Commit 2cb16181 authored by Brian Gerst's avatar Brian Gerst Committed by Ingo Molnar
Browse files

x86/boot: Simplify boot stack setup 



Define the symbol __top_init_kernel_stack instead of duplicating
the offset from __end_init_task in multiple places.

Signed-off-by: default avatarBrian Gerst <brgerst@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Uros Bizjak <ubizjak@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20240321180506.89030-1-brgerst@gmail.com
parent 4ae3dc83

arch/x86/include/asm/processor.h

+2 −4
Original line number Diff line number Diff line
@@ -636,12 +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 __top_init_kernel_stack[];



#define INIT_THREAD {							\

	.sp	= (unsigned long)&__end_init_task -			\

		  TOP_OF_KERNEL_STACK_PADDING -				\

		  sizeof(struct pt_regs),				\

	.sp	= (unsigned long)&__top_init_kernel_stack,		\

}



extern unsigned long KSTK_ESP(struct task_struct *task);

arch/x86/kernel/head_32.S

+1 −10
Original line number Diff line number Diff line
@@ -44,9 +44,6 @@ 
#define X86_CAPABILITY	new_cpu_data+CPUINFO_x86_capability

#define X86_VENDOR_ID	new_cpu_data+CPUINFO_x86_vendor_id





#define SIZEOF_PTREGS 17*4



/*

 * Worst-case size of the kernel mapping we need to make:

 * a relocatable kernel can live anywhere in lowmem, so we need to be able
@@ -488,13 +485,7 @@ SYM_DATA_END(initial_page_table) 


.data

.balign 4

/*

 * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder

 * reliably detect the end of the stack.

 */

SYM_DATA(initial_stack,

		.long init_thread_union + THREAD_SIZE -

		SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING)

SYM_DATA(initial_stack, .long __top_init_kernel_stack)



__INITRODATA

int_msg:

arch/x86/kernel/head_64.S

+1 −1
Original line number Diff line number Diff line
@@ -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	__top_init_kernel_stack(%rip), %rsp



	/* Setup GSBASE to allow stack canary access for C code */

	movl	$MSR_GS_BASE, %ecx

arch/x86/kernel/vmlinux.lds.S

+3 −0
Original line number Diff line number Diff line
@@ -172,6 +172,9 @@ SECTIONS 
		/* init_task */

		INIT_TASK_DATA(THREAD_SIZE)



		/* equivalent to task_pt_regs(&init_task) */

		__top_init_kernel_stack = __end_init_task - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE;



#ifdef CONFIG_X86_32

		/* 32 bit has nosave before _edata */

		NOSAVE_DATA

arch/x86/xen/xen-head.S

+1 −1
Original line number Diff line number Diff line
@@ -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	__top_init_kernel_stack(%rip), %rsp



	/* Set up %gs.

	 *