Re: Unaligned access trade-offs for SFrame FRE layout

Steven Rostedt <[email protected]> Mon, 15 Sep 2025 12:07:42 -0400
Newsgroups org.kernel.vger.linux-toolchains
Message-ID <[email protected]>
On Sun, 14 Sep 2025 22:42:46 -0700
Indu Bhagat <[email protected]> wrote:

> In such cases, the routines reading the SFrame data under consideration 
> here (SFrame FRE start addr, and SFrame FRE stack offsets) from memory 
> will need to use a memcpy to copy out the data to an aligned location.
> 
> In GNU Binutils libsframe (used by ld), we do the above. Such a "SFrame 
> FRE decoding" routine could be provided in a arch-specific manner in 
> SFrame stack tracers.

I'm perfectly fine with making it a requirement for the reader of the
SFrame section having to use memcpy into an aligned structure for reading
if the architecture requires it. Let only the architectures that have
issues with unaligned access take the performance hit.

-- Steve