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>

1 files changed, 51 insertions, 2 deletions

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index c72e0d8e1e65..584636c9e2eb 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -22,7 +22,7 @@
 #include "map_in_map.h"
 
 #define ARRAY_CREATE_FLAG_MASK \
-	(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
+	(BPF_F_NUMA_NODE | BPF_F_ACCESS_MASK)
 
 static void bpf_array_free_percpu(struct bpf_array *array)
 {
@@ -63,6 +63,7 @@ int array_map_alloc_check(union bpf_attr *attr)
 	if (attr->max_entries == 0 || attr->key_size != 4 ||
 	    attr->value_size == 0 ||
 	    attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||
+	    !bpf_map_flags_access_ok(attr->map_flags) ||
 	    (percpu && numa_node != NUMA_NO_NODE))
 		return -EINVAL;
 
@@ -160,6 +161,36 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key)
 	return array->value + array->elem_size * (index & array->index_mask);
 }
 
+static int array_map_direct_value_addr(const struct bpf_map *map, u64 *imm,
+				       u32 off)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+
+	if (map->max_entries != 1)
+		return -ENOTSUPP;
+	if (off >= map->value_size)
+		return -EINVAL;
+
+	*imm = (unsigned long)array->value;
+	return 0;
+}
+
+static int array_map_direct_value_meta(const struct bpf_map *map, u64 imm,
+				       u32 *off)
+{
+	struct bpf_array *array = container_of(map, struct bpf_array, map);
+	u64 base = (unsigned long)array->value;
+	u64 range = array->elem_size;
+
+	if (map->max_entries != 1)
+		return -ENOTSUPP;
+	if (imm < base || imm >= base + range)
+		return -ENOENT;
+
+	*off = imm - base;
+	return 0;
+}
+
 /* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
 static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
 {
@@ -360,7 +391,8 @@ static void array_map_seq_show_elem(struct bpf_map *map, void *key,
 		return;
 	}
 
-	seq_printf(m, "%u: ", *(u32 *)key);
+	if (map->btf_key_type_id)
+		seq_printf(m, "%u: ", *(u32 *)key);
 	btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
 	seq_puts(m, "\n");
 
@@ -397,6 +429,18 @@ static int array_map_check_btf(const struct bpf_map *map,
 {
 	u32 int_data;
 
+	/* One exception for keyless BTF: .bss/.data/.rodata map */
+	if (btf_type_is_void(key_type)) {
+		if (map->map_type != BPF_MAP_TYPE_ARRAY ||
+		    map->max_entries != 1)
+			return -EINVAL;
+
+		if (BTF_INFO_KIND(value_type->info) != BTF_KIND_DATASEC)
+			return -EINVAL;
+
+		return 0;
+	}
+
 	if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
 		return -EINVAL;
 
@@ -419,6 +463,8 @@ const struct bpf_map_ops array_map_ops = {
 	.map_update_elem = array_map_update_elem,
 	.map_delete_elem = array_map_delete_elem,
 	.map_gen_lookup = array_map_gen_lookup,
+	.map_direct_value_addr = array_map_direct_value_addr,
+	.map_direct_value_meta = array_map_direct_value_meta,
 	.map_seq_show_elem = array_map_seq_show_elem,
 	.map_check_btf = array_map_check_btf,
 };
@@ -440,6 +486,9 @@ static int fd_array_map_alloc_check(union bpf_attr *attr)
 	/* only file descriptors can be stored in this type of map */
 	if (attr->value_size != sizeof(u32))
 		return -EINVAL;
+	/* Program read-only/write-only not supported for special maps yet. */
+	if (attr->map_flags & (BPF_F_RDONLY_PROG | BPF_F_WRONLY_PROG))
+		return -EINVAL;
 	return array_map_alloc_check(attr);
 }