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To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,  Steven Rostedt <rostedt@goodmis.org>, 	  lkml<linux-kernel@vger.kernel.org>, 	  systemtap<systemtap@sources.redhat.com>,  kvm<kvm@vger.kernel.org>, 	  DLE<dle-develop@lists.sourceforge.net>, 	  Christoph Hellwig <hch@infradead.org>, 	  Ananth N Mavinakayanahalli <ananth@in.ibm.com>, 	  Frederic Weisbecker <fweisbec@gmail.com>, 	  Roland McGrath <roland@redhat.com>, 	  Srikar Dronamraju <srikar@linux.vnet.ibm.com>, 	  linux-arch@vger.kernel.org
Subject: Re: [PATCH -tip -v10 5/7] x86: add pt_regs register and stack access APIs
From: Andi Kleen <andi@firstfloor.org>
References: <20090701010838.32547.62843.stgit@localhost.localdomain> 	<20090701010911.32547.1313.stgit@localhost.localdomain>
Date: Mon, 06 Jul 2009 14:37:00 -0000
In-Reply-To: <20090701010911.32547.1313.stgit@localhost.localdomain> (Masami Hiramatsu's message of "Tue, 30 Jun 2009 21:09:11 -0400")
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Masami Hiramatsu <mhiramat@redhat.com> writes:

> Add following APIs for accessing registers and stack entries from pt_regs.

You forgot to state who calls these functions/why are they added?
Who only has strings for registers?

I can see the point of having a function for nth argument though,
that's useful.

> +static inline unsigned long regs_get_argument_nth(struct pt_regs *regs,
> +						  unsigned n)
> +{
> +	if (n < NR_REGPARMS) {
> +		switch (n) {
> +		case 0:
> +			return regs->ax;
> +		case 1:
> +			return regs->dx;
> +		case 2:
> +			return regs->cx;


[....]

That could be done shorter with a offsetof table.

> +	if (n < NR_REGPARMS) {
> +		switch (n) {
> +		case 0:
> +			return regs->di;
> +		case 1:
> +			return regs->si;
> +		case 2:
> +			return regs->dx;
> +		case 3:
> +			return regs->cx;
> +		case 4:
> +			return regs->r8;
> +		case 5:
> +			return regs->r9;

and that too.


-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.