Merge branch 'bpf: BTF support for ksyms'

Hao Luo says:

====================
v3 -> v4:
 - Rebasing
 - Cast bpf_[per|this]_cpu_ptr's parameter to void __percpu * before
   passing into per_cpu_ptr.

v2 -> v3:
 - Rename functions and variables in verifier for better readability.
 - Stick to logging message convention in libbpf.
 - Move bpf_per_cpu_ptr and bpf_this_cpu_ptr from trace-specific
   helper set to base helper set.
 - More specific test in ksyms_btf.
 - Fix return type cast in bpf_*_cpu_ptr.
 - Fix btf leak in ksyms_btf selftest.
 - Fix return error code for kallsyms_find().

v1 -> v2:
 - Move check_pseudo_btf_id from check_ld_imm() to
   replace_map_fd_with_map_ptr() and rename the latter.
 - Add bpf_this_cpu_ptr().
 - Use bpf_core_types_are_compat() in libbpf.c for checking type
   compatibility.
 - Rewrite typed ksym extern type in BTF with int to save space.
 - Minor revision of bpf_per_cpu_ptr()'s comments.
 - Avoid using long in tests that use skeleton.
 - Refactored test_ksyms.c by moving kallsyms_find() to trace_helpers.c
 - Fold the patches that sync include/linux/uapi and
   tools/include/linux/uapi.

rfc -> v1:
 - Encode VAR's btf_id for PSEUDO_BTF_ID.
 - More checks in verifier. Checking the btf_id passed as
   PSEUDO_BTF_ID is valid VAR, its name and type.
 - Checks in libbpf on type compatibility of ksyms.
 - Add bpf_per_cpu_ptr() to access kernel percpu vars. Introduced
   new ARG and RET types for this helper.

This patch series extends the previously added __ksym externs with
btf support.

Right now the __ksym externs are treated as pure 64-bit scalar value.
Libbpf replaces ld_imm64 insn of __ksym by its kernel address at load
time. This patch series extend those externs with their btf info. Note
that btf support for __ksym must come with the kernel btf that has
VARs encoded to work properly. The corresponding chagnes in pahole
is available at [1] (with a fix at [2] for gcc 4.9+).

The first 3 patches in this series add support for general kernel
global variables, which include verifier checking (01/06), libpf
support (02/06) and selftests for getting typed ksym extern's kernel
address (03/06).

The next 3 patches extends that capability further by introducing
helpers bpf_per_cpu_ptr() and bpf_this_cpu_ptr(), which allows accessing
kernel percpu variables correctly (04/06 and 05/06).

The tests of this feature were performed against pahole that is extended
with [1] and [2]. For kernel BTF that does not have VARs encoded, the
selftests will be skipped.

[1] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=f3d9054ba8ff1df0fc44e507e3a01c0964cabd42
[2] https://www.spinics.net/lists/dwarves/msg00451.html
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 0 insertions, 25 deletions

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 4d0ee7839fdb..ed7d02e8bc93 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -188,11 +188,6 @@
 	     i < btf_type_vlen(struct_type);				\
 	     i++, member++)
 
-#define for_each_vsi(i, struct_type, member)			\
-	for (i = 0, member = btf_type_var_secinfo(struct_type);	\
-	     i < btf_type_vlen(struct_type);			\
-	     i++, member++)
-
 #define for_each_vsi_from(i, from, struct_type, member)				\
 	for (i = from, member = btf_type_var_secinfo(struct_type) + from;	\
 	     i < btf_type_vlen(struct_type);					\
@@ -440,16 +435,6 @@ static bool btf_type_nosize_or_null(const struct btf_type *t)
 	return !t || btf_type_nosize(t);
 }
 
-/* union is only a special case of struct:
- * all its offsetof(member) == 0
- */
-static bool btf_type_is_struct(const struct btf_type *t)
-{
-	u8 kind = BTF_INFO_KIND(t->info);
-
-	return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
-}
-
 static bool __btf_type_is_struct(const struct btf_type *t)
 {
 	return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
@@ -460,11 +445,6 @@ static bool btf_type_is_array(const struct btf_type *t)
 	return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
 }
 
-static bool btf_type_is_var(const struct btf_type *t)
-{
-	return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
-}
-
 static bool btf_type_is_datasec(const struct btf_type *t)
 {
 	return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
@@ -613,11 +593,6 @@ static const struct btf_var *btf_type_var(const struct btf_type *t)
 	return (const struct btf_var *)(t + 1);
 }
 
-static const struct btf_var_secinfo *btf_type_var_secinfo(const struct btf_type *t)
-{
-	return (const struct btf_var_secinfo *)(t + 1);
-}
-
 static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
 {
 	return kind_ops[BTF_INFO_KIND(t->info)];