cpu-exec: Allow "-d exec" in non-debug builds (drop CONFIG_DEBUG_EXEC)

The CONFIG_DEBUG_EXEC define compiles out a single qemu_log_mask()
call, which is a pretty trivial cost even for something in the main
cpu_exec() loop.  Having this be conditionally defined means that
'-d exec' on a non-debug build will silently do nothing.  Drop the
define and the configure machinery that sets it, in favour of just
always allowing this log option to be enabled at runtime.  As a
concession to the mainloopiness, we use qemu_loglevel_mask()+qemu_log()
rather than qemu_log_mask() to avoid the function call overhead.

Note that DEBUG_DISAS is always defined, so removing the
'|| defined(CONFIG_DEBUG_EXEC)' from those conditionals makes
no behavioural change for that logging.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit c30d1aea1478cd55e8cfdf866afa39cd00bb4ea1)
Ensure good ordering of memory instruction in cpu_exec

The IO thread, when it senses cpu_single_env == 0, expects exit_request
to be checked later on. A compiler scheduling constraint is not strong
enough to ensure this on modern architecture. A memory fence is needed
as well.

Signed-off-by: Olivier Hainque <hainque@adacore.com>
Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
(cherry picked from commit ec9bd89fa48147e1d16e078217513c1235f9132a)
Check effective suspension of TCG thread

On multi-core systems, SuspendThread does not guaranty immediate thread
suspension. We add busy loop to wait for effective thread suspension
after call to ThreadSuspend().

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
(cherry picked from commit ed9164a3549f93204d6b096136cda2ce54e9f03a)
Release SMP restriction on Windows

The previous patches make QEMU SMP safe on Windows, we can now release
the restriction.

Signed-off-by: Fabien Chouteau <chouteau@adacore.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
(cherry picked from commit 1046127d1fcc69359b3f5a44de08e6c5b16c90bc)
unicode: New mod_utf8_codepoint()

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
(cherry picked from commit cb2744ea343d8cb96bab0389f6b7d6e1a3ddf6c1)
check-qjson: Improve a few comments, delete bogus ones

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
(cherry picked from commit d6244e2ce48b353402eff271d382ee6fd47ce166)
check-qjson: Test noncharacters other than U+FFFE, U+FFFF in strings

Test cases cover the two noncharacters in the BMP.  Add tests for the
other 64 noncharacters.

Three existing test cases involve noncharacters U+FFFF and U+10FFFF.
Instead of deleting them as now duplicates, adjust them to use U+FFFC
and U+10FFFFD.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
(cherry picked from commit 1d50c8e947180174acb02bad9ff95e0aee6249ea)
qjson: to_json() case QTYPE_QSTRING is buggy, rewrite

Known bugs in to_json():

* A start byte for a three-byte sequence followed by less than two
  continuation bytes is split into one-byte sequences.

* Start bytes for sequences longer than three bytes get misinterpreted
  as start bytes for three-byte sequences.  Continuation bytes beyond
  byte three become one-byte sequences.

  This means all characters outside the BMP are decoded incorrectly.

* One-byte sequences with the MSB are put into the JSON string
  verbatim when char is unsigned, producing invalid UTF-8.  When char
  is signed, they're replaced by "\\uFFFF" instead.

  This includes \xFE, \xFF, and stray continuation bytes.

* Overlong sequences are happily accepted, unless screwed up by the
  bugs above.

* Likewise, sequences encoding surrogate code points or noncharacters.

* Unlike other control characters, ASCII DEL is not escaped.  Except
  in overlong encodings.

My rewrite fixes them as follows:

* Malformed UTF-8 sequences are replaced.

  Except the overlong encoding \xC0\x80 of U+0000 is still accepted.
  Permits embedding NUL characters in C strings.  This trick is known
  as "Modified UTF-8".

* Sequences encoding code points beyond Unicode range are replaced.

* Sequences encoding code points beyond the BMP produce a surrogate
  pair.

* Sequences encoding surrogate code points are replaced.

* Sequences encoding noncharacters are replaced.

* ASCII DEL is now always escaped.

The replacement character is U+FFFD.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
(cherry picked from commit e2ec3f976803b360c70d9ae2ba13852fa5d11665)