From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Tue,  1 Apr 2008 00:34:06 +0200
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To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] getcallerpc on arm7
Topicbox-Message-UUID: 85db85d8-ead3-11e9-9d60-3106f5b1d025

> it should be the same as the other risc machines, and seems all right
> when i test it with 5c/5l.  gcc typically also uses a frame pointer,
> which might make it nearly as easy for that compiler.

This seems to work well:

	.text
	.globl getcallerpc
	getcallerpc:
		ldr	r0, [fp, #-4]
		bx	lr

I was a bit confused about whether or not the firstarg pointer
is expected to be used by a getcallerpc implementation (so that
it would also work in subfunctions of the current, provided
&firstarg is passed down). The BUGS section of getcallerpc(2/3)
gives a hint how this could be answered.