Support -fstack-clash-protection for x86
Implement protection against the stack clash attack [0] through inline stack
probing.
Probe stack allocation every PAGE_SIZE during frame lowering or dynamic
allocation to make sure the page guard, if any, is touched when touching the
stack, in a similar manner to GCC[1].
This extends the existing `probe-stack' mechanism with a special value `inline-asm'.
Technically the former uses function call before stack allocation while this
patch provides inlined stack probes and chunk allocation.
Only implemented for x86.
[0] https://www.qualys.com/2017/06/19/stack-clash/stack-clash.txt
[1] https://gcc.gnu.org/ml/gcc-patches/2017-07/msg00556.html
This a recommit of 39f50da2a357a8f685b3540246c5d762734e035f with proper LiveIn
declaration, better option handling and more portable testing.
Differential Revision: https://reviews.llvm.org/D68720
diff --git a/clang/docs/ClangCommandLineReference.rst b/clang/docs/ClangCommandLineReference.rst
index 24c8ee2..609e7fa 100644
--- a/clang/docs/ClangCommandLineReference.rst
+++ b/clang/docs/ClangCommandLineReference.rst
@@ -1917,6 +1917,10 @@
Emit section containing metadata on function stack sizes
+.. option:: -fstack-clash-protection, -fno-stack-clash-protection
+
+Instrument stack allocation to prevent stack clash attacks (x86, non-Windows only).
+
.. option:: -fstandalone-debug, -fno-limit-debug-info, -fno-standalone-debug
Emit full debug info for all types used by the program