On Mon, Dec 01, 2025 at 10:38:01AM +0100, Christophe Leroy (CS GROUP) wrote:
>
>
> Le 29/11/2025 à 20:53, Yury Norov (NVIDIA) a écrit :
> > The macro is only used by i915. Move it to a local header and drop from
> > the kernel.h.
>
> At the begining of the git history we have:
>
> $ git grep STACK_MAGIC 1da177e4c3f41
> 1da177e4c3f41:arch/h8300/kernel/traps.c: if (STACK_MAGIC !=
> *(unsigned long *)((unsigned long)current+PAGE_SIZE))
> 1da177e4c3f41:arch/m68k/mac/macints.c: if (STACK_MAGIC !=
> *(unsigned long *)current->kernel_stack_page)
> 1da177e4c3f41:include/linux/kernel.h:#define STACK_MAGIC 0xdeadbeef
>
> Would be good to know the history of its usage over time.
>
> I see:
> - Removed from m68k by 3cd53b14e7c4 ("m68k/mac: Improve NMI handler")
> - Removed from h8300 by 1c4b5ecb7ea1 ("remove the h8300 architecture")
> - Started being used in i915 selftest by 250f8c8140ac ("drm/i915/gtt:
> Read-only pages for insert_entries on bdw+")
STACK_MAGIC was added in 1994 in 1.0.2. It was indeed used in a couple
of places in core subsystems back then to detect stack corruption. But
since that people invented better ways to guard stacks.
You can check commit 4914d770dec4 in this project:
https://archive.org/details/git-history-of-linux
