Snap for 7526832 from bb1485f836d496570a337f6d7b809a3e44191f71 to sc-v2-releaseandroid-vts-12.1_r9android-vts-12.1_r8android-vts-12.1_r7android-vts-12.1_r6android-vts-12.1_r5android-vts-12.1_r4android-vts-12.1_r3android-vts-12.1_r2android-vts-12.1_r10android-vts-12.1_r1android-platform-12.1.0_r9android-platform-12.1.0_r8android-platform-12.1.0_r7android-platform-12.1.0_r6android-platform-12.1.0_r5android-platform-12.1.0_r4android-platform-12.1.0_r3android-platform-12.1.0_r27android-platform-12.1.0_r26android-platform-12.1.0_r25android-platform-12.1.0_r24android-platform-12.1.0_r23android-platform-12.1.0_r22android-platform-12.1.0_r21android-platform-12.1.0_r20android-platform-12.1.0_r2android-platform-12.1.0_r19android-platform-12.1.0_r18android-platform-12.1.0_r17android-platform-12.1.0_r16android-platform-12.1.0_r15android-platform-12.1.0_r14android-platform-12.1.0_r13android-platform-12.1.0_r12android-platform-12.1.0_r11android-platform-12.1.0_r10android-platform-12.1.0_r1android-cts-12.1_r9android-cts-12.1_r8android-cts-12.1_r7android-cts-12.1_r6android-cts-12.1_r5android-cts-12.1_r4android-cts-12.1_r3android-cts-12.1_r2android-cts-12.1_r10android-cts-12.1_r1android-12.1.0_r6android-12.1.0_r5android-12.1.0_r4android-12.1.0_r3android-12.1.0_r27android-12.1.0_r2android-12.1.0_r1android12L-tests-releaseandroid12L-s1-releaseandroid12L-releaseandroid12L-platform-releaseandroid12L-gsi

Change-Id: Ief52c115940a7a55e36ba1dda99cebed153c15ed

4 files changed, 119 insertions, 26 deletions

diff --git a/libbpf_android/Loader.cpp b/libbpf_android/Loader.cpp
index b1af34f..259068a 100644
--- a/libbpf_android/Loader.cpp
+++ b/libbpf_android/Loader.cpp
@@ -28,10 +28,9 @@
 #include <sys/utsname.h>
 #include <unistd.h>
 
-// This is BpfLoader 0.1, we need to define this prior to including bpf_map_def.h
-// to get the 0.1 struct definitions
+// This is BpfLoader v0.2
 #define BPFLOADER_VERSION_MAJOR 0u
-#define BPFLOADER_VERSION_MINOR 1u
+#define BPFLOADER_VERSION_MINOR 2u
 #define BPFLOADER_VERSION ((BPFLOADER_VERSION_MAJOR << 16) | BPFLOADER_VERSION_MINOR)
 
 #include "../progs/include/bpf_map_def.h"
@@ -211,7 +210,7 @@ static int readSectionByName(const char* name, ifstream& elfFile, vector<char>&
     return -2;
 }
 
-static unsigned int readSectionUint(const char* name, ifstream& elfFile, unsigned int defVal) {
+unsigned int readSectionUint(const char* name, ifstream& elfFile, unsigned int defVal) {
     vector<char> theBytes;
     int ret = readSectionByName(name, elfFile, theBytes);
     if (ret) {
@@ -494,6 +493,7 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
         memset(&m, 0, sizeof(m));
         // Then we set non-zero defaults
         m.bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER;  // v1.0
+        m.max_kver = 0xFFFFFFFFu;                         // matches KVER_INF from bpf_helpers.h
         // Then we copy over the structure prefix from the ELF file.
         memcpy(&m, dataPtr, trimmedSize);
         // Move to next struct in the ELF file
@@ -503,14 +503,9 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
     ret = getSectionSymNames(elfFile, "maps", mapNames);
     if (ret) return ret;
 
-    for (int i = 0; i < (int)mapNames.size(); i++) {
-        unique_fd fd;
-        int saved_errno;
-        // Format of pin location is /sys/fs/bpf/<prefix>map_<filename>_<mapname>
-        string mapPinLoc =
-                string(BPF_FS_PATH) + prefix + "map_" + fname + "_" + string(mapNames[i]);
-        bool reuse = false;
+    unsigned kvers = kernelVersion();
 
+    for (int i = 0; i < (int)mapNames.size(); i++) {
         if (BPFLOADER_VERSION < md[i].bpfloader_min_ver) {
             ALOGI("skipping map %s which requires bpfloader min ver 0x%05x\n", mapNames[i].c_str(),
                   md[i].bpfloader_min_ver);
@@ -525,6 +520,27 @@ static int createMaps(const char* elfPath, ifstream& elfFile, vector<unique_fd>&
             continue;
         }
 
+        if (kvers < md[i].min_kver) {
+            ALOGI("skipping map %s which requires kernel version 0x%x >= 0x%x\n",
+                  mapNames[i].c_str(), kvers, md[i].min_kver);
+            mapFds.push_back(unique_fd());
+            continue;
+        }
+
+        if (kvers >= md[i].max_kver) {
+            ALOGI("skipping map %s which requires kernel version 0x%x < 0x%x\n",
+                  mapNames[i].c_str(), kvers, md[i].max_kver);
+            mapFds.push_back(unique_fd());
+            continue;
+        }
+
+        // Format of pin location is /sys/fs/bpf/<prefix>map_<filename>_<mapname>
+        string mapPinLoc =
+                string(BPF_FS_PATH) + prefix + "map_" + fname + "_" + string(mapNames[i]);
+        bool reuse = false;
+        unique_fd fd;
+        int saved_errno;
+
         if (access(mapPinLoc.c_str(), F_OK) == 0) {
             fd.reset(bpf_obj_get(mapPinLoc.c_str()));
             saved_errno = errno;
diff --git a/libbpf_android/include/libbpf_android.h b/libbpf_android/include/libbpf_android.h
index 90c9906..640f35b 100644
--- a/libbpf_android/include/libbpf_android.h
+++ b/libbpf_android/include/libbpf_android.h
@@ -29,6 +29,9 @@ namespace bpf {
 // BPF loader implementation. Loads an eBPF ELF object
 int loadProg(const char* elfPath, bool* isCritical, const char* prefix = "");
 
+// Exposed for testing
+unsigned int readSectionUint(const char* name, std::ifstream& elfFile, unsigned int defVal);
+
 // Wait for bpfloader to load BPF programs.
 static inline void waitForProgsLoaded() {
     // infinite loop until success with 5/10/20/40/60/60/60... delay
diff --git a/progs/include/bpf_helpers.h b/progs/include/bpf_helpers.h
index 6e5fe69..abd19c6 100644
--- a/progs/include/bpf_helpers.h
+++ b/progs/include/bpf_helpers.h
@@ -59,6 +59,10 @@
  * implemented in the kernel sources.
  */
 
+#define KVER_NONE 0
+#define KVER(a, b, c) (((a) << 24) + ((b) << 16) + (c))
+#define KVER_INF 0xFFFFFFFFu
+
 /* generic functions */
 
 /*
@@ -110,6 +114,8 @@ static int (*bpf_map_delete_elem_unsafe)(const struct bpf_map_def* map,
             .mode = (md),                                                                        \
             .bpfloader_min_ver = DEFAULT_BPFLOADER_MIN_VER,                                      \
             .bpfloader_max_ver = DEFAULT_BPFLOADER_MAX_VER,                                      \
+            .min_kver = KVER_NONE,                                                               \
+            .max_kver = KVER_INF,                                                                \
     };                                                                                           \
                                                                                                  \
     static inline __always_inline __unused TypeOfValue* bpf_##the_map##_lookup_elem(             \
@@ -147,10 +153,6 @@ static unsigned long long (*bpf_get_current_pid_tgid)(void) = (void*) BPF_FUNC_g
 static unsigned long long (*bpf_get_current_uid_gid)(void) = (void*) BPF_FUNC_get_current_uid_gid;
 static unsigned long long (*bpf_get_smp_processor_id)(void) = (void*) BPF_FUNC_get_smp_processor_id;
 
-#define KVER_NONE 0
-#define KVER(a, b, c) (((a) << 24) + ((b) << 16) + (c))
-#define KVER_INF 0xFFFFFFFF
-
 #define DEFINE_BPF_PROG_KVER_RANGE_OPT(SECTION_NAME, prog_uid, prog_gid, the_prog, min_kv, max_kv, \
                                        opt)                                                        \
     const struct bpf_prog_def SEC("progs") the_prog##_def = {                                      \
diff --git a/progs/include/bpf_map_def.h b/progs/include/bpf_map_def.h
index 0034a35..647c813 100644
--- a/progs/include/bpf_map_def.h
+++ b/progs/include/bpf_map_def.h
@@ -42,16 +42,74 @@
  *                                                                            *
  ******************************************************************************/
 
-// We currently default to v0.1 format
-#ifndef BPFLOADER_VERSION
-#define BPFLOADER_VERSION 1u
-#endif
-
 // These are the values used if these fields are missing
 #define DEFAULT_BPFLOADER_MIN_VER 0u        // v0.0 (this is inclusive ie. >= v0.0)
 #define DEFAULT_BPFLOADER_MAX_VER 0x10000u  // v1.0 (this is exclusive ie. < v1.0)
-#define DEFAULT_SIZEOF_BPF_MAP_DEF 32       // v0.0 struct: enum + alignment padding + 7 uint
-#define DEFAULT_SIZEOF_BPF_PROG_DEF 20      // v0.0 struct: 4 uint + bool + alignment padding
+#define DEFAULT_SIZEOF_BPF_MAP_DEF 32       // v0.0 struct: enum (uint sized) + 7 uint
+#define DEFAULT_SIZEOF_BPF_PROG_DEF 20      // v0.0 struct: 4 uint + bool + 3 byte alignment pad
+
+/*
+ * The bpf_{map,prog}_def structures are compiled for different architectures.
+ * Once by the BPF compiler for the BPF architecture, and once by a C++
+ * compiler for the native Android architecture for the bpfloader.
+ *
+ * For things to work, their layout must be the same between the two.
+ * The BPF architecture is platform independent ('64-bit LSB bpf').
+ * So this effectively means these structures must be the same layout
+ * on 5 architectures, all of them little endian:
+ *   64-bit BPF, x86_64, arm  and  32-bit x86 and arm
+ *
+ * As such for any types we use inside of these structs we must make sure that
+ * the size and alignment are the same, so the same amount of padding is used.
+ *
+ * Currently we only use: bool, enum bpf_map_type and unsigned int.
+ * Additionally we use char for padding.
+ *
+ * !!! WARNING: HERE BE DRAGONS !!!
+ *
+ * Be particularly careful with 64-bit integers.
+ * You will need to manually override their alignment to 8 bytes.
+ *
+ * To quote some parts of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69560
+ *
+ * Some types have weaker alignment requirements when they are structure members.
+ *
+ * unsigned long long on x86 is such a type.
+ *
+ * C distinguishes C11 _Alignof (the minimum alignment the type is guaranteed
+ * to have in all contexts, so 4, see min_align_of_type) from GNU C __alignof
+ * (the normal alignment of the type, so 8).
+ *
+ * alignof / _Alignof == minimum alignment required by target ABI
+ * __alignof / __alignof__ == preferred alignment
+ *
+ * When in a struct, apparently the minimum alignment is used.
+ */
+
+_Static_assert(sizeof(bool) == 1, "sizeof bool != 1");
+_Static_assert(__alignof__(bool) == 1, "__alignof__ bool != 1");
+_Static_assert(_Alignof(bool) == 1, "_Alignof bool != 1");
+
+_Static_assert(sizeof(char) == 1, "sizeof char != 1");
+_Static_assert(__alignof__(char) == 1, "__alignof__ char != 1");
+_Static_assert(_Alignof(char) == 1, "_Alignof char != 1");
+
+// This basically verifies that an enum is 'just' a 32-bit int
+_Static_assert(sizeof(enum bpf_map_type) == 4, "sizeof enum bpf_map_type != 4");
+_Static_assert(__alignof__(enum bpf_map_type) == 4, "__alignof__ enum bpf_map_type != 4");
+_Static_assert(_Alignof(enum bpf_map_type) == 4, "_Alignof enum bpf_map_type != 4");
+
+// Linux kernel requires sizeof(int) == 4, sizeof(void*) == sizeof(long), sizeof(long long) == 8
+_Static_assert(sizeof(unsigned int) == 4, "sizeof unsigned int != 4");
+_Static_assert(__alignof__(unsigned int) == 4, "__alignof__ unsigned int != 4");
+_Static_assert(_Alignof(unsigned int) == 4, "_Alignof unsigned int != 4");
+
+// We don't currently use any 64-bit types in these structs, so this is purely to document issue.
+// Here sizeof & __alignof__ are consistent, but _Alignof is not: compile for 'aosp_cf_x86_phone'
+_Static_assert(sizeof(unsigned long long) == 8, "sizeof unsigned long long != 8");
+_Static_assert(__alignof__(unsigned long long) == 8, "__alignof__ unsigned long long != 8");
+// BPF wants 8, but 32-bit x86 wants 4
+//_Static_assert(_Alignof(unsigned long long) == 8, "_Alignof unsigned long long != 8");
 
 /*
  * Map structure to be used by Android eBPF C programs. The Android eBPF loader
@@ -80,13 +138,21 @@ struct bpf_map_def {
     unsigned int gid;   // gid_t
     unsigned int mode;  // mode_t
 
-#if BPFLOADER_VERSION >= 1u
     // The following fields were added in version 0.1
     unsigned int bpfloader_min_ver;  // if missing, defaults to 0, ie. v0.0
     unsigned int bpfloader_max_ver;  // if missing, defaults to 0x10000, ie. v1.0
-#endif
+
+    // The following fields were added in version 0.2
+    // kernelVersion() must be >= min_kver and < max_kver
+    unsigned int min_kver;
+    unsigned int max_kver;
 };
 
+// This needs to be updated whenever the above structure definition is expanded.
+_Static_assert(sizeof(struct bpf_map_def) == 48, "sizeof struct bpf_map_def != 48");
+_Static_assert(__alignof__(struct bpf_map_def) == 4, "__alignof__ struct bpf_map_def != 4");
+_Static_assert(_Alignof(struct bpf_map_def) == 4, "_Alignof struct bpf_map_def != 4");
+
 struct bpf_prog_def {
     unsigned int uid;
     unsigned int gid;
@@ -96,10 +162,16 @@ struct bpf_prog_def {
     unsigned int max_kver;
 
     bool optional;  // program section (ie. function) may fail to load, continue onto next func.
+    char pad0[3];
 
-#if BPFLOADER_VERSION >= 1u
     // The following fields were added in version 0.1
     unsigned int bpfloader_min_ver;  // if missing, defaults to 0, ie. v0.0
     unsigned int bpfloader_max_ver;  // if missing, defaults to 0x10000, ie. v1.0
-#endif
+
+    // No new fields in version 0.2
 };
+
+// This needs to be updated whenever the above structure definition is expanded.
+_Static_assert(sizeof(struct bpf_prog_def) == 28, "sizeof struct bpf_prog_def != 28");
+_Static_assert(__alignof__(struct bpf_prog_def) == 4, "__alignof__ struct bpf_prog_def != 4");
+_Static_assert(_Alignof(struct bpf_prog_def) == 4, "_Alignof struct bpf_prog_def != 4");