Merge branch 'support-global-data'

Daniel Borkmann says:

====================
This series is a major rework of previously submitted libbpf
patches [0] in order to add global data support for BPF. The
kernel has been extended to add proper infrastructure that allows
for full .bss/.data/.rodata sections on BPF loader side based
upon feedback from LPC discussions [1]. Latter support is then
also added into libbpf in this series which allows for more
natural C-like programming of BPF programs. For more information
on loader, please refer to 'bpf, libbpf: support global data/bss/
rodata sections' patch in this series.

Thanks a lot!

  v5 -> v6:
   - Removed synchronize_rcu() from map freeze (Jann)
   - Rest as-is
  v4 -> v5:
   - Removed index selection again for ldimm64 (Alexei)
   - Adapted related test cases and added new ones to test
     rejection of off != 0
  v3 -> v4:
   - Various fixes in BTF verification e.g. to disallow
     Var and DataSec to be an intermediate type during resolve (Martin)
   - More BTF test cases added
   - Few cleanups in key-less BTF commit (Martin)
   - Bump libbpf minor version from 2 to 3
   - Renamed and simplified read-only locking
   - Various minor improvements all over the place
  v2 -> v3:
   - Implement BTF support in kernel, libbpf, bpftool, add tests
   - Fix idx + off conversion (Andrii)
   - Document lower / higher bits for direct value access (Andrii)
   - Add tests with small value size (Andrii)
   - Add index selection into ldimm64 (Andrii)
   - Fix missing fdput() (Jann)
   - Reject invalid flags in BPF_F_*_PROG (Jakub)
   - Complete rework of libbpf support, includes:
    - Add objname to map name (Stanislav)
    - Make .rodata map full read-only after setup (Andrii)
    - Merge relocation handling into single one (Andrii)
    - Store global maps into obj->maps array (Andrii, Alexei)
    - Debug message when skipping section (Andrii)
    - Reject non-static global data till we have
      semantics for sharing them (Yonghong, Andrii, Alexei)
    - More test cases and completely reworked prog test (Alexei)
   - Fixes, cleanups, etc all over the set
   - Not yet addressed:
    - Make BTF mandatory for these maps (Alexei)
    -> Waiting till BTF support for these lands first
  v1 -> v2:
    - Instead of 32-bit static data, implement full global
      data support (Alexei)

  [0] https://patchwork.ozlabs.org/cover/1040290/
  [1] http://vger.kernel.org/lpc-bpf2018.html#session-3
====================

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

2 files changed, 46 insertions, 6 deletions

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 837024512baf..af1cbd951f26 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -105,6 +105,7 @@ enum bpf_cmd {
 	BPF_BTF_GET_FD_BY_ID,
 	BPF_TASK_FD_QUERY,
 	BPF_MAP_LOOKUP_AND_DELETE_ELEM,
+	BPF_MAP_FREEZE,
 };
 
 enum bpf_map_type {
@@ -255,8 +256,19 @@ enum bpf_attach_type {
  */
 #define BPF_F_ANY_ALIGNMENT	(1U << 1)
 
-/* when bpf_ldimm64->src_reg == BPF_PSEUDO_MAP_FD, bpf_ldimm64->imm == fd */
+/* When BPF ldimm64's insn[0].src_reg != 0 then this can have
+ * two extensions:
+ *
+ * insn[0].src_reg:  BPF_PSEUDO_MAP_FD   BPF_PSEUDO_MAP_VALUE
+ * insn[0].imm:      map fd              map fd
+ * insn[1].imm:      0                   offset into value
+ * insn[0].off:      0                   0
+ * insn[1].off:      0                   0
+ * ldimm64 rewrite:  address of map      address of map[0]+offset
+ * verifier type:    CONST_PTR_TO_MAP    PTR_TO_MAP_VALUE
+ */
 #define BPF_PSEUDO_MAP_FD	1
+#define BPF_PSEUDO_MAP_VALUE	2
 
 /* when bpf_call->src_reg == BPF_PSEUDO_CALL, bpf_call->imm == pc-relative
  * offset to another bpf function
@@ -283,7 +295,7 @@ enum bpf_attach_type {
 
 #define BPF_OBJ_NAME_LEN 16U
 
-/* Flags for accessing BPF object */
+/* Flags for accessing BPF object from syscall side. */
 #define BPF_F_RDONLY		(1U << 3)
 #define BPF_F_WRONLY		(1U << 4)
 
@@ -293,6 +305,10 @@ enum bpf_attach_type {
 /* Zero-initialize hash function seed. This should only be used for testing. */
 #define BPF_F_ZERO_SEED		(1U << 6)
 
+/* Flags for accessing BPF object from program side. */
+#define BPF_F_RDONLY_PROG	(1U << 7)
+#define BPF_F_WRONLY_PROG	(1U << 8)
+
 /* flags for BPF_PROG_QUERY */
 #define BPF_F_QUERY_EFFECTIVE	(1U << 0)
 
diff --git a/include/uapi/linux/btf.h b/include/uapi/linux/btf.h
index 7b7475ef2f17..9310652ca4f9 100644
--- a/include/uapi/linux/btf.h
+++ b/include/uapi/linux/btf.h
@@ -39,11 +39,11 @@ struct btf_type {
 	 *             struct, union and fwd
 	 */
 	__u32 info;
-	/* "size" is used by INT, ENUM, STRUCT and UNION.
+	/* "size" is used by INT, ENUM, STRUCT, UNION and DATASEC.
 	 * "size" tells the size of the type it is describing.
 	 *
 	 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
-	 * FUNC and FUNC_PROTO.
+	 * FUNC, FUNC_PROTO and VAR.
 	 * "type" is a type_id referring to another type.
 	 */
 	union {
@@ -70,8 +70,10 @@ struct btf_type {
 #define BTF_KIND_RESTRICT	11	/* Restrict	*/
 #define BTF_KIND_FUNC		12	/* Function	*/
 #define BTF_KIND_FUNC_PROTO	13	/* Function Proto	*/
-#define BTF_KIND_MAX		13
-#define NR_BTF_KINDS		14
+#define BTF_KIND_VAR		14	/* Variable	*/
+#define BTF_KIND_DATASEC	15	/* Section	*/
+#define BTF_KIND_MAX		BTF_KIND_DATASEC
+#define NR_BTF_KINDS		(BTF_KIND_MAX + 1)
 
 /* For some specific BTF_KIND, "struct btf_type" is immediately
  * followed by extra data.
@@ -138,4 +140,26 @@ struct btf_param {
 	__u32	type;
 };
 
+enum {
+	BTF_VAR_STATIC = 0,
+	BTF_VAR_GLOBAL_ALLOCATED,
+};
+
+/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
+ * additional information related to the variable such as its linkage.
+ */
+struct btf_var {
+	__u32	linkage;
+};
+
+/* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
+ * to describe all BTF_KIND_VAR types it contains along with it's
+ * in-section offset as well as size.
+ */
+struct btf_var_secinfo {
+	__u32	type;
+	__u32	offset;
+	__u32	size;
+};
+
 #endif /* _UAPI__LINUX_BTF_H__ */