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Message-ID: <20191213223214.2791885-7-andriin@fb.com>
Date: Fri, 13 Dec 2019 14:32:03 -0800
From: Andrii Nakryiko <andriin@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
<daniel@...earbox.net>
CC: <andrii.nakryiko@...il.com>, <kernel-team@...com>,
Andrii Nakryiko <andriin@...com>
Subject: [PATCH v3 bpf-next 06/17] libbpf: expose btf__align_of() API
Expose BTF API that calculates type alignment requirements.
Signed-off-by: Andrii Nakryiko <andriin@...com>
---
tools/lib/bpf/btf.c | 39 +++++++++++++++++++++++++++++++++
tools/lib/bpf/btf.h | 1 +
tools/lib/bpf/btf_dump.c | 47 +++++-----------------------------------
tools/lib/bpf/libbpf.map | 1 +
4 files changed, 47 insertions(+), 41 deletions(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 88efa2bb7137..84fe82f27bef 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -278,6 +278,45 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
return nelems * size;
}
+int btf__align_of(const struct btf *btf, __u32 id)
+{
+ const struct btf_type *t = btf__type_by_id(btf, id);
+ __u16 kind = btf_kind(t);
+
+ switch (kind) {
+ case BTF_KIND_INT:
+ case BTF_KIND_ENUM:
+ return min(sizeof(void *), t->size);
+ case BTF_KIND_PTR:
+ return sizeof(void *);
+ case BTF_KIND_TYPEDEF:
+ case BTF_KIND_VOLATILE:
+ case BTF_KIND_CONST:
+ case BTF_KIND_RESTRICT:
+ return btf__align_of(btf, t->type);
+ case BTF_KIND_ARRAY:
+ return btf__align_of(btf, btf_array(t)->type);
+ case BTF_KIND_STRUCT:
+ case BTF_KIND_UNION: {
+ const struct btf_member *m = btf_members(t);
+ __u16 vlen = btf_vlen(t);
+ int i, align = 1, t;
+
+ for (i = 0; i < vlen; i++, m++) {
+ t = btf__align_of(btf, m->type);
+ if (t <= 0)
+ return t;
+ align = max(align, t);
+ }
+
+ return align;
+ }
+ default:
+ pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
+ return 0;
+ }
+}
+
int btf__resolve_type(const struct btf *btf, __u32 type_id)
{
const struct btf_type *t;
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 5fc23b988deb..a114c8ef4f08 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -77,6 +77,7 @@ LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,
__u32 id);
LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
+LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id);
LIBBPF_API int btf__fd(const struct btf *btf);
LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index cb126d8fcf75..53393026d085 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -752,41 +752,6 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
}
}
-static int btf_align_of(const struct btf *btf, __u32 id)
-{
- const struct btf_type *t = btf__type_by_id(btf, id);
- __u16 kind = btf_kind(t);
-
- switch (kind) {
- case BTF_KIND_INT:
- case BTF_KIND_ENUM:
- return min(sizeof(void *), t->size);
- case BTF_KIND_PTR:
- return sizeof(void *);
- case BTF_KIND_TYPEDEF:
- case BTF_KIND_VOLATILE:
- case BTF_KIND_CONST:
- case BTF_KIND_RESTRICT:
- return btf_align_of(btf, t->type);
- case BTF_KIND_ARRAY:
- return btf_align_of(btf, btf_array(t)->type);
- case BTF_KIND_STRUCT:
- case BTF_KIND_UNION: {
- const struct btf_member *m = btf_members(t);
- __u16 vlen = btf_vlen(t);
- int i, align = 1;
-
- for (i = 0; i < vlen; i++, m++)
- align = max(align, btf_align_of(btf, m->type));
-
- return align;
- }
- default:
- pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
- return 1;
- }
-}
-
static bool btf_is_struct_packed(const struct btf *btf, __u32 id,
const struct btf_type *t)
{
@@ -794,18 +759,18 @@ static bool btf_is_struct_packed(const struct btf *btf, __u32 id,
int align, i, bit_sz;
__u16 vlen;
- align = btf_align_of(btf, id);
+ align = btf__align_of(btf, id);
/* size of a non-packed struct has to be a multiple of its alignment*/
- if (t->size % align)
+ if (align && t->size % align)
return true;
m = btf_members(t);
vlen = btf_vlen(t);
/* all non-bitfield fields have to be naturally aligned */
for (i = 0; i < vlen; i++, m++) {
- align = btf_align_of(btf, m->type);
+ align = btf__align_of(btf, m->type);
bit_sz = btf_member_bitfield_size(t, i);
- if (bit_sz == 0 && m->offset % (8 * align) != 0)
+ if (align && bit_sz == 0 && m->offset % (8 * align) != 0)
return true;
}
@@ -889,7 +854,7 @@ static void btf_dump_emit_struct_def(struct btf_dump *d,
fname = btf_name_of(d, m->name_off);
m_sz = btf_member_bitfield_size(t, i);
m_off = btf_member_bit_offset(t, i);
- align = packed ? 1 : btf_align_of(d->btf, m->type);
+ align = packed ? 1 : btf__align_of(d->btf, m->type);
btf_dump_emit_bit_padding(d, off, m_off, m_sz, align, lvl + 1);
btf_dump_printf(d, "\n%s", pfx(lvl + 1));
@@ -907,7 +872,7 @@ static void btf_dump_emit_struct_def(struct btf_dump *d,
/* pad at the end, if necessary */
if (is_struct) {
- align = packed ? 1 : btf_align_of(d->btf, id);
+ align = packed ? 1 : btf__align_of(d->btf, id);
btf_dump_emit_bit_padding(d, off, t->size * 8, 0, align,
lvl + 1);
}
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 757a88f64b5a..e7fcca36f186 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -212,4 +212,5 @@ LIBBPF_0.0.6 {
LIBBPF_0.0.7 {
global:
bpf_program__attach;
+ btf__align_of;
} LIBBPF_0.0.6;
--
2.17.1
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