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Remove UninitializedUnwindContext #593

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merged 4 commits into from
Oct 7, 2021
Merged

Remove UninitializedUnwindContext #593

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fc9b2b5
Remove UninitializedUnwindContext
nbdd0121 Oct 6, 2021
31b21eb
Use `Self` as return type for ctors
nbdd0121 Oct 7, 2021
a3f31d7
Bump cargo fuzz version for CI
nbdd0121 Oct 7, 2021
270a76a
Fix fuzz
nbdd0121 Oct 7, 2021
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2 changes: 1 addition & 1 deletion .github/workflows/rust.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ jobs:
rustup install nightly
rustup default nightly
- name: Install `cargo fuzz`
run: cargo install cargo-fuzz --vers "^0.7.4"
run: cargo install cargo-fuzz --vers "^0.11.0"
- run: cargo fuzz build -Oa
- uses: actions/upload-artifact@v2
with:
Expand Down
10 changes: 5 additions & 5 deletions benches/bench.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -579,8 +579,8 @@ mod cfi {
use fallible_iterator::FallibleIterator;

use gimli::{
BaseAddresses, CieOrFde, EhFrame, FrameDescriptionEntry, LittleEndian,
UninitializedUnwindContext, UnwindSection,
BaseAddresses, CieOrFde, EhFrame, FrameDescriptionEntry, LittleEndian, UnwindContext,
UnwindSection,
};

#[bench]
Expand Down Expand Up @@ -677,7 +677,7 @@ mod cfi {
.set_got(0)
.set_text(0);

let mut ctx = UninitializedUnwindContext::new();
let mut ctx = Box::new(UnwindContext::new());

b.iter(|| {
let mut entries = eh_frame.entries(&bases);
Expand Down Expand Up @@ -773,7 +773,7 @@ mod cfi {
let fde = get_fde_with_longest_cfi_instructions(&eh_frame, &bases);

b.iter(|| {
let mut ctx = UninitializedUnwindContext::new();
let mut ctx = Box::new(UnwindContext::new());
let mut table = fde
.rows(&eh_frame, &bases, &mut ctx)
.expect("Should initialize the ctx OK");
Expand All @@ -793,7 +793,7 @@ mod cfi {
.set_text(0);
let fde = get_fde_with_longest_cfi_instructions(&eh_frame, &bases);

let mut ctx = UninitializedUnwindContext::new();
let mut ctx = Box::new(UnwindContext::new());

b.iter(|| {
let mut table = fde
Expand Down
4 changes: 2 additions & 2 deletions fuzz/fuzz_targets/eh_frame.rs
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Original file line number Diff line number Diff line change
@@ -1,15 +1,15 @@
#![no_main]

use gimli::{
read::{BaseAddresses, CieOrFde, EhFrame, UninitializedUnwindContext, UnwindSection},
read::{BaseAddresses, CieOrFde, EhFrame, UnwindContext, UnwindSection},
LittleEndian,
};
use libfuzzer_sys::fuzz_target;

fuzz_target!(|eh_frame: &[u8]| {
let eh_frame = EhFrame::new(&eh_frame, LittleEndian);

let mut ctx = UninitializedUnwindContext::new();
let mut ctx = Box::new(UnwindContext::new());
let bases = BaseAddresses::default()
.set_eh_frame(0)
.set_eh_frame_hdr(0)
Expand Down
117 changes: 48 additions & 69 deletions src/read/cfi.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@
use alloc::boxed::Box;
use core::cmp::{Ord, Ordering};
use core::fmt::Debug;
use core::iter::FromIterator;
Expand Down Expand Up @@ -373,7 +372,7 @@ impl<'a, R: Reader + 'a> EhHdrTable<'a, R> {
&self,
frame: &EhFrame<R>,
bases: &BaseAddresses,
ctx: &'ctx mut UninitializedUnwindContext<R>,
ctx: &'ctx mut UnwindContext<R>,
address: u64,
get_cie: F,
) -> Result<&'ctx UnwindTableRow<R>>
Expand Down Expand Up @@ -637,7 +636,7 @@ pub trait UnwindSection<R: Reader>: Clone + Debug + _UnwindSectionPrivate<R> {
/// CFI evaluation fails, the error is returned.
///
/// ```
/// use gimli::{BaseAddresses, EhFrame, EndianSlice, NativeEndian, UninitializedUnwindContext,
/// use gimli::{BaseAddresses, EhFrame, EndianSlice, NativeEndian, UnwindContext,
/// UnwindSection};
///
/// # fn foo() -> gimli::Result<()> {
Expand All @@ -651,7 +650,7 @@ pub trait UnwindSection<R: Reader>: Clone + Debug + _UnwindSectionPrivate<R> {
/// let address = get_frame_pc();
///
/// // This context is reusable, which cuts down on heap allocations.
/// let ctx = UninitializedUnwindContext::new();
/// let ctx = UnwindContext::new();
///
/// // Optionally provide base addresses for any relative pointers. If a
/// // base address isn't provided and a pointer is found that is relative to
Expand Down Expand Up @@ -679,7 +678,7 @@ pub trait UnwindSection<R: Reader>: Clone + Debug + _UnwindSectionPrivate<R> {
fn unwind_info_for_address<'ctx, F>(
&self,
bases: &BaseAddresses,
ctx: &'ctx mut UninitializedUnwindContext<R>,
ctx: &'ctx mut UnwindContext<R>,
address: u64,
get_cie: F,
) -> Result<&'ctx UnwindTableRow<R>>
Expand Down Expand Up @@ -1611,7 +1610,7 @@ impl<R: Reader> FrameDescriptionEntry<R> {
&self,
section: &'a Section,
bases: &'a BaseAddresses,
ctx: &'ctx mut UninitializedUnwindContext<R>,
ctx: &'ctx mut UnwindContext<R>,
) -> Result<UnwindTable<'a, 'ctx, R>> {
UnwindTable::new(section, bases, ctx, self)
}
Expand All @@ -1626,7 +1625,7 @@ impl<R: Reader> FrameDescriptionEntry<R> {
&self,
section: &Section,
bases: &BaseAddresses,
ctx: &'ctx mut UninitializedUnwindContext<R>,
ctx: &'ctx mut UnwindContext<R>,
address: u64,
) -> Result<&'ctx UnwindTableRow<R>> {
let mut table = self.rows(section, bases, ctx)?;
Expand Down Expand Up @@ -1733,25 +1732,23 @@ impl<R: Reader> FrameDescriptionEntry<R> {
}
}

const MAX_UNWIND_STACK_DEPTH: usize = 4;

/// Common context needed when evaluating the call frame unwinding information.
///
/// This structure can be large so it is advisable to place it on the heap.
/// To avoid re-allocating the context multiple times when evaluating multiple
/// CFI programs, it can be reused. At first, a context is uninitialized
/// (`UninitializedUnwindContext`). It can be initialized by providing the
/// `CommonInformationEntry` for the CFI program about to be evaluated and
/// calling `UninitializedUnwindContext::initialize`. The result is a `&mut UnwindContext`
/// which borrows the uninitialized context, and can be used to evaluate and run a
/// `FrameDescriptionEntry`'s CFI program.
/// CFI programs, it can be reused.
///
/// ```
/// use gimli::{UninitializedUnwindContext, UnwindTable};
/// use gimli::{UnwindContext, UnwindTable};
///
/// # fn foo<'a>(some_fde: gimli::FrameDescriptionEntry<gimli::EndianSlice<'a, gimli::LittleEndian>>)
/// # -> gimli::Result<()> {
/// # let eh_frame: gimli::EhFrame<_> = unreachable!();
/// # let bases = unimplemented!();
/// // An uninitialized context.
/// let mut ctx = UninitializedUnwindContext::new();
/// let mut ctx = Box::new(UnwindContext::new());
///
/// // Initialize the context by evaluating the CIE's initial instruction program,
/// // and generate the unwind table.
Expand All @@ -1763,50 +1760,6 @@ impl<R: Reader> FrameDescriptionEntry<R> {
/// # unreachable!()
/// # }
/// ```
#[derive(Clone, Debug)]
pub struct UninitializedUnwindContext<R: Reader>(Box<UnwindContext<R>>);

impl<R: Reader> UninitializedUnwindContext<R> {
/// Construct a new call frame unwinding context.
pub fn new() -> UninitializedUnwindContext<R> {
UninitializedUnwindContext(Box::new(UnwindContext::new()))
}
}

impl<R: Reader> Default for UninitializedUnwindContext<R> {
fn default() -> Self {
Self::new()
}
}

/// # Signal Safe Methods
///
/// These methods are guaranteed not to allocate, acquire locks, or perform any
/// other signal-unsafe operations.
impl<R: Reader> UninitializedUnwindContext<R> {
/// Run the CIE's initial instructions, creating and return an
/// `UnwindContext`.
pub fn initialize<Section: UnwindSection<R>>(
&mut self,
section: &Section,
bases: &BaseAddresses,
cie: &CommonInformationEntry<R>,
) -> Result<&mut UnwindContext<R>> {
if self.0.is_initialized {
self.0.reset();
}

let mut table = UnwindTable::new_for_cie(section, bases, &mut self.0, cie);
while let Some(_) = table.next_row()? {}

self.0.save_initial_rules();
Ok(&mut self.0)
}
}

const MAX_UNWIND_STACK_DEPTH: usize = 4;

/// An unwinding context.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct UnwindContext<R: Reader> {
// Stack of rows. The last row is the row currently being built by the
Expand All @@ -1824,12 +1777,19 @@ pub struct UnwindContext<R: Reader> {
is_initialized: bool,
}

impl<R: Reader> Default for UnwindContext<R> {
fn default() -> Self {
Self::new()
}
}

/// # Signal Safe Methods
///
/// These methods are guaranteed not to allocate, acquire locks, or perform any
/// other signal-unsafe operations.
impl<R: Reader> UnwindContext<R> {
fn new() -> UnwindContext<R> {
/// Construct a new call frame unwinding context.
pub fn new() -> Self {
let mut ctx = UnwindContext {
stack: Default::default(),
is_initialized: false,
Expand All @@ -1839,6 +1799,24 @@ impl<R: Reader> UnwindContext<R> {
ctx
}

/// Run the CIE's initial instructions and initialize this `UnwindContext`.
fn initialize<Section: UnwindSection<R>>(
&mut self,
section: &Section,
bases: &BaseAddresses,
cie: &CommonInformationEntry<R>,
) -> Result<()> {
if self.is_initialized {
self.reset();
}

let mut table = UnwindTable::new_for_cie(section, bases, self, cie);
while let Some(_) = table.next_row()? {}

self.save_initial_rules();
Ok(())
}

fn reset(&mut self) {
self.stack.clear();
let res = self.stack.try_push(UnwindTableRow::default());
Expand Down Expand Up @@ -1997,10 +1975,10 @@ impl<'a, 'ctx, R: Reader> UnwindTable<'a, 'ctx, R> {
pub fn new<Section: UnwindSection<R>>(
section: &'a Section,
bases: &'a BaseAddresses,
ctx: &'ctx mut UninitializedUnwindContext<R>,
ctx: &'ctx mut UnwindContext<R>,
fde: &FrameDescriptionEntry<R>,
) -> Result<UnwindTable<'a, 'ctx, R>> {
let ctx = ctx.initialize(section, bases, fde.cie())?;
) -> Result<Self> {
ctx.initialize(section, bases, fde.cie())?;
Ok(Self::new_for_fde(section, bases, ctx, fde))
}

Expand All @@ -2009,7 +1987,7 @@ impl<'a, 'ctx, R: Reader> UnwindTable<'a, 'ctx, R> {
bases: &'a BaseAddresses,
ctx: &'ctx mut UnwindContext<R>,
fde: &FrameDescriptionEntry<R>,
) -> UnwindTable<'a, 'ctx, R> {
) -> Self {
assert!(ctx.stack.len() >= 1);
UnwindTable {
code_alignment_factor: Wrapping(fde.cie().code_alignment_factor()),
Expand All @@ -2028,7 +2006,7 @@ impl<'a, 'ctx, R: Reader> UnwindTable<'a, 'ctx, R> {
bases: &'a BaseAddresses,
ctx: &'ctx mut UnwindContext<R>,
cie: &CommonInformationEntry<R>,
) -> UnwindTable<'a, 'ctx, R> {
) -> Self {
assert!(ctx.stack.len() >= 1);
UnwindTable {
code_alignment_factor: Wrapping(cie.code_alignment_factor()),
Expand Down Expand Up @@ -3320,6 +3298,7 @@ mod tests {
EndianSlice, Error, Expression, Pointer, ReaderOffsetId, Result, Section as ReadSection,
};
use crate::test_util::GimliSectionMethods;
use alloc::boxed::Box;
use alloc::vec::Vec;
use core::marker::PhantomData;
use core::mem;
Expand Down Expand Up @@ -5479,8 +5458,8 @@ mod tests {

let section = &DebugFrame::from(EndianSlice::default());
let bases = &BaseAddresses::default();
let mut ctx = UninitializedUnwindContext::new();
ctx.0.assert_fully_uninitialized();
let mut ctx = Box::new(UnwindContext::new());
ctx.assert_fully_uninitialized();

let mut table = fde
.rows(section, bases, &mut ctx)
Expand Down Expand Up @@ -5679,7 +5658,7 @@ mod tests {

// Get the second row of the unwind table in `instrs3`.
let bases = Default::default();
let mut ctx = UninitializedUnwindContext::new();
let mut ctx = Box::new(UnwindContext::new());
let result = debug_frame.unwind_info_for_address(
&bases,
&mut ctx,
Expand Down Expand Up @@ -5708,7 +5687,7 @@ mod tests {
fn test_unwind_info_for_address_not_found() {
let debug_frame = DebugFrame::new(&[], NativeEndian);
let bases = Default::default();
let mut ctx = UninitializedUnwindContext::new();
let mut ctx = Box::new(UnwindContext::new());
let result = debug_frame.unwind_info_for_address(
&bases,
&mut ctx,
Expand Down