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Attempt to backtrace through jit frames on x86_64 Windows #274

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Merged
merged 1 commit into from
Jan 15, 2020
Merged

Attempt to backtrace through jit frames on x86_64 Windows #274

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33 changes: 29 additions & 4 deletions src/backtrace/dbghelp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,31 @@ pub unsafe fn trace(cb: &mut FnMut(&super::Frame) -> bool) {
Err(()) => return, // oh well...
};

// On x86_64 and ARM64 we opt to not use the default `Sym*` functions from
// dbghelp for getting the function table and module base. Instead we use
// the `RtlLookupFunctionEntry` function in kernel32 which will account for
// JIT compiler frames as well. These should be equivalent, but using
// `Rtl*` allows us to backtrace through JIT frames.
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Just thinking that we should perhaps mention that this is limited to in-process walking only, which is fine for backtrace's use case.

cfg_if::cfg_if! {
if #[cfg(target_pointer_width = "64")] {
use core::ptr;

unsafe extern "system" fn function_table_access(_process: HANDLE, addr: DWORD64) -> PVOID {
let mut base = 0;
RtlLookupFunctionEntry(addr, &mut base, ptr::null_mut()).cast()
}

unsafe extern "system" fn get_module_base(_process: HANDLE, addr: DWORD64) -> DWORD64 {
let mut base = 0;
RtlLookupFunctionEntry(addr, &mut base, ptr::null_mut());
base
}
} else {
let function_table_access = dbghelp.SymFunctionTableAccess64();
let get_module_base = dbghelp.SymGetModuleBase64();
}
}

// Attempt to use `StackWalkEx` if we can, but fall back to `StackWalk64`
// since it's in theory supported on more systems.
match (*dbghelp.dbghelp()).StackWalkEx() {
Expand All @@ -113,8 +138,8 @@ pub unsafe fn trace(cb: &mut FnMut(&super::Frame) -> bool) {
frame_ptr,
&mut context.0 as *mut CONTEXT as *mut _,
None,
Some(dbghelp.SymFunctionTableAccess64()),
Some(dbghelp.SymGetModuleBase64()),
Some(function_table_access),
Some(get_module_base),
None,
0,
) == TRUE
Expand All @@ -141,8 +166,8 @@ pub unsafe fn trace(cb: &mut FnMut(&super::Frame) -> bool) {
frame_ptr,
&mut context.0 as *mut CONTEXT as *mut _,
None,
Some(dbghelp.SymFunctionTableAccess64()),
Some(dbghelp.SymGetModuleBase64()),
Some(function_table_access),
Some(get_module_base),
None,
) == TRUE
{
Expand Down
19 changes: 19 additions & 0 deletions src/windows.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,10 @@ cfg_if::cfg_if! {
pub use self::winapi::HINSTANCE;
pub use self::winapi::FARPROC;
pub use self::winapi::LPSECURITY_ATTRIBUTES;
#[cfg(target_pointer_width = "64")]
pub use self::winapi::PUNWIND_HISTORY_TABLE;
#[cfg(target_pointer_width = "64")]
pub use self::winapi::PRUNTIME_FUNCTION;

mod winapi {
pub use winapi::ctypes::*;
Expand All @@ -35,6 +39,10 @@ cfg_if::cfg_if! {
pub type HINSTANCE = *mut c_void;
pub type FARPROC = *mut c_void;
pub type LPSECURITY_ATTRIBUTES = *mut c_void;
#[cfg(target_pointer_width = "64")]
pub type PRUNTIME_FUNCTION = *mut c_void;
#[cfg(target_pointer_width = "64")]
pub type PUNWIND_HISTORY_TABLE = *mut c_void;
}
}

Expand Down Expand Up @@ -374,6 +382,17 @@ ffi! {
}
}

#[cfg(target_pointer_width = "64")]
ffi! {
extern "system" {
pub fn RtlLookupFunctionEntry(
ControlPc: DWORD64,
ImageBase: PDWORD64,
HistoryTable: PUNWIND_HISTORY_TABLE,
) -> PRUNTIME_FUNCTION;
}
}

#[cfg(target_arch = "aarch64")]
ffi! {
#[repr(C, align(16))]
Expand Down