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SubjectRe: [PATCH 06/10] ARM: ftrace: add Thumb-2 support
On Sun, Mar 14, 2010 at 10:30:15PM +0000, Catalin Marinas wrote:
> On Sat, 2010-03-13 at 06:49 +0000, Rabin Vincent wrote:
> > - The problem with the "mov lr, pc", is that it does not set the lsb when
> > storing the pc in lr. The called function returns with "bx lr", and the
> > mode changes to ARM. The blx is to avoid this.
>
> I'm not familiar with ftrace but why does the called function returns
> using "bx lr". Is this generated by the compiler? I had the impression
> that if we don't enable interworking, we wouldn't get this instruction
> (but haven't tried this yet).

There's nothing special about the called function: it's just a regular C
function. GCC uses "bx lr" for the return.

Rabin


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