This option was used to override the behavior of
`-fsanitize=shadowcallstack` on RISC-V backend, which by default use a
hardware implementation if possible, to use the software implementation
instead. After #112477 and #112478, now two implementation
is represented by independent options and we no longer need it.
This patch enable hardware shadow stack with `Zicifss` and
`mno-forced-sw-shadow-stack`. New feature forced-sw-shadow-stack
disables hardware shadow stack even when `Zicfiss` enabled.
Summary:
ShadowCallStack on x86_64 suffered from the same racy security issues as
Return Flow Guard and had performance overhead as high as 13% depending
on the benchmark. x86_64 ShadowCallStack was always an experimental
feature and never shipped a runtime required to support it, as such
there are no expected downstream users.
Reviewers: pcc
Reviewed By: pcc
Subscribers: mgorny, javed.absar, hiraditya, jdoerfert, cfe-commits, #sanitizers, llvm-commits
Tags: #clang, #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D59034
llvm-svn: 355624
- Remove most of the discussion of the x86_64 implementation;
link to an older version of the documentation for details of
that implementation.
- Add description of the compatibility and security issues discovered
during the development of the aarch64 implementation for Android.
Differential Revision: https://reviews.llvm.org/D58105
llvm-svn: 353890
The implementation of shadow call stack on aarch64 is quite different to
the implementation on x86_64. Instead of reserving a segment register for
the shadow call stack, we reserve the platform register, x18. Any function
that spills lr to sp also spills it to the shadow call stack, a pointer to
which is stored in x18.
Differential Revision: https://reviews.llvm.org/D45239
llvm-svn: 329236
Summary:
Add support for the -fsanitize=shadow-call-stack flag which causes clang
to add ShadowCallStack attribute to functions compiled with that flag
enabled.
Reviewers: pcc, kcc
Reviewed By: pcc, kcc
Subscribers: cryptoad, cfe-commits, kcc
Differential Revision: https://reviews.llvm.org/D44801
llvm-svn: 329122
