Auto merge of rust-lang#117895 - mzohreva:mz/fix-sgx-backtrace, r=Mark-Simulacrum

Adjust frame IP in backtraces relative to image base for SGX target

This is followup to rust-lang/backtrace-rs#566.

The backtraces printed by `panic!` or generated by `std::backtrace::Backtrace` in SGX target are not usable. The frame addresses need to be relative to image base address so they can be used for symbol resolution. Here's an example panic backtrace generated before this change:

```
$ cargo r --target x86_64-fortanix-unknown-sgx
...
stack backtrace:
   0:     0x7f8fe401d3a5 - <unknown>
   1:     0x7f8fe4034780 - <unknown>
   2:     0x7f8fe401c5a3 - <unknown>
   3:     0x7f8fe401d1f5 - <unknown>
   4:     0x7f8fe401e6f6 - <unknown>
```
Here's the same panic after this change:
```
$ cargo +stage1 r --target x86_64-fortanix-unknown-sgx
stack backtrace:
   0:            0x198bf - <unknown>
   1:            0x3d181 - <unknown>
   2:            0x26164 - <unknown>
   3:            0x19705 - <unknown>
   4:            0x1ef36 - <unknown>
```
cc `@jethrogb` and `@workingjubilee`

Author: bors

library/std/src/backtrace.rs

@@ -95,7 +95,7 @@ use crate::fmt;
 use crate::panic::UnwindSafe;
 use crate::sync::atomic::{AtomicUsize, Ordering::Relaxed};
 use crate::sync::LazyLock;
-use crate::sys_common::backtrace::{lock, output_filename};
+use crate::sys_common::backtrace::{lock, output_filename, set_image_base};
 use crate::vec::Vec;
 
 /// A captured OS thread stack backtrace.
@@ -327,6 +327,7 @@ impl Backtrace {
         let _lock = lock();
         let mut frames = Vec::new();
         let mut actual_start = None;
+        set_image_base();
         unsafe {
             backtrace_rs::trace_unsynchronized(|frame| {
                 frames.push(BacktraceFrame {

library/std/src/sys_common/backtrace.rs

@@ -64,6 +64,7 @@ unsafe fn _print_fmt(fmt: &mut fmt::Formatter<'_>, print_fmt: PrintFmt) -> fmt::
     let mut first_omit = true;
     // Start immediately if we're not using a short backtrace.
     let mut start = print_fmt != PrintFmt::Short;
+    set_image_base();
     backtrace_rs::trace_unsynchronized(|frame| {
         if print_fmt == PrintFmt::Short && idx > MAX_NB_FRAMES {
             return false;
@@ -213,3 +214,14 @@ pub fn output_filename(
     }
     fmt::Display::fmt(&file.display(), fmt)
 }
+
+#[cfg(all(target_vendor = "fortanix", target_env = "sgx"))]
+pub fn set_image_base() {
+    let image_base = crate::os::fortanix_sgx::mem::image_base();
+    backtrace_rs::set_image_base(crate::ptr::invalid_mut(image_base as _));
+}
+
+#[cfg(not(all(target_vendor = "fortanix", target_env = "sgx")))]
+pub fn set_image_base() {
+    // nothing to do for platforms other than SGX
+}