linux-kernel - Re: [PATCH v1 1/1] x86: Rename __{start,end}_init_task to __{start,end}_init

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Message-ID: <ab57dce7-6e89-44aa-a87a-2ffa8cc87fc4@suse.com>
Date: Wed, 13 Mar 2024 08:09:55 +0100
From: Jürgen Groß <jgross@...e.com>
To: "Xin Li (Intel)" <xin@...or.com>, linux-kernel@...r.kernel.org,
 xen-devel@...ts.xenproject.org, linux-arch@...r.kernel.org
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 boris.ostrovsky@...cle.com, arnd@...db.de
Subject: Re: [PATCH v1 1/1] x86: Rename __{start,end}_init_task to
 __{start,end}_init_stack

On 13.03.24 07:05, Xin Li (Intel) wrote:
> The stack of a task has been separated from the memory of a task_struct
> struture for a long time on x86, as a result __{start,end}_init_task no
> longer mark the start and end of the init_task structure, but its stack
> only.
> 
> Rename __{start,end}_init_task to __{start,end}_init_stack.
> 
> Note other architectures are not affected because __{start,end}_init_task
> are used on x86 only.
> 
> Signed-off-by: Xin Li (Intel) <xin@...or.com>
> ---
>   arch/x86/include/asm/processor.h  | 4 ++--
>   arch/x86/kernel/head_64.S         | 2 +-
>   arch/x86/xen/xen-head.S           | 2 +-
>   include/asm-generic/vmlinux.lds.h | 8 ++++----
>   4 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
> index 811548f131f4..8b3a3f3bb859 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -636,10 +636,10 @@ static __always_inline void prefetchw(const void *x)
>   #define KSTK_ESP(task)		(task_pt_regs(task)->sp)
>   
>   #else
> -extern unsigned long __end_init_task[];
> +extern unsigned long __end_init_stack[];
>   
>   #define INIT_THREAD {							\
> -	.sp	= (unsigned long)&__end_init_task -			\
> +	.sp	= (unsigned long)&__end_init_stack -			\
>   		  TOP_OF_KERNEL_STACK_PADDING -				\
>   		  sizeof(struct pt_regs),				\
>   }
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index d8198fbd70e5..c7babd7ebb0f 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -66,7 +66,7 @@ SYM_CODE_START_NOALIGN(startup_64)
>   	mov	%rsi, %r15
>   
>   	/* Set up the stack for verify_cpu() */
> -	leaq	(__end_init_task - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
> +	leaq	(__end_init_stack - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
>   
>   	/* Setup GSBASE to allow stack canary access for C code */
>   	movl	$MSR_GS_BASE, %ecx
> diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
> index 04101b984f24..43eadf03f46d 100644
> --- a/arch/x86/xen/xen-head.S
> +++ b/arch/x86/xen/xen-head.S
> @@ -49,7 +49,7 @@ SYM_CODE_START(startup_xen)
>   	ANNOTATE_NOENDBR
>   	cld
>   
> -	leaq	(__end_init_task - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
> +	leaq	(__end_init_stack - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
>   
>   	/* Set up %gs.
>   	 *
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 5dd3a61d673d..a168be99d522 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -399,13 +399,13 @@
>   
>   #define INIT_TASK_DATA(align)						\
>   	. = ALIGN(align);						\
> -	__start_init_task = .;						\
> +	__start_init_stack = .;						\
>   	init_thread_union = .;						\
>   	init_stack = .;							\
> -	KEEP(*(.data..init_task))					\
> +	KEEP(*(.data..init_stack))					\

Is this modification really correct?

>   	KEEP(*(.data..init_thread_info))				\
> -	. = __start_init_task + THREAD_SIZE;				\
> -	__end_init_task = .;
> +	. = __start_init_stack + THREAD_SIZE;				\
> +	__end_init_stack = .;
>   
>   #define JUMP_TABLE_DATA							\
>   	. = ALIGN(8);							\
> 
> base-commit: 626856ae97054963e7b8c35335d4418271c8d0c4


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