Not so sure about that. I am reading the merge commit, and comments are pretty interesting: --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include

Not so sure about that. I am reading the merge commit, and comments are pretty interesting: --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h + * On Intel CPUs, if a SYSCALL instruction is at the highest canonical + * address, then that syscall will enter the kernel with a + * non-canonical return address, and SYSRET will explode dangerously. + * We avoid this particular problem by preventing anything executable + * from being mapped at the maximum canonical address. + * + * On AMD CPUs in the Ryzen family, there's a nasty bug in which the + * CPUs malfunction if they execute code from the highest canonical page. + * They'll speculate right off the end of the canonical space, and + * bad things happen. This is worked around in the same way as the + * Intel problem.