On 2/19/21 7:49 PM, Ilya Leoshkevich wrote:
The logic follows that of BTF_KIND_INT most of the time. Sanitization
replaces BTF_KIND_FLOATs with BTF_KIND_CONSTs pointing to
equally-sized BTF_KIND_ARRAYs on older kernels.
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
tools/lib/bpf/btf.c | 44 ++++++++++++++++++++++++++++++
tools/lib/bpf/btf.h | 8 ++++++
tools/lib/bpf/btf_dump.c | 4 +++
tools/lib/bpf/libbpf.c | 48 ++++++++++++++++++++++++++++++++-
tools/lib/bpf/libbpf.map | 5 ++++
tools/lib/bpf/libbpf_internal.h | 2 ++
6 files changed, 110 insertions(+), 1 deletion(-)
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index fdfff544f59a..1ebfcc687dab 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -292,6 +292,7 @@ static int btf_type_size(const struct btf_type *t)
case BTF_KIND_PTR:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
return base_size;
case BTF_KIND_INT:
return base_size + sizeof(__u32);
@@ -339,6 +340,7 @@ static int btf_bswap_type_rest(struct btf_type *t)
case BTF_KIND_PTR:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
+ case BTF_KIND_FLOAT:
return 0;
case BTF_KIND_INT:
*(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
@@ -579,6 +581,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_DATASEC:
+ case BTF_KIND_FLOAT:
size = t->size;
goto done;
case BTF_KIND_PTR:
@@ -622,6 +625,7 @@ int btf__align_of(const struct btf *btf, __u32 id)
switch (kind) {
case BTF_KIND_INT:
case BTF_KIND_ENUM:
+ case BTF_KIND_FLOAT:
return min(btf_ptr_sz(btf), (size_t)t->size);
case BTF_KIND_PTR:
return btf_ptr_sz(btf);
@@ -2400,6 +2404,42 @@ int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
return btf_commit_type(btf, sz);
}
[...]
I skipped deduplication part, Andrii can take a look later.
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index d43cc3f29dae..b79a6a2e6faa 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -178,6 +178,8 @@ enum kern_feature_id {
FEAT_PROG_BIND_MAP,
/* Kernel support for module BTFs */
FEAT_MODULE_BTF,
+ /* BTF_KIND_FLOAT support */
+ FEAT_BTF_FLOAT,
__FEAT_CNT,
};
@@ -1935,6 +1937,7 @@ static const char *btf_kind_str(const struct btf_type *t)
case BTF_KIND_FUNC_PROTO: return "func_proto";
case BTF_KIND_VAR: return "var";
case BTF_KIND_DATASEC: return "datasec";
+ case BTF_KIND_FLOAT: return "float";
default: return "unknown";
}
}
@@ -2384,18 +2387,22 @@ static bool btf_needs_sanitization(struct bpf_object *obj)
{
bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
+ bool has_float = kernel_supports(FEAT_BTF_FLOAT);
bool has_func = kernel_supports(FEAT_BTF_FUNC);
- return !has_func || !has_datasec || !has_func_global;
+ return !has_func || !has_datasec || !has_func_global || !has_float;
}
static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
{
bool has_func_global = kernel_supports(FEAT_BTF_GLOBAL_FUNC);
bool has_datasec = kernel_supports(FEAT_BTF_DATASEC);
+ bool has_float = kernel_supports(FEAT_BTF_FLOAT);
bool has_func = kernel_supports(FEAT_BTF_FUNC);
struct btf_type *t;
+ int t_uchar = 0;
int i, j, vlen;
+ int t_uint = 0;
for (i = 1; i <= btf__get_nr_types(btf); i++) {
t = (struct btf_type *)btf__type_by_id(btf, i);
@@ -2445,6 +2452,26 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
} else if (!has_func_global && btf_is_func(t)) {
/* replace BTF_FUNC_GLOBAL with BTF_FUNC_STATIC */
t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0);
+ } else if (!has_float && btf_is_float(t)) {
+ /* replace FLOAT with TYPEDEF(u8[]) */
replace FLOAT with CONST(u8[]).
+ int t_array;
+ __u32 size;
+
+ size = t->size;
+ if (!t_uchar)
+ t_uchar = btf__add_int(btf, "unsigned char", 1,
+ 0);
+ if (!t_uint)
+ t_uint = btf__add_int(btf, "unsigned int", 4,
+ 0);
+ t_array = btf__add_array(btf, t_uint, t_uchar, size);
Checking whether t_array is valid here or not?
We do not need to check t_uchar/t_uint. If they are invalid
btf__add_array() will return -EINVAL.
+
+ /* adding new types may have invalidated t */
+ t = (struct btf_type *)btf__type_by_id(btf, i);
+
+ t->name_off = 0;
+ t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);
+ t->type = t_array;
}
}
}
@@ -3882,6 +3909,18 @@ static int probe_kern_btf_datasec(void)
strs, sizeof(strs)));
}
+static int probe_kern_btf_float(void)
+{
+ static const char strs[] = "\0float";
+ __u32 types[] = {
+ /* float */
+ BTF_TYPE_FLOAT_ENC(1, 4),
+ };
+
+ return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs)));
+}
+
static int probe_kern_array_mmap(void)
{
struct bpf_create_map_attr attr = {
@@ -4061,6 +4100,9 @@ static struct kern_feature_desc {
[FEAT_MODULE_BTF] = {
"module BTF support", probe_module_btf,
},
+ [FEAT_BTF_FLOAT] = {
+ "BTF_KIND_FLOAT support", probe_kern_btf_float,
+ },
};
static bool kernel_supports(enum kern_feature_id feat_id)
@@ -4940,6 +4982,8 @@ static int bpf_core_fields_are_compat(const struct btf *local_btf,
local_id = btf_array(local_type)->type;
targ_id = btf_array(targ_type)->type;
goto recur;
+ case BTF_KIND_FLOAT:
+ return local_type->size == targ_type->size;
default:
pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
btf_kind(local_type), local_id, targ_id);
@@ -5122,6 +5166,8 @@ static int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id
skip_mods_and_typedefs(targ_btf, targ_type->type, &targ_id);
goto recur;
}
+ case BTF_KIND_FLOAT:
+ return local_type->size == targ_type->size;
default:
pr_warn("unexpected kind %s relocated, local [%d], target [%d]\n",
btf_kind_str(local_type), local_id, targ_id);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 1c0fd2dd233a..ec898f464ab9 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -350,3 +350,8 @@ LIBBPF_0.3.0 {
xsk_setup_xdp_prog;
xsk_socket__update_xskmap;
} LIBBPF_0.2.0;
+
+LIBBPF_0.4.0 {
+ global:
+ btf__add_float;
+} LIBBPF_0.3.0;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 969d0ac592ba..343f6eb05637 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -31,6 +31,8 @@
#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
#define BTF_PARAM_ENC(name, type) (name), (type)
#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
+#define BTF_TYPE_FLOAT_ENC(name, sz) \
+ BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_FLOAT, 0, 0), sz)
#ifndef likely
#define likely(x) __builtin_expect(!!(x), 1)
