[Bug 1924669] [NEW] VFP code cannot see CPACR write in the same TB

[Hansni Bu]

Public bug reported:

If FPU is enabled by writing to CPACR, and the code is in the same
translation block as the following VFP code, qemu generates "v7M NOCP
UsageFault".

This can be reproduced with git HEAD (commit
8fe9f1f891eff4e37f82622b7480ee748bf4af74).

The target binary is attached. The qemu command is:
qemu-system-arm -nographic -monitor null -serial null -semihosting -machine 
mps2-an505 -cpu cortex-m33 -kernel cpacr_vfp.elf -d 
in_asm,int,exec,cpu,cpu_reset,unimp,guest_errors,nochain -D log

If the code is changed a little, so that they are not in the same block,
VFP code can see the effect of CPACR, or -singlestep of qemu has the
same result.

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: arm vfp

** Attachment added: "cpacr_vfp.elf"
   
https://bugs.launchpad.net/bugs/1924669/+attachment/5488612/+files/cpacr_vfp.elf

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https://bugs.launchpad.net/bugs/1924669

Title:
  VFP code cannot see CPACR write in the same TB

Status in QEMU:
  New

Bug description:
  If FPU is enabled by writing to CPACR, and the code is in the same
  translation block as the following VFP code, qemu generates "v7M NOCP
  UsageFault".

  This can be reproduced with git HEAD (commit
  8fe9f1f891eff4e37f82622b7480ee748bf4af74).

  The target binary is attached. The qemu command is:
  qemu-system-arm -nographic -monitor null -serial null -semihosting -machine 
mps2-an505 -cpu cortex-m33 -kernel cpacr_vfp.elf -d 
in_asm,int,exec,cpu,cpu_reset,unimp,guest_errors,nochain -D log

  If the code is changed a little, so that they are not in the same
  block, VFP code can see the effect of CPACR, or -singlestep of qemu
  has the same result.

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