On Fri, 2009-02-13 at 10:00 -0500, Steven Rostedt wrote: > plain text document attachment > (0002-powerpc-ftrace-use-create_branch-lib-function.patch) > From: Steven Rostedt <srost...@redhat.com> > > Impact: clean up, remove duplicate code > > When ftrace was first ported to PowerPC, there existed a > create_function_call that would create the instruction to make a call > to a given address. Unfortunately, this call expected to write to > the address it was given, and since it used the address to calculate > the offset, it could not be faked. > > ftrace needed a way to create the instruction without actually writing > that instruction to the text section. So ftrace had to implement its > own code. > > Now we have create_branch in the code patching library, which does > exactly what ftrace needs. This patch replaces ftrace's implementation > with the library function.
Thanks for doing this, I was going to once the ftrace code had settled a
little but you beat me to it.
> @@ -46,17 +41,10 @@ ftrace_call_replace(unsigned long ip, unsigned long addr,
> int link)
> {
> unsigned int op;
>
> - /*
> - * It would be nice to just use create_function_call, but that will
> - * update the code itself. Here we need to just return the
> - * instruction that is going to be modified, without modifying the
> - * code.
> - */
> addr = GET_ADDR(addr);
>
> /* if (link) set op to 'bl' else 'b' */
> - op = 0x48000000 | (link ? 1 : 0);
> - op |= (ftrace_calc_offset(ip, addr) & 0x03fffffc);
> + op = create_branch((unsigned int *)ip, addr, link ? 1 : 0);
If I was feeling nit-picky I'd say you should use:
op = create_branch((unsigned int *)ip, addr, link ? BRANCH_SET_LINK : 0);
But admittedly we're unlikely to ever change the flag handling, so it's
probably not worth the effort of a respin (or this email :).
cheers
--
Michael Ellerman
OzLabs, IBM Australia Development Lab
wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)
We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person
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