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Subject[PATCH 1/1] tools/dtrace: initial implementation of DTrace
This initial implementation of a tiny subset of DTrace functionality
provides the following options:

dtrace [-lvV] [-b bufsz] -s script
-b set trace buffer size
-l list probes (only works with '-s script' for now)
-s enable or list probes for the specified BPF program
-V report DTrace API version

The patch comprises quite a bit of code due to DTrace requiring a few
crucial components, even in its most basic form.

The code is structured around the command line interface implemented in
dtrace.c. It provides option parsing and drives the three modes of
operation that are currently implemented:

1. Report DTrace API version information.
Report the version information and terminate.

2. List probes in BPF programs.
Initialize the list of probes that DTrace recognizes, load BPF
programs, parse all BPF ELF section names, resolve them into
known probes, and emit the probe names. Then terminate.

3. Load BPF programs and collect tracing data.
Initialize the list of probes that DTrace recognizes, load BPF
programs and attach them to their corresponding probes, set up
perf event output buffers, and start processing tracing data.

This implementation makes extensive use of BPF (handled by dt_bpf.c) and
the perf event output ring buffer (handled by dt_buffer.c). DTrace-style
probe handling (dt_probe.c) offers an interface to probes that hides the
implementation details of the individual probe types by provider (dt_fbt.c
and dt_syscall.c). Probe lookup by name uses a hashtable implementation
(dt_hash.c). The dt_utils.c code populates a list of online CPU ids, so
we know what CPUs we can obtain tracing data from.

Building the tool is trivial because its only dependency (libbpf) is in
the kernel tree under tools/lib/bpf. A simple 'make' in the tools/dtrace
directory suffices.

The 'dtrace' executable needs to run as root because BPF programs cannot
be loaded by non-root users.

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: David Mc Lean <david.mclean@oracle.com>
Reviewed-by: Eugene Loh <eugene.loh@oracle.com>
---
MAINTAINERS | 6 +
tools/dtrace/Makefile | 88 ++++++++++
tools/dtrace/bpf_sample.c | 145 ++++++++++++++++
tools/dtrace/dt_bpf.c | 188 +++++++++++++++++++++
tools/dtrace/dt_buffer.c | 331 +++++++++++++++++++++++++++++++++++++
tools/dtrace/dt_fbt.c | 201 ++++++++++++++++++++++
tools/dtrace/dt_hash.c | 211 +++++++++++++++++++++++
tools/dtrace/dt_probe.c | 230 ++++++++++++++++++++++++++
tools/dtrace/dt_syscall.c | 179 ++++++++++++++++++++
tools/dtrace/dt_utils.c | 132 +++++++++++++++
tools/dtrace/dtrace.c | 249 ++++++++++++++++++++++++++++
tools/dtrace/dtrace.h | 13 ++
tools/dtrace/dtrace_impl.h | 101 +++++++++++
13 files changed, 2074 insertions(+)
create mode 100644 tools/dtrace/Makefile
create mode 100644 tools/dtrace/bpf_sample.c
create mode 100644 tools/dtrace/dt_bpf.c
create mode 100644 tools/dtrace/dt_buffer.c
create mode 100644 tools/dtrace/dt_fbt.c
create mode 100644 tools/dtrace/dt_hash.c
create mode 100644 tools/dtrace/dt_probe.c
create mode 100644 tools/dtrace/dt_syscall.c
create mode 100644 tools/dtrace/dt_utils.c
create mode 100644 tools/dtrace/dtrace.c
create mode 100644 tools/dtrace/dtrace.h
create mode 100644 tools/dtrace/dtrace_impl.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 606d1f80bc49..668468834865 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5474,6 +5474,12 @@ W: https://linuxtv.org
S: Odd Fixes
F: drivers/media/pci/dt3155/

+DTRACE
+M: Kris Van Hees <kris.van.hees@oracle.com>
+L: dtrace-devel@oss.oracle.com
+S: Maintained
+F: tools/dtrace/
+
DVB_USB_AF9015 MEDIA DRIVER
M: Antti Palosaari <crope@iki.fi>
L: linux-media@vger.kernel.org
diff --git a/tools/dtrace/Makefile b/tools/dtrace/Makefile
new file mode 100644
index 000000000000..99fd0f9dd1d6
--- /dev/null
+++ b/tools/dtrace/Makefile
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# This Makefile is based on samples/bpf.
+#
+# Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+
+DT_VERSION := 2.0.0
+DT_GIT_VERSION := $(shell git rev-parse HEAD 2>/dev/null || \
+ echo Unknown)
+
+DTRACE_PATH ?= $(abspath $(srctree)/$(src))
+TOOLS_PATH := $(DTRACE_PATH)/..
+SAMPLES_PATH := $(DTRACE_PATH)/../../samples
+
+hostprogs-y := dtrace
+
+LIBBPF := $(TOOLS_PATH)/lib/bpf/libbpf.a
+OBJS := dt_bpf.o dt_buffer.o dt_utils.o dt_probe.o \
+ dt_hash.o \
+ dt_fbt.o dt_syscall.o
+
+dtrace-objs := $(OBJS) dtrace.o
+
+always := $(hostprogs-y)
+always += bpf_sample.o
+
+KBUILD_HOSTCFLAGS += -DDT_VERSION=\"$(DT_VERSION)\"
+KBUILD_HOSTCFLAGS += -DDT_GIT_VERSION=\"$(DT_GIT_VERSION)\"
+KBUILD_HOSTCFLAGS += -I$(srctree)/tools/lib
+KBUILD_HOSTCFLAGS += -I$(srctree)/tools/perf
+KBUILD_HOSTCFLAGS += -I$(srctree)/tools/include/uapi
+KBUILD_HOSTCFLAGS += -I$(srctree)/tools/include/
+KBUILD_HOSTCFLAGS += -I$(srctree)/usr/include
+
+KBUILD_HOSTLDLIBS := $(LIBBPF) -lelf
+
+LLC ?= llc
+CLANG ?= clang
+LLVM_OBJCOPY ?= llvm-objcopy
+
+ifdef CROSS_COMPILE
+HOSTCC = $(CROSS_COMPILE)gcc
+CLANG_ARCH_ARGS = -target $(ARCH)
+endif
+
+all:
+ $(MAKE) -C ../../ $(CURDIR)/ DTRACE_PATH=$(CURDIR)
+
+clean:
+ $(MAKE) -C ../../ M=$(CURDIR) clean
+ @rm -f *~
+
+$(LIBBPF): FORCE
+ $(MAKE) -C $(dir $@) RM='rm -rf' LDFLAGS= srctree=$(DTRACE_PATH)/../../ O=
+
+FORCE:
+
+.PHONY: verify_cmds verify_target_bpf $(CLANG) $(LLC)
+
+verify_cmds: $(CLANG) $(LLC)
+ @for TOOL in $^ ; do \
+ if ! (which -- "$${TOOL}" > /dev/null 2>&1); then \
+ echo "*** ERROR: Cannot find LLVM tool $${TOOL}" ;\
+ exit 1; \
+ else true; fi; \
+ done
+
+verify_target_bpf: verify_cmds
+ @if ! (${LLC} -march=bpf -mattr=help > /dev/null 2>&1); then \
+ echo "*** ERROR: LLVM (${LLC}) does not support 'bpf' target" ;\
+ echo " NOTICE: LLVM version >= 3.7.1 required" ;\
+ exit 2; \
+ else true; fi
+
+$(DTRACE_PATH)/*.c: verify_target_bpf $(LIBBPF)
+$(src)/*.c: verify_target_bpf $(LIBBPF)
+
+$(obj)/%.o: $(src)/%.c
+ @echo " CLANG-bpf " $@
+ $(Q)$(CLANG) $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(EXTRA_CFLAGS) -I$(obj) \
+ -I$(srctree)/tools/testing/selftests/bpf/ \
+ -D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign \
+ -D__TARGET_ARCH_$(ARCH) -Wno-compare-distinct-pointer-types \
+ -Wno-gnu-variable-sized-type-not-at-end \
+ -Wno-address-of-packed-member -Wno-tautological-compare \
+ -Wno-unknown-warning-option $(CLANG_ARCH_ARGS) \
+ -I$(srctree)/samples/bpf/ -include asm_goto_workaround.h \
+ -O2 -emit-llvm -c $< -o -| $(LLC) -march=bpf $(LLC_FLAGS) -filetype=obj -o $@
diff --git a/tools/dtrace/bpf_sample.c b/tools/dtrace/bpf_sample.c
new file mode 100644
index 000000000000..49f350390b5f
--- /dev/null
+++ b/tools/dtrace/bpf_sample.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This sample DTrace BPF tracing program demonstrates how actions can be
+ * associated with different probe types.
+ *
+ * The kprobe/ksys_write probe is a Function Boundary Tracing (FBT) entry probe
+ * on the ksys_write(fd, buf, count) function in the kernel. Arguments to the
+ * function can be retrieved from the CPU registers (struct pt_regs).
+ *
+ * The tracepoint/syscalls/sys_enter_write probe is a System Call entry probe
+ * for the write(d, buf, count) system call. Arguments to the system call can
+ * be retrieved from the tracepoint data passed to the BPF program as context
+ * struct syscall_data) when the probe fires.
+ *
+ * The BPF program associated with each probe prepares a DTrace BPF context
+ * (struct dt_bpf_context) that stores the probe ID and up to 10 arguments.
+ * Only 3 arguments are used in this sample. Then the prorgams call a shared
+ * BPF function (bpf_action) that implements the actual action to be taken when
+ * a probe fires. It prepares a data record to be stored in the tracing buffer
+ * and submits it to the buffer. The data in the data record is obtained from
+ * the DTrace BPF context.
+ *
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <uapi/linux/bpf.h>
+#include <linux/ptrace.h>
+#include <linux/version.h>
+#include <uapi/linux/unistd.h>
+#include "bpf_helpers.h"
+
+#include "dtrace.h"
+
+struct syscall_data {
+ struct pt_regs *regs;
+ long syscall_nr;
+ long arg[6];
+};
+
+struct bpf_map_def SEC("maps") buffers = {
+ .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(u32),
+ .max_entries = NR_CPUS,
+};
+
+#if defined(__amd64)
+# define GET_REGS_ARG0(regs) ((regs)->di)
+# define GET_REGS_ARG1(regs) ((regs)->si)
+# define GET_REGS_ARG2(regs) ((regs)->dx)
+# define GET_REGS_ARG3(regs) ((regs)->cx)
+# define GET_REGS_ARG4(regs) ((regs)->r8)
+# define GET_REGS_ARG5(regs) ((regs)->r9)
+#else
+# warning Argument retrieval from pt_regs is not supported yet on this arch.
+# define GET_REGS_ARG0(regs) 0
+# define GET_REGS_ARG1(regs) 0
+# define GET_REGS_ARG2(regs) 0
+# define GET_REGS_ARG3(regs) 0
+# define GET_REGS_ARG4(regs) 0
+# define GET_REGS_ARG5(regs) 0
+#endif
+
+/*
+ * We must pass a valid BPF context pointer because the bpf_perf_event_output()
+ * helper requires a BPF context pointer as first argument (and the verifier is
+ * validating that we pass a value that is known to be a context pointer).
+ *
+ * This BPF function implements the following D action:
+ * {
+ * trace(curthread);
+ * trace(arg0);
+ * trace(arg1);
+ * trace(arg2);
+ * }
+ *
+ * Expected output will look like:
+ * CPU ID
+ * 15 70423 0xffff8c0968bf8ec0 0x00000000000001 0x0055e019eb3f60 0x0000000000002c
+ * 15 18876 0xffff8c0968bf8ec0 0x00000000000001 0x0055e019eb3f60 0x0000000000002c
+ * | | +-- curthread +--> arg0 (fd) +--> arg1 (buf) +-- arg2 (count)
+ * | |
+ * | +--> probe ID
+ * |
+ * +--> CPU the probe fired on
+ */
+static noinline int bpf_action(void *bpf_ctx, struct dt_bpf_context *ctx)
+{
+ int cpu = bpf_get_smp_processor_id();
+ struct data {
+ u32 probe_id; /* mandatory */
+
+ u64 task; /* first data item (current task) */
+ u64 arg0; /* 2nd data item (arg0, fd) */
+ u64 arg1; /* 3rd data item (arg1, buf) */
+ u64 arg2; /* 4th data item (arg2, count) */
+ } rec;
+
+ memset(&rec, 0, sizeof(rec));
+
+ rec.probe_id = ctx->probe_id;
+ rec.task = bpf_get_current_task();
+ rec.arg0 = ctx->argv[0];
+ rec.arg1 = ctx->argv[1];
+ rec.arg2 = ctx->argv[2];
+
+ bpf_perf_event_output(bpf_ctx, &buffers, cpu, &rec, sizeof(rec));
+
+ return 0;
+}
+
+SEC("kprobe/ksys_write")
+int bpf_kprobe(struct pt_regs *regs)
+{
+ struct dt_bpf_context ctx;
+
+ memset(&ctx, 0, sizeof(ctx));
+
+ ctx.probe_id = 18876;
+ ctx.argv[0] = GET_REGS_ARG0(regs);
+ ctx.argv[1] = GET_REGS_ARG1(regs);
+ ctx.argv[2] = GET_REGS_ARG2(regs);
+ ctx.argv[3] = GET_REGS_ARG3(regs);
+ ctx.argv[4] = GET_REGS_ARG4(regs);
+ ctx.argv[5] = GET_REGS_ARG5(regs);
+
+ return bpf_action(regs, &ctx);
+}
+
+SEC("tracepoint/syscalls/sys_enter_write")
+int bpf_tp(struct syscall_data *scd)
+{
+ struct dt_bpf_context ctx;
+
+ memset(&ctx, 0, sizeof(ctx));
+
+ ctx.probe_id = 70423;
+ ctx.argv[0] = scd->arg[0];
+ ctx.argv[1] = scd->arg[1];
+ ctx.argv[2] = scd->arg[2];
+
+ return bpf_action(scd, &ctx);
+}
+
+char _license[] SEC("license") = "GPL";
+u32 _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/tools/dtrace/dt_bpf.c b/tools/dtrace/dt_bpf.c
new file mode 100644
index 000000000000..6db1833c731a
--- /dev/null
+++ b/tools/dtrace/dt_bpf.c
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file provides the interface for handling BPF. It uses the bpf library
+ * to interact with BPF ELF object files.
+ *
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <bpf/libbpf.h>
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <sys/ioctl.h>
+
+#include "dtrace_impl.h"
+
+/*
+ * Validate the output buffer map that is specified in the BPF ELF object. It
+ * must match the following definition to be valid:
+ *
+ * struct bpf_map_def SEC("maps") buffers = {
+ * .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+ * .key_size = sizeof(u32),
+ * .value_size = sizeof(u32),
+ * .max_entries = num,
+ * };
+ * where num is greater than dt_maxcpuid.
+ */
+static int is_valid_buffers(const struct bpf_map_def *mdef)
+{
+ return mdef->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
+ mdef->key_size == sizeof(u32) &&
+ mdef->value_size == sizeof(u32) &&
+ mdef->max_entries > dt_maxcpuid;
+}
+
+/*
+ * List the probes specified in the given BPF ELF object file.
+ */
+int dt_bpf_list_probes(const char *fn)
+{
+ struct bpf_object *obj;
+ struct bpf_program *prog;
+ int rc, fd;
+
+ libbpf_set_print(NULL);
+
+ /*
+ * Listing probes is done before the DTrace command line utility loads
+ * the supplied programs. We load them here without attaching them to
+ * probes so that we can retrieve the ELF section names for each BPF
+ * program. The section name indicates the probe that the program is
+ * associated with.
+ */
+ rc = bpf_prog_load(fn, BPF_PROG_TYPE_UNSPEC, &obj, &fd);
+ if (rc)
+ return rc;
+
+ /*
+ * Loop through the programs in the BPF ELF object, and try to resolve
+ * the section names into probes. Use the supplied callback function
+ * to emit the probe description.
+ */
+ for (prog = bpf_program__next(NULL, obj); prog != NULL;
+ prog = bpf_program__next(prog, obj)) {
+ struct dt_probe *probe;
+
+ probe = dt_probe_resolve_event(bpf_program__title(prog, false));
+
+ printf("%5d %10s %17s %33s %s\n", probe->id,
+ probe->prv_name ? probe->prv_name : "",
+ probe->mod_name ? probe->mod_name : "",
+ probe->fun_name ? probe->fun_name : "",
+ probe->prb_name ? probe->prb_name : "");
+ }
+
+
+ /* Done with the BPF ELF object. */
+ bpf_object__close(obj);
+
+ return 0;
+}
+
+/*
+ * Load the given BPF ELF object file.
+ */
+int dt_bpf_load_file(const char *fn)
+{
+ struct bpf_object *obj;
+ struct bpf_map *map;
+ struct bpf_program *prog;
+ int rc, fd;
+
+ libbpf_set_print(NULL);
+
+ /* Load the BPF ELF object file. */
+ rc = bpf_prog_load(fn, BPF_PROG_TYPE_UNSPEC, &obj, &fd);
+ if (rc)
+ return rc;
+
+ /* Validate buffers map. */
+ map = bpf_object__find_map_by_name(obj, "buffers");
+ if (map && is_valid_buffers(bpf_map__def(map)))
+ dt_bufmap_fd = bpf_map__fd(map);
+ else
+ goto fail;
+
+ /*
+ * Loop through the programs and resolve each into the matching probe.
+ * Attach the program to the probe.
+ */
+ for (prog = bpf_program__next(NULL, obj); prog != NULL;
+ prog = bpf_program__next(prog, obj)) {
+ struct dt_probe *probe;
+
+ probe = dt_probe_resolve_event(bpf_program__title(prog, false));
+ if (!probe)
+ return -ENOENT;
+ if (probe->prov && probe->prov->attach)
+ probe->prov->attach(bpf_program__title(prog, false),
+ bpf_program__fd(prog));
+ }
+
+ return 0;
+
+fail:
+ bpf_object__close(obj);
+ return -EINVAL;
+}
+
+/*
+ * Store the (key, value) pair in the map referenced by the given fd.
+ */
+int dt_bpf_map_update(int fd, const void *key, const void *val)
+{
+ union bpf_attr attr;
+
+ memset(&attr, 0, sizeof(attr));
+
+ attr.map_fd = fd;
+ attr.key = (u64)(unsigned long)key;
+ attr.value = (u64)(unsigned long)val;
+ attr.flags = 0;
+
+ return bpf(BPF_MAP_UPDATE_ELEM, &attr);
+}
+
+/*
+ * Attach a trace event and associate a BPF program with it.
+ */
+int dt_bpf_attach(int event_id, int bpf_fd)
+{
+ int event_fd;
+ int rc;
+ struct perf_event_attr attr = {};
+
+ attr.type = PERF_TYPE_TRACEPOINT;
+ attr.sample_type = PERF_SAMPLE_RAW;
+ attr.sample_period = 1;
+ attr.wakeup_events = 1;
+ attr.config = event_id;
+
+ /* Register the event (based on its id), and obtain a fd. */
+ event_fd = perf_event_open(&attr, -1, 0, -1, 0);
+ if (event_fd < 0) {
+ perror("sys_perf_event_open");
+ return -1;
+ }
+
+ /* Enable the probe. */
+ rc = ioctl(event_fd, PERF_EVENT_IOC_ENABLE, 0);
+ if (rc < 0) {
+ perror("PERF_EVENT_IOC_ENABLE");
+ return -1;
+ }
+
+ /* Associate the BPF program with the event. */
+ rc = ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, bpf_fd);
+ if (rc < 0) {
+ perror("PERF_EVENT_IOC_SET_BPF");
+ return -1;
+ }
+
+ return 0;
+}
diff --git a/tools/dtrace/dt_buffer.c b/tools/dtrace/dt_buffer.c
new file mode 100644
index 000000000000..1714388a7ae6
--- /dev/null
+++ b/tools/dtrace/dt_buffer.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file provides the tracing buffer handling for DTrace. It makes use of
+ * the perf event output ring buffers that can be written to from BPF programs.
+ *
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syscall.h>
+#include <unistd.h>
+#include <sys/epoll.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <linux/bpf.h>
+#include <linux/perf_event.h>
+
+#include "dtrace_impl.h"
+
+/*
+ * Probe data is recorded in per-CPU perf ring buffers.
+ */
+struct dtrace_buffer {
+ int cpu; /* ID of CPU that uses this buffer */
+ int fd; /* fd of perf output buffer */
+ size_t page_size; /* size of each page in buffer */
+ size_t data_size; /* total buffer size */
+ void *base; /* address of buffer */
+};
+
+static struct dtrace_buffer *dt_buffers;
+
+/*
+ * File descriptor for the BPF map that holds the buffers for the online CPUs.
+ * The map is a bpf_array indexed by CPU id, and it stores a file descriptor as
+ * value (the fd for the perf_event that represents the CPU buffer).
+ */
+int dt_bufmap_fd = -1;
+
+/*
+ * Create a perf_event buffer for the given DTrace buffer. This will create
+ * a perf_event ring_buffer, mmap it, and enable the perf_event that owns the
+ * buffer.
+ */
+static int perf_buffer_open(struct dtrace_buffer *buf)
+{
+ int pefd;
+ struct perf_event_attr attr = {};
+
+ /*
+ * Event configuration for BPF-generated output in perf_event ring
+ * buffers.
+ */
+ attr.config = PERF_COUNT_SW_BPF_OUTPUT;
+ attr.type = PERF_TYPE_SOFTWARE;
+ attr.sample_type = PERF_SAMPLE_RAW;
+ attr.sample_period = 1;
+ attr.wakeup_events = 1;
+ pefd = perf_event_open(&attr, -1, buf->cpu, -1, PERF_FLAG_FD_CLOEXEC);
+ if (pefd < 0) {
+ fprintf(stderr, "perf_event_open(cpu %d): %s\n", buf->cpu,
+ strerror(errno));
+ goto fail;
+ }
+
+ /*
+ * We add buf->page_size to the buf->data_size, because perf maintains
+ * a meta-data page at the beginning of the memory region. That page
+ * is used for reader/writer symchronization.
+ */
+ buf->fd = pefd;
+ buf->base = mmap(NULL, buf->page_size + buf->data_size,
+ PROT_READ | PROT_WRITE, MAP_SHARED, buf->fd, 0);
+ if (!buf->base)
+ goto fail;
+
+ if (ioctl(pefd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+ fprintf(stderr, "PERF_EVENT_IOC_ENABLE(cpu %d): %s\n",
+ buf->cpu, strerror(errno));
+ goto fail;
+ }
+
+ return 0;
+
+fail:
+ if (buf->base) {
+ munmap(buf->base, buf->page_size + buf->data_size);
+ buf->base = NULL;
+ }
+ if (buf->fd) {
+ close(buf->fd);
+ buf->fd = -1;
+ }
+
+ return -1;
+}
+
+/*
+ * Close the given DTrace buffer. This function disables the perf_event that
+ * owns the buffer, munmaps the memory space, and closes the perf buffer fd.
+ */
+static void perf_buffer_close(struct dtrace_buffer *buf)
+{
+ /*
+ * If the perf buffer failed to open, there is no need to close it.
+ */
+ if (buf->fd < 0)
+ return;
+
+ if (ioctl(buf->fd, PERF_EVENT_IOC_DISABLE, 0) < 0)
+ fprintf(stderr, "PERF_EVENT_IOC_DISABLE(cpu %d): %s\n",
+ buf->cpu, strerror(errno));
+
+ munmap(buf->base, buf->page_size + buf->data_size);
+
+ if (close(buf->fd))
+ fprintf(stderr, "perf buffer close(cpu %d): %s\n",
+ buf->cpu, strerror(errno));
+
+ buf->base = NULL;
+ buf->fd = -1;
+}
+
+/*
+ * Initialize the probe data buffers (one per online CPU). Each buffer will
+ * contain the given number of pages (i.e. total size of each buffer will be
+ * num_pages * getpagesize()). This function also sets up an event polling
+ * descriptor that monitors all CPU buffers at once.
+ */
+int dt_buffer_init(int num_pages)
+{
+ int i;
+ int epoll_fd;
+
+ if (dt_bufmap_fd < 0)
+ return -EINVAL;
+
+ /* Allocate the per-CPU buffer structs. */
+ dt_buffers = calloc(dt_numcpus, sizeof(struct dtrace_buffer));
+ if (dt_buffers == NULL)
+ return -ENOMEM;
+
+ /* Set up the event polling file descriptor. */
+ epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+ if (epoll_fd < 0) {
+ free(dt_buffers);
+ return -errno;
+ }
+
+ for (i = 0; i < dt_numcpus; i++) {
+ int cpu = dt_cpuids[i];
+ struct epoll_event ev;
+ struct dtrace_buffer *buf = &dt_buffers[i];
+
+ buf->cpu = cpu;
+ buf->page_size = getpagesize();
+ buf->data_size = num_pages * buf->page_size;
+
+ /* Try to create the perf buffer for this DTrace buffer. */
+ if (perf_buffer_open(buf) == -1)
+ continue;
+
+ /* Store the perf buffer fd in the buffer map. */
+ dt_bpf_map_update(dt_bufmap_fd, &cpu, &buf->fd);
+
+ /* Add the buffer to the event polling descriptor. */
+ ev.events = EPOLLIN;
+ ev.data.ptr = buf;
+ if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, buf->fd, &ev) == -1) {
+ fprintf(stderr, "EPOLL_CTL_ADD(cpu %d): %s\n",
+ buf->cpu, strerror(errno));
+ continue;
+ }
+ }
+
+ return epoll_fd;
+}
+
+/*
+ * Clean up the buffers.
+ */
+void dt_buffer_exit(int epoll_fd)
+{
+ int i;
+
+ for (i = 0; i < dt_numcpus; i++)
+ perf_buffer_close(&dt_buffers[i]);
+
+ free(dt_buffers);
+ close(epoll_fd);
+}
+
+/*
+ * Read the data_head offset from the header page of the ring buffer. The
+ * argument is declared 'volatile' because it references a memory mapped page
+ * that the kernel may be writing to while we access it here.
+ */
+static u64 read_rb_head(volatile struct perf_event_mmap_page *rb_page)
+{
+ u64 head = rb_page->data_head;
+
+ asm volatile("" ::: "memory");
+
+ return head;
+}
+
+/*
+ * Write the data_tail offset in the header page of the ring buffer. The
+ * argument is declared 'volatile' because it references a memory mapped page
+ * that the kernel may be writing to while we access it here.
+ */
+static void write_rb_tail(volatile struct perf_event_mmap_page *rb_page,
+ u64 tail)
+{
+ asm volatile("" ::: "memory");
+
+ rb_page->data_tail = tail;
+}
+
+/*
+ * Process and output the probe data at the supplied address.
+ */
+static int output_event(int cpu, u64 *buf)
+{
+ u8 *data = (u8 *)buf;
+ struct perf_event_header *hdr;
+
+ hdr = (struct perf_event_header *)data;
+ data += sizeof(struct perf_event_header);
+
+ if (hdr->type == PERF_RECORD_SAMPLE) {
+ u8 *ptr = data;
+ u32 i, size, probe_id;
+
+ /*
+ * struct {
+ * struct perf_event_header header;
+ * u32 size;
+ * u32 probe_id;
+ * u32 gap;
+ * u64 data[n];
+ * }
+ * and data points to the 'size' member at this point.
+ */
+ if (ptr > (u8 *)buf + hdr->size) {
+ fprintf(stderr, "BAD: corrupted sample header\n");
+ goto out;
+ }
+
+ size = *(u32 *)data;
+ data += sizeof(size);
+ ptr += sizeof(size) + size;
+ if (ptr != (u8 *)buf + hdr->size) {
+ fprintf(stderr, "BAD: invalid sample size\n");
+ goto out;
+ }
+
+ probe_id = *(u32 *)data;
+ data += sizeof(probe_id);
+ size -= sizeof(probe_id);
+ data += sizeof(u32); /* skip 32-bit gap */
+ size -= sizeof(u32);
+ buf = (u64 *)data;
+
+ printf("%3d %6d ", cpu, probe_id);
+ for (i = 0, size /= sizeof(u64); i < size; i++)
+ printf("%#016lx ", buf[i]);
+ printf("\n");
+ } else if (hdr->type == PERF_RECORD_LOST) {
+ u64 lost;
+
+ /*
+ * struct {
+ * struct perf_event_header header;
+ * u64 id;
+ * u64 lost;
+ * }
+ * and data points to the 'id' member at this point.
+ */
+ lost = *(u64 *)(data + sizeof(u64));
+
+ printf("[%ld probes dropped]\n", lost);
+ } else
+ fprintf(stderr, "UNKNOWN: record type %d\n", hdr->type);
+
+out:
+ return hdr->size;
+}
+
+/*
+ * Process the available probe data in the given buffer.
+ */
+static void process_data(struct dtrace_buffer *buf)
+{
+ /* This is volatile because the kernel may be updating the content. */
+ volatile struct perf_event_mmap_page *rb_page = buf->base;
+ u8 *base = (u8 *)buf->base +
+ buf->page_size;
+ u64 head = read_rb_head(rb_page);
+
+ while (rb_page->data_tail != head) {
+ u64 tail = rb_page->data_tail;
+ u64 *ptr = (u64 *)(base + tail % buf->data_size);
+ int len;
+
+ len = output_event(buf->cpu, ptr);
+
+ write_rb_tail(rb_page, tail + len);
+ head = read_rb_head(rb_page);
+ }
+}
+
+/*
+ * Wait for data to become available in any of the buffers.
+ */
+int dt_buffer_poll(int epoll_fd, int timeout)
+{
+ struct epoll_event events[dt_numcpus];
+ int i, cnt;
+
+ cnt = epoll_wait(epoll_fd, events, dt_numcpus, timeout);
+ if (cnt < 0)
+ return -errno;
+
+ for (i = 0; i < cnt; i++)
+ process_data((struct dtrace_buffer *)events[i].data.ptr);
+
+ return cnt;
+}
diff --git a/tools/dtrace/dt_fbt.c b/tools/dtrace/dt_fbt.c
new file mode 100644
index 000000000000..fcf95243bf97
--- /dev/null
+++ b/tools/dtrace/dt_fbt.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The Function Boundary Tracing (FBT) provider for DTrace.
+ *
+ * FBT probes are exposed by the kernel as kprobes. They are listed in the
+ * TRACEFS/available_filter_functions file. Some kprobes are associated with
+ * a specific kernel module, while most are in the core kernel.
+ *
+ * Mapping from event name to DTrace probe name:
+ *
+ * <name> fbt:vmlinux:<name>:entry
+ * fbt:vmlinux:<name>:return
+ * or
+ * <name> [<modname>] fbt:<modname>:<name>:entry
+ * fbt:<modname>:<name>:return
+ *
+ * Mapping from BPF section name to DTrace probe name:
+ *
+ * kprobe/<name> fbt:vmlinux:<name>:entry
+ * kretprobe/<name> fbt:vmlinux:<name>:return
+ *
+ * (Note that the BPF section does not carry information about the module that
+ * the function is found in. This means that BPF section name cannot be used
+ * to distinguish between functions with the same name occurring in different
+ * modules.)
+ *
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/bpf.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "dtrace_impl.h"
+
+#define KPROBE_EVENTS TRACEFS "kprobe_events"
+#define PROBE_LIST TRACEFS "available_filter_functions"
+
+static const char provname[] = "fbt";
+static const char modname[] = "vmlinux";
+
+/*
+ * Scan the PROBE_LIST file and add entry and return probes for every function
+ * that is listed.
+ */
+static int fbt_populate(void)
+{
+ FILE *f;
+ char buf[256];
+ char *p;
+
+ f = fopen(PROBE_LIST, "r");
+ if (f == NULL)
+ return -1;
+
+ while (fgets(buf, sizeof(buf), f)) {
+ /*
+ * Here buf is either "funcname\n" or "funcname [modname]\n".
+ */
+ p = strchr(buf, '\n');
+ if (p) {
+ *p = '\0';
+ if (p > buf && *(--p) == ']')
+ *p = '\0';
+ } else {
+ /* If we didn't see a newline, the line was too long.
+ * Report it, and continue until the end of the line.
+ */
+ fprintf(stderr, "%s: Line too long: %s\n",
+ PROBE_LIST, buf);
+ do
+ fgets(buf, sizeof(buf), f);
+ while (strchr(buf, '\n') == NULL);
+ continue;
+ }
+
+ /*
+ * Now buf is either "funcname" or "funcname [modname". If
+ * there is no module name provided, we will use the default.
+ */
+ p = strchr(buf, ' ');
+ if (p) {
+ *p++ = '\0';
+ if (*p == '[')
+ p++;
+ }
+
+ dt_probe_new(&dt_fbt, provname, p ? p : modname, buf, "entry");
+ dt_probe_new(&dt_fbt, provname, p ? p : modname, buf, "return");
+ }
+
+ fclose(f);
+
+ return 0;
+}
+
+#define ENTRY_PREFIX "kprobe/"
+#define EXIT_PREFIX "kretprobe/"
+
+/*
+ * Perform a probe lookup based on an event name (BPF ELF section name).
+ */
+static struct dt_probe *fbt_resolve_event(const char *name)
+{
+ const char *prbname;
+ struct dt_probe tmpl;
+ struct dt_probe *probe;
+
+ if (!name)
+ return NULL;
+
+ if (strncmp(name, ENTRY_PREFIX, sizeof(ENTRY_PREFIX) - 1) == 0) {
+ name += sizeof(ENTRY_PREFIX) - 1;
+ prbname = "entry";
+ } else if (strncmp(name, EXIT_PREFIX, sizeof(EXIT_PREFIX) - 1) == 0) {
+ name += sizeof(EXIT_PREFIX) - 1;
+ prbname = "return";
+ } else
+ return NULL;
+
+ memset(&tmpl, 0, sizeof(tmpl));
+ tmpl.prv_name = provname;
+ tmpl.mod_name = modname;
+ tmpl.fun_name = name;
+ tmpl.prb_name = prbname;
+
+ probe = dt_probe_by_name(&tmpl);
+
+ return probe;
+}
+
+/*
+ * Attach the given BPF program (identified by its file descriptor) to the
+ * kprobe identified by the given section name.
+ */
+static int fbt_attach(const char *name, int bpf_fd)
+{
+ char efn[256];
+ char buf[256];
+ int event_id, fd, rc;
+
+ name += 7; /* skip "kprobe/" */
+ snprintf(buf, sizeof(buf), "p:%s %s\n", name, name);
+
+ /*
+ * Register the kprobe with the tracing subsystem. This will create
+ * a tracepoint event.
+ */
+ fd = open(KPROBE_EVENTS, O_WRONLY | O_APPEND);
+ if (fd < 0) {
+ perror(KPROBE_EVENTS);
+ return -1;
+ }
+ rc = write(fd, buf, strlen(buf));
+ if (rc < 0) {
+ perror(KPROBE_EVENTS);
+ close(fd);
+ return -1;
+ }
+ close(fd);
+
+ /*
+ * Read the tracepoint event id for the kprobe we just registered.
+ */
+ strcpy(efn, EVENTSFS);
+ strcat(efn, "kprobes/");
+ strcat(efn, name);
+ strcat(efn, "/id");
+
+ fd = open(efn, O_RDONLY);
+ if (fd < 0) {
+ perror(efn);
+ return -1;
+ }
+ rc = read(fd, buf, sizeof(buf));
+ if (rc < 0 || rc >= sizeof(buf)) {
+ perror(efn);
+ close(fd);
+ return -1;
+ }
+ close(fd);
+ buf[rc] = '\0';
+ event_id = atoi(buf);
+
+ /*
+ * Attaching a BPF program (by file descriptor) to an event (by ID) is
+ * a generic operation provided by the BPF interface code.
+ */
+ return dt_bpf_attach(event_id, bpf_fd);
+}
+
+struct dt_provider dt_fbt = {
+ .name = "fbt",
+ .populate = &fbt_populate,
+ .resolve_event = &fbt_resolve_event,
+ .attach = &fbt_attach,
+};
diff --git a/tools/dtrace/dt_hash.c b/tools/dtrace/dt_hash.c
new file mode 100644
index 000000000000..b1f563bc0773
--- /dev/null
+++ b/tools/dtrace/dt_hash.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file provides a generic hashtable implementation for probes.
+ *
+ * The hashtable is created with 4 user-provided functions:
+ * hval(probe) - calculate a hash value for the given probe
+ * cmp(probe1, probe2) - compare two probes
+ * add(head, probe) - add a probe to a list of probes
+ * del(head, probe) - delete a probe from a list of probes
+ *
+ * Probes are hashed into a hashtable slot based on the return value of
+ * hval(probe). Each hashtable slot holds a list of buckets, with each
+ * bucket storing probes that are equal under the cmp(probe1, probe2)
+ * function. Probes are added to the list of probes in a bucket using the
+ * add(head, probe) function, and they are deleted using a call to the
+ * del(head, probe) function.
+ *
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "dtrace_impl.h"
+
+/*
+ * Hashtable implementation for probes.
+ */
+struct dt_hbucket {
+ u32 hval;
+ struct dt_hbucket *next;
+ struct dt_probe *head;
+ int nprobes;
+};
+
+struct dt_htab {
+ struct dt_hbucket **tab;
+ int size;
+ int mask;
+ int nbuckets;
+ dt_hval_fn hval; /* calculate hash value */
+ dt_cmp_fn cmp; /* compare 2 probes */
+ dt_add_fn add; /* add probe to list */
+ dt_del_fn del; /* delete probe from list */
+};
+
+/*
+ * Create a new (empty) hashtable.
+ */
+struct dt_htab *dt_htab_new(dt_hval_fn hval, dt_cmp_fn cmp, dt_add_fn add,
+ dt_del_fn del)
+{
+ struct dt_htab *htab = malloc(sizeof(struct dt_htab));
+
+ if (!htab)
+ return NULL;
+
+ htab->size = 1;
+ htab->mask = htab->size - 1;
+ htab->nbuckets = 0;
+ htab->hval = hval;
+ htab->cmp = cmp;
+ htab->add = add;
+ htab->del = del;
+
+ htab->tab = calloc(htab->size, sizeof(struct dt_hbucket *));
+ if (!htab->tab) {
+ free(htab);
+ return NULL;
+ }
+
+ return htab;
+}
+
+/*
+ * Resize the hashtable by doubling the number of slots.
+ */
+static int resize(struct dt_htab *htab)
+{
+ int i;
+ int osize = htab->size;
+ int nsize = osize << 1;
+ int nmask = nsize - 1;
+ struct dt_hbucket **ntab;
+
+ ntab = calloc(nsize, sizeof(struct dt_hbucket *));
+ if (!ntab)
+ return -ENOMEM;
+
+ for (i = 0; i < osize; i++) {
+ struct dt_hbucket *bucket, *next;
+
+ for (bucket = htab->tab[i]; bucket; bucket = next) {
+ int idx = bucket->hval & nmask;
+
+ next = bucket->next;
+ bucket->next = ntab[idx];
+ ntab[idx] = bucket;
+ }
+ }
+
+ free(htab->tab);
+ htab->tab = ntab;
+ htab->size = nsize;
+ htab->mask = nmask;
+
+ return 0;
+}
+
+/*
+ * Add a probe to the hashtable. Resize if necessary, and allocate a new
+ * bucket if necessary.
+ */
+int dt_htab_add(struct dt_htab *htab, struct dt_probe *probe)
+{
+ u32 hval = htab->hval(probe);
+ int idx;
+ struct dt_hbucket *bucket;
+
+retry:
+ idx = hval & htab->mask;
+ for (bucket = htab->tab[idx]; bucket; bucket = bucket->next) {
+ if (htab->cmp(bucket->head, probe) == 0)
+ goto add;
+ }
+
+ if ((htab->nbuckets >> 1) > htab->size) {
+ int err;
+
+ err = resize(htab);
+ if (err)
+ return err;
+
+ goto retry;
+ }
+
+ bucket = malloc(sizeof(struct dt_hbucket));
+ if (!bucket)
+ return -ENOMEM;
+
+ bucket->hval = hval;
+ bucket->next = htab->tab[idx];
+ bucket->head = NULL;
+ bucket->nprobes = 0;
+ htab->tab[idx] = bucket;
+ htab->nbuckets++;
+
+add:
+ bucket->head = htab->add(bucket->head, probe);
+ bucket->nprobes++;
+
+ return 0;
+}
+
+/*
+ * Find a probe in the hashtable.
+ */
+struct dt_probe *dt_htab_lookup(const struct dt_htab *htab,
+ const struct dt_probe *probe)
+{
+ u32 hval = htab->hval(probe);
+ int idx = hval & htab->mask;
+ struct dt_hbucket *bucket;
+
+ for (bucket = htab->tab[idx]; bucket; bucket = bucket->next) {
+ if (htab->cmp(bucket->head, probe) == 0)
+ return bucket->head;
+ }
+
+ return NULL;
+}
+
+/*
+ * Remove a probe from the hashtable. If we are deleting the last probe in a
+ * bucket, get rid of the bucket.
+ */
+int dt_htab_del(struct dt_htab *htab, struct dt_probe *probe)
+{
+ u32 hval = htab->hval(probe);
+ int idx = hval & htab->mask;
+ struct dt_hbucket *bucket;
+ struct dt_probe *head;
+
+ for (bucket = htab->tab[idx]; bucket; bucket = bucket->next) {
+ if (htab->cmp(bucket->head, probe) == 0)
+ break;
+ }
+
+ if (bucket == NULL)
+ return -ENOENT;
+
+ head = htab->del(bucket->head, probe);
+ if (!head) {
+ struct dt_hbucket *b = htab->tab[idx];
+
+ if (bucket == b)
+ htab->tab[idx] = bucket->next;
+ else {
+ while (b->next != bucket)
+ b = b->next;
+
+ b->next = bucket->next;
+ }
+
+ htab->nbuckets--;
+ free(bucket);
+ } else
+ bucket->head = head;
+
+ return 0;
+}
diff --git a/tools/dtrace/dt_probe.c b/tools/dtrace/dt_probe.c
new file mode 100644
index 000000000000..0b6228eaff29
--- /dev/null
+++ b/tools/dtrace/dt_probe.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file implements the interface to probes grouped by provider.
+ *
+ * Probes are named by a set of 4 identifiers:
+ * - provider name
+ * - module name
+ * - function name
+ * - probe name
+ *
+ * The Fully Qualified Name (FQN) is "provider:module:function:name".
+ *
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <linux/bpf.h>
+#include <linux/kernel.h>
+
+#include "dtrace_impl.h"
+
+static struct dt_provider *dt_providers[] = {
+ &dt_fbt,
+ &dt_syscall,
+ };
+
+static struct dt_htab *ht_byfqn;
+
+static u32 next_probe_id;
+
+/*
+ * Calculate a hash value based on a given string and an initial value. The
+ * initial value is used to calculate compound hash values, e.g.
+ *
+ * u32 hval;
+ *
+ * hval = str2hval(str1, 0);
+ * hval = str2hval(str2, hval);
+ */
+static u32 str2hval(const char *p, u32 hval)
+{
+ u32 g;
+
+ if (!p)
+ return hval;
+
+ while (*p) {
+ hval = (hval << 4) + *p++;
+ g = hval & 0xf0000000;
+ if (g != 0)
+ hval ^= g >> 24;
+
+ hval &= ~g;
+ }
+
+ return hval;
+}
+
+/*
+ * String compare function that can handle either or both strings being NULL.
+ */
+static int safe_strcmp(const char *p, const char *q)
+{
+ return (!p) ? (!q) ? 0
+ : -1
+ : (!q) ? 1
+ : strcmp(p, q);
+}
+
+/*
+ * Calculate the hash value of a probe as the cummulative hash value of the
+ * FQN.
+ */
+static u32 fqn_hval(const struct dt_probe *probe)
+{
+ u32 hval = 0;
+
+ hval = str2hval(probe->prv_name, hval);
+ hval = str2hval(":", hval);
+ hval = str2hval(probe->mod_name, hval);
+ hval = str2hval(":", hval);
+ hval = str2hval(probe->fun_name, hval);
+ hval = str2hval(":", hval);
+ hval = str2hval(probe->prb_name, hval);
+
+ return hval;
+}
+
+/*
+ * Compare two probes based on the FQN.
+ */
+static int fqn_cmp(const struct dt_probe *p, const struct dt_probe *q)
+{
+ int rc;
+
+ rc = safe_strcmp(p->prv_name, q->prv_name);
+ if (rc)
+ return rc;
+ rc = safe_strcmp(p->mod_name, q->mod_name);
+ if (rc)
+ return rc;
+ rc = safe_strcmp(p->fun_name, q->fun_name);
+ if (rc)
+ return rc;
+ rc = safe_strcmp(p->prb_name, q->prb_name);
+ if (rc)
+ return rc;
+
+ return 0;
+}
+
+/*
+ * Add the given probe 'new' to the double-linked probe list 'head'. Probe
+ * 'new' becomes the new list head.
+ */
+static struct dt_probe *fqn_add(struct dt_probe *head, struct dt_probe *new)
+{
+ if (!head)
+ return new;
+
+ new->he_fqn.next = head;
+ head->he_fqn.prev = new;
+
+ return new;
+}
+
+/*
+ * Remove the given probe 'probe' from the double-linked probe list 'head'.
+ * If we are deleting the current head, the next probe in the list is returned
+ * as the new head. If that value is NULL, the list is now empty.
+ */
+static struct dt_probe *fqn_del(struct dt_probe *head, struct dt_probe *probe)
+{
+ if (head == probe) {
+ if (!probe->he_fqn.next)
+ return NULL;
+
+ head = probe->he_fqn.next;
+ head->he_fqn.prev = NULL;
+ probe->he_fqn.next = NULL;
+
+ return head;
+ }
+
+ if (!probe->he_fqn.next) {
+ probe->he_fqn.prev->he_fqn.next = NULL;
+ probe->he_fqn.prev = NULL;
+
+ return head;
+ }
+
+ probe->he_fqn.prev->he_fqn.next = probe->he_fqn.next;
+ probe->he_fqn.next->he_fqn.prev = probe->he_fqn.prev;
+ probe->he_fqn.prev = probe->he_fqn.next = NULL;
+
+ return head;
+}
+
+/*
+ * Initialize the probe handling by populating the FQN hashtable with probes
+ * from all providers.
+ */
+int dt_probe_init(void)
+{
+ int i;
+
+ ht_byfqn = dt_htab_new(fqn_hval, fqn_cmp, fqn_add, fqn_del);
+
+ for (i = 0; i < ARRAY_SIZE(dt_providers); i++) {
+ if (dt_providers[i]->populate() < 0)
+ return -1;
+ }
+
+ return 0;
+}
+
+/*
+ * Allocate a new probe and add it to the FQN hashtable.
+ */
+int dt_probe_new(const struct dt_provider *prov, const char *pname,
+ const char *mname, const char *fname, const char *name)
+{
+ struct dt_probe *probe;
+
+ probe = malloc(sizeof(struct dt_probe));
+ if (!probe)
+ return -ENOMEM;
+
+ memset(probe, 0, sizeof(struct dt_probe));
+ probe->id = next_probe_id++;
+ probe->prov = prov;
+ probe->prv_name = pname ? strdup(pname) : NULL;
+ probe->mod_name = mname ? strdup(mname) : NULL;
+ probe->fun_name = fname ? strdup(fname) : NULL;
+ probe->prb_name = name ? strdup(name) : NULL;
+
+ dt_htab_add(ht_byfqn, probe);
+
+ return 0;
+}
+
+/*
+ * Perform a probe lookup based on FQN.
+ */
+struct dt_probe *dt_probe_by_name(const struct dt_probe *tmpl)
+{
+ return dt_htab_lookup(ht_byfqn, tmpl);
+}
+
+/*
+ * Resolve an event name (BPF ELF section name) into a probe. We query each
+ * provider, and as soon as we get a hit, we return the result.
+ */
+struct dt_probe *dt_probe_resolve_event(const char *name)
+{
+ int i;
+ struct dt_probe *probe;
+
+ for (i = 0; i < ARRAY_SIZE(dt_providers); i++) {
+ if (!dt_providers[i]->resolve_event)
+ continue;
+ probe = dt_providers[i]->resolve_event(name);
+ if (probe)
+ return probe;
+ }
+
+ return NULL;
+}
diff --git a/tools/dtrace/dt_syscall.c b/tools/dtrace/dt_syscall.c
new file mode 100644
index 000000000000..6695a4a1c701
--- /dev/null
+++ b/tools/dtrace/dt_syscall.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The syscall provider for DTrace.
+ *
+ * System call probes are exposed by the kernel as tracepoint events in the
+ * "syscalls" group. Entry probe names start with "sys_enter_" and exit probes
+ * start with "sys_exit_".
+ *
+ * Mapping from event name to DTrace probe name:
+ *
+ * syscalls:sys_enter_<name> syscall:vmlinux:<name>:entry
+ * syscalls:sys_exit_<name> syscall:vmlinux:<name>:return
+ *
+ * Mapping from BPF section name to DTrace probe name:
+ *
+ * tracepoint/syscalls/sys_enter_<name> syscall:vmlinux:<name>:entry
+ * tracepoint/syscalls/sys_exit_<name> syscall:vmlinux:<name>:return
+ *
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <ctype.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/bpf.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "dtrace_impl.h"
+
+static const char provname[] = "syscall";
+static const char modname[] = "vmlinux";
+
+#define PROBE_LIST TRACEFS "available_events"
+
+#define PROV_PREFIX "syscalls:"
+#define ENTRY_PREFIX "sys_enter_"
+#define EXIT_PREFIX "sys_exit_"
+
+/*
+ * Scan the PROBE_LIST file and add probes for any syscalls events.
+ */
+static int syscall_populate(void)
+{
+ FILE *f;
+ char buf[256];
+
+ f = fopen(PROBE_LIST, "r");
+ if (f == NULL)
+ return -1;
+
+ while (fgets(buf, sizeof(buf), f)) {
+ char *p;
+
+ /* * Here buf is "group:event". */
+ p = strchr(buf, '\n');
+ if (p)
+ *p = '\0';
+ else {
+ /*
+ * If we didn't see a newline, the line was too long.
+ * Report it, and continue until the end of the line.
+ */
+ fprintf(stderr, "%s: Line too long: %s\n",
+ PROBE_LIST, buf);
+ do
+ fgets(buf, sizeof(buf), f);
+ while (strchr(buf, '\n') == NULL);
+ continue;
+ }
+
+ /* We need "group:" to match "syscalls:". */
+ p = buf;
+ if (memcmp(p, PROV_PREFIX, sizeof(PROV_PREFIX) - 1) != 0)
+ continue;
+
+ p += sizeof(PROV_PREFIX) - 1;
+ /*
+ * Now p will be just "event", and we are only interested in
+ * events that match "sys_enter_*" or "sys_exit_*".
+ */
+ if (!memcmp(p, ENTRY_PREFIX, sizeof(ENTRY_PREFIX) - 1)) {
+ p += sizeof(ENTRY_PREFIX) - 1;
+ dt_probe_new(&dt_syscall, provname, modname, p,
+ "entry");
+ } else if (!memcmp(p, EXIT_PREFIX, sizeof(EXIT_PREFIX) - 1)) {
+ p += sizeof(EXIT_PREFIX) - 1;
+ dt_probe_new(&dt_syscall, provname, modname, p,
+ "return");
+ }
+ }
+
+ fclose(f);
+
+ return 0;
+}
+
+#define EVENT_PREFIX "tracepoint/syscalls/"
+
+/*
+ * Perform a probe lookup based on an event name (BPF ELF section name).
+ */
+static struct dt_probe *systrace_resolve_event(const char *name)
+{
+ const char *prbname;
+ struct dt_probe tmpl;
+ struct dt_probe *probe;
+
+ if (!name)
+ return NULL;
+
+ /* Exclude anything that is not a syscalls tracepoint */
+ if (strncmp(name, EVENT_PREFIX, sizeof(EVENT_PREFIX) - 1) != 0)
+ return NULL;
+ name += sizeof(EVENT_PREFIX) - 1;
+
+ if (strncmp(name, ENTRY_PREFIX, sizeof(ENTRY_PREFIX) - 1) == 0) {
+ name += sizeof(ENTRY_PREFIX) - 1;
+ prbname = "entry";
+ } else if (strncmp(name, EXIT_PREFIX, sizeof(EXIT_PREFIX) - 1) == 0) {
+ name += sizeof(EXIT_PREFIX) - 1;
+ prbname = "return";
+ } else
+ return NULL;
+
+ memset(&tmpl, 0, sizeof(tmpl));
+ tmpl.prv_name = provname;
+ tmpl.mod_name = modname;
+ tmpl.fun_name = name;
+ tmpl.prb_name = prbname;
+
+ probe = dt_probe_by_name(&tmpl);
+
+ return probe;
+}
+
+#define SYSCALLSFS EVENTSFS "syscalls/"
+
+/*
+ * Attach the given BPF program (identified by its file descriptor) to the
+ * event identified by the given section name.
+ */
+static int syscall_attach(const char *name, int bpf_fd)
+{
+ char efn[256];
+ char buf[256];
+ int event_id, fd, rc;
+
+ name += sizeof(EVENT_PREFIX) - 1;
+ strcpy(efn, SYSCALLSFS);
+ strcat(efn, name);
+ strcat(efn, "/id");
+
+ fd = open(efn, O_RDONLY);
+ if (fd < 0) {
+ perror(efn);
+ return -1;
+ }
+ rc = read(fd, buf, sizeof(buf));
+ if (rc < 0 || rc >= sizeof(buf)) {
+ perror(efn);
+ close(fd);
+ return -1;
+ }
+ close(fd);
+ buf[rc] = '\0';
+ event_id = atoi(buf);
+
+ return dt_bpf_attach(event_id, bpf_fd);
+}
+
+struct dt_provider dt_syscall = {
+ .name = "syscall",
+ .populate = &syscall_populate,
+ .resolve_event = &systrace_resolve_event,
+ .attach = &syscall_attach,
+};
diff --git a/tools/dtrace/dt_utils.c b/tools/dtrace/dt_utils.c
new file mode 100644
index 000000000000..55d51bae1d97
--- /dev/null
+++ b/tools/dtrace/dt_utils.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "dtrace_impl.h"
+
+#define BUF_SIZE 1024 /* max size for online cpu data */
+
+int dt_numcpus; /* number of online CPUs */
+int dt_maxcpuid; /* highest CPU id */
+int *dt_cpuids; /* list of CPU ids */
+
+/*
+ * Populate the online CPU id information from sysfs data. We only do this
+ * once because we do not care about CPUs coming online after we started
+ * tracing. If a CPU goes offline during tracing, we do not care either
+ * because that simply means that it won't be writing any new probe data into
+ * its buffer.
+ */
+void cpu_list_populate(void)
+{
+ char buf[BUF_SIZE];
+ int fd, cnt, start, end, i;
+ int *cpu;
+ char *p, *q;
+
+ fd = open("/sys/devices/system/cpu/online", O_RDONLY);
+ if (fd < 0)
+ goto fail;
+ cnt = read(fd, buf, sizeof(buf));
+ close(fd);
+ if (cnt <= 0)
+ goto fail;
+
+ /*
+ * The string should always end with a newline, but let's make sure.
+ */
+ if (buf[cnt - 1] == '\n')
+ buf[--cnt] = 0;
+
+ /*
+ * Count how many CPUs we have.
+ */
+ dt_numcpus = 0;
+ p = buf;
+ do {
+ start = (int)strtol(p, &q, 10);
+ switch (*q) {
+ case '-': /* range */
+ p = q + 1;
+ end = (int)strtol(p, &q, 10);
+ dt_numcpus += end - start + 1;
+ if (*q == 0) { /* end of string */
+ p = q;
+ break;
+ }
+ if (*q != ',')
+ goto fail;
+ p = q + 1;
+ break;
+ case 0: /* end of string */
+ dt_numcpus++;
+ p = q;
+ break;
+ case ',': /* gap */
+ dt_numcpus++;
+ p = q + 1;
+ break;
+ }
+ } while (*p != 0);
+
+ dt_cpuids = calloc(dt_numcpus, sizeof(int));
+ cpu = dt_cpuids;
+
+ /*
+ * Fill in the CPU ids.
+ */
+ p = buf;
+ do {
+ start = (int)strtol(p, &q, 10);
+ switch (*q) {
+ case '-': /* range */
+ p = q + 1;
+ end = (int)strtol(p, &q, 10);
+ for (i = start; i <= end; i++)
+ *cpu++ = i;
+ if (*q == 0) { /* end of string */
+ p = q;
+ break;
+ }
+ if (*q != ',')
+ goto fail;
+ p = q + 1;
+ break;
+ case 0: /* end of string */
+ *cpu = start;
+ p = q;
+ break;
+ case ',': /* gap */
+ *cpu++ = start;
+ p = q + 1;
+ break;
+ }
+ } while (*p != 0);
+
+ /* Record the highest CPU id of the set of online CPUs. */
+ dt_maxcpuid = *(cpu - 1);
+
+ return;
+fail:
+ if (dt_cpuids)
+ free(dt_cpuids);
+
+ dt_numcpus = 0;
+ dt_maxcpuid = 0;
+ dt_cpuids = NULL;
+}
+
+void cpu_list_free(void)
+{
+ free(dt_cpuids);
+ dt_numcpus = 0;
+ dt_maxcpuid = 0;
+ dt_cpuids = NULL;
+}
diff --git a/tools/dtrace/dtrace.c b/tools/dtrace/dtrace.c
new file mode 100644
index 000000000000..36ad526c1cd4
--- /dev/null
+++ b/tools/dtrace/dtrace.c
@@ -0,0 +1,249 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#include <errno.h>
+#include <libgen.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/log2.h>
+
+#include "dtrace_impl.h"
+
+#define DTRACE_BUFSIZE 32 /* default buffer size (in pages) */
+
+#define DMODE_VERS 0 /* display version information (-V) */
+#define DMODE_LIST 1 /* list probes (-l) */
+#define DMODE_EXEC 2 /* compile program and start tracing */
+
+#define E_SUCCESS 0
+#define E_ERROR 1
+#define E_USAGE 2
+
+#define NUM_PAGES(sz) (((sz) + getpagesize() - 1) / getpagesize())
+
+static const char *dtrace_options = "+b:ls:V";
+
+static char *g_pname;
+static int g_mode = DMODE_EXEC;
+
+static int usage(void)
+{
+ fprintf(stderr, "Usage: %s [-lV] [-b bufsz] -s script\n", g_pname);
+ fprintf(stderr,
+ "\t-b set trace buffer size\n"
+ "\t-l list probes matching specified criteria\n"
+ "\t-s enable or list probes for the specified BPF program\n"
+ "\t-V report DTrace API version\n");
+
+ return E_USAGE;
+}
+
+static u64 parse_size(const char *arg)
+{
+ long long mul = 1;
+ long long neg, val;
+ size_t len;
+ char *end;
+
+ if (!arg)
+ return -1;
+
+ len = strlen(arg);
+ if (!len)
+ return -1;
+
+ switch (arg[len - 1]) {
+ case 't':
+ case 'T':
+ mul *= 1024;
+ /* fall-through */
+ case 'g':
+ case 'G':
+ mul *= 1024;
+ /* fall-through */
+ case 'm':
+ case 'M':
+ mul *= 1024;
+ /* fall-through */
+ case 'k':
+ case 'K':
+ mul *= 1024;
+ /* fall-through */
+ default:
+ break;
+ }
+
+ neg = strtoll(arg, NULL, 0);
+ errno = 0;
+ val = strtoull(arg, &end, 0) * mul;
+
+ if ((mul > 1 && end != &arg[len - 1]) || (mul == 1 && *end != '\0') ||
+ val < 0 || neg < 0 || errno != 0)
+ return -1;
+
+ return val;
+}
+
+int main(int argc, char *argv[])
+{
+ int i;
+ int modec = 0;
+ int bufsize = DTRACE_BUFSIZE;
+ int epoll_fd;
+ int cnt;
+ char **prgv;
+ int prgc;
+
+ g_pname = basename(argv[0]);
+
+ if (argc == 1)
+ return usage();
+
+ prgc = 0;
+ prgv = calloc(argc, sizeof(char *));
+ if (!prgv) {
+ fprintf(stderr, "failed to allocate memory for arguments: %s\n",
+ strerror(errno));
+ return E_ERROR;
+ }
+
+ argv[0] = g_pname; /* argv[0] for getopt errors */
+
+ for (optind = 1; optind < argc; optind++) {
+ int opt;
+
+ while ((opt = getopt(argc, argv, dtrace_options)) != EOF) {
+ u64 val;
+
+ switch (opt) {
+ case 'b':
+ val = parse_size(optarg);
+ if (val < 0) {
+ fprintf(stderr, "invalid: -b %s\n",
+ optarg);
+ return E_ERROR;
+ }
+
+ /*
+ * Bufsize needs to be a number of pages, and
+ * must be a power of 2. This is required by
+ * the perf event buffer code.
+ */
+ bufsize = roundup_pow_of_two(NUM_PAGES(val));
+ if ((u64)bufsize * getpagesize() > val)
+ fprintf(stderr,
+ "bufsize increased to %ld\n",
+ (u64)bufsize * getpagesize());
+
+ break;
+ case 'l':
+ g_mode = DMODE_LIST;
+ modec++;
+ break;
+ case 's':
+ prgv[prgc++] = optarg;
+ break;
+ case 'V':
+ g_mode = DMODE_VERS;
+ modec++;
+ break;
+ default:
+ if (strchr(dtrace_options, opt) == NULL)
+ return usage();
+ }
+ }
+
+ if (optind < argc) {
+ fprintf(stderr, "unknown option '%s'\n", argv[optind]);
+ return E_ERROR;
+ }
+ }
+
+ if (modec > 1) {
+ fprintf(stderr,
+ "only one of [-lV] can be specified at a time\n");
+ return E_USAGE;
+ }
+
+ /*
+ * We handle requests for version information first because we do not
+ * need probe information for it.
+ */
+ if (g_mode == DMODE_VERS) {
+ printf("%s\n"
+ "This is DTrace %s\n"
+ "dtrace(1) version-control ID: %s\n",
+ DT_VERS_STRING, DT_VERSION, DT_GIT_VERSION);
+
+ return E_SUCCESS;
+ }
+
+ /* Initialize probes. */
+ if (dt_probe_init() < 0) {
+ fprintf(stderr, "failed to initialize probes: %s\n",
+ strerror(errno));
+ return E_ERROR;
+ }
+
+ /*
+ * We handle requests to list probes next.
+ */
+ if (g_mode == DMODE_LIST) {
+ int rc = 0;
+
+ printf("%5s %10s %17s %33s %s\n",
+ "ID", "PROVIDER", "MODULE", "FUNCTION", "NAME");
+ for (i = 0; i < prgc; i++) {
+ rc = dt_bpf_list_probes(prgv[i]);
+ if (rc < 0)
+ fprintf(stderr, "failed to load %s: %s\n",
+ prgv[i], strerror(errno));
+ }
+
+ return rc ? E_ERROR : E_SUCCESS;
+ }
+
+ if (!prgc) {
+ fprintf(stderr, "missing BPF program(s)\n");
+ return E_ERROR;
+ }
+
+ /* Process the BPF program. */
+ for (i = 0; i < prgc; i++) {
+ int err;
+
+ err = dt_bpf_load_file(prgv[i]);
+ if (err) {
+ errno = -err;
+ fprintf(stderr, "failed to load %s: %s\n",
+ prgv[i], strerror(errno));
+ return E_ERROR;
+ }
+ }
+
+ /* Get the list of online CPUs. */
+ cpu_list_populate();
+
+ /* Initialize buffers. */
+ epoll_fd = dt_buffer_init(bufsize);
+ if (epoll_fd < 0) {
+ errno = -epoll_fd;
+ fprintf(stderr, "failed to allocate buffers: %s\n",
+ strerror(errno));
+ return E_ERROR;
+ }
+
+ /* Process probe data. */
+ printf("%3s %6s\n", "CPU", "ID");
+ do {
+ cnt = dt_buffer_poll(epoll_fd, 100);
+ } while (cnt >= 0);
+
+ dt_buffer_exit(epoll_fd);
+
+ return E_SUCCESS;
+}
diff --git a/tools/dtrace/dtrace.h b/tools/dtrace/dtrace.h
new file mode 100644
index 000000000000..c79398432d17
--- /dev/null
+++ b/tools/dtrace/dtrace.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#ifndef _UAPI_LINUX_DTRACE_H
+#define _UAPI_LINUX_DTRACE_H
+
+struct dt_bpf_context {
+ u32 probe_id;
+ u64 argv[10];
+};
+
+#endif /* _UAPI_LINUX_DTRACE_H */
diff --git a/tools/dtrace/dtrace_impl.h b/tools/dtrace/dtrace_impl.h
new file mode 100644
index 000000000000..9aa51b4c4aee
--- /dev/null
+++ b/tools/dtrace/dtrace_impl.h
@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ */
+#ifndef _DTRACE_H
+#define _DTRACE_H
+
+#include <unistd.h>
+#include <bpf/libbpf.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/perf_event.h>
+#include <sys/syscall.h>
+
+#include "dtrace.h"
+
+#define DT_DEBUG
+
+#define DT_VERS_STRING "Oracle D 2.0.0"
+
+#define TRACEFS "/sys/kernel/debug/tracing/"
+#define EVENTSFS TRACEFS "events/"
+
+extern int dt_numcpus;
+extern int dt_maxcpuid;
+extern int *dt_cpuids;
+
+extern void cpu_list_populate(void);
+extern void cpu_list_free(void);
+
+struct dt_provider {
+ char *name;
+ int (*populate)(void);
+ struct dt_probe *(*resolve_event)(const char *name);
+ int (*attach)(const char *name, int bpf_fd);
+};
+
+extern struct dt_provider dt_fbt;
+extern struct dt_provider dt_syscall;
+
+struct dt_hentry {
+ struct dt_probe *next;
+ struct dt_probe *prev;
+};
+
+struct dt_htab;
+
+typedef u32 (*dt_hval_fn)(const struct dt_probe *);
+typedef int (*dt_cmp_fn)(const struct dt_probe *, const struct dt_probe *);
+typedef struct dt_probe *(*dt_add_fn)(struct dt_probe *, struct dt_probe *);
+typedef struct dt_probe *(*dt_del_fn)(struct dt_probe *, struct dt_probe *);
+
+extern struct dt_htab *dt_htab_new(dt_hval_fn hval, dt_cmp_fn cmp,
+ dt_add_fn add, dt_del_fn del);
+extern int dt_htab_add(struct dt_htab *htab, struct dt_probe *probe);
+extern struct dt_probe *dt_htab_lookup(const struct dt_htab *htab,
+ const struct dt_probe *probe);
+extern int dt_htab_del(struct dt_htab *htab, struct dt_probe *probe);
+
+struct dt_probe {
+ u32 id;
+ int event_fd;
+ const struct dt_provider *prov;
+ const char *prv_name; /* provider name */
+ const char *mod_name; /* module name */
+ const char *fun_name; /* function name */
+ const char *prb_name; /* probe name */
+ struct dt_hentry he_fqn;
+};
+
+typedef void (*dt_probe_fn)(const struct dt_probe *probe);
+
+extern int dt_probe_init(void);
+extern int dt_probe_new(const struct dt_provider *prov, const char *pname,
+ const char *mname, const char *fname, const char *name);
+extern struct dt_probe *dt_probe_by_name(const struct dt_probe *tmpl);
+extern struct dt_probe *dt_probe_resolve_event(const char *name);
+
+extern int dt_bpf_list_probes(const char *fn);
+extern int dt_bpf_load_file(const char *fn);
+extern int dt_bpf_map_update(int fd, const void *key, const void *val);
+extern int dt_bpf_attach(int event_id, int bpf_fd);
+
+extern int dt_bufmap_fd;
+
+extern int dt_buffer_init(int num_pages);
+extern int dt_buffer_poll(int epoll_fd, int timeout);
+extern void dt_buffer_exit(int epoll_fd);
+
+static inline int perf_event_open(struct perf_event_attr *attr, pid_t pid,
+ int cpu, int group_fd, unsigned long flags)
+{
+ return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags);
+}
+
+extern inline int bpf(enum bpf_cmd cmd, union bpf_attr *attr)
+{
+ return syscall(__NR_bpf, cmd, attr, sizeof(union bpf_attr));
+}
+
+#endif /* _DTRACE_H */
--
2.20.1
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