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author | Philippe Mathieu-Daudé <f4bug@amsat.org> | 2018-09-27 02:24:16 +0200 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-10-02 19:09:14 +0200 |
commit | 98f52cdbb5cb44c0ec69a133fc34505ea7c26520 (patch) | |
tree | ec4057ddb63a16c18effd4c3da538832c3cd1703 /include/exec | |
parent | 3c754a9383ac70f316f1b98aec203182de250c42 (diff) | |
download | qemu-98f52cdbb5cb44c0ec69a133fc34505ea7c26520.zip qemu-98f52cdbb5cb44c0ec69a133fc34505ea7c26520.tar.gz qemu-98f52cdbb5cb44c0ec69a133fc34505ea7c26520.tar.bz2 |
memory: Fix access_with_adjusted_size(small size) on big-endian memory regions
Memory regions configured as DEVICE_BIG_ENDIAN (or DEVICE_NATIVE_ENDIAN on
big-endian guest) behave incorrectly when the memory access 'size' is smaller
than the implementation 'access_size'.
In the following code segment from access_with_adjusted_size():
if (memory_region_big_endian(mr)) {
for (i = 0; i < size; i += access_size) {
r |= access_fn(mr, addr + i, value, access_size,
(size - access_size - i) * 8, access_mask, attrs);
}
(size - access_size - i) * 8 is the number of bits that will arithmetic
shift the current value.
Currently we can only 'left' shift a read() access, and 'right' shift a write().
When the access 'size' is smaller than the implementation, we get a negative
number of bits to shift.
For the read() case, a negative 'left' shift is a 'right' shift :)
However since the 'shift' type is unsigned, there is currently no way to
right shift.
Fix this by changing the access_fn() prototype to handle signed shift values,
and modify the memory_region_shift_read|write_access() helpers to correctly
arithmetic shift the opposite direction when the 'shift' value is negative.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20180927002416.1781-4-f4bug@amsat.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/exec')
0 files changed, 0 insertions, 0 deletions