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Date: Wed, 10 Jan 2024 18:31:11 +0000
From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Vladimir Oltean <olteanv@gmail.com>
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Subject: Re: [PATCH net-next 08/30] net: dsa: mt7530: change p{5,6}_interface
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Sender: Russell King (Oracle) <linux@armlinux.org.uk>

On Wed, Jan 10, 2024 at 08:05:25PM +0200, Vladimir Oltean wrote:
> On Wed, Jan 10, 2024 at 08:15:20PM +0300, Arınç ÜNAL wrote:
> > __builtin_return_address(1) doesn't seem to work. I'm running this on arm64.
> 
> I can't tell you why either, I'm sorry. I can just point to the
> documentation, which does specify that "On some machines it may be
> impossible to determine the return address of any function other than
> the current one". If somebody knows what this depends on, feel free to
> interject.
> https://gcc.gnu.org/onlinedocs/gcc/Return-Address.html
> 
> On my NXP LS1028A (also arm64) plus clang-16 compiler, __builtin_return_address()
> does work with multiple nesting levels.

gcc will probably need to be using frame pointers so it can walk the
stack, if gcc even implements non-zero values to
__builtin_return_address(). Without frame pointers, it would need an
unwinder.

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