[qemu-s390x] [PATCH v2 00/28] s390x/tcg: mem_helper: Fault-safe handling

[David Hildenbrand]

This is the successor of
    "[PATCH v1 0/4] s390x/tcg: MOVE (MVC): Fault-safe handling"

----

This series fixes a bunch of issues related to some mem helpers and makes
sure that they are fault-safe, meaning no system state is modified in case
a fault is triggered.

I can spot tons of other issues with other mem helpers that will have
to be fixed later. Also, fault-safe handling for some instructions
(especially TR) might be harder to implement (you don't know what will
actually be accessed upfront - we might need a buffer and go over
inputs twice). Focusing on the MOVE instructions for now.

----

Newer versions of glibc use memcpy() in memmove() for forward moves. The
implementation makese use of MVC. The TCG implementation of MVC is
currently not able to handle faults reliably when crossing pages. MVC
can cross with 256 bytes at most two pages.

In case we get a fault on the second page, we already moved data. When
continuing after the fault we might try to move already overwritten data,
which is very bad in case we have overlapping data on a forward move.

Triggered for now only by rpmbuild (crashes when checking the spec file)
and rpm (database corruptions). This fixes installing Fedora rawhide (31)
under TCG.

This was horrible to debug as it barely triggers and we fail at completely
different places.

Cc: Stefano Brivio <address@hidden>
Cc: Florian Weimer <address@hidden>

v1 -> v2:
- Include many fixes
- Fix more instructions
- Use the new probe_access() function
- Include "tests/tcg: target/s390x: Test MVO"

David Hildenbrand (28):
  s390x/tcg: Reset exception_index to -1 instead of 0
  s390x/tcg: MVCL: Zero out unused bits of address
  s390x/tcg: MVCL: Detect destructive overlaps
  s390x/tcg: MVCL: Process max 2k bytes at a time
  s390x/tcg: MVC: Increment the length once
  s390x/tcg: MVC: Use is_destructive_overlap()
  s390x/tcg: MVPG: Check for specification exceptions
  s390x/tcg: MVPG: Properly wrap the addresses
  s390x/tcg: MVCLU/MVCLE: Process max 4k bytes at a time
  s390x/tcg: MVCS/MVCP: Check for special operation exceptions
  s390x/tcg: MVCS/MVCP: Properly wrap the length
  s390x/tcg: MVST: Check for specification exceptions
  s390x/tcg: MVST: Fix storing back the addresses to registers
  s390x/tcg: Always use MMU_USER_IDX for CONFIG_USER_ONLY
  s390x/tcg: Fault-safe memset
  s390x/tcg: Fault-safe memmove
  s390x/tcg: MVCS/MVCP: Use access_memmove_idx()
  s390x/tcg: MVC: Fault-safe handling on destructive overlaps
  s390x/tcg: MVCLU: Fault-safe handling
  s390x/tcg: OC: Fault-safe handling
  s390x/tcg: XC: Fault-safe handling
  s390x/tcg: NC: Fault-safe handling
  s390x/tcg: MVCIN: Fault-safe handling
  s390x/tcg: MVN: Fault-safe handling
  s390x/tcg: MVZ: Fault-safe handling
  s390x/tcg: MVST: Fault-safe handling
  s390x/tcg: MVO: Fault-safe handling
  tests/tcg: target/s390x: Test MVO

 target/s390x/cpu.h              |   4 +
 target/s390x/helper.h           |   2 +-
 target/s390x/insn-data.def      |   2 +-
 target/s390x/mem_helper.c       | 672 ++++++++++++++++++++++----------
 target/s390x/translate.c        |  12 +-
 tests/tcg/s390x/Makefile.target |   1 +
 tests/tcg/s390x/mvo.c           |  25 ++
 7 files changed, 507 insertions(+), 211 deletions(-)
 create mode 100644 tests/tcg/s390x/mvo.c

-- 
2.21.0