KIND_VAR || kind == BTF_KIND_DATASEC)
+			d->map[i] = i;
+		else
+			d->map[i] = BTF_UNPROCESSED_ID;
+	}
 
 	d->hypot_map = malloc(sizeof(__u32) * (1 + btf->nr_types));
 	if (!d->hypot_map) {
@@ -1946,6 +1954,8 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
 	case BTF_KIND_UNION:
 	case BTF_KIND_FUNC:
 	case BTF_KIND_FUNC_PROTO:
+	case BTF_KIND_VAR:
+	case BTF_KIND_DATASEC:
 		return 0;
 
 	case BTF_KIND_INT:
@@ -2699,6 +2709,7 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 	case BTF_KIND_PTR:
 	case BTF_KIND_TYPEDEF:
 	case BTF_KIND_FUNC:
+	case BTF_KIND_VAR:
 		r = btf_dedup_remap_type_id(d, t->type);
 		if (r < 0)
 			return r;
@@ -2753,6 +2764,20 @@ static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
 		break;
 	}
 
+	case BTF_KIND_DATASEC: {
+		struct btf_var_secinfo *var = (struct btf_var_secinfo *)(t + 1);
+		__u16 vlen = BTF_INFO_VLEN(t->info);
+
+		for (i = 0; i < vlen; i++) {
+			r = btf_dedup_remap_type_id(d, var->type);
+			if (r < 0)
+				return r;
+			var->type = r;
+			var++;
+		}
+		break;
+	}
+
 	default:
 		return -EINVAL;
 	}
-- 
2.17.1

[PATCH bpf-next 2/2] selftests/btf: add VAR and DATASEC case for dedup tests

[andrii.nakryiko]

From: Andrii Nakryiko <andriin@fb.com>

Add test case verifying that dedup happens (INTs are deduped in this
case) and VAR/DATASEC types are not deduped, but have their referenced
type IDs adjusted correctly.

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Yonghong Song <yhs@fb.com>
Cc: Alexei Starovoitov <ast@fb.com>
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
---
 tools/testing/selftests/bpf/test_btf.c | 49 ++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/tools/testing/selftests/bpf/test_btf.c b/tools/testing/selftests/bpf/test_btf.c
index 44cd3378d216..f8eb7987b794 100644
--- a/tools/testing/selftests/bpf/test_btf.c
+++ b/tools/testing/selftests/bpf/test_btf.c
@@ -6642,6 +6642,51 @@ const struct btf_dedup_test dedup_tests[] = {
 		.dont_resolve_fwds = false,
 	},
 },
+{
+	.descr = "dedup: datasec and vars pass-through",
+	.input = {
+		.raw_types = {
+			/* int */
+			BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+			/* static int t */
+			BTF_VAR_ENC(NAME_NTH(2), 1, 0),			/* [2] */
+			/* .bss section */				/* [3] */
+			BTF_TYPE_ENC(NAME_NTH(1), BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+			BTF_VAR_SECINFO_ENC(2, 0, 4),
+			/* int, referenced from [5] */
+			BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [4] */
+			/* another static int t */
+			BTF_VAR_ENC(NAME_NTH(2), 4, 0),			/* [5] */
+			/* another .bss section */			/* [6] */
+			BTF_TYPE_ENC(NAME_NTH(1), BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+			BTF_VAR_SECINFO_ENC(5, 0, 4),
+			BTF_END_RAW,
+		},
+		BTF_STR_SEC("\0.bss\0t"),
+	},
+	.expect = {
+		.raw_types = {
+			/* int */
+			BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+			/* static int t */
+			BTF_VAR_ENC(NAME_NTH(2), 1, 0),			/* [2] */
+			/* .bss section */				/* [3] */
+			BTF_TYPE_ENC(NAME_NTH(1), BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+			BTF_VAR_SECINFO_ENC(2, 0, 4),
+			/* another static int t */
+			BTF_VAR_ENC(NAME_NTH(2), 1, 0),			/* [4] */
+			/* another .bss section */			/* [5] */
+			BTF_TYPE_ENC(NAME_NTH(1), BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+			BTF_VAR_SECINFO_ENC(4, 0, 4),
+			BTF_END_RAW,
+		},
+		BTF_STR_SEC("\0.bss\0t"),
+	},
+	.opts = {
+		.dont_resolve_fwds = false,
+		.dedup_table_size = 1
+	},
+},
 
 };
 
@@ -6671,6 +6716,10 @@ static int btf_type_size(const struct btf_type *t)
 		return base_size + vlen * sizeof(struct btf_member);
 	case BTF_KIND_FUNC_PROTO:
 		return base_size + vlen * sizeof(struct btf_param);
+	case BTF_KIND_VAR:
+		return base_size + sizeof(struct btf_var);
+	case BTF_KIND_DATASEC:
+		return base_size + vlen * sizeof(struct btf_var_secinfo);
 	default:
 		fprintf(stderr, "Unsupported BTF_KIND:%u\n", kind);
 		return -EINVAL;
-- 
2.17.1

Re: [PATCH bpf-next 0/2] add btf_dedup() support for VAR and DATASEC

[Daniel Borkmann]

On 04/16/2019 01:48 AM, andrii.nakryiko@gmail.com wrote:
> From: Andrii Nakryiko <andriin@fb.com>
> 
> This patchset adds support for new BTF_KIND_VAR and BTF_KIND_DATASEC BTF types
> in btf_dedup() algorithm. VAR and DATASEC are not deduplicated and are always
> considered to be unique, but they require referenced type IDs adjustment.
> 
> Patch #1 adds VAR/DATASEC pass-through support to btf_dedup().
> Patch #2 adds a test validating all the type ID adjustments are correct.
> 
> Andrii Nakryiko (2):
>   btf: add support for VAR and DATASEC in btf_dedup()
>   selftests/btf: add VAR and DATASEC case for dedup tests
> 
>  tools/lib/bpf/btf.c                    | 29 +++++++++++++--
>  tools/testing/selftests/bpf/test_btf.c | 49 ++++++++++++++++++++++++++
>  2 files changed, 76 insertions(+), 2 deletions(-)
> 

Looks good, applied, thanks!