Its quite simple:
int sys_foo(struct pt_regs regs)
does not reveal the user space registers on ARM. It instead reveals crap.
Why? The ARM procedure call standard specifies that the first 4 words
of "regs" in this case are in 4 processor registers. The other words
are on the stack immediately above the frame created by foo. This is
not how the stack is layed out on ARM on entry to a sys_* function
due to the requirement for these to be restartable.
Instead, we must pass a pointer thusly:
int sys_foo(struct pt_regs *regs)
and the pointer is specifically setup and passed in by a very small
> The first sentence tell me that the "struct pt_regs ..." line is x86
> specific and this was the reason behind my proposition to not add a _signal
> macro but a _sys_nanosleep macro to include this too.
Correct. But the act of getting "struct pt_regs" on entry to the function
is also architecture specific.
> The second sentence seem's to indicate that this is a classic problem for
> the ARM port. So if this is correct what is the best way to solve it ?
It used to be with such functions as sys_execve. Then, sys_execve
became an architecture specific wrapper around do_execve (not by my
hand), so I guess that its not an ARM specific problem.
-- Russell King (firstname.lastname@example.org) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html
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