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Fix kernel module symbol tables. #152

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merged 1 commit into from
Apr 25, 2024
Merged

Fix kernel module symbol tables. #152

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4 changes: 2 additions & 2 deletions Cargo.lock
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2 changes: 1 addition & 1 deletion samply/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@ fxprof-processed-profile = { version = "0.7", path = "../fxprof-processed-profil
# framehop = { path = "../../framehop" }
framehop = "0.11.1"
# linux-perf-data = { path = "../../linux-perf-data" }
linux-perf-data = "0.10.0"
linux-perf-data = "0.10.1"

tokio = { version = "1.37.0", features = ["rt", "rt-multi-thread", "macros"] }
tokio-util = "0.7.10"
Expand Down
80 changes: 48 additions & 32 deletions samply/src/linux_shared/converter.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ use fxprof_processed_profile::{
SymbolTable, ThreadHandle,
};
use linux_perf_data::linux_perf_event_reader;
use linux_perf_data::simpleperf_dso_type::{DSO_KERNEL, DSO_KERNEL_MODULE};
use linux_perf_data::{
DsoInfo, DsoKey, Endianness, SimpleperfFileRecord, SimpleperfSymbol, SimpleperfTypeSpecificInfo,
};
Expand Down Expand Up @@ -75,7 +76,8 @@ where
kernel_symbols: Option<KernelSymbols>,
kernel_image_mapping: Option<KernelImageMapping>,
simpleperf_symbol_tables_user: HashMap<Vec<u8>, SymbolTableFromSimpleperf>,
simpleperf_symbol_tables_kernel: HashMap<Vec<u8>, Vec<SimpleperfSymbol>>,
simpleperf_symbol_tables_kernel_image: Option<Vec<SimpleperfSymbol>>,
simpleperf_symbol_tables_kernel_modules: HashMap<Vec<u8>, SymbolTableFromSimpleperf>,
pe_mappings: PeMappings,
jit_category_manager: JitCategoryManager,
cpus: Option<Cpus>,
Expand Down Expand Up @@ -127,17 +129,13 @@ where
};

let mut simpleperf_symbol_tables_user = HashMap::new();
let mut simpleperf_symbol_tables_kernel = HashMap::new();
let mut simpleperf_symbol_tables_kernel_image = None;
let mut simpleperf_symbol_tables_kernel_modules = HashMap::new();
if let Some(simpleperf_symbol_tables) = simpleperf_symbol_tables {
for f in simpleperf_symbol_tables {
let path = f.path.clone().into_bytes();
if f.path == "[kernel.kallsyms]"
|| matches!(
f.type_specific_msg,
Some(SimpleperfTypeSpecificInfo::KernelModule(_))
)
{
simpleperf_symbol_tables_kernel.insert(path, f.symbol);
if f.r#type == DSO_KERNEL {
simpleperf_symbol_tables_kernel_image = Some(f.symbol);
} else {
let file_offset_of_min_vaddr_in_elf_file = match f.type_specific_msg {
Some(SimpleperfTypeSpecificInfo::ElfFile(elf)) => {
Expand All @@ -160,7 +158,11 @@ where
min_vaddr: f.min_vaddr,
symbol_table: Arc::new(symbol_table),
};
simpleperf_symbol_tables_user.insert(path, symbol_table);
if f.r#type == DSO_KERNEL_MODULE {
simpleperf_symbol_tables_kernel_modules.insert(path, symbol_table);
} else {
simpleperf_symbol_tables_user.insert(path, symbol_table);
}
}
}
}
Expand Down Expand Up @@ -199,7 +201,8 @@ where
kernel_symbols,
kernel_image_mapping: None,
simpleperf_symbol_tables_user,
simpleperf_symbol_tables_kernel,
simpleperf_symbol_tables_kernel_image,
simpleperf_symbol_tables_kernel_modules,
pe_mappings: PeMappings::new(),
jit_category_manager: JitCategoryManager::new(),
fold_recursive_prefix: profile_creation_props.fold_recursive_prefix,
Expand Down Expand Up @@ -975,7 +978,6 @@ where
build_id: Option<&[u8]>,
path_slice: &[u8],
) {
let original_path = path_slice;
let path = std::str::from_utf8(path_slice).unwrap().to_string();
let build_id: Option<Vec<u8>> = match (build_id, self.kernel_symbols.as_ref()) {
(None, Some(kernel_symbols)) if kernel_symbols.base_avma == base_address => {
Expand All @@ -991,34 +993,46 @@ where
.map(|id| DebugId::from_identifier(id, self.endian == Endianness::LittleEndian));

let debug_path = match self.linux_version.as_deref() {
Some(linux_version) if path.starts_with("[kernel.kallsyms]") => {
Some(linux_version) if dso_key == DsoKey::Kernel => {
// Take a guess at the vmlinux debug file path.
format!("/usr/lib/debug/boot/vmlinux-{linux_version}")
}
_ => path.clone(),
};
let symbol_table = if let Some(symbols) =
self.simpleperf_symbol_tables_kernel.remove(original_path)
{
let symbols: Vec<_> = symbols
.into_iter()
.map(|s| fxprof_processed_profile::Symbol {
address: (s.vaddr - base_address) as u32,
size: Some(s.len),
name: s.name,
})
.collect();
Some(Arc::new(SymbolTable::new(symbols)))
} else {
match (&dso_key, &build_id, self.kernel_symbols.as_ref()) {
(DsoKey::Kernel, Some(build_id), Some(kernel_symbols))

let symbol_table = if dso_key == DsoKey::Kernel {
match (&build_id, self.kernel_symbols.as_ref()) {
(Some(build_id), Some(kernel_symbols))
if build_id == &kernel_symbols.build_id && kernel_symbols.base_avma != 0 =>
{
// Run `echo '0' | sudo tee /proc/sys/kernel/kptr_restrict` to get here without root.
Some(kernel_symbols.symbol_table.clone())
}
_ => None,
_ => {
if let Some(symbols) = self.simpleperf_symbol_tables_kernel_image.take() {
let symbols: Vec<_> = symbols
.into_iter()
.filter_map(|s| {
let address = s.vaddr.checked_sub(base_address)?;
let address = u32::try_from(address).ok()?;
let sym = fxprof_processed_profile::Symbol {
address,
size: Some(s.len),
name: s.name,
};
Some(sym)
})
.collect();
Some(Arc::new(SymbolTable::new(symbols)))
} else {
None
}
}
}
} else {
self.simpleperf_symbol_tables_kernel_modules
.get(path_slice)
.map(|s| s.symbol_table.clone())
};

let lib_handle = self.profile.add_lib(LibraryInfo {
Expand All @@ -1036,7 +1050,7 @@ where
self.profile
.add_kernel_lib_mapping(lib_handle, base_address, end_address, 0);

if path_slice == b"[kernel.kallsyms]" {
if dso_key == DsoKey::Kernel {
// Store information about this mapping so that we can later adjust the mapping,
// if we find that other kernel modules overlap with it.
self.kernel_image_mapping = Some(KernelImageMapping {
Expand Down Expand Up @@ -1139,14 +1153,16 @@ where
let relative_address_at_start = if let Some(file_offset_of_min_vaddr) =
&symbol_table.file_offset_of_min_vaddr_in_elf_file
{
let min_vaddr = symbol_table.min_vaddr;
// Example:
// - start_avma: 0x721e13c000
// - mapping_start_file_offset: 0x4535000
// - file_offset_of_min_vaddr: 0x45357e0
// - min_vaddr: 0x45367e0,
// println!("file_offset_of_min_vaddr={file_offset_of_min_vaddr:x}, mapping_start_file_offset={mapping_start_file_offset:x}, min_vaddr={min_vaddr:x}, path={path}");
let min_vaddr_offset_from_mapping_start =
file_offset_of_min_vaddr - mapping_start_file_offset;
let vaddr_at_start = symbol_table.min_vaddr - min_vaddr_offset_from_mapping_start;
file_offset_of_min_vaddr.wrapping_sub(mapping_start_file_offset);
let vaddr_at_start = min_vaddr.wrapping_sub(min_vaddr_offset_from_mapping_start);

// Assume vaddr = SVMA == relative address
vaddr_at_start as u32
Expand Down
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