diff mbox series

[bpf-next,v2,6/9] libbpf: Honor TYPE_MATCH relocation

Message ID 20220623212205.2805002-7-deso@posteo.net (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series Introduce type match support | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next-VM_Test-3 fail Logs for Kernel LATEST on z15 with gcc
bpf/vmtest-bpf-next-VM_Test-1 fail Logs for Kernel LATEST on ubuntu-latest with gcc
bpf/vmtest-bpf-next-VM_Test-2 fail Logs for Kernel LATEST on ubuntu-latest with llvm-15
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/subject_prefix success Link
netdev/cover_letter success Series has a cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 8
netdev/cc_maintainers warning 10 maintainers not CCed: netdev@vger.kernel.org songliubraving@fb.com nathan@kernel.org yhs@fb.com john.fastabend@gmail.com trix@redhat.com llvm@lists.linux.dev kafai@fb.com ndesaulniers@google.com kpsingh@kernel.org
netdev/build_clang success Errors and warnings before: 8 this patch: 6
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 9 this patch: 8
netdev/checkpatch warning WARNING: line length of 82 exceeds 80 columns WARNING: line length of 97 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Daniel Müller June 23, 2022, 9:22 p.m. UTC 
This patch finalizes support for the proposed type match relation in
libbpf by hooking it up to the TYPE_MATCH relocation. For this
relocation to be handled correctly by LLVM we have D126838
(https://reviews.llvm.org/D126838).
The main functionality is present behind the newly introduced
bpf_core_type_matches macro (similar to bpf_core_type_exists). This
macro can be used to check whether a local type has a "match" in a
target BTF.

Signed-off-by: Daniel Müller <deso@posteo.net>
---
 tools/lib/bpf/bpf_core_read.h | 10 ++++++++++
 tools/lib/bpf/libbpf.c        |  6 ++++++
 tools/lib/bpf/relo_core.c     | 16 ++++++++++++----
 tools/lib/bpf/relo_core.h     |  2 ++
 4 files changed, 30 insertions(+), 4 deletions(-)

Comments

Andrii Nakryiko June 24, 2022, 9:41 p.m. UTC | #1 
On Thu, Jun 23, 2022 at 2:22 PM Daniel Müller <deso@posteo.net> wrote:
>
> This patch finalizes support for the proposed type match relation in
> libbpf by hooking it up to the TYPE_MATCH relocation. For this
> relocation to be handled correctly by LLVM we have D126838
> (https://reviews.llvm.org/D126838).

I think we are getting pretty close, is it time to land LLVM diff?
Yonghong, WDYT?

> The main functionality is present behind the newly introduced
> bpf_core_type_matches macro (similar to bpf_core_type_exists). This
> macro can be used to check whether a local type has a "match" in a
> target BTF.
>
> Signed-off-by: Daniel Müller <deso@posteo.net>
> ---
>  tools/lib/bpf/bpf_core_read.h | 10 ++++++++++
>  tools/lib/bpf/libbpf.c        |  6 ++++++
>  tools/lib/bpf/relo_core.c     | 16 ++++++++++++----
>  tools/lib/bpf/relo_core.h     |  2 ++
>  4 files changed, 30 insertions(+), 4 deletions(-)
>

[...]
diff mbox series

Patch

diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h
index 2308f49..496e6a 100644
--- a/tools/lib/bpf/bpf_core_read.h
+++ b/tools/lib/bpf/bpf_core_read.h
@@ -184,6 +184,16 @@  enum bpf_enum_value_kind {
 #define bpf_core_type_exists(type)					    \
 	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_EXISTS)
 
+/*
+ * Convenience macro to check that provided named type
+ * (struct/union/enum/typedef) "matches" that in a target kernel.
+ * Returns:
+ *    1, if the type matches in the target kernel's BTF;
+ *    0, if the type does not match any in the target kernel
+ */
+#define bpf_core_type_matches(type)					    \
+	__builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_MATCHES)
+
 /*
  * Convenience macro to get the byte size of a provided named type
  * (struct/union/enum/typedef) in a target kernel.
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 49e359c..fee15d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -5805,6 +5805,12 @@  int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
 	}
 }
 
+int bpf_core_types_match(const struct btf *local_btf, __u32 local_id,
+			 const struct btf *targ_btf, __u32 targ_id)
+{
+	return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, 32);
+}
+
 static size_t bpf_core_hash_fn(const void *key, void *ctx)
 {
 	return (size_t)key;
diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c
index bc5b060..862185 100644
--- a/tools/lib/bpf/relo_core.c
+++ b/tools/lib/bpf/relo_core.c
@@ -95,6 +95,7 @@  static const char *core_relo_kind_str(enum bpf_core_relo_kind kind)
 	case BPF_CORE_TYPE_ID_LOCAL: return "local_type_id";
 	case BPF_CORE_TYPE_ID_TARGET: return "target_type_id";
 	case BPF_CORE_TYPE_EXISTS: return "type_exists";
+	case BPF_CORE_TYPE_MATCHES: return "type_matches";
 	case BPF_CORE_TYPE_SIZE: return "type_size";
 	case BPF_CORE_ENUMVAL_EXISTS: return "enumval_exists";
 	case BPF_CORE_ENUMVAL_VALUE: return "enumval_value";
@@ -123,6 +124,7 @@  static bool core_relo_is_type_based(enum bpf_core_relo_kind kind)
 	case BPF_CORE_TYPE_ID_LOCAL:
 	case BPF_CORE_TYPE_ID_TARGET:
 	case BPF_CORE_TYPE_EXISTS:
+	case BPF_CORE_TYPE_MATCHES:
 	case BPF_CORE_TYPE_SIZE:
 		return true;
 	default:
@@ -171,7 +173,7 @@  static bool core_relo_is_enumval_based(enum bpf_core_relo_kind kind)
  *   - field 'a' access (corresponds to '2' in low-level spec);
  *   - array element #3 access (corresponds to '3' in low-level spec).
  *
- * Type-based relocations (TYPE_EXISTS/TYPE_SIZE,
+ * Type-based relocations (TYPE_EXISTS/TYPE_MATCHES/TYPE_SIZE,
  * TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their
  * spec and raw_spec are kept empty.
  *
@@ -488,9 +490,14 @@  static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
 	targ_spec->relo_kind = local_spec->relo_kind;
 
 	if (core_relo_is_type_based(local_spec->relo_kind)) {
-		return bpf_core_types_are_compat(local_spec->btf,
-						 local_spec->root_type_id,
-						 targ_btf, targ_id);
+		if (local_spec->relo_kind == BPF_CORE_TYPE_MATCHES)
+			return bpf_core_types_match(local_spec->btf,
+						    local_spec->root_type_id,
+						    targ_btf, targ_id);
+		else
+			return bpf_core_types_are_compat(local_spec->btf,
+							 local_spec->root_type_id,
+							 targ_btf, targ_id);
 	}
 
 	local_acc = &local_spec->spec[0];
@@ -739,6 +746,7 @@  static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo,
 			*validate = false;
 		break;
 	case BPF_CORE_TYPE_EXISTS:
+	case BPF_CORE_TYPE_MATCHES:
 		*val = 1;
 		break;
 	case BPF_CORE_TYPE_SIZE:
diff --git a/tools/lib/bpf/relo_core.h b/tools/lib/bpf/relo_core.h
index 289c63..9230234 100644
--- a/tools/lib/bpf/relo_core.h
+++ b/tools/lib/bpf/relo_core.h
@@ -72,6 +72,8 @@  int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
 			      const struct btf *targ_btf, __u32 targ_id);
 int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
 			   __u32 targ_id, int level);
+int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
+			 __u32 targ_id);
 
 size_t bpf_core_essential_name_len(const char *name);