accel/tcg: Check whether TLB entry is RAM consistently with how we set it up

We set up TLB entries in tlb_set_page_with_attrs(), where we have
some logic for determining whether the TLB entry is considered
to be RAM-backed, and thus has a valid addend field. When we
look at the TLB entry in get_page_addr_code(), we use different
logic for determining whether to treat the page as RAM-backed
and use the addend field. This is confusing, and in fact buggy,
because the code in tlb_set_page_with_attrs() correctly decides
that rom_device memory regions not in romd mode are not RAM-backed,
but the code in get_page_addr_code() thinks they are RAM-backed.
This typically results in "Bad ram pointer" assertion if the
guest tries to execute from such a memory region.

Fix this by making get_page_addr_code() just look at the
TLB_MMIO bit in the code_address field of the TLB, which
tlb_set_page_with_attrs() sets if and only if the addend
field is not valid for code execution.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180713150945.12348-1-peter.maydell@linaro.org

1 files changed, 0 insertions, 6 deletions

diff --git a/exec.c b/exec.c
index 4f5df07..e7be076 100644
--- a/exec.c
+++ b/exec.c
@@ -402,12 +402,6 @@ static MemoryRegionSection *phys_page_find(AddressSpaceDispatch *d, hwaddr addr)
     }
 }
 
-bool memory_region_is_unassigned(MemoryRegion *mr)
-{
-    return mr != &io_mem_rom && mr != &io_mem_notdirty && !mr->rom_device
-        && mr != &io_mem_watch;
-}
-
 /* Called from RCU critical section */
 static MemoryRegionSection *address_space_lookup_region(AddressSpaceDispatch *d,
                                                         hwaddr addr,