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Fix some minor issues with the explorer command (#5988)

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This commit fixes a few minor issues that Nick and I ran into walking
through some code with the `wasmtime explore` command:

* When a new function is reached the address map iterator is advanced
  past the prior function to avoid accidentally attributing instructions
  across functions.

* A `<` comparison was changed to `<=` to fix some off-by-one
  attributions from instructions to wasm instructions.

* The `skipdata` option is enabled in Capstone to avoid truncating
  AArch64 disassemblies too early.
This commit is contained in:
Alex Crichton
2023-03-10 20:31:31 -06:00
committed by GitHub
parent 9ed441e657
commit af7ef8df9a
1 changed files with 18 additions and 4 deletions
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22
crates/explorer/src/lib.rs
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@@ -111,9 +111,17 @@ fn annotate_asm(
let mut address_map_iter = address_map.into_iter().peekable();
let mut current_entry = address_map_iter.next();
let mut wasm_offset_for_address = |address: u32| -> Option<WasmOffset> {
let mut wasm_offset_for_address = |start: usize, address: u32| -> Option<WasmOffset> {
// Consume any entries that happened before the current function for the
// first instruction.
while current_entry.map_or(false, |cur| cur.0 < start) {
current_entry = address_map_iter.next();
}
// Next advance the address map up to the current `address` specified,
// including it.
while address_map_iter.peek().map_or(false, |next_entry| {
u32::try_from(next_entry.0).unwrap() < address
u32::try_from(next_entry.0).unwrap() <= address
}) {
current_entry = address_map_iter.next();
}
@@ -126,7 +134,7 @@ fn annotate_asm(
.map(|(start, len)| {
let body = &text[start..][..len];
let cs = match target.architecture {
let mut cs = match target.architecture {
target_lexicon::Architecture::Aarch64(_) => capstone::Capstone::new()
.arm64()
.mode(capstone::arch::arm64::ArchMode::Arm)
@@ -150,6 +158,12 @@ fn annotate_asm(
_ => anyhow::bail!("Unsupported target: {target}"),
};
// This tells capstone to skip over anything that looks like data,
// such as inline constant pools and things like that. This also
// additionally is required to skip over trapping instructions on
// AArch64.
cs.set_skipdata(true).unwrap();
let instructions = cs
.disasm_all(body, start as u64)
.map_err(|e| anyhow::anyhow!("{e}"))?;
@@ -157,7 +171,7 @@ fn annotate_asm(
.iter()
.map(|inst| {
let address = u32::try_from(inst.address()).unwrap();
let wasm_offset = wasm_offset_for_address(address);
let wasm_offset = wasm_offset_for_address(start, address);
Ok(AnnotatedInstruction {
wasm_offset,
address,