[Info-vax] Android development Was Re: OT: Larry Ellison takes retirement as CEO of Oracle

[JF Mezei]

On 14-09-23 14:20, John Reagan wrote:

> SYS$QIO (and all system services) are specially known to the linker/image activator (called the public vectors).

Would it be correct to state that the image activator would simply stick
the address of SYS$QIO entry point in the loaded executable ?

> Privilege checks are performed by the services against the process' current privs.

But surely system services perform operations that would not be
permitted if done by the user application that only has no special privs ?

So, when my user code takes the address of SYS$QIO furnished by the
image activator and does a "CALL" instruction to it, what happens to
allow my process (without privs) to be able to perform privileged
operations because the code resides in area of memory that contains
system services code ?

Put it another way: if I were to take the exact same
instructions/arguments located in the SYS$QIO system service and run
them inside my process, it would not have the required privileges and
fail, right ? So what happens to magically grant the same code
privileges when I branch to a certain area of memory ?