diff options
| author | Philippe Mathieu-Daudé <f4bug@amsat.org> | 2018-09-27 02:24:16 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2018-10-02 19:09:14 +0200 |
| commit | 98f52cdbb5cb44c0ec69a133fc34505ea7c26520 (patch) | |
| tree | ec4057ddb63a16c18effd4c3da538832c3cd1703 | |
| parent | 3c754a9383ac70f316f1b98aec203182de250c42 (diff) | |
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>
| -rw-r--r-- | memory.c | 34 |
1 files changed, 23 insertions, 11 deletions
@@ -375,18 +375,30 @@ static void adjust_endianness(MemoryRegion *mr, uint64_t *data, unsigned size) } static inline void memory_region_shift_read_access(uint64_t *value, - unsigned shift, + signed shift, uint64_t mask, uint64_t tmp) { - *value |= (tmp & mask) << shift; + if (shift >= 0) { + *value |= (tmp & mask) << shift; + } else { + *value |= (tmp & mask) >> -shift; + } } static inline uint64_t memory_region_shift_write_access(uint64_t *value, - unsigned shift, + signed shift, uint64_t mask) { - return (*value >> shift) & mask; + uint64_t tmp; + + if (shift >= 0) { + tmp = (*value >> shift) & mask; + } else { + tmp = (*value << -shift) & mask; + } + + return tmp; } static hwaddr memory_region_to_absolute_addr(MemoryRegion *mr, hwaddr offset) @@ -415,7 +427,7 @@ static MemTxResult memory_region_oldmmio_read_accessor(MemoryRegion *mr, hwaddr addr, uint64_t *value, unsigned size, - unsigned shift, + signed shift, uint64_t mask, MemTxAttrs attrs) { @@ -441,7 +453,7 @@ static MemTxResult memory_region_read_accessor(MemoryRegion *mr, hwaddr addr, uint64_t *value, unsigned size, - unsigned shift, + signed shift, uint64_t mask, MemTxAttrs attrs) { @@ -467,7 +479,7 @@ static MemTxResult memory_region_read_with_attrs_accessor(MemoryRegion *mr, hwaddr addr, uint64_t *value, unsigned size, - unsigned shift, + signed shift, uint64_t mask, MemTxAttrs attrs) { @@ -494,7 +506,7 @@ static MemTxResult memory_region_oldmmio_write_accessor(MemoryRegion *mr, hwaddr addr, uint64_t *value, unsigned size, - unsigned shift, + signed shift, uint64_t mask, MemTxAttrs attrs) { @@ -519,7 +531,7 @@ static MemTxResult memory_region_write_accessor(MemoryRegion *mr, hwaddr addr, uint64_t *value, unsigned size, - unsigned shift, + signed shift, uint64_t mask, MemTxAttrs attrs) { @@ -544,7 +556,7 @@ static MemTxResult memory_region_write_with_attrs_accessor(MemoryRegion *mr, hwaddr addr, uint64_t *value, unsigned size, - unsigned shift, + signed shift, uint64_t mask, MemTxAttrs attrs) { @@ -574,7 +586,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr, hwaddr addr, uint64_t *value, unsigned size, - unsigned shift, + signed shift, uint64_t mask, MemTxAttrs attrs), MemoryRegion *mr, |