https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92424
Will Deacon <will at kernel dot org> changed:
What |Removed |Added
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CC| |will at kernel dot org
--- Comment #1 from Will Deacon <will at kernel dot org> ---
I just ran into this with GCC 9.2 and reproduced on trunk. The combination of
-fpatchable-function-entry with -mbranch-protection={standard,bti} is likely to
be used for building the Linux kernel when in-kernel BTI is used in conjunction
with dynamic function tracing. I think this will be a common configuration, so
although forcing the options to be mutually exclusive is definitely better than
broken codegen, ultimately we're going to need a way to combine them.
I suspect that placing the PACIASP before the NOPs is going to be problematic
unless it's done for all functions (including leaf functions), otherwise
hooking the NOPs at runtime is difficult because you can't tell whether or not
x30 is signed. You may end up needing to use BTI for the target instead.
The Clang folks are starting to look at -fpatchable-function-entry for AArch64
and will need to follow whatever you end up doing here.
