[libvirt] [PATCH v3 01/15] util: introduce virbpf helpers

[Ján Tomko]

On Thu, Apr 25, 2019 at 09:44:18AM +0200, Pavel Hrdina wrote:
>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 at redhat.com>
>---
> configure.ac                |   5 +
> include/libvirt/virterror.h |   2 +
> src/libvirt_private.syms    |  16 ++
> src/util/Makefile.inc.am    |   2 +
> src/util/virbpf.c           | 438 ++++++++++++++++++++++++++++++++++++
> src/util/virbpf.h           | 259 +++++++++++++++++++++
> src/util/virerror.c         |   2 +
> 7 files changed, 724 insertions(+)
> create mode 100644 src/util/virbpf.c
> create mode 100644 src/util/virbpf.h
>
>diff --git a/src/util/virbpf.h b/src/util/virbpf.h
>new file mode 100644
>index 0000000000..b5874e1e8d
>--- /dev/null
>+++ b/src/util/virbpf.h
>@@ -0,0 +1,259 @@
>+/*
>+ * virbpf.h: methods for eBPF
>+ *
>+ * 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

#pragma once is the new avocado toast.

>+
>+# if HAVE_DECL_BPF_PROG_QUERY
>+
>+#  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, \
>+     })
>+
>+/* mov of registers, 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, \
>+     })
>+
>+/* mov of immediates, 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, \
>+     })
>+
>+/* helper to encode 16 byte instruction */
>+
>+#  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 = (uint32_t)immval, \
>+     }), \
>+    ((struct bpf_insn) { \
>+     .code = 0, \
>+     .dst_reg = 0, \
>+     .src_reg = 0, \
>+     .off = 0, \
>+     .imm = ((uint64_t)immval) >> 32, \
>+     })
>+

Trust, yada, yada..
Reviewed-by: Ján Tomko <jtomko at redhat.com>

Jano
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