Backport commits to support Control Flow Guard #61
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Summary: A new function pass (Transforms/CFGuard/CFGuard.cpp) inserts CFGuard checks on indirect function calls, using either the check mechanism (X86, ARM, AArch64) or or the dispatch mechanism (X86-64). The check mechanism requires a new calling convention for the supported targets. The dispatch mechanism adds the target as an operand bundle, which is processed by SelectionDAG. Another pass (CodeGen/CFGuardLongjmp.cpp) identifies and emits valid longjmp targets, as required by /guard:cf. This feature is enabled using the `cfguard` CC1 option. Reviewers: thakis, rnk, theraven, pcc Subscribers: ychen, hans, metalcanine, dmajor, tomrittervg, alex, mehdi_amini, mgorny, javed.absar, kristof.beyls, hiraditya, steven_wu, dexonsmith, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D65761
Ran:
git show --diff-filter=A --stat d157a9b | grep '|' | \
awk '{ print $1 }' | xargs dos2unix
AL is only used for varargs on SysV platforms. Don't forward it on Windows. This allows control flow guard to set up an extra hidden parameter in RAX, as described in PR44049. This also has the effect of freeing up RAX for use in virtual member pointer thunks, which may also be a nice little code size improvement on Win64. Fixes PR44049 Reviewers: ajpaverd, efriedma, hans Differential Revision: https://reviews.llvm.org/D70413
Summary: Avoid using the `nocf_check` attribute with Control Flow Guard. Instead, use a new `"guard_nocf"` function attribute to indicate that checks should not be added on indirect calls within that function. Add support for `__declspec(guard(nocf))` following the same syntax as MSVC. Reviewers: rnk, dmajor, pcc, hans, aaron.ballman Reviewed By: aaron.ballman Subscribers: aaron.ballman, tomrittervg, hiraditya, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D72167
8 tasks
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FYI, the LLVM 10 upgrade in rust-lang/rust#67759 is finally queued to merge, which I suppose will make this PR moot. |
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Ok, we've now landed on LLVM 10! Please open a new PR if there's anything else you need. |
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Apr 27, 2023
61: Fix changes to stackmaps made by the register allocator. r=ltratt a=ptersilie Co-authored-by: Lukas Diekmann <lukas.diekmann@gmail.com>
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These commits from LLVM 10.0 are required to enable Windows Control Flow Guard (CFG). CFG is an exploit mitigation technology on Microsoft Windows to limit the available targets of indirect jumps. This provides security benefits when Rust is linked against C/C++ code.
Rustc currently supports the
-Z control_flow_guardoption to emit the necessary LLVM module flags. These commits enable LLVM to add the necessary CFG functionality when the module flags are present.Rust tracking issue: rust-lang/rust#68793
CFG documentation: https://docs.microsoft.com/en-us/windows/win32/secbp/control-flow-guard