This patch adds MSVC's "/guard:signret" flag to the C/C++ compilation
flags so that the VM code includes signing and authentication
instructions to ensure that the return address is not tampered by any
callee. Specifically, MSVC chooses signing using the B key, so every
non-leaf function starts with the `pacibsp` instruction (for signining
the return address) and ends with the `autibsp` instruction (for
authenticating the return address). Both `pacibsp` and `autibsp`
instructions are in the NOP space, so older AArch64 processors that do
not support these instructions shouldn't be impacted by these
instructions.
As a matter of slight detail, this patch adds the "/guard:signret" flag
only when the OpenJDK build is passed the "--enable-branch-protection"
flag, which is off by default. Consequently, this change will not
impact ordinary builds of OpenJDK.
I've validated this patch by running the test/jdk:tier{1,2,3},
test/hotspot/jtreg:tier{1,2,3}, test/langtools:tier{1,2,3}, and
test/lib-test:tier1 tests with branch protection enabled. This patch
does not introduce any new failures.
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- [x] I confirm that I make this contribution in accordance with the [OpenJDK
Interim AI Policy](https://openjdk.org/legal/ai).
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Commit messages:
- Add "/guard:signret" to build flags when branch protection is requested
Changes: https://git.openjdk.org/jdk/pull/31795/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=31795&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8387792
Stats: 20 lines in 4 files changed: 10 ins; 0 del; 10 mod
Patch: https://git.openjdk.org/jdk/pull/31795.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/31795/head:pull/31795
PR: https://git.openjdk.org/jdk/pull/31795
