feat: DWARF unwind support

agent/Cargo.toml

@@ -28,8 +28,9 @@ cloud_platform = { path = "plugins/cloud_platform" }
 dashmap = "5.3.3"
 dns-lookup = "1.0.8"
 elf = "0.4.0"
-enum_dispatch = "0.3.7"
 enterprise-utils = { path = "crates/enterprise-utils", optional = true }
+enum_dispatch = "0.3.7"
+envmnt = "0.10.4"
 flate2 = "1.0.23"
 # the feature flag fixes the following problem:
 #
@@ -86,7 +87,7 @@ thiserror = "1.0"
 time = "0.3.9"
 tokio = { version = "1.20.1", features = ["full"] }
 tonic = "0.8.1"
-envmnt = "0.10.4"
+trace-utils = { path = "crates/trace-utils" }
 wasmtime = "12.0.1"
 wasmtime-wasi = "12.0.1"
 

agent/crates/trace-utils/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "trace-utils"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+ahash = "0.8"
+gimli = "0.31"
+libc = "0.2"
+log = "0.4"
+object = "0.36"
+rustc-demangle = "0.1"
+thiserror = "1.0"
+
+[build-dependencies]
+cc = "1.0"
+
+[dev-dependencies]
+env_logger = "0.11"

agent/crates/trace-utils/build.rs

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2024 Yunshan Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+fn main() {
+    cc::Build::new().file("src/bpf.c").compile("dummy");
+    println!("cargo:rerun-if-changed=src/bpf.c");
+}

agent/crates/trace-utils/cbindgen.toml

@@ -0,0 +1,69 @@
+################################################################################
+#                                                                              #
+# Copyright (c) 2024 Yunshan Networks                                          #
+#                                                                              #
+# Licensed under the Apache License, Version 2.0 (the "License");              #
+# you may not use this file except in compliance with the License.             #
+# You may obtain a copy of the License at                                      #
+#                                                                              #
+#     http://www.apache.org/licenses/LICENSE-2.0                               #
+#                                                                              #
+# Unless required by applicable law or agreed to in writing, software          #
+# distributed under the License is distributed on an "AS IS" BASIS,            #
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.     #
+# See the License for the specific language governing permissions and          #
+# limitations under the License.                                               #
+#                                                                              #
+################################################################################
+
+language = "C"
+
+header = """
+/*
+ * Copyright (c) 2024 Yunshan Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */"""
+include_guard = "TRACE_UTILS_H"
+autogen_warning = "/* Warning, this file is autogenerated by cbindgen. Don't modify this manually. */"
+sys_includes = ["stdint.h"]
+no_includes = true
+
+#### code style ####
+line_length = 100
+tab_width = 4
+line_endings = "LF"
+
+#### codegen options ####
+style = "type"
+sort_by = "Name"
+usize_is_size_t = true
+
+[export]
+include = ["ProcessShardList", "UnwindEntryShard"]
+exclude = ["bpf_update_elem", "bpf_delete_elem"]
+item_types = []
+renaming_overrides_prefixing = false
+
+[export.rename]
+ShardInfo = "shard_info_t"
+ProcessShardList = "process_shard_list_t"
+UnwindEntry = "unwind_entry_t"
+UnwindEntryShard = "unwind_entry_shard_t"
+UnwindTable = "unwind_table_t"
+
+[struct]
+rename_fields = "SnakeCase"
+
+[enum]
+rename_variants = "QualifiedScreamingSnakeCase"

agent/crates/trace-utils/examples/unwind_table.rs

@@ -0,0 +1,13 @@
+use trace_utils::unwind::dwarf::read_unwind_entries;
+
+use std::fs;
+
+use log::info;
+
+fn main() {
+    env_logger::init();
+    let filename = std::env::args().nth(1).unwrap();
+    info!("read {filename}");
+    let contents = fs::read(filename).unwrap();
+    read_unwind_entries(&contents);
+}

agent/crates/trace-utils/src/bpf.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2024 Yunshan Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Phony functions to make examples in this crate work
+ * Linking with libbpf will replace these weak symbols
+ */
+
+#include <stdint.h>
+
+#define UNUSED(x) (void)(x)
+
+int __attribute__((weak))
+    bpf_update_elem(int fd, const void *key, const void *value, uint64_t flags) {
+    UNUSED(fd);
+    UNUSED(key);
+    UNUSED(value);
+    UNUSED(flags);
+    return 0;
+}
+
+int __attribute__((weak)) bpf_delete_elem(int fd, const void *key) {
+    UNUSED(fd);
+    UNUSED(key);
+    return 0;
+}

agent/crates/trace-utils/src/error.rs

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2024 Yunshan Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    FileReadError(#[from] std::io::Error),
+    #[error(transparent)]
+    ElfReadError(#[from] object::Error),
+    #[error(transparent)]
+    ElfParseError(#[from] gimli::Error),
+    #[error(".eh_frame section not found in object file")]
+    NoEhFrame,
+}
+
+pub type Result<T> = std::result::Result<T, Error>;

agent/crates/trace-utils/src/lib.rs

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2024 Yunshan Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+pub mod error;
+pub mod unwind;
+
+use std::io::Write;
+
+use unwind::UnwindTable;
+
+#[no_mangle]
+pub unsafe extern "C" fn unwind_table_create(
+    process_shard_list_map_fd: i32,
+    unwind_entry_shard_map_fd: i32,
+) -> *mut UnwindTable {
+    let table = Box::new(UnwindTable::new(
+        process_shard_list_map_fd,
+        unwind_entry_shard_map_fd,
+    ));
+    Box::into_raw(table)
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn unwind_table_destroy(table: *mut UnwindTable) {
+    if table.is_null() {
+        return;
+    }
+    std::mem::drop(Box::from_raw(table));
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn unwind_table_load(table: *mut UnwindTable, pid: u32) {
+    (*table).load(pid);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn unwind_table_unload(table: *mut UnwindTable, pid: u32) {
+    (*table).unload(pid);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn unwind_table_unload_all(table: *mut UnwindTable) {
+    (*table).unload_all();
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn frame_pointer_heuristic_check(pid: u32) -> bool {
+    unwind::dwarf::frame_pointer_heuristic_check(pid)
+}
+
+// forwards rust demangle to C api
+// The code is from: https://github.com/rust-lang/rustc-demangle/blob/main/crates/capi/src/lib.rs
+#[no_mangle]
+pub unsafe extern "C" fn rustc_demangle(
+    mangled: *const libc::c_char,
+    out: *mut libc::c_char,
+    out_size: usize,
+) -> libc::c_int {
+    let mangled_str = match std::ffi::CStr::from_ptr(mangled).to_str() {
+        Ok(s) => s,
+        Err(_) => return 0,
+    };
+    match rustc_demangle::try_demangle(mangled_str) {
+        Ok(demangle) => {
+            let mut out_slice = std::slice::from_raw_parts_mut(out as *mut u8, out_size);
+            match write!(out_slice, "{:#}\0", demangle) {
+                Ok(_) => return 1,
+                Err(_) => return 0,
+            }
+        }
+        Err(_) => return 0,
+    }
+}

agent/crates/trace-utils/src/trace_utils.h

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2024 Yunshan Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef TRACE_UTILS_H
+#define TRACE_UTILS_H
+
+/* Warning, this file is autogenerated by cbindgen. Don't modify this manually. */
+
+#include <stdint.h>
+
+#define UNWIND_ENTRIES_PER_SHARD 65535
+
+#define UNWIND_SHARDS_PER_PROCESS 256
+
+enum CfaType {
+    CFA_TYPE_RBP_OFFSET,
+    CFA_TYPE_RSP_OFFSET,
+    CFA_TYPE_EXPRESSION,
+    CFA_TYPE_UNSUPPORTED,
+    CFA_TYPE_NO_ENTRY,
+};
+typedef uint8_t CfaType;
+
+enum RegType {
+    REG_TYPE_UNDEFINED,
+    REG_TYPE_SAME_VALUE,
+    REG_TYPE_OFFSET,
+    REG_TYPE_UNSUPPORTED,
+};
+typedef uint8_t RegType;
+
+typedef struct unwind_table_t unwind_table_t;
+
+typedef struct {
+    uint32_t id;
+    uint64_t offset;
+    uint64_t pc_min;
+    uint64_t pc_max;
+    uint32_t entry_start;
+    uint32_t entry_end;
+} shard_info_t;
+
+typedef struct {
+    uint8_t len;
+    shard_info_t entries[UNWIND_SHARDS_PER_PROCESS];
+} process_shard_list_t;
+
+typedef struct {
+    uint64_t pc;
+    CfaType cfa_type;
+    RegType rbp_type;
+    int16_t cfa_offset;
+    int16_t rbp_offset;
+} unwind_entry_t;
+
+typedef struct {
+    uint32_t id;
+    uint32_t len;
+    unwind_entry_t entries[UNWIND_ENTRIES_PER_SHARD];
+} unwind_entry_shard_t;
+
+bool frame_pointer_heuristic_check(uint32_t pid);
+
+int rustc_demangle(const char *mangled, char *out, size_t out_size);
+
+unwind_table_t *unwind_table_create(int32_t process_shard_list_map_fd,
+                                    int32_t unwind_entry_shard_map_fd);
+
+void unwind_table_destroy(unwind_table_t *table);
+
+void unwind_table_load(unwind_table_t *table, uint32_t pid);
+
+void unwind_table_unload(unwind_table_t *table, uint32_t pid);
+
+void unwind_table_unload_all(unwind_table_t *table);
+
+#endif /* TRACE_UTILS_H */