On Mon, Feb 10, 2020 at 11:42:06AM +0000, Andrew Cooper wrote: > Writing to the stack pointer in the middle of a line of pop operations is > specifically recommended against by the optimisation guide, and is a technique > used by Speculative Load Hardening to combat SpectreRSB. > > In practice, it causes all further stack-relative accesses to block until the > write to the stack pointer retires, so the stack engine can get back in sync. > > Pop into any dead register to discard %rax's value without clobbering the > stack engine. Smaller compiled code, and runs faster. > > Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
Reviewed-by: Roger Pau Monné <roger....@citrix.com> Thanks. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
