translate-all: fix locking of TBs whose two pages share the same physical page
authorEmilio G. Cota <cota@braap.org>
Mon, 25 Jun 2018 16:31:42 +0000 (12:31 -0400)
committerRichard Henderson <richard.henderson@linaro.org>
Mon, 2 Jul 2018 15:02:20 +0000 (08:02 -0700)
commita688e73ba8c2e3b6f3e5e683c4a9c37d2ddc8984
treeab984da818a04b6ba128d881cd16c22f59e8cabe
parent2d58e33ec1b76990f09bc1e3412e0b36e1ac4634
translate-all: fix locking of TBs whose two pages share the same physical page

Commit 0b5c91f ("translate-all: use per-page locking in !user-mode",
2018-06-15) introduced per-page locking. It assumed that the physical
pages corresponding to a TB (at most two pages) are always distinct,
which is wrong. For instance, an xtensa test provided by Max Filippov
is broken by the commit, since the test maps two virtual pages
to the same physical page:

virt1: 7fff, virt2: 8000
phys1 6000fff, phys2 6000000

Fix it by removing the assumption from page_lock_pair.
If the two physical page addresses are equal, we only lock
the PageDesc once. Note that the two callers of page_lock_pair,
namely page_unlock_tb and tb_link_page, are also updated so that
we do not try to unlock the same PageDesc twice.

Fixes: 0b5c91f74f3c83a36f37740969df8c775c997e69
Reported-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-Id: <1529944302-14186-1-git-send-email-cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
accel/tcg/translate-all.c