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| author | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2014-04-10 12:17:09 -0400 |
|---|---|---|
| committer | David Vrabel <david.vrabel@citrix.com> | 2014-04-15 15:00:14 +0100 |
| commit | 4461bbc05bf11fa4251acded60e4645863a4158a (patch) | |
| tree | 170e93580f872fdb8e781bb83f6b1999322fbc7c | |
| parent | d06eb3ee9b09d753dc0883cc388d9a503839d6ca (diff) | |
| download | linux-4461bbc05bf11fa4251acded60e4645863a4158a.tar.gz linux-4461bbc05bf11fa4251acded60e4645863a4158a.tar.bz2 linux-4461bbc05bf11fa4251acded60e4645863a4158a.zip | |
x86/xen: Fix 32-bit PV guests's usage of kernel_stack
Commit 198d208df4371734ac4728f69cb585c284d20a15 ("x86: Keep
thread_info on thread stack in x86_32") made 32-bit kernels use
kernel_stack to point to thread_info. That change missed a couple of
updates needed by Xen's 32-bit PV guests:
1. kernel_stack needs to be initialized for secondary CPUs
2. GET_THREAD_INFO() now uses %fs register which may not be the
kernel's version when executing xen_iret().
With respect to the second issue, we don't need GET_THREAD_INFO()
anymore: we used it as an intermediate step to get to per_cpu xen_vcpu
and avoid referencing %fs. Now that we are going to use %fs anyway we
may as well go directly to xen_vcpu.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
| -rw-r--r-- | arch/x86/xen/smp.c | 3 | ||||
| -rw-r--r-- | arch/x86/xen/xen-asm_32.S | 25 |
2 files changed, 19 insertions, 9 deletions
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index a18eadd8bb40..7005974c3ff3 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -441,10 +441,11 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle) irq_ctx_init(cpu); #else clear_tsk_thread_flag(idle, TIF_FORK); +#endif per_cpu(kernel_stack, cpu) = (unsigned long)task_stack_page(idle) - KERNEL_STACK_OFFSET + THREAD_SIZE; -#endif + xen_setup_runstate_info(cpu); xen_setup_timer(cpu); xen_init_lock_cpu(cpu); diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S index 33ca6e42a4ca..fd92a64d748e 100644 --- a/arch/x86/xen/xen-asm_32.S +++ b/arch/x86/xen/xen-asm_32.S @@ -75,6 +75,17 @@ ENDPROC(xen_sysexit) * stack state in whatever form its in, we keep things simple by only * using a single register which is pushed/popped on the stack. */ + +.macro POP_FS +1: + popw %fs +.pushsection .fixup, "ax" +2: movw $0, (%esp) + jmp 1b +.popsection + _ASM_EXTABLE(1b,2b) +.endm + ENTRY(xen_iret) /* test eflags for special cases */ testl $(X86_EFLAGS_VM | XEN_EFLAGS_NMI), 8(%esp) @@ -83,15 +94,13 @@ ENTRY(xen_iret) push %eax ESP_OFFSET=4 # bytes pushed onto stack - /* - * Store vcpu_info pointer for easy access. Do it this way to - * avoid having to reload %fs - */ + /* Store vcpu_info pointer for easy access */ #ifdef CONFIG_SMP - GET_THREAD_INFO(%eax) - movl %ss:TI_cpu(%eax), %eax - movl %ss:__per_cpu_offset(,%eax,4), %eax - mov %ss:xen_vcpu(%eax), %eax + pushw %fs + movl $(__KERNEL_PERCPU), %eax + movl %eax, %fs + movl %fs:xen_vcpu, %eax + POP_FS #else movl %ss:xen_vcpu, %eax #endif |