From 0dd76d736eeb3e0ef86c5b103b47ae0e15edebad Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Wed, 21 Jan 2009 17:26:05 +0900 Subject: [PATCH] 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: Brian Gerst Signed-off-by: Tejun Heo --- arch/x86/kernel/cpu/common.c | 2 +- arch/x86/kernel/head_32.S | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index a8f0ded..fbebbce 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -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); diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index e835b4e..24c0e5c 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -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 */ -- 2.7.4