[PATCH v2 00/19] Mirror map JIT memory for TCG

[Richard Henderson]

This is my take on Joelle's patch set:
https://lists.nongnu.org/archive/html/qemu-devel/2020-10/msg07837.html

First, lots more patches.  For the most part, I convert one interface
at a time, instead of trying to do it all at once.  Then, convert the
tcg backends one at a time, allowing for a backend to say that it has
not been updated and not to use the split.  This takes care of TCI,
for one, which would never be converted, as it makes no sense.  But I
don't expect to ever try to convert mips either -- the memory mapping
constraints there are ugly.

There are many more places that "const" could logically be pushed.
I stopped at several major interfaces and left TODO comments.

I have only converted tcg/i386 and tcg/aarch64 so far.  That should
certainly be sufficient for immediate darwin/iOS testing.

Second, I've taken the start with rw and offset to rx approach, which
is the opposite of Joelle's patch set.  It's a close call, but this
direction may be slightly cleaner.

Third, there are almost no ifdefs.  The only ones are related to host
specific support.  That means that this is always available, modulo
the actual tcg backend support.  When the feature is disabled, we will
be adding and subtracting a 0 stored in a global variable.

Fourth, I have renamed the command-line parameter to "split-rwx".
I don't think this is perfect, and I'm not even sure if it's better
than "mirror-jit".  What this has done, though, is left the code
with inconsistant language -- "mirror" in some places, "split" in
others.  I'll clean that up once we know decide on naming.

Fifth, I have auto-enabled the feature for CONFIG_DEBUG_TCG, so that
it will fall-back to disabled without error.  But if you try to enable
it from the command-line without complete host support a fatal error
will be generated.  But this will make sure that the feature is
regularly tested.


r~


Richard Henderson (19):
  tcg: Enhance flush_icache_range with separate data pointer
  tcg: Move tcg prologue pointer out of TCGContext
  tcg: Move tcg epilogue pointer out of TCGContext
  tcg: Introduce tcg_mirror_rw_to_rx/tcg_mirror_rx_to_rw
  tcg: Adjust tcg_out_call for const
  tcg: Adjust tcg_out_label for const
  tcg: Adjust tcg_register_jit for const
  tcg: Adjust tb_target_set_jmp_target for split rwx
  tcg: Make DisasContextBase.tb const
  tcg: Make tb arg to synchronize_from_tb const
  tcg: Use Error with alloc_code_gen_buffer
  tcg: Add --accel tcg,split-rwx property
  accel/tcg: Support split-rwx for linux with memfd
  RFC: accel/tcg: Support split-rwx for darwin/iOS with vm_remap
  tcg: Return the rx mirror of TranslationBlock from exit_tb
  tcg/i386: Support split-rwx code generation
  tcg/aarch64: Use B not BL for tcg_out_goto_long
  tcg/aarch64: Implement flush_idcache_range manually
  tcg/aarch64: Support split-rwx code generation

 accel/tcg/tcg-runtime.h      |   2 +-
 include/disas/disas.h        |   2 +-
 include/exec/exec-all.h      |   2 +-
 include/exec/gen-icount.h    |   4 +-
 include/exec/log.h           |   2 +-
 include/exec/translator.h    |   2 +-
 include/hw/core/cpu.h        |   3 +-
 include/sysemu/tcg.h         |   2 +-
 include/tcg/tcg-op.h         |   2 +-
 include/tcg/tcg.h            |  37 +++--
 tcg/aarch64/tcg-target.h     |   9 +-
 tcg/arm/tcg-target.h         |  11 +-
 tcg/i386/tcg-target.h        |  10 +-
 tcg/mips/tcg-target.h        |  11 +-
 tcg/ppc/tcg-target.h         |   5 +-
 tcg/riscv/tcg-target.h       |  11 +-
 tcg/s390/tcg-target.h        |  12 +-
 tcg/sparc/tcg-target.h       |  11 +-
 tcg/tci/tcg-target.h         |  12 +-
 accel/tcg/cpu-exec.c         |  41 +++---
 accel/tcg/tcg-all.c          |  26 +++-
 accel/tcg/tcg-runtime.c      |   4 +-
 accel/tcg/translate-all.c    | 255 ++++++++++++++++++++++++++++-------
 accel/tcg/translator.c       |   4 +-
 bsd-user/main.c              |   2 +-
 disas.c                      |   4 +-
 linux-user/main.c            |   2 +-
 softmmu/physmem.c            |   9 +-
 target/arm/cpu.c             |   3 +-
 target/arm/translate-a64.c   |   2 +-
 target/avr/cpu.c             |   3 +-
 target/hppa/cpu.c            |   3 +-
 target/i386/cpu.c            |   3 +-
 target/microblaze/cpu.c      |   3 +-
 target/mips/cpu.c            |   3 +-
 target/riscv/cpu.c           |   3 +-
 target/rx/cpu.c              |   3 +-
 target/sh4/cpu.c             |   3 +-
 target/sparc/cpu.c           |   3 +-
 target/tricore/cpu.c         |   2 +-
 tcg/tcg-op.c                 |  15 ++-
 tcg/tcg.c                    |  85 +++++++++---
 tcg/tci.c                    |   4 +-
 accel/tcg/trace-events       |   2 +-
 tcg/aarch64/tcg-target.c.inc | 130 +++++++++++++-----
 tcg/arm/tcg-target.c.inc     |   6 +-
 tcg/i386/tcg-target.c.inc    |  38 +++---
 tcg/mips/tcg-target.c.inc    |  18 +--
 tcg/ppc/tcg-target.c.inc     |  45 ++++---
 tcg/riscv/tcg-target.c.inc   |  12 +-
 tcg/s390/tcg-target.c.inc    |   8 +-
 tcg/sparc/tcg-target.c.inc   |  22 +--
 tcg/tcg-pool.c.inc           |   6 +-
 tcg/tci/tcg-target.c.inc     |   2 +-
 54 files changed, 655 insertions(+), 269 deletions(-)

-- 
2.25.1