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* Preserve full native stack traces in errors This commit builds on #759 by performing a few refactorings: * The `backtrace` crate is updated to 0.3.42 which incorporates the Windows-specific stack-walking code, so that's no longer needed. * A full `backtrace::Backtrace` type is held in a trap at all times. * The trap structures in the `wasmtime-*` internal crates were refactored a bit to preserve more information and deal with raw values rather than converting between various types and strings. * The `wasmtime::Trap` type has been updated with these various changes. Eventually I think we'll want to likely render full stack traces (and/or partial wasm ones) into error messages, but for now that's left as-is and we can always improve it later. I suspect the most relevant thing we need to do is to implement function name symbolication for wasm functions first, and then afterwards we can incorporate native function names! * Fix some test suite assertionspull/825/head
Alex Crichton
5 years ago
committed by
GitHub
GitHub
12 changed files with 89 additions and 239 deletions
@ -1,148 +0,0 @@ |
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//! Backtrace object and utilities.
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use crate::jit_function_registry; |
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use std::sync::Arc; |
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/// Information about backtrace frame.
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#[derive(Debug, Copy, Clone, PartialEq, Eq)] |
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pub struct BacktraceFrame { |
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pc: usize, |
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} |
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impl Default for BacktraceFrame { |
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fn default() -> Self { |
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Self { pc: 0 } |
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} |
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} |
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impl BacktraceFrame { |
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/// Current PC or IP pointer for the frame.
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pub fn pc(&self) -> usize { |
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self.pc |
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} |
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/// Additinal frame information.
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pub fn tag(&self) -> Option<Arc<jit_function_registry::JITFunctionTag>> { |
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jit_function_registry::find(self.pc) |
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} |
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} |
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const BACKTRACE_LIMIT: usize = 32; |
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/// Backtrace during WebAssembly trap.
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#[derive(Copy, Clone, PartialEq, Eq)] |
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pub struct Backtrace { |
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len: usize, |
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frames: [BacktraceFrame; BACKTRACE_LIMIT], |
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} |
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impl Backtrace { |
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fn new() -> Self { |
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Self { |
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len: 0, |
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frames: [Default::default(); BACKTRACE_LIMIT], |
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} |
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} |
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fn full(&self) -> bool { |
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self.len >= BACKTRACE_LIMIT |
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} |
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fn push(&mut self, frame: BacktraceFrame) { |
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assert!(self.len < BACKTRACE_LIMIT); |
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self.frames[self.len] = frame; |
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self.len += 1; |
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} |
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/// Amount of the backtrace frames.
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pub fn len(&self) -> usize { |
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self.len |
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} |
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} |
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impl std::ops::Index<usize> for Backtrace { |
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type Output = BacktraceFrame; |
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fn index(&self, index: usize) -> &Self::Output { |
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assert!(index < self.len); |
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&self.frames[index] |
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} |
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} |
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impl std::fmt::Debug for Backtrace { |
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { |
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writeln!(f, "Backtrace![")?; |
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for i in 0..self.len() { |
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let frame = &self.frames[i]; |
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writeln!(f, " {:x}: {:?}", frame.pc(), frame.tag())?; |
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} |
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write!(f, "]")?; |
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Ok(()) |
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} |
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} |
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#[cfg(not(all(target_os = "windows", target_arch = "x86_64")))] |
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fn capture_stack<F>(mut f: F) |
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where |
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F: FnMut(usize) -> bool, |
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{ |
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use backtrace::trace; |
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trace(|frame| { |
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let pc = frame.ip() as usize; |
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f(pc) |
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}); |
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} |
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#[cfg(all(target_os = "windows", target_arch = "x86_64"))] |
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fn capture_stack<F>(mut f: F) |
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where |
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F: FnMut(usize) -> bool, |
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{ |
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use std::mem::MaybeUninit; |
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use std::ptr; |
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use winapi::um::winnt::{ |
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RtlCaptureContext, RtlLookupFunctionEntry, RtlVirtualUnwind, CONTEXT, UNW_FLAG_NHANDLER, |
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}; |
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#[repr(C, align(16))] |
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struct WrappedContext(CONTEXT); |
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unsafe { |
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let mut ctx = WrappedContext(MaybeUninit::uninit().assume_init()); |
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RtlCaptureContext(&mut ctx.0); |
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let mut unwind_history_table = MaybeUninit::zeroed().assume_init(); |
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while ctx.0.Rip != 0 { |
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let cont = f(ctx.0.Rip as usize); |
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if !cont { |
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break; |
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} |
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let mut image_base: u64 = 0; |
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let mut handler_data: *mut core::ffi::c_void = ptr::null_mut(); |
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let mut establisher_frame: u64 = 0; |
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let rf = RtlLookupFunctionEntry(ctx.0.Rip, &mut image_base, &mut unwind_history_table); |
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if rf.is_null() { |
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ctx.0.Rip = ptr::read(ctx.0.Rsp as *const u64); |
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ctx.0.Rsp += 8; |
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} else { |
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RtlVirtualUnwind( |
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UNW_FLAG_NHANDLER, |
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image_base, |
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ctx.0.Rip, |
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rf, |
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&mut ctx.0, |
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&mut handler_data, |
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&mut establisher_frame, |
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ptr::null_mut(), |
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); |
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} |
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} |
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} |
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} |
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/// Returns current backtrace. Only registered wasmtime functions will be listed.
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pub fn get_backtrace() -> Backtrace { |
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let mut frames = Backtrace::new(); |
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capture_stack(|pc| { |
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if let Some(_) = jit_function_registry::find(pc) { |
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frames.push(BacktraceFrame { pc }); |
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} |
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!frames.full() |
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}); |
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frames |
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} |
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