[PATCH 5.4 v2 1/6] x86, vmlinux.lds: Add RUNTIME_DISCARD_EXIT to generic DISCARDS

[Greg Kroah-Hartman]

On Fri, Feb 10, 2023 at 01:20:22PM -0700, Tom Saeger wrote:
> From: "H.J. Lu" <hjl.tools at gmail.com>
> 
> commit 84d5f77fc2ee4e010c2c037750e32f06e55224b0 upstream.
> 
> In the x86 kernel, .exit.text and .exit.data sections are discarded at
> runtime, not by the linker. Add RUNTIME_DISCARD_EXIT to generic DISCARDS
> and define it in the x86 kernel linker script to keep them.
> 
> The sections are added before the DISCARD directive so document here
> only the situation explicitly as this change doesn't have any effect on
> the generated kernel. Also, other architectures like ARM64 will use it
> too so generalize the approach with the RUNTIME_DISCARD_EXIT define.
> 
>  [ bp: Massage and extend commit message. ]
> 
> Signed-off-by: H.J. Lu <hjl.tools at gmail.com>
> Signed-off-by: Borislav Petkov <bp at suse.de>
> Reviewed-by: Kees Cook <keescook at chromium.org>
> Link: https://lkml.kernel.org/r/20200326193021.255002-1-hjl.tools@gmail.com
> Signed-off-by: Tom Saeger <tom.saeger at oracle.com>
> ---
>  arch/x86/kernel/vmlinux.lds.S     |  1 +
>  include/asm-generic/vmlinux.lds.h | 11 +++++++++--
>  2 files changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
> index 1afe211d7a7c..0ae3cd9a25ea 100644
> --- a/arch/x86/kernel/vmlinux.lds.S
> +++ b/arch/x86/kernel/vmlinux.lds.S
> @@ -21,6 +21,7 @@
>  #define LOAD_OFFSET __START_KERNEL_map
>  #endif
>  
> +#define RUNTIME_DISCARD_EXIT
>  #include <asm-generic/vmlinux.lds.h>
>  #include <asm/asm-offsets.h>
>  #include <asm/thread_info.h>

Does this backport look correct from a style point-of-view?

Hint, extra blank line needed after the define, like what is done in the
original...

thanks,

greg k-h