summaryrefslogtreecommitdiffstats
path: root/tools/profiler/rust-helper/src/elf.rs
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--tools/profiler/rust-helper/src/elf.rs101
1 files changed, 101 insertions, 0 deletions
diff --git a/tools/profiler/rust-helper/src/elf.rs b/tools/profiler/rust-helper/src/elf.rs
new file mode 100644
index 0000000000..4930884f05
--- /dev/null
+++ b/tools/profiler/rust-helper/src/elf.rs
@@ -0,0 +1,101 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use compact_symbol_table::CompactSymbolTable;
+use object::read::{NativeFile, Object};
+use object::{ObjectSection, ObjectSymbol, SectionKind, SymbolKind};
+use std::cmp;
+use std::collections::HashMap;
+use uuid::Uuid;
+
+const UUID_SIZE: usize = 16;
+const PAGE_SIZE: usize = 4096;
+
+fn get_symbol_map<'a: 'b, 'b, T>(object_file: &'b T) -> HashMap<u32, &'a str>
+where
+ T: Object<'a, 'b>,
+{
+ object_file
+ .dynamic_symbols()
+ .chain(object_file.symbols())
+ .filter(|symbol| symbol.kind() == SymbolKind::Text)
+ .filter_map(|symbol| {
+ symbol
+ .name()
+ .map(|name| (symbol.address() as u32, name))
+ .ok()
+ })
+ .collect()
+}
+
+pub fn get_compact_symbol_table(
+ buffer: &[u8],
+ breakpad_id: Option<&str>,
+) -> Option<CompactSymbolTable> {
+ let elf_file = NativeFile::parse(buffer).ok()?;
+ let elf_id = get_elf_id(&elf_file)?;
+ if !breakpad_id.map_or(true, |id| id == format!("{:X}0", elf_id.as_simple())) {
+ return None;
+ }
+ return Some(CompactSymbolTable::from_map(get_symbol_map(&elf_file)));
+}
+
+fn create_elf_id(identifier: &[u8], little_endian: bool) -> Uuid {
+ // Make sure that we have exactly UUID_SIZE bytes available
+ let mut data = [0 as u8; UUID_SIZE];
+ let len = cmp::min(identifier.len(), UUID_SIZE);
+ data[0..len].copy_from_slice(&identifier[0..len]);
+
+ if little_endian {
+ // The file ELF file targets a little endian architecture. Convert to
+ // network byte order (big endian) to match the Breakpad processor's
+ // expectations. For big endian object files, this is not needed.
+ data[0..4].reverse(); // uuid field 1
+ data[4..6].reverse(); // uuid field 2
+ data[6..8].reverse(); // uuid field 3
+ }
+
+ Uuid::from_bytes(data)
+}
+
+/// Tries to obtain the object identifier of an ELF object.
+///
+/// As opposed to Mach-O, ELF does not specify a unique ID for object files in
+/// its header. Compilers and linkers usually add either `SHT_NOTE` sections or
+/// `PT_NOTE` program header elements for this purpose. If one of these notes
+/// is present, ElfFile's build_id() method will find it.
+///
+/// If neither of the above are present, this function will hash the first page
+/// of the `.text` section (program code). This matches what the Breakpad
+/// processor does.
+///
+/// If all of the above fails, this function will return `None`.
+pub fn get_elf_id(elf_file: &NativeFile) -> Option<Uuid> {
+ if let Ok(Some(identifier)) = elf_file.build_id() {
+ return Some(create_elf_id(identifier, elf_file.is_little_endian()));
+ }
+
+ // We were not able to locate the build ID, so fall back to hashing the
+ // first page of the ".text" (program code) section. This algorithm XORs
+ // 16-byte chunks directly into a UUID buffer.
+ if let Some(section_data) = find_text_section(elf_file) {
+ let mut hash = [0; UUID_SIZE];
+ for i in 0..cmp::min(section_data.len(), PAGE_SIZE) {
+ hash[i % UUID_SIZE] ^= section_data[i];
+ }
+ return Some(create_elf_id(&hash, elf_file.is_little_endian()));
+ }
+
+ None
+}
+
+/// Returns a reference to the data of the the .text section in an ELF binary.
+fn find_text_section<'elf>(elf_file: &'elf NativeFile) -> Option<&'elf [u8]> {
+ if let Some(section) = elf_file.section_by_name(".text") {
+ if section.kind() == SectionKind::Text {
+ return section.data().ok();
+ }
+ }
+ None
+}