[llvm] r347588 - Revert "[clang][slh] add attribute for speculative load hardening"

[Zola Bridges via llvm-commits]

Author: zbrid
Date: Mon Nov 26 12:11:18 2018
New Revision: 347588

URL: http://llvm.org/viewvc/llvm-project?rev=347588&view=rev
Log:
Revert "[clang][slh] add attribute for speculative load hardening"

This reverts commit 801eaf91221ba6dd6996b29ff82659ad6359e885.

Modified:
    llvm/trunk/docs/LangRef.rst

Modified: llvm/trunk/docs/LangRef.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=347588&r1=347587&r2=347588&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.rst (original)
+++ llvm/trunk/docs/LangRef.rst Mon Nov 26 12:11:18 2018
@@ -1643,15 +1643,19 @@ example:
 ``speculative_load_hardening``
     This attribute indicates that
     `Speculative Load Hardening <https://llvm.org/docs/SpeculativeLoadHardening.html>`_
-    should be enabled for the function body.
-
-    Speculative Load Hardening is a best-effort mitigation against
-    information leak attacks that make use of control flow
-    miss-speculation - specifically miss-speculation of whether a branch
-    is taken or not. Typically vulnerabilities enabling such attacks are
-    classified as "Spectre variant #1". Notably, this does not attempt to
-    mitigate against miss-speculation of branch target, classified as
-    "Spectre variant #2" vulnerabilities.
+    should be enabled for the function body. This is a best-effort attempt to
+    mitigate all known speculative execution information leak vulnerabilities
+    that are based on the fundamental principles of modern processors'
+    speculative execution. These vulnerabilities are classified as "Spectre
+    variant #1" vulnerabilities typically. Notably, this does not attempt to
+    mitigate any vulnerabilities where the speculative execution and/or
+    prediction devices of specific processors can be *completely* undermined
+    (such as "Branch Target Injection", a.k.a, "Spectre variant #2"). Instead,
+    this is a target-independent request to harden against the completely
+    generic risk posed by speculative execution to incorrectly load secret data,
+    making it available to some micro-architectural side-channel for information
+    leak. For a processor without any speculative execution or predictors, this
+    is expected to be a no-op.
 
     When inlining, the attribute is sticky. Inlining a function that carries
     this attribute will cause the caller to gain the attribute. This is intended