Store bytes under a mask is fundamentally a cmpxchg, not a straight store.
Use HAVE_CMPXCHG128 instead of HAVE_ATOMIC128_RW.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230916220151.526140-8-richard.henderson@linaro.org>
We handled the HAVE_ATOMIC128_RW case with atomic16_set at the top of
the function; the only thing left for a host without that support is
to fall through to cpu_loop_exit_atomic.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230916220151.526140-7-richard.henderson@linaro.org>
Makes ldst_atomicity.c.inc almost target-independent, with the exception
of TARGET_PAGE_MASK, which will be addressed in a future patch.
Signed-off-by: Anton Johansson <anjo@rev.ng>
Message-Id: <20230912153428.17816-8-anjo@rev.ng>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
When load_atom_extract_al16_or_al8 is inexpensive, we want to use
it early, in order to avoid the overhead of required_atomicity.
However, we must not read past the end of the page.
If there are more than 8 bytes remaining, then both the "aligned 16"
and "aligned 8" paths align down so that the read has at least
16 bytes remaining on the page.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
For user-only, the probe for page writability may race with another
thread's mprotect. Take the mmap_lock around the operation. This
is still faster than the start/end_exclusive fallback.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
In the initial commit, cdfac37be0, the sense of the test is incorrect,
as the -1/0 return was confusing. In bef6f008b9, we mechanically
invert all callers while changing to false/true return, preserving the
incorrectness of the test.
Now that the return sense is sane, it's easy to see that if !write,
then the page is not modifiable (i.e. most likely read-only, with
PROT_NONE handled via SIGSEGV).
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Replace the 0/-1 result with true/false.
Invert the sense of the test of all callers.
Document the function.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230707204054.8792-25-richard.henderson@linaro.org>
The computation is documented as unused in this case,
but triggers an ubsan error:
../accel/tcg/ldst_atomicity.c.inc:837:33: runtime error: shift exponent -32 is negative
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior ../accel/tcg/ldst_atomicity.c.inc:837:33 in
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20230606171629.98157-1-richard.henderson@linaro.org>
PAGE_WRITE is current writability, as modified by TB protection;
PAGE_WRITE_ORG is the original page writability.
Fixes: cdfac37be0 ("accel/tcg: Honor atomicity of loads")
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Remove the locally defined load_atomic16 and store_atomic16,
along with HAVE_al16 and HAVE_al16_fast in favor of the
routines defined in atomic128.h.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Not only the routines in ldst_atomicity.c.inc need markup,
but also the ones in the headers.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
There is an edge condition prior to gcc13 for which optimization
is required to generate 16-byte atomic sequences. Detect this.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Create ldst_atomicity.c.inc.
Not required for user-only code loads, because we've ensured that
the page is read-only before beginning to translate code.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
