Merge remote-tracking branch 'remotes/palmer/tags/riscv-for-master-5.0-sf1' into...

Merge remote-tracking branch 'remotes/palmer/tags/riscv-for-master-5.0-sf1' into staging

RISC-V Patches for the 5.0 Soft Freeze, Part 1

This patch set contains a handful of collected fixes that I'd like to target
for the 5.0 soft freeze (I know that's a long way away, I just don't know what
else to call these):

* A fix for a memory leak initializing the sifive_u board.
* Fixes to privilege mode emulation related to interrupts and fstatus.

Notably absent is the H extension implementation.  That's pretty much reviewed,
but not quite ready to go yet and I didn't want to hold back these important
fixes.  This boots 32-bit and 64-bit Linux (buildroot this time, just for fun)
and passes "make check".

# gpg: Signature made Tue 21 Jan 2020 22:55:28 GMT
# gpg:                using RSA key 2B3C3747446843B24A943A7A2E1319F35FBB1889
# gpg:                issuer "palmer@dabbelt.com"
# gpg: Good signature from "Palmer Dabbelt <palmer@dabbelt.com>" [unknown]
# gpg:                 aka "Palmer Dabbelt <palmer@sifive.com>" [unknown]
# gpg:                 aka "Palmer Dabbelt <palmerdabbelt@google.com>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 00CE 76D1 8349 60DF CE88  6DF8 EF4C A150 2CCB AB41
#      Subkey fingerprint: 2B3C 3747 4468 43B2 4A94  3A7A 2E13 19F3 5FBB 1889

* remotes/palmer/tags/riscv-for-master-5.0-sf1:
  target/riscv: update mstatus.SD when FS is set dirty
  target/riscv: fsd/fsw doesn't dirty FP state
  target/riscv: Fix tb->flags FS status
  riscv: Set xPIE to 1 after xRET
  riscv/sifive_u: fix a memory leak in soc_realize()

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>