[RFC PATCH v2 09/26] perf bpf: Implement empty instruction handler and build bpf-vm

From: He Kuang
Date: Sun Jun 26 2016 - 07:26:10 EST


This patch includes the existing code in "kernel/bpf/vm.c", and uses
empty handlers for building the userspace version of bpf-vm
code. Userspace bpf programs won't deal with 'struct skb' data so an
empty bpf_load_pointer() is placed here to help save us from including
too much kernel structures and headers.

CFLAGS are modified for supressing warnings of the existing bpf code.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
---
tools/perf/util/Build | 2 ++
tools/perf/util/bpf-vm.c | 34 ++++++++++++++++++++++++++++++++++
tools/perf/util/bpf-vm.h | 7 +++++++
3 files changed, 43 insertions(+)
create mode 100644 tools/perf/util/bpf-vm.c
create mode 100644 tools/perf/util/bpf-vm.h

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index fced833..1d24d94 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -90,6 +90,7 @@ libperf-$(CONFIG_BPF_PROLOGUE) += bpf-prologue.o
libperf-$(CONFIG_LIBELF) += symbol-elf.o
libperf-$(CONFIG_LIBELF) += probe-file.o
libperf-$(CONFIG_LIBELF) += probe-event.o
+libperf-$(CONFIG_UBPF) += bpf-vm.o

ifndef CONFIG_LIBELF
libperf-y += symbol-minimal.o
@@ -152,6 +153,7 @@ CFLAGS_rbtree.o += -Wno-unused-parameter -DETC_PERFCONFIG="BUILD_STR($(ET
CFLAGS_libstring.o += -Wno-unused-parameter -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
CFLAGS_hweight.o += -Wno-unused-parameter -DETC_PERFCONFIG="BUILD_STR($(ETC_PERFCONFIG_SQ))"
CFLAGS_parse-events.o += -Wno-redundant-decls
+CFLAGS_bpf-vm.o += -Wno-override-init -Wno-switch-default -Wno-sign-compare

$(OUTPUT)util/kallsyms.o: ../lib/symbol/kallsyms.c FORCE
$(call rule_mkdir)
diff --git a/tools/perf/util/bpf-vm.c b/tools/perf/util/bpf-vm.c
new file mode 100644
index 0000000..23ac784
--- /dev/null
+++ b/tools/perf/util/bpf-vm.c
@@ -0,0 +1,34 @@
+#include <linux/atomic.h>
+#include "util.h"
+#include "tools/be_byteshift.h"
+#include "bpf-vm.h"
+
+static inline void
+bpf_vm_jmp_call_handler(u64 *regs __maybe_unused, void *ctx __maybe_unused,
+ const struct bpf_insn *insn __maybe_unused) {}
+
+static inline int
+bpf_vm_jmp_tail_call_handler(u64 *regs __maybe_unused,
+ u32 *p_tail_call_cnt __maybe_unused,
+ const struct bpf_insn **p_insn __maybe_unused) {
+ return 0;
+}
+
+static inline void
+bpf_vm_default_label_handler(void *ctx __maybe_unused,
+ const struct bpf_insn *insn __maybe_unused) {}
+
+/* instructions for dealing with socket data use this function,
+ * userspace bpf don't use it now so leave it blank here, which saves
+ * us from including too much kernel structures.
+ */
+static inline void *bpf_load_pointer(const void *skb __maybe_unused,
+ int k __maybe_unused,
+ unsigned int size __maybe_unused,
+ void *buffer __maybe_unused)
+{
+ return NULL;
+}
+
+#define UBPF_BUILD
+#include <../../../kernel/bpf/vm.c>
diff --git a/tools/perf/util/bpf-vm.h b/tools/perf/util/bpf-vm.h
new file mode 100644
index 0000000..bf96caa
--- /dev/null
+++ b/tools/perf/util/bpf-vm.h
@@ -0,0 +1,7 @@
+#ifndef _BPF_VM_H
+#define _BPF_VM_H
+
+struct bpf_insn;
+unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn);
+
+#endif /* _BPF_VM_H */
--
1.8.5.2