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[libvirt] [PATCH 01/19] util: introduce virbpf helpers



In order to implement devices controller with cgroup v2 we need to
add support for BPF programs, cgroup v2 doesn't have devices controller.

This introduces required helpers wrapping linux syscalls.

Signed-off-by: Pavel Hrdina <phrdina redhat com>
---
 include/libvirt/virterror.h |   1 +
 src/libvirt_private.syms    |  16 +++
 src/util/Makefile.inc.am    |   2 +
 src/util/virbpf.c           | 263 ++++++++++++++++++++++++++++++++++++
 src/util/virbpf.h           | 246 +++++++++++++++++++++++++++++++++
 src/util/virerror.c         |   1 +
 6 files changed, 529 insertions(+)
 create mode 100644 src/util/virbpf.c
 create mode 100644 src/util/virbpf.h

diff --git a/include/libvirt/virterror.h b/include/libvirt/virterror.h
index fbbe2d5624..d47bed4390 100644
--- a/include/libvirt/virterror.h
+++ b/include/libvirt/virterror.h
@@ -131,6 +131,7 @@ typedef enum {
     VIR_FROM_PERF = 65,         /* Error from perf */
     VIR_FROM_LIBSSH = 66,       /* Error from libssh connection transport */
     VIR_FROM_RESCTRL = 67,      /* Error from resource control */
+    VIR_FROM_BPF = 68,          /* Error from BPF code */
 
 # ifdef VIR_ENUM_SENTINELS
     VIR_ERR_DOMAIN_LAST
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index c3d6306809..0cff580de2 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1477,6 +1477,22 @@ virBitmapToDataBuf;
 virBitmapToString;
 
 
+# util/virbpf.h
+virBPFAttachProg;
+virBPFCreateMap;
+virBPFDeleteElem;
+virBPFDetachProg;
+virBPFGetMap;
+virBPFGetMapInfo;
+virBPFGetNextElem;
+virBPFGetProg;
+virBPFGetProgInfo;
+virBPFLoadProg;
+virBPFLookupElem;
+virBPFQueryProg;
+virBPFUpdateElem;
+
+
 # util/virbuffer.h
 virBufferAdd;
 virBufferAddBuffer;
diff --git a/src/util/Makefile.inc.am b/src/util/Makefile.inc.am
index 4295babac3..1fd7ad2d43 100644
--- a/src/util/Makefile.inc.am
+++ b/src/util/Makefile.inc.am
@@ -17,6 +17,8 @@ UTIL_SOURCES = \
 	util/virauthconfig.h \
 	util/virbitmap.c \
 	util/virbitmap.h \
+	util/virbpf.c \
+	util/virbpf.h \
 	util/virbuffer.c \
 	util/virbuffer.h \
 	util/virperf.c \
diff --git a/src/util/virbpf.c b/src/util/virbpf.c
new file mode 100644
index 0000000000..be5ebbc033
--- /dev/null
+++ b/src/util/virbpf.c
@@ -0,0 +1,263 @@
+/*
+ * virbpf.c: methods for eBPF
+ *
+ * Copyright (C) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+#include <config.h>
+
+#include <sys/syscall.h>
+
+#include "internal.h"
+
+#include "virbpf.h"
+#include "virerror.h"
+#include "virfile.h"
+#include "virlog.h"
+#include "virstring.h"
+
+VIR_LOG_INIT("util.bpf");
+
+#define VIR_FROM_THIS VIR_FROM_BPF
+
+int
+virBPFCreateMap(unsigned int mapType,
+                unsigned int keySize,
+                unsigned int valSize,
+                unsigned int maxEntries)
+{
+    union bpf_attr attr = {
+        .map_type = mapType,
+        .key_size = keySize,
+        .value_size = valSize,
+        .max_entries = maxEntries,
+    };
+
+    return syscall(SYS_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
+}
+
+#define LOG_BUF_SIZE (256 * 1024)
+
+int
+virBPFLoadProg(struct bpf_insn *insns,
+               int progType,
+               unsigned int insnCnt)
+{
+    VIR_AUTOFREE(char *) logbuf = NULL;
+    int progfd = -1;
+
+    if (VIR_ALLOC_N(logbuf, LOG_BUF_SIZE) < 0)
+        return -1;
+
+    union bpf_attr attr = {
+        .prog_type = progType,
+        .insn_cnt = (__u32)insnCnt,
+        .insns = (__u64)insns,
+        .license = (__u64)"GPL",
+        .log_buf = (__u64)logbuf,
+        .log_size = LOG_BUF_SIZE,
+        .log_level = 1,
+    };
+
+    progfd = syscall(SYS_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
+
+    if (progfd < 0)
+        VIR_DEBUG("%s", logbuf);
+
+    return progfd;
+}
+
+int
+virBPFAttachProg(int progfd,
+                 int targetfd,
+                 int attachType)
+{
+    union bpf_attr attr = {
+        .target_fd = targetfd,
+        .attach_bpf_fd = progfd,
+        .attach_type = attachType,
+    };
+
+    return syscall(SYS_bpf, BPF_PROG_ATTACH, &attr, sizeof(attr));
+}
+
+int
+virBPFDetachProg(int progfd,
+                 int targetfd,
+                 int attachType)
+{
+    union bpf_attr attr = {
+        .target_fd = targetfd,
+        .attach_bpf_fd = progfd,
+        .attach_type = attachType,
+    };
+
+    return syscall(SYS_bpf, BPF_PROG_DETACH, &attr, sizeof(attr));
+}
+
+int
+virBPFQueryProg(int targetfd,
+                unsigned int maxprogids,
+                int attachType,
+                unsigned int *progcnt,
+                void *progids)
+{
+    int rc;
+
+    union bpf_attr attr = {
+        .query.target_fd = targetfd,
+        .query.attach_type = attachType,
+        .query.prog_cnt = maxprogids,
+        .query.prog_ids = (__u64)progids,
+    };
+
+    rc = syscall(SYS_bpf, BPF_PROG_QUERY, &attr, sizeof(attr));
+
+    if (rc >= 0)
+        *progcnt = attr.query.prog_cnt;
+
+    return rc;
+}
+
+int
+virBPFGetProg(unsigned int id)
+{
+    union bpf_attr attr = {
+        .prog_id = id,
+    };
+
+    return syscall(SYS_bpf, BPF_PROG_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
+int
+virBPFGetProgInfo(int progfd,
+                  struct bpf_prog_info *info,
+                  unsigned int **mapIDs)
+{
+    int rc;
+
+    union bpf_attr attr = {
+        .info.bpf_fd = progfd,
+        .info.info_len = sizeof(struct bpf_prog_info),
+        .info.info = (__u64)info,
+    };
+
+    rc = syscall(SYS_bpf, BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
+    if (rc < 0)
+        return rc;
+
+    if (mapIDs && info->nr_map_ids > 0) {
+        unsigned int maplen = info->nr_map_ids;
+        VIR_AUTOFREE(unsigned int *) retmapIDs = NULL;
+
+        if (VIR_ALLOC_N(retmapIDs, maplen) < 0)
+            return -1;
+
+        memset(info, 0, sizeof(struct bpf_prog_info));
+        info->nr_map_ids = maplen;
+        info->map_ids = (__u64)retmapIDs;
+
+        memset(&attr, 0, sizeof(attr));
+        attr.info.bpf_fd = progfd;
+        attr.info.info_len = sizeof(struct bpf_prog_info);
+        attr.info.info = (__u64)info;
+
+        rc = syscall(SYS_bpf, BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
+        if (rc < 0)
+            return rc;
+
+        VIR_STEAL_PTR(*mapIDs, retmapIDs);
+    }
+
+    return rc;
+}
+
+int
+virBPFGetMap(unsigned int id)
+{
+    union bpf_attr attr = {
+        .map_id = id,
+    };
+
+    return syscall(SYS_bpf, BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
+int
+virBPFGetMapInfo(int mapfd,
+                 struct bpf_map_info *info)
+{
+    union bpf_attr attr = {
+        .info.bpf_fd = mapfd,
+        .info.info_len = sizeof(struct bpf_map_info),
+        .info.info = (__u64)info,
+    };
+
+    return syscall(SYS_bpf, BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
+}
+
+int
+virBPFLookupElem(int mapfd,
+                 void *key,
+                 void *val)
+{
+    union bpf_attr attr = {
+        .map_fd = mapfd,
+        .key = (__u64)key,
+        .value = (__u64)val,
+    };
+
+    return syscall(SYS_bpf, BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+}
+
+int
+virBPFGetNextElem(int mapfd,
+                  void *key,
+                  void *nextKey)
+{
+    union bpf_attr attr = {
+        .map_fd = mapfd,
+        .key = (__u64)key,
+        .next_key = (__u64)nextKey,
+    };
+
+    return syscall(SYS_bpf, BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
+}
+
+int
+virBPFUpdateElem(int mapfd,
+                 void *key,
+                 void *val)
+{
+    union bpf_attr attr = {
+        .map_fd = mapfd,
+        .key = (__u64)key,
+        .value = (__u64)val,
+    };
+
+    return syscall(SYS_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
+}
+
+int
+virBPFDeleteElem(int mapfd,
+                 void *key)
+{
+    union bpf_attr attr = {
+        .map_fd = mapfd,
+        .key = (__u64)key,
+    };
+
+    return syscall(SYS_bpf, BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
+}
diff --git a/src/util/virbpf.h b/src/util/virbpf.h
new file mode 100644
index 0000000000..7085edaacc
--- /dev/null
+++ b/src/util/virbpf.h
@@ -0,0 +1,246 @@
+/*
+ * virbpf.h: methods for eBPF
+ *
+ * Copyright (C) 2018 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LIBVIRT_VIRBPF_H
+# define LIBVIRT_VIRBPF_H
+
+# include <linux/bpf.h>
+
+/* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
+
+# define VIR_BPF_ALU64_REG(op, dst, src) \
+    ((struct bpf_insn) { \
+     .code = BPF_ALU64 | BPF_OP(op) | BPF_X, \
+     .dst_reg = dst, \
+     .src_reg = src, \
+     .off = 0, \
+     .imm = 0, \
+     })
+
+/* ALU ops on immediates, bpf_add|sub|...: dst_reg += imm32 */
+
+# define VIR_BPF_ALU64_IMM(op, dst, immval) \
+    ((struct bpf_insn) { \
+     .code = BPF_ALU64 | BPF_OP(op) | BPF_K, \
+     .dst_reg = dst, \
+     .src_reg = 0, \
+     .off = 0, \
+     .imm = immval, \
+     })
+
+/* Short form of mov, dst_reg = src_reg */
+
+# define VIR_BPF_MOV64_REG(dst, src) \
+    ((struct bpf_insn) { \
+     .code = BPF_ALU64 | BPF_MOV | BPF_X, \
+     .dst_reg = dst, \
+     .src_reg = src, \
+     .off = 0, \
+     .imm = 0, \
+     })
+
+/* Short form of mov, dst_reg = imm32 */
+
+# define VIR_BPF_MOV64_IMM(dst, immval) \
+    ((struct bpf_insn) { \
+     .code = BPF_ALU64 | BPF_MOV | BPF_K, \
+     .dst_reg = dst, \
+     .src_reg = 0, \
+     .off = 0, \
+     .imm = immval, \
+     })
+
+# define VIR_BPF_MOV32_IMM(dst, immval) \
+    ((struct bpf_insn) { \
+     .code = BPF_ALU | BPF_MOV | BPF_K, \
+     .dst_reg = dst, \
+     .src_reg = 0, \
+     .off = 0, \
+     .imm = immval, \
+     })
+
+/* BPF_LD_IMM64 macro encodes single 'load 64-bit immediate' insn */
+# define VIR_BPF_LD_IMM64(dst, imm) \
+    BPF_LD_IMM64_RAW(dst, 0, imm)
+
+# define VIR_BPF_LD_IMM64_RAW(dst, src, immval) \
+    ((struct bpf_insn) { \
+     .code = BPF_LD | BPF_DW | BPF_IMM, \
+     .dst_reg = dst, \
+     .src_reg = src, \
+     .off = 0, \
+     .imm = (__u32)immval, \
+     }), \
+    ((struct bpf_insn) { \
+     .code = 0, \
+     .dst_reg = 0, \
+     .src_reg = 0, \
+     .off = 0, \
+     .imm = ((__u64)immval) >> 32, \
+     })
+
+# ifndef VIR_BPF_PSEUDO_MAP_FD
+#  define VIR_BPF_PSEUDO_MAP_FD	1
+# endif
+
+/* pseudo VIR_BPF_LD_IMM64 insn used to refer to process-local map_fd */
+# define VIR_BPF_LD_MAP_FD(dst, mapfd) \
+    VIR_BPF_LD_IMM64_RAW(dst, VIR_BPF_PSEUDO_MAP_FD, mapfd)
+
+/* Memory load, dst_reg = *(uint *) (src_reg + off16) */
+
+# define VIR_BPF_LDX_MEM(size, dst, src, offval) \
+    ((struct bpf_insn) { \
+     .code = BPF_LDX | BPF_SIZE(size) | BPF_MEM, \
+     .dst_reg = dst, \
+     .src_reg = src, \
+     .off = offval, \
+     .imm = 0, \
+     })
+
+/* Memory store, *(uint *) (dst_reg + off16) = src_reg */
+
+# define VIR_BPF_STX_MEM(size, dst, src, offval) \
+    ((struct bpf_insn) { \
+     .code = BPF_STX | BPF_SIZE(size) | BPF_MEM, \
+     .dst_reg = dst, \
+     .src_reg = src, \
+     .off = offval, \
+     .imm = 0, \
+     })
+
+/* Memory store, *(uint *) (dst_reg + off16) = imm32 */
+
+# define VIR_BPF_ST_MEM(size, dst, immval, offval) \
+    ((struct bpf_insn) { \
+     .code = BPF_ST | BPF_SIZE(size) | BPF_MEM, \
+     .dst_reg = dst, \
+     .src_reg = 0, \
+     .off = offval, \
+     .imm = immval, \
+     })
+
+/* Conditional jumps against registers, if (dst_reg 'op' src_reg) goto pc + off16 */
+
+# define VIR_BPF_JMP_REG(op, dst, src, offval) \
+    ((struct bpf_insn) { \
+     .code = BPF_JMP | BPF_OP(op) | BPF_X, \
+     .dst_reg = dst, \
+     .src_reg = src, \
+     .off = offval, \
+     .imm = 0, \
+     })
+
+/* Conditional jumps against immediates, if (dst_reg 'op' imm32) goto pc + off16 */
+
+# define VIR_BPF_JMP_IMM(op, dst, immval, offval) \
+    ((struct bpf_insn) { \
+     .code = BPF_JMP | BPF_OP(op) | BPF_K, \
+     .dst_reg = dst, \
+     .src_reg = 0, \
+     .off = offval, \
+     .imm = immval, \
+     })
+
+/* Call eBPF function */
+
+# define VIR_BPF_CALL_INSN(func) \
+    ((struct bpf_insn) { \
+     .code = BPF_JMP | BPF_CALL, \
+     .dst_reg = 0, \
+     .src_reg = 0, \
+     .off = 0, \
+     .imm = func, \
+     })
+
+/* Program exit */
+
+# define VIR_BPF_EXIT_INSN() \
+    ((struct bpf_insn) { \
+     .code = BPF_JMP | BPF_EXIT, \
+     .dst_reg = 0, \
+     .src_reg = 0, \
+     .off = 0, \
+     .imm = 0, \
+     })
+
+int
+virBPFCreateMap(unsigned int mapType,
+                unsigned int keySize,
+                unsigned int valSize,
+                unsigned int maxEntries);
+
+int
+virBPFGetMapInfo(int mapfd,
+                 struct bpf_map_info *info);
+
+int
+virBPFLoadProg(struct bpf_insn *insns,
+               int progType,
+               unsigned int insnCnt);
+
+int
+virBPFAttachProg(int progfd,
+                 int targetfd,
+                 int attachType);
+
+int
+virBPFDetachProg(int progfd,
+                 int targetfd,
+                 int attachType);
+
+int
+virBPFQueryProg(int targetfd,
+                unsigned int maxprogids,
+                int attachType,
+                unsigned int *progcnt,
+                void *progids);
+
+int
+virBPFGetProg(unsigned int id);
+
+int
+virBPFGetProgInfo(int progfd,
+                  struct bpf_prog_info *info,
+                  unsigned int **mapIDs);
+
+int
+virBPFGetMap(unsigned int id);
+
+int
+virBPFLookupElem(int mapfd,
+                 void *key,
+                 void *val);
+
+int
+virBPFGetNextElem(int mapfd,
+                  void *key,
+                  void *nextKey);
+
+int
+virBPFUpdateElem(int mapfd,
+                 void *key,
+                 void *val);
+
+int
+virBPFDeleteElem(int mapfd,
+                 void *key);
+
+#endif /* LIBVIRT_VIRBPF_H */
diff --git a/src/util/virerror.c b/src/util/virerror.c
index 61b47d2be0..a40076f8ec 100644
--- a/src/util/virerror.c
+++ b/src/util/virerror.c
@@ -138,6 +138,7 @@ VIR_ENUM_IMPL(virErrorDomain, VIR_ERR_DOMAIN_LAST,
               "Perf", /* 65 */
               "Libssh transport layer",
               "Resource control",
+              "BPF",
               )
 
 
-- 
2.20.1


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