[for-6.1,0/6] arm: Fix a handful of M-profile bugs

Message

Peter Maydell July 23, 2021, 4:21 p.m. UTC

This patchset fixes a handful of minor M-profile bugs:
 * The low 2 bits of SP should not be writeable (they are always 0)
 * Missing 'return' statements for some "tail chain to another
   exception after detecting an error during exception return" cases
 * Alignment faults were being incorrectly reported to the guest
   as MMU faults
 * ISCR.ISRPENDING wasn't being set if there was a pending
   but non-enabled interrupt
 * ISCR.VECTPENDING is 9 bits, not 8
 * ISCR.VECTPENDING was missing the new-for-v8.1M behaviour where
   it hides the identity of a pending Secure exception from a
   NonSecure read of the register

Nothing here is very critical, but they might as well go into
6.1 because they are bugfixes.

thanks
-- PMM

Peter Maydell (6):
  target/arm: Enforce that M-profile SP low 2 bits are always zero
  target/arm: Add missing 'return's after calling v7m_exception_taken()
  target/arm: Report M-profile alignment faults correctly to the guest
  hw/intc/armv7m_nvic: ISCR.ISRPENDING is set for non-enabled pending
    interrupts
  hw/intc/armv7m_nvic: Correct size of ICSR.VECTPENDING
  hw/intc/armv7m_nvic: for v8.1M VECTPENDING hides S exceptions from NS

 hw/intc/armv7m_nvic.c  | 40 ++++++++++++++++++++++++++++------------
 target/arm/gdbstub.c   |  4 ++++
 target/arm/m_helper.c  | 24 ++++++++++++++++++------
 target/arm/translate.c |  3 +++
 4 files changed, 53 insertions(+), 18 deletions(-)