On 10/11/23 17:25, Peter Maydell wrote:
When we are doing a FEAT_MOPS copy that must be performed backwards, we call mte_mops_probe_rev(), passing it the address of the last byte in the region we are probing. However, allocation_tag_mem_probe() wants the address of the first byte to get the tag memory for. Because we passed it (ptr, size) we could incorrectly trip the allocation_tag_mem_probe() check for "does this access run across to the following page", and if that following page happened not to be valid then we would assert.We know we will always be only dealing with a single page because the code that calls mte_mops_probe_rev() ensures that. We could make mte_mops_probe_rev() pass 'ptr - (size - 1)' to allocation_tag_mem_probe(), but then we would have to adjust the returned 'mem' pointer to get back to the tag RAM for the last byte of the region. It's simpler to just pass in a size of 1 byte, because we know that allocation_tag_mem_probe() in pure-probe single-page mode doesn't care about the size. Fixes: 69c51dc3723b ("target/arm: Implement MTE tag-checking functions for FEAT_MOPS copies") Signed-off-by: Peter Maydell <[email protected]> --- target/arm/tcg/mte_helper.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
