Summary:
The Pointer Authentication Extension (PAC) was added in Armv8.3-A. Some
instructions are implemented in the HINT space to allow compiling code
common to CPUs regardless of whether they feature PAC or not, and still
benefit from PAC protection in the PAC-enabled CPUs.
The 8.3-specific mnemonics were currently enabled in any architecture, and
LLVM was emitting them in assembly files when PAC code generation was
enabled. This was ok for compilations where both LLVM codegen and the
integrated assembler were used. However, the LLVM codegen was not
compatible with other assemblers (e.g. GAS). Given the fact that the
approach from these assemblers (i.e. to disallow Armv8.3-A mnemonics if
compiling for Armv8.2-A or lower) is entirely reasonable, this patch makes
LLVM to emit HINT when building for Armv8.2-A and below, instead of
PACIASP, AUTIASP and friends. Then, LLVM assembly should be compatible
with other assemblers.
Reviewers: samparker, chill, LukeCheeseman
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71658
Summary:
Reland after fixing a bug that allowed outlining of SP modifying instructions
that invalidated return address signing.
During AArch64 frame lowering instructions to enable return address
signing are inserted into functions if needed. Functions generated during
machine outlining don't run through target frame lowering and hence are
missing such instructions.
This patch introduces the following changes:
1. If not all functions that potentially participate in function outlining agree
on their return address signing scope and their return address signing key,
outlining is disabled for these functions.
2. If not all functions that potentially participate in function outlining agree
on their support for v8.3A features, outlining is disabled for these
functions.
3. If an outlining candidate would outline instructions that modify sp in a way
that invalidates return address signing, outlining is disabled for that
particular candidate.
4. If all candidate functions agree on the signing scope, signing key and their
support for v8.3 features, the outlined function behaves as if it had the
same scope and key attributes and as if it would provide the same v8.3A
support as the original functions.
Reviewers: ostannard, paquette
Reviewed By: ostannard
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70635
Summary:
Reland after fixing an ASan failure by stopping outlining early if the
constraints for return address signing removed too many outlining candidates.
During AArch64 frame lowering instructions to enable return address
signing are inserted into functions if needed. Functions generated during
machine outlining don't run through target frame lowering and hence are
missing such instructions.
This patch introduces the following changes:
1. If not all functions that potentially participate in function outlining agree
on their return address signing scope and their return address signing key,
outlining is disabled for these functions.
2. If not all functions that potentially participate in function outlining agree
on their support for v8.3A features, outlining is disabled for these
functions.
3. If an outlining candidate would outline instructions that modify sp in a way
that invalidates return address signing, outlining is disabled for that
particular candidate.
4. If all candidate functions agree on the signing scope, signing key and their
support for v8.3 features, the outlined function behaves as if it had the
same scope and key attributes and as if it would provide the same v8.3A
support as the original functions.
Reviewers: ostannard, paquette
Reviewed By: ostannard
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70635
Summary:
Reland after fixing a bug that allowed outlining of SP modifying instructions
that invalidated return address signing.
During AArch64 frame lowering instructions to enable return address
signing are inserted into functions if needed. Functions generated during
machine outlining don't run through target frame lowering and hence are
missing such instructions.
This patch introduces the following changes:
1. If not all functions that potentially participate in function outlining agree
on their return address signing scope and their return address signing key,
outlining is disabled for these functions.
2. If not all functions that potentially participate in function outlining agree
on their support for v8.3A features, outlining is disabled for these
functions.
3. If an outlining candidate would outline instructions that modify sp in a way
that invalidates return address signing, outlining is disabled for that
particular candidate.
4. If all candidate functions agree on the signing scope, signing key and their
support for v8.3 features, the outlined function behaves as if it had the
same scope and key attributes and as if it would provide the same v8.3A
support as the original functions.
Reviewers: ostannard, paquette
Reviewed By: ostannard
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70635
This is causing faults when an instruction which modifies SP is
outlined, causing the PAC and AUT instructions to not match.
This reverts commits 70caa1fc30 and
55314d3237.
Summary:
During AArch64 frame lowering instructions to enable return address
signing are inserted into function if needed. Functions generated during
machine outlining don't run through target frame lowering and hence are
missing such instructions.
This patch introduces the following changes:
1. If not all functions that potentially participate in function outlining
agree on their return address signing scope and their return address
signing key, outlining is disabled for these functions.
2. If not all functions that potentially participate in function outlining
agree on their support for v8.3A features, outlining is disabled for
these functions.
2. If all candidate functions agree on the signing scope, signing key and
and their support for v8.3 features, the outlined function behaves as
if it had the same scope and key attributes and as if it would provide
the same v8.3A support as the original functions.
Reviewers: olista01, paquette, t.p.northover, ostannard
Reviewed By: ostannard
Subscribers: ostannard, kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69097
Pablo Barrio