Re: [PATCH RFC 1/7] x86/head/64: Mark startup_gdt and startup_gdt_descr as __initdata

From: Ingo Molnar
Date: Mon Oct 16 2023 - 07:57:15 EST



* Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx> wrote:

> As startup_gdt and startup_gdt_descr are only used in booting, make them
> as __initdata to allow them to be freed after boot.
>
> Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
> ---
> arch/x86/kernel/head64.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index 49f7629b17f7..dd357807ffb5 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -69,7 +69,7 @@ EXPORT_SYMBOL(vmemmap_base);
> /*
> * GDT used on the boot CPU before switching to virtual addresses.
> */
> -static struct desc_struct startup_gdt[GDT_ENTRIES] = {
> +static struct desc_struct startup_gdt[GDT_ENTRIES] __initdata = {
> [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(0xc09b, 0, 0xfffff),
> [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(0xa09b, 0, 0xfffff),
> [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(0xc093, 0, 0xfffff),
> @@ -79,7 +79,7 @@ static struct desc_struct startup_gdt[GDT_ENTRIES] = {
> * Address needs to be set at runtime because it references the startup_gdt
> * while the kernel still uses a direct mapping.
> */
> -static struct desc_ptr startup_gdt_descr = {
> +static struct desc_ptr startup_gdt_descr __initdata = {
> .size = sizeof(startup_gdt),
> .address = 0,

Yeah, so I think this and patch #1 are independently useful of the PIE
feature, and I merged them into tip:x86/boot for a v6.7 merge.

Mind re-sending any other patches for x86 that can be merged? For example
patch #6 looks good too, but was mixed up a bit with a previous
PIE-enablement patch. Moving the __head definition to a header should also
probably done as a separate patch, followed by the widening of its use.

Thanks,

Ingo