commit 2c6069d3f8bb12ed6c61060191eefab8a236f7ac
author Abhinav Anil Sharma <sharmaabhinav@google.com> Thu Mar 28 16:56:03 2024
committer GitHub <noreply@github.com> Thu Mar 28 16:56:03 2024
tree 1e436797712234f0906560ad2278ee8d81e798d8
parent 98d55a6e4f0b516c9d1d914ce3c8e473cc70a6a5

i#6495: Handle invariant errors in x86 QEMU syscall templates (#6718)

Handles various invariant errors seen in system call trace templates
collected on x86 QEMU.

Modifies syscall trace template file format to use the
TRACE_MARKER_TYPE_SYSCALL_TRACE_START and
TRACE_MARKER_TYPE_SYSCALL_TRACE_END markers to show start and end
respectively of each syscall trace template, instead of separating them
using a TRACE_MARKER_TYPE_SYSCALL marker. This makes it easier to write
invariant checks that also work for the syscall trace template file (in
addition to an actual trace file injected with trace templates). Also adds
cache line size and page size markers to the template, similar to the
context switch sequence template file.

Handles cases where there are a different number of read/write records
than expected by the decoder; after iret, variants of xrstor, variants
of xsaves, and prefetch instrs.

Relaxes the PC discontinuity check after hlt, and within two instrs of
sti (which enables interrupts, so there may be an interrupt shortly
after, as empirically seen in some QEMU syscall trace templates).

Makes other misc changes to make sure the syscall trace template file
passes the invariant checker: add thread exit (since we already have a
thread start), relaxation of various invariant checks.

Adds and implements the instr_is_xrstor API that identifies variants of
the xrstor opcode, and adds supervisor versions of xsave to
instr_is_xsave.

Adds unit tests for these new scenarios. Added a TODO to handle other
arch equivalent versions of these scenarios.

Adds a new flag `-abort_on_invariant_error` which is true by default, to
allow the user to instruct the invariant checker to continue past
invariant errors (using `-no_abort_on_invariant_error`). This is helpful
since there are still a few instances of some invariant errors in the
syscall trace template that are harder to generalize and fix/ignore.

Issue: #6495