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x86/boot: Simplify boot stack setup

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

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo 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
This commit is contained in:
Brian Gerst 2024-03-21 14:05:06 -04:00 committed by Ingo Molnar
parent 4ae3dc83b0
commit 2cb16181a1
5 changed files with 8 additions and 16 deletions
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6
arch/x86/include/asm/processor.h
View file

@ -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);

11
arch/x86/kernel/head_32.S
View file

@ -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:

2
arch/x86/kernel/head_64.S
View file

@ -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

3
arch/x86/kernel/vmlinux.lds.S
View file

@ -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

2
arch/x86/xen/xen-head.S
View file

@ -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.
*