[PATCH v4 0/8] Implement assembly cortex-M PACBTI functionality

[Victor L. Do Nascimento]

Hi all,

This respin of the patch series builds upon the previously-proposed prologue/
epilogue interfaces, making them more flexible by the addition of novel
parameters controlling their behavior and adds important corrections as well
as simplifications to the employed CFI directives.

Thanks,
Victor

------

This patch series modifies hand-written assembly files for Arm
targets, introducing a uniform prologue/epilogue interface,
responsible for pushing/popping registers on function entry and exit,
while conditionally enabling branch target identification as well as
address return signature and verification based on Armv8.1-M Pointer
Authentication [1] using ACLE feature test macros at compile-time [2].

The incorportaion of PACBTI functionality in function prologues/
epilogues is dictated by the combination of parameter macros in
arm-asm.h and arguments passed to the `-mbranch-protection' flag at
the time of Newlib compilation.

Regression tested on arm-none-eabi with and without MVE extension and
for Newlib and Newlib-nano.

[1]
<https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/armv8-1-m-pointer-authentication-and-branch-target-identification-extension>
[2] <https://developer.arm.com/documentation/101028/0012/5--Feature-test-macros>

Victor Do Nascimento (8):
  newlib: libc: define M-profile PACBTI-enablement macros
  newlib: libc: strcmp M-profile PACBTI-enablement
  newlib: libc: strlen M-profile PACBTI-enablement
  newlib: libc: memchr M-profile PACBTI-enablement
  newlib: libc: memcpy M-profile PACBTI-enablement
  newlib: libc: setjmp/longjmp M-profile PACBTI-enablement
  newlib: libc: aeabi_memmove M-profile PACBTI-enablement
  newlib: libc: aeabi_memset M-profile PACBTI-enablement

 .../libc/machine/arm/aeabi_memmove-thumb2.S   |  17 +-
 newlib/libc/machine/arm/aeabi_memset-thumb2.S |  14 +-
 newlib/libc/machine/arm/arm_asm.h             | 441 ++++++++++++++++++
 newlib/libc/machine/arm/memchr.S              |  42 +-
 newlib/libc/machine/arm/memcpy-armv7m.S       |  37 +-
 newlib/libc/machine/arm/setjmp.S              |  33 +-
 newlib/libc/machine/arm/strcmp-arm-tiny.S     |   8 +-
 newlib/libc/machine/arm/strcmp-armv7.S        |  44 +-
 newlib/libc/machine/arm/strcmp-armv7m.S       |  26 +-
 newlib/libc/machine/arm/strlen-armv7.S        |  17 +-
 newlib/libc/machine/arm/strlen-thumb2-Os.S    |  14 +-
 11 files changed, 636 insertions(+), 57 deletions(-)

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2.36.1