Hello Brian, On 01-22-16, Brian Gerst wrote: > > > > - /* Is the address not 2M aligned? */ > > - movq %rbp, %rax > > - andl $~PMD_PAGE_MASK, %eax > > - testl %eax, %eax > > - jnz bad_address > > - > > /* > > * Is the address too large? > > */ > > I think we still need to do the check, in case we came from a 64-bit > bootloader that directly jumped to startup_64. However, this check > can be simplified to: > > testl $~PMD_PAGE_MASK, %ebp > jnz bad_address
Ah, ok, in this way we can't trust a bootloader. I just thought that 64-bit entry point is startup_64 from arch/x86/boot/compressed/head_64.S Thank you.
