[PATCHv3] arm: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS
Russell King - ARM Linux
linux at armlinux.org.uk
Thu Feb 9 07:49:13 PST 2017
On Thu, Feb 09, 2017 at 04:38:32PM +0100, Jean-Jacques Hiblot wrote:
> 2017-02-07 23:57 GMT+01:00 Abel Vesa <abelvesa at linux.com>:
> > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER
> > +.macro __ftrace_graph_regs_caller
> > +
> > + sub r0, fp, #4 @ lr of instrumented routine (parent)
> > +
> > + @ called from __ftrace_regs_caller
> > + ldr r1, [sp, #56] @ instrumented routine (func)
> > + mcount_adjust_addr r1, r1
> > +
> > + sub r2, r0, #4 @ frame pointer
> why not mov r2, fp ?
r0 = fp - 4
r2 = r0 - 4
therefore
r2 = (fp - 4) - 4
r2 = fp - 8, not r2 = fp
--
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