On Fri, Jul 28, 2023 at 11:08:56AM +0200, Ard Biesheuvel wrote:
> Instead of pushing/popping %RSI to/from the stack every time a function
> is called from startup_64(), store it in a callee preserved register
> and grab it from there when its value is actually needed.
>
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> ---
> arch/x86/kernel/head_64.S | 23 +++++---------------
> 1 file changed, 5 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index c5b9289837dcbad2..dbc80fe098f86860 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -62,6 +62,7 @@ SYM_CODE_START_NOALIGN(startup_64)
> * compiled to run at we first fixup the physical addresses in our page
> * tables and then reload them.
> */
> + mov %rsi, %r15 /* Preserve boot_params pointer */
Please move those side comments over the insn.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
