diff options
Diffstat (limited to 'llvm/docs')
| -rw-r--r-- | llvm/docs/CFIVerify.rst | 20 | ||||
| -rw-r--r-- | llvm/docs/RISCVUsage.rst | 2 |
2 files changed, 11 insertions, 11 deletions
diff --git a/llvm/docs/CFIVerify.rst b/llvm/docs/CFIVerify.rst index 6403347..f766be1 100644 --- a/llvm/docs/CFIVerify.rst +++ b/llvm/docs/CFIVerify.rst @@ -10,7 +10,7 @@ Objective This document provides an overview of an external tool to verify the protection mechanisms implemented by Clang's *Control Flow Integrity* (CFI) schemes -(``-fsanitize=cfi``). This tool, provided a binary or DSO, should infer whether +(``-fsanitize=cfi``). This tool, given a binary or DSO, should infer whether indirect control flow operations are protected by CFI, and should output these results in a human-readable form. @@ -22,12 +22,12 @@ Location ======== This tool will be present as a part of the LLVM toolchain, and will reside in -the "/llvm/tools/llvm-cfi-verify" directory, relative to the LLVM trunk. It will +the ``/llvm/tools/llvm-cfi-verify`` directory, relative to the LLVM trunk. It will be tested in two methods: - Unit tests to validate code sections, present in - "/llvm/unittests/tools/llvm-cfi-verify". -- Integration tests, present in "/llvm/tools/clang/test/LLVMCFIVerify". These + ``/llvm/unittests/tools/llvm-cfi-verify``. +- Integration tests, present in ``/llvm/tools/clang/test/LLVMCFIVerify``. These integration tests are part of clang as part of a continuous integration framework, ensuring updates to the compiler that reduce CFI coverage on indirect control flow instructions are identified. @@ -38,16 +38,16 @@ Background This tool will continuously validate that CFI directives are properly implemented around all indirect control flows by analysing the output machine code. The analysis of machine code is important as it ensures that any bugs -present in linker or compiler do not subvert CFI protections in the final +present in the linker or compiler do not subvert CFI protections in the final shipped binary. Unprotected indirect control flow instructions will be flagged for manual -review. These unexpected control flows may simply have not been accounted for in -the compiler implementation of CFI (e.g. indirect jumps to facilitate switch +review. These unexpected control flows may not have been accounted for in +the compiler implementation of CFI (e.g., indirect jumps to facilitate switch statements may not be fully protected). It may be possible in the future to extend this tool to flag unnecessary CFI -directives (e.g. CFI directives around a static call to a non-polymorphic base +directives (e.g., CFI directives around a static call to a non-polymorphic base type). This type of directive has no security implications, but may present performance impacts. @@ -66,7 +66,7 @@ the disassembly. A control flow graph would be generated from a small buffer of the instructions surrounding the 'target' control flow instruction. If the target instruction is branched-to, the fallthrough of the branch should be the CFI trap (on x86, this is a ``ud2`` instruction). If the target instruction is -the fallthrough (i.e. immediately succeeds) of a conditional jump, the +the fallthrough (i.e., immediately succeeds) of a conditional jump, the conditional jump target should be the CFI trap. If an indirect control flow instruction does not conform to one of these formats, the target will be noted as being CFI-unprotected. @@ -76,7 +76,7 @@ fallthrough of a conditional jump), if the target represents a vcall that takes arguments, these arguments may be pushed to the stack after the branch but before the target instruction. In these cases, a secondary 'spill graph' in constructed, to ensure the register argument used by the indirect jump/call is -not spilled from the stack at any point in the interim period. If there are no +not spilled from the stack at any point in the interim. If there are no spills that affect the target register, the target is marked as CFI-protected. Other Design Notes diff --git a/llvm/docs/RISCVUsage.rst b/llvm/docs/RISCVUsage.rst index f9e2e4a..49184e3 100644 --- a/llvm/docs/RISCVUsage.rst +++ b/llvm/docs/RISCVUsage.rst @@ -334,7 +334,7 @@ LLVM supports (to various degrees) a number of experimental extensions. All exp The primary goal of experimental support is to assist in the process of ratification by providing an existence proof of an implementation, and simplifying efforts to validate the value of a proposed extension against large code bases. Experimental extensions are expected to either transition to ratified status, or be eventually removed. The decision on whether to accept an experimental extension is currently done on an entirely case by case basis; if you want to propose one, attending the bi-weekly RISC-V sync-up call is strongly advised. ``experimental-zalasr`` - LLVM implements the `0.0.5 draft specification <https://github.com/mehnadnerd/riscv-zalasr>`__. + LLVM implements the `0.9 draft specification <https://github.com/riscv/riscv-zalasr/releases/tag/v0.9>`__. ``experimental-zibi`` LLVM implements the `0.1 release specification <https://github.com/riscv/zibi/releases/tag/v0.1.0>`__. |