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🔒🌯 Provide LLVMTypeWrapper trait, add more safe wrappers #223

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🔒🌯 Provide LLVMTypeWrapper trait, add more safe wrappers #223

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69 changes: 41 additions & 28 deletions src/linker.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,18 +14,15 @@ use std::{
use ar::Archive;
use llvm_sys::{
bit_writer::LLVMWriteBitcodeToFile,
core::{
LLVMContextCreate, LLVMContextDispose, LLVMContextSetDiagnosticHandler, LLVMDisposeModule,
LLVMGetTarget,
},
core::{LLVMContextCreate, LLVMContextDispose, LLVMContextSetDiagnosticHandler, LLVMGetTarget},
error_handling::{LLVMEnablePrettyStackTrace, LLVMInstallFatalErrorHandler},
prelude::{LLVMContextRef, LLVMModuleRef},
prelude::LLVMContextRef,
target_machine::{LLVMCodeGenFileType, LLVMDisposeTargetMachine, LLVMTargetMachineRef},
};
use thiserror::Error;
use tracing::{debug, error, info, warn};

use crate::llvm;
use crate::llvm::{self, LLVMTypeError, LLVMTypeWrapper, Module};

/// Linker error
#[derive(Debug, Error)]
Expand Down Expand Up @@ -77,6 +74,10 @@ pub enum LinkerError {
/// The input object file does not have embedded bitcode.
#[error("no bitcode section found in {0}")]
MissingBitcodeSection(PathBuf),

/// Instantiating of an LLVM type failed.
#[error(transparent)]
LLVMType(#[from] LLVMTypeError),
}

/// BPF Cpu type
Expand Down Expand Up @@ -224,21 +225,26 @@ pub struct LinkerOptions {
}

/// BPF Linker
pub struct Linker {
pub struct Linker<'ctx> {
options: LinkerOptions,
context: LLVMContextRef,
module: LLVMModuleRef,
module: Module<'ctx>,
target_machine: LLVMTargetMachineRef,
diagnostic_handler: DiagnosticHandler,
}

impl Linker {
impl Linker<'_> {
/// Create a new linker instance with the given options.
pub fn new(options: LinkerOptions) -> Self {
let context = unsafe { LLVMContextCreate() };
let module = Module::new(
options.output.file_stem().unwrap().to_str().unwrap(),
context,
);
Linker {
options,
context: ptr::null_mut(),
module: ptr::null_mut(),
context,
module,
target_machine: ptr::null_mut(),
diagnostic_handler: DiagnosticHandler::new(),
}
Expand Down Expand Up @@ -365,7 +371,7 @@ impl Linker {
Archive => panic!("nested archives not supported duh"),
};

if unsafe { !llvm::link_bitcode_buffer(self.context, self.module, &bitcode) } {
if unsafe { !llvm::link_bitcode_buffer(self.context, self.module.as_ptr(), &bitcode) } {
return Err(LinkerError::LinkModuleError(path.to_owned()));
}

Expand Down Expand Up @@ -407,11 +413,11 @@ impl Linker {
})
}
None => {
let c_triple = unsafe { LLVMGetTarget(*module) };
let c_triple = unsafe { LLVMGetTarget(module.as_ptr()) };
let triple = unsafe { CStr::from_ptr(c_triple) }.to_str().unwrap();
if triple.starts_with("bpf") {
// case 2
(triple, unsafe { llvm::target_from_module(*module) })
(triple, unsafe { llvm::target_from_module(module.as_ptr()) })
} else {
// case 3.
info!("detected non-bpf input target {} and no explicit output --target specified, selecting `bpf'", triple);
Expand Down Expand Up @@ -452,17 +458,18 @@ impl Linker {

if self.options.btf {
// if we want to emit BTF, we need to sanitize the debug information
llvm::DISanitizer::new(self.context, self.module).run(&self.options.export_symbols);
llvm::DISanitizer::new(self.context, &self.module)
.run(&mut self.module, &self.options.export_symbols)?;
} else {
// if we don't need BTF emission, we can strip DI
let ok = unsafe { llvm::strip_debug_info(self.module) };
let ok = unsafe { llvm::strip_debug_info(self.module.as_ptr()) };
debug!("Stripping DI, changed={}", ok);
}

unsafe {
llvm::optimize(
self.target_machine,
self.module,
&mut self.module,
self.options.optimize,
self.options.ignore_inline_never,
&self.options.export_symbols,
Expand All @@ -486,7 +493,7 @@ impl Linker {
fn write_bitcode(&mut self, output: &CStr) -> Result<(), LinkerError> {
info!("writing bitcode to {:?}", output);

if unsafe { LLVMWriteBitcodeToFile(self.module, output.as_ptr()) } == 1 {
if unsafe { LLVMWriteBitcodeToFile(self.module.as_ptr(), output.as_ptr()) } == 1 {
return Err(LinkerError::WriteBitcodeError);
}

Expand All @@ -496,14 +503,21 @@ impl Linker {
fn write_ir(&mut self, output: &CStr) -> Result<(), LinkerError> {
info!("writing IR to {:?}", output);

unsafe { llvm::write_ir(self.module, output) }.map_err(LinkerError::WriteIRError)
unsafe { llvm::write_ir(self.module.as_ptr(), output) }.map_err(LinkerError::WriteIRError)
}

fn emit(&mut self, output: &CStr, output_type: LLVMCodeGenFileType) -> Result<(), LinkerError> {
info!("emitting {:?} to {:?}", output_type, output);

unsafe { llvm::codegen(self.target_machine, self.module, output, output_type) }
.map_err(LinkerError::EmitCodeError)
unsafe {
llvm::codegen(
self.target_machine,
self.module.as_ptr(),
output,
output_type,
)
}
.map_err(LinkerError::EmitCodeError)
}

fn llvm_init(&mut self) {
Expand Down Expand Up @@ -542,24 +556,23 @@ impl Linker {
);
LLVMInstallFatalErrorHandler(Some(llvm::fatal_error));
LLVMEnablePrettyStackTrace();
self.module = llvm::create_module(
self.module = Module::new(
self.options.output.file_stem().unwrap().to_str().unwrap(),
self.context,
)
.unwrap();
);
}
}
}

impl Drop for Linker {
impl Drop for Linker<'_> {
fn drop(&mut self) {
unsafe {
if !self.target_machine.is_null() {
LLVMDisposeTargetMachine(self.target_machine);
}
if !self.module.is_null() {
LLVMDisposeModule(self.module);
}
// if !self.module.is_null() {
// LLVMDisposeModule(self.module);
// }
if !self.context.is_null() {
LLVMContextDispose(self.context);
}
Expand Down
95 changes: 52 additions & 43 deletions src/llvm/di.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,18 +3,24 @@ use std::{
collections::{hash_map::DefaultHasher, HashMap, HashSet},
ffi::c_char,
hash::Hasher,
ptr,
ptr::{self, NonNull},
};

use gimli::{DW_TAG_pointer_type, DW_TAG_structure_type, DW_TAG_variant_part};
use llvm_sys::{core::*, debuginfo::*, prelude::*};
use tracing::{span, trace, warn, Level};

use super::types::{
di::DIType,
ir::{Function, MDNode, Metadata, Value},
use crate::llvm::{
iter::*,
types::{
di::{DISubprogram, DIType},
ir::{
Argument, Function, GlobalAlias, GlobalVariable, Instruction, MDNode, Metadata, Module,
Value,
},
LLVMTypeError, LLVMTypeWrapper,
},
};
use crate::llvm::{iter::*, types::di::DISubprogram};

// KSYM_NAME_LEN from linux kernel intentionally set
// to lower value found accross kernel versions to ensure
Expand All @@ -23,7 +29,6 @@ const MAX_KSYM_NAME_LEN: usize = 128;

pub struct DISanitizer {
context: LLVMContextRef,
module: LLVMModuleRef,
builder: LLVMDIBuilderRef,
visited_nodes: HashSet<u64>,
replace_operands: HashMap<u64, LLVMMetadataRef>,
Expand Down Expand Up @@ -59,11 +64,11 @@ fn sanitize_type_name<T: AsRef<str>>(name: T) -> String {
}

impl DISanitizer {
pub fn new(context: LLVMContextRef, module: LLVMModuleRef) -> DISanitizer {
pub fn new(context: LLVMContextRef, module: &Module<'_>) -> Self {
let builder = unsafe { LLVMCreateDIBuilder(module.as_ptr()) };
DISanitizer {
context,
module,
builder: unsafe { LLVMCreateDIBuilder(module) },
builder,
visited_nodes: HashSet::new(),
replace_operands: HashMap::new(),
skipped_types: Vec::new(),
Expand Down Expand Up @@ -227,7 +232,7 @@ impl DISanitizer {
// An operand with no value is valid and means that the operand is
// not set
(v, Item::Operand { .. }) if v.is_null() => return,
(v, _) if !v.is_null() => Value::new(v),
(v, _) if !v.is_null() => Value::from_ptr(NonNull::new(v).unwrap()).unwrap(),
// All other items should have values
(_, item) => panic!("{item:?} has no value"),
};
Expand Down Expand Up @@ -283,16 +288,18 @@ impl DISanitizer {
}
}

pub fn run(mut self, exported_symbols: &HashSet<Cow<'static, str>>) {
let module = self.module;
pub fn run(
mut self,
module: &mut Module<'_>,
exported_symbols: &HashSet<Cow<'static, str>>,
) -> Result<(), LLVMTypeError> {
self.replace_operands = self.fix_subprogram_linkage(module, exported_symbols)?;

self.replace_operands = self.fix_subprogram_linkage(exported_symbols);

for value in module.globals_iter() {
self.visit_item(Item::GlobalVariable(value));
for global in module.globals_iter() {
self.visit_item(Item::GlobalVariable(global));
}
for value in module.global_aliases_iter() {
self.visit_item(Item::GlobalAlias(value));
for alias in module.global_aliases_iter() {
self.visit_item(Item::GlobalAlias(alias));
}

for function in module.functions_iter() {
Expand All @@ -307,6 +314,8 @@ impl DISanitizer {
}

unsafe { LLVMDisposeDIBuilder(self.builder) };

Ok(())
}

// Make it so that only exported symbols (programs marked as #[no_mangle]) get BTF
Expand All @@ -324,16 +333,13 @@ impl DISanitizer {
// See tests/btf/assembly/exported-symbols.rs .
fn fix_subprogram_linkage(
&mut self,
module: &mut Module<'_>,
export_symbols: &HashSet<Cow<'static, str>>,
) -> HashMap<u64, LLVMMetadataRef> {
) -> Result<HashMap<u64, LLVMMetadataRef>, LLVMTypeError> {
let mut replace = HashMap::new();

for mut function in self
.module
.functions_iter()
.map(|value| unsafe { Function::from_value_ref(value) })
{
if export_symbols.contains(function.name()) {
for mut function in module.functions_iter() {
if export_symbols.contains(&function.name()) {
continue;
}

Expand Down Expand Up @@ -370,7 +376,10 @@ impl DISanitizer {
// replace retained nodes manually below.
LLVMDIBuilderFinalizeSubprogram(self.builder, new_program);

DISubprogram::from_value_ref(LLVMMetadataAsValue(self.context, new_program))
let new_program = LLVMMetadataAsValue(self.context, new_program);
let new_program =
NonNull::new(new_program).expect("new program should not be null");
DISubprogram::from_ptr(new_program)?
};

// Point the function to the new subprogram.
Expand All @@ -396,23 +405,23 @@ impl DISanitizer {
unsafe { LLVMMDNodeInContext2(self.context, core::ptr::null_mut(), 0) };
subprogram.set_retained_nodes(empty_node);

let ret = replace.insert(subprogram.value_ref as u64, unsafe {
LLVMValueAsMetadata(new_program.value_ref)
let ret = replace.insert(subprogram.as_ptr() as u64, unsafe {
LLVMValueAsMetadata(new_program.as_ptr())
});
assert!(ret.is_none());
}

replace
Ok(replace)
}
}

#[derive(Clone, Debug, Eq, PartialEq)]
enum Item {
GlobalVariable(LLVMValueRef),
GlobalAlias(LLVMValueRef),
Function(LLVMValueRef),
FunctionParam(LLVMValueRef),
Instruction(LLVMValueRef),
enum Item<'ctx> {
GlobalVariable(GlobalVariable<'ctx>),
GlobalAlias(GlobalAlias<'ctx>),
Function(Function<'ctx>),
FunctionParam(Argument<'ctx>),
Instruction(Instruction<'ctx>),
Operand(Operand),
MetadataEntry(LLVMValueRef, u32, usize),
}
Expand All @@ -437,16 +446,16 @@ impl Operand {
}
}

impl Item {
impl Item<'_> {
fn value_ref(&self) -> LLVMValueRef {
match self {
Item::GlobalVariable(value)
| Item::GlobalAlias(value)
| Item::Function(value)
| Item::FunctionParam(value)
| Item::Instruction(value)
| Item::Operand(Operand { value, .. })
| Item::MetadataEntry(value, _, _) => *value,
Item::GlobalVariable(global) => global.as_ptr(),
Item::GlobalAlias(global) => global.as_ptr(),
Item::Function(function) => function.as_ptr(),
Item::FunctionParam(function_param) => function_param.as_ptr(),
Item::Instruction(instruction) => instruction.as_ptr(),
Item::Operand(Operand { value, .. }) => *value,
Item::MetadataEntry(value, _, _) => *value,
}
}

Expand Down
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