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Commit 0dd76d73 authored by Brian Gerst's avatar Brian Gerst Committed by Tejun Heo
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x86: set %fs to __KERNEL_PERCPU unconditionally for x86_32 



Impact: cleanup

%fs is currently set to __KERNEL_DS at boot, and conditionally
switched to __KERNEL_PERCPU for secondary cpus.  Instead, initialize
GDT_ENTRY_PERCPU to the same attributes as GDT_ENTRY_KERNEL_DS and
set %fs to __KERNEL_PERCPU unconditionally.

Signed-off-by: default avatarBrian Gerst <brgerst@gmail.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 299e2699

arch/x86/kernel/cpu/common.c

+1 −1
Original line number Diff line number Diff line
@@ -111,7 +111,7 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = { 
	[GDT_ENTRY_APMBIOS_BASE+2] = { { { 0x0000ffff, 0x00409200 } } },



	[GDT_ENTRY_ESPFIX_SS] = { { { 0x00000000, 0x00c09200 } } },

	[GDT_ENTRY_PERCPU] = { { { 0x00000000, 0x00000000 } } },

	[GDT_ENTRY_PERCPU] = { { { 0x0000ffff, 0x00cf9200 } } },

#endif

} };

EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);

arch/x86/kernel/head_32.S

+3 −3
Original line number Diff line number Diff line
@@ -429,12 +429,14 @@ is386: movl $2,%ecx # set MP 
	ljmp $(__KERNEL_CS),$1f

1:	movl $(__KERNEL_DS),%eax	# reload all the segment registers

	movl %eax,%ss			# after changing gdt.

	movl %eax,%fs			# gets reset once there's real percpu



	movl $(__USER_DS),%eax		# DS/ES contains default USER segment

	movl %eax,%ds

	movl %eax,%es



	movl $(__KERNEL_PERCPU), %eax

	movl %eax,%fs			# set this cpu's percpu



	xorl %eax,%eax			# Clear GS and LDT

	movl %eax,%gs

	lldt %ax
@@ -446,8 +448,6 @@ is386: movl $2,%ecx # set MP 
	movb $1, ready

	cmpb $0,%cl		# the first CPU calls start_kernel

	je   1f

	movl $(__KERNEL_PERCPU), %eax

	movl %eax,%fs		# set this cpu's percpu

	movl (stack_start), %esp

1:

#endif /* CONFIG_SMP */