[PATCH 2/2] ftrace - add ftrace function_graph support on ARM

[Rabin Vincent]

On Sun, Mar 7, 2010 at 1:48 AM, Russell King - ARM Linux
<linux at arm.linux.org.uk> wrote:
> On Fri, Mar 05, 2010 at 04:36:47PM -0800, Tim Bird wrote:
>> IRQENTRY_TEXT was added to vmlinux.lds.S (to eliminate
>> a compiler error on kernel/trace/trace_functions_graph.c),
>> although no routines were marked as __irq_entry.
>
> Well, ARM already places the assembly exception text in its own separate
> section for other reasons.  We can't place it in two sections.
>
> What is __irq_entry used for?  Just the low level assembly or C functions?

It's used just for the C entry functions for interrupts: asm_do_IRQ()
and the IPI and local timer functions.

AFAICS __exception seems to be used only for is_exception_text().  If
that's the case, would it be OK to just place those functions in
__irq_entry if ftrace is built and have is_exception_text() check that
section too?