As it turns out, our "generic" arm64 implementations of certain string.h
functions are not actually generic, since they will eagerly read memory
possibly outside of the bounds of an MTE granule, which may lead to a segfault
on MTE-enabled hardware. Therefore, move the implementations into a "default"
directory and use ifuncs to select between them and a new set of "mte"
implementations, conditional on whether the hardware and kernel support MTE.
The MTE implementations are currently naive implementations written in C
but will later be replaced with a set of optimized assembly implementations.
Bug: 135772972
Change-Id: Ife37c4e0e6fd60ff20a34594cc09c541af4d1dd7
We're going to have to add ifuncs to libm, and there will be some SVE
ones for arm64 soon too, so let's start sharing the absolute minimum...
Test: builds
Change-Id: Idbb9dd9477291ed3c15dc3902f65e593b766dfb9
This reverts commit e4788d4c7e,
which undid this change during the Q betas.
Bug: http://b/120989619
Change-Id: Iea589fd0e56426971adf9f7c19c2aedf0d7a7a60
Did this for fun but turns out it generates better assembly code.
With a C implementation, compiler can expand both the comparison
loop and cpu_variant_names array. Results in a decision tree like
structure. For example the "cortex-a" prefix common in many variants
will only be compared once.
Test: run bionic unit tests.
Test: use debugger to check which variant is used.
Change-Id: Id70e5536f968161f20b18f35d46430457c338f0f
Previous change was reverted in 9690b121e3.
This change added .arch directive to kryo/ to avoid invalid instruction error.
Test: Run bionic unit test.
Test: Use gdb to make sure the right function is selected.
Test: Build previously failed target: make PRODUCT-sdk_phone_arm64-sdk
Change-Id: I14de41851121fc1a0b38c98fda5eb844b6a9695c
This reverts commit ce4ff9c44d.
Reason for revert: broke master in ab/5138164 target sdk_phone_armv7-sdk
Change-Id: Ia4b0c7e6117a37df694509078116963f41d7865e
