On 2024-03-02 21:56, Stephen Hemminger wrote:
On Sat, 2 Mar 2024 12:49:23 -0800 Stephen Hemminger <step...@networkplumber.org> wrote:The rte_memcpy code would do extra instructions for size 16 and 32 which potentially could reference past end of data. For size of 16, only single mov16 is needed. same for size of 32, only single mov32. Fixes: f5472703c0bd ("eal: optimize aligned memcpy on x86") Fixes: d35cc1fe6a7a ("eal/x86: revert select optimized memcpy at run-time") Suggested-by: Morten Brørup <m...@smartsharesystems.com> Signed-off-by: Stephen Hemminger <step...@networkplumber.org>Self-NAK, more is needed here. The code has lots of pre-existing bugs where it will reference past the end of the data in some cases.
Memory beyond the buffer is not accessed in this case. The rte_mov16() copies just overlap.
A colleague pointed out the same "bug" to me a couple of years ago. We didn't realize what code would be generated in the n == 16 case though. That seems very much worth fixing.
Maybe it's worth adding a comment regarding the overlap.
