[0/3] OpenRISC updates for user space FPU

Message

Stafford Horne May 2, 2023, 6:57 p.m. UTC

This series adds support for the FPU related architecture changes defined in
architecture spec revision v1.4.

 - https://openrisc.io/revisions/r1.4

In summary the architecture changes are:

 - Change FPCSR SPR permissions to allow for reading and writing from user
   space.
 - Clarify that FPU underflow detection is done by detecting tininess before
   rounding.

Previous to this series FPCSR reads and writes from user-mode in QEMU would
throw an illegal argument exception.  The proper behavior should have been to
treat these operations as no-ops as the cpu implementations do.  As mentioned
series changes FPCSR read/write to follow the spec.

The series has been tested with the FPU support added in glibc test suite and
all math tests are passing.

Stafford Horne (3):
  target/openrisc: Allow fpcsr access in user mode
  target/openrisc: Set PC to cpu state on FPU exception
  target/openrisc: Setup FPU for detecting tininess before rounding

 target/openrisc/cpu.c        |  5 +++
 target/openrisc/fpu_helper.c |  4 ++
 target/openrisc/sys_helper.c | 45 +++++++++++++++++-----
 target/openrisc/translate.c  | 72 ++++++++++++++++--------------------
 4 files changed, 76 insertions(+), 50 deletions(-)