This patch adds the safe stack instrumentation pass to LLVM, which separates
the program stack into a safe stack, which stores return addresses, register
spills, and local variables that are statically verified to be accessed
in a safe way, and the unsafe stack, which stores everything else. Such
separation makes it much harder for an attacker to corrupt objects on the
safe stack, including function pointers stored in spilled registers and
return addresses. You can find more information about the safe stack, as
well as other parts of or control-flow hijack protection technique in our
OSDI paper on code-pointer integrity (http://dslab.epfl.ch/pubs/cpi.pdf)
and our project website (http://levee.epfl.ch).
The overhead of our implementation of the safe stack is very close to zero
(0.01% on the Phoronix benchmarks). This is lower than the overhead of
stack cookies, which are supported by LLVM and are commonly used today,
yet the security guarantees of the safe stack are strictly stronger than
stack cookies. In some cases, the safe stack improves performance due to
better cache locality.
Our current implementation of the safe stack is stable and robust, we
used it to recompile multiple projects on Linux including Chromium, and
we also recompiled the entire FreeBSD user-space system and more than 100
packages. We ran unit tests on the FreeBSD system and many of the packages
and observed no errors caused by the safe stack. The safe stack is also fully
binary compatible with non-instrumented code and can be applied to parts of
a program selectively.
This patch is our implementation of the safe stack on top of LLVM. The
patches make the following changes:
- Add the safestack function attribute, similar to the ssp, sspstrong and
sspreq attributes.
- Add the SafeStack instrumentation pass that applies the safe stack to all
functions that have the safestack attribute. This pass moves all unsafe local
variables to the unsafe stack with a separate stack pointer, whereas all
safe variables remain on the regular stack that is managed by LLVM as usual.
- Invoke the pass as the last stage before code generation (at the same time
the existing cookie-based stack protector pass is invoked).
- Add unit tests for the safe stack.
Original patch by Volodymyr Kuznetsov and others at the Dependable Systems
Lab at EPFL; updates and upstreaming by myself.
Differential Revision: http://reviews.llvm.org/D6094
llvm-svn: 239761
This makes use of the new API which can remove attributes from a set given a builder.
This is much faster than creating a temporary set and reduces llc time by about 0.3% which was all spent creating temporary attributes sets on the context.
llvm-svn: 236668
Prior to this change we would have to construct a temporary AttributeSet (which isn't temporary at all given that its allocated on the context), just to contain the attributes in the builder, then call remove on that.
Now we can just remove any attributes from the (lightweight and really temporary) builder itself.
Will be used in a future commit to remove some temporary attributes sets.
llvm-svn: 236666
Summary:
If a pointer is marked as dereferenceable_or_null(N), LLVM assumes it
is either `null` or `dereferenceable(N)` or both. This change only
introduces the attribute and adds a token test case for the `llvm-as`
/ `llvm-dis`. It does not hook up other parts of the optimizer to
actually exploit the attribute -- those changes will come later.
For pointers in address space 0, `dereferenceable(N)` is now exactly
equivalent to `dereferenceable_or_null(N)` && `nonnull`. For other
address spaces, `dereferenceable(N)` is potentially weaker than
`dereferenceable_or_null(N)` && `nonnull` (since we could have a null
`dereferenceable(N)` pointer).
The motivating case for this change is Java (and other managed
languages), where pointers are either `null` or dereferenceable up to
some usually known-at-compile-time constant offset.
Reviewers: rafael, hfinkel
Reviewed By: hfinkel
Subscribers: nicholas, llvm-commits
Differential Revision: http://reviews.llvm.org/D8650
llvm-svn: 235132
The "dereferenceable" attribute cannot be added via .addAttribute(),
since it also expects a size in bytes. AttrBuilder#addAttribute or
AttributeSet#addAttribute is wrapped by classes Function, InvokeInst,
and CallInst. Add corresponding wrappers to
AttrBuilder#addDereferenceableAttr.
Having done this, propagate the dereferenceable attribute via
gc.relocate, adding a test to exercise it. Note that -datalayout is
required during execution over and above -instcombine, because
InstCombine only optionally requires DataLayoutPass.
Differential Revision: http://reviews.llvm.org/D7510
llvm-svn: 229265
This attribute indicates that the parameter or return pointer is
dereferenceable. Practically speaking, loads from such a pointer within the
associated byte range are safe to speculatively execute. Such pointer
parameters are common in source languages (C++ references, for example).
llvm-svn: 213385
Currently the only kind of integer IR attributes that we have are alignment
attributes, and so the attribute kind that takes an integer parameter is called
AlignAttr, but that will change (we'll soon be adding a dereferenceable
attribute that also takes an integer value). Accordingly, rename AlignAttribute
to IntAttribute (class names, enums, etc.).
No functionality change intended.
llvm-svn: 213352
It includes a pass that rewrites all indirect calls to jumptable functions to pass through these tables.
This also adds backend support for generating the jump-instruction tables on ARM and X86.
Note that since the jumptable attribute creates a second function pointer for a
function, any function marked with jumptable must also be marked with unnamed_addr.
llvm-svn: 210280
Breaks the MSVC build.
DataStream.cpp(44): error C2552: 'llvm::Statistic::Value' : non-aggregates cannot be initialized with initializer list
llvm-svn: 202731
With C++11 we finally have a standardized way to specify atomic operations. Use
them to replace the existing custom implemention. Sadly the translation is not
entirely trivial as std::atomic allows more fine-grained control over the
atomicity. I tried to preserve the old semantics as well as possible.
Differential Revision: http://llvm-reviews.chandlerc.com/D2915
llvm-svn: 202730
The inalloca attribute is designed to support passing C++ objects by
value in the Microsoft C++ ABI. It behaves the same as byval, except
that it always implies that the argument is in memory and that the bytes
are never copied. This attribute allows the caller to take the address
of an outgoing argument's memory and execute arbitrary code to store
into it.
This patch adds basic IR support, docs, and verification. It does not
attempt to implement any lowering or fix any possibly broken transforms.
When this patch lands, a complete description of this feature should
appear at http://llvm.org/docs/InAlloca.html .
Differential Revision: http://llvm-reviews.chandlerc.com/D2173
llvm-svn: 197645
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file. The memory leaks in this version have been fixed. Thanks
Alexey for pointing them out.
Differential Revision: http://llvm-reviews.chandlerc.com/D2068
Reviewed by Andy
llvm-svn: 195064
This change is incorrect. If you delete virtual destructor of both a base class
and a subclass, then the following code:
Base *foo = new Child();
delete foo;
will not cause the destructor for members of Child class. As a result, I observe
plently of memory leaks. Notable examples I investigated are:
ObjectBuffer and ObjectBufferStream, AttributeImpl and StringSAttributeImpl.
llvm-svn: 194997
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file.
Differential Revision: http://llvm-reviews.chandlerc.com/D2068
Reviewed by Andy
llvm-svn: 194865
This function attribute indicates that the function is not optimized
by any optimization or code generator passes with the
exception of interprocedural optimization passes.
llvm-svn: 189101
There's no need to specify a flag to omit frame pointer elimination on non-leaf
nodes...(Honestly, I can't parse that option out.) Use the function attribute
stuff instead.
llvm-svn: 187093
- Coallocate entires for AttributeSetImpls and Nodes after the class itself.
- Remove mutable iterators from immutable classes.
- Remove unused context field from AttributeImpl.
- Derive Enum/Align/String attribute implementations from AttributeImpl instead
of having a whole new inheritance tree for them.
- Derive AlignAttributeImpl from EnumAttributeImpl.
llvm-svn: 186075
The Builtin attribute is an attribute that can be placed on function call site that signal that even though a function is declared as being a builtin,
rdar://problem/13727199
llvm-svn: 185049
Other than recognizing the attribute, the patch does little else.
It changes the branch probability analyzer so that edges into
blocks postdominated by a cold function are given low weight.
Added analysis and code generation tests. Added documentation for the
new attribute.
llvm-svn: 182638
The cause of the windows failures was fixed by r180791. Revert to the state
after Sabre's original revert.
Original message:
revert r179735, it has no testcases, and doesn't really make sense.
llvm-svn: 180844
The actual storage was already using unsigned, but the interface was using
uint64_t. This is wasteful on 32 bits and looks to be the root causes of
a miscompilation on Windows where a value was being sign extended to 64bits
to compare with the result of getSlotIndex.
Patch by Pasi Parviainen!
llvm-svn: 180791
This un-reverts r179735 and reverts commit r180574.
This fixes assertion failures for me locally and should fix the failures
on Windows reported widely on llvm-dev. We should check if the bots
caught this and if so why not.
llvm-svn: 180722
Semantics of parameters named Index and Idx were inconsistent between
"include/llvm/IR/Attributes.h", "lib/IR/AttributeImpl.h" and
"lib/IR/Attributes.cpp": sometimes these were fixed 1-based indexes of IR
parameters (or AttributeSet::ReturnIndex for IR return values or
AttributeSet::FunctionIndex for IR functions), other times they were the
internal slot for storage in the underlying AttributeSetImpl. I renamed usage of
the former to "Index" and usage of the latter to "Slot" ("Slot" was already
being used consistently for the latter in a subset of cases)
Patch by Stephen Lin!
llvm-svn: 179791
1. Verify::VerifyParameterAttrs in "lib/IR/Verifier.cpp" and
AttrBuilder::removeFunctionOnlyAttrs in "lib/IR/Attributes.cpp" (only called
by Verify::VerifyFunctionAttrs) separately maintained a list of function-only
attribute types. I've consolidated the logic into a new function used for
both cases in "lib/IR/Verifier.cpp", so this logic is in one place (other
than the AsmParser front-end)
2. Various functions in "lib/IR/Verifier.cpp" passed AttributeSet around by
reference needlessly, as it's just a handle to an immutable pimpl body.
Patch by Stephen Lin!
llvm-svn: 179790
These are two related changes (one in llvm, one in clang).
LLVM:
- rename address_safety => sanitize_address (the enum value is the same, so we preserve binary compatibility with old bitcode)
- rename thread_safety => sanitize_thread
- rename no_uninitialized_checks -> sanitize_memory
CLANG:
- add __attribute__((no_sanitize_address)) as a synonym for __attribute__((no_address_safety_analysis))
- add __attribute__((no_sanitize_thread))
- add __attribute__((no_sanitize_memory))
for S in address thread memory
If -fsanitize=S is present and __attribute__((no_sanitize_S)) is not
set llvm attribute sanitize_S
llvm-svn: 176075
Peter Collingbourne