On Fri, Feb 24, 2023 at 06:15:09AM +0530, Viresh Kumar wrote:
> Hi Greg,
>
> On 23-02-23, 15:14, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> > From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> >
> > commit f3dd0c53370e70c0f9b7e931bbec12916f3bb8cc upstream.
> >
> > Commit 74e19ef0ff80 ("uaccess: Add speculation barrier to
> > copy_from_user()") built fine on x86-64 and arm64, and that's the extent
> > of my local build testing.
> >
> > It turns out those got the <linux/nospec.h> include incidentally through
> > other header files (<linux/kvm_host.h> in particular), but that was not
> > true of other architectures, resulting in build errors
> >
> > kernel/bpf/core.c: In function ‘___bpf_prog_run’:
> > kernel/bpf/core.c:1913:3: error: implicit declaration of function ‘barrier_nospec’
> >
> > so just make sure to explicitly include the proper <linux/nospec.h>
> > header file to make everybody see it.
> >
> > Fixes: 74e19ef0ff80 ("uaccess: Add speculation barrier to copy_from_user()")
>
> The commit that introduced the build failure (74e19ef0ff80) is part of the
> current merge window. I am not sure why we need to backport the fix to any
> earlier kernel release.
Because it is part of the stable patch series right now, see
https://lore.kernel.org/r/20230223130426.229532388@xxxxxxxxxxxxxxxxxxx
as one example.
thanks,
greg k-h
