x86/xen: Fix 32-bit PV guests's usage of kernel_stack
Commit 198d208df4
("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>
This commit is contained in:
parent
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@ -441,10 +441,11 @@ static int xen_cpu_up(unsigned int cpu, struct task_struct *idle)
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irq_ctx_init(cpu);
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#else
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clear_tsk_thread_flag(idle, TIF_FORK);
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#endif
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per_cpu(kernel_stack, cpu) =
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(unsigned long)task_stack_page(idle) -
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KERNEL_STACK_OFFSET + THREAD_SIZE;
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#endif
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xen_setup_runstate_info(cpu);
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xen_setup_timer(cpu);
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xen_init_lock_cpu(cpu);
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@ -75,6 +75,17 @@ ENDPROC(xen_sysexit)
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* stack state in whatever form its in, we keep things simple by only
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* using a single register which is pushed/popped on the stack.
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*/
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.macro POP_FS
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1:
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popw %fs
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.pushsection .fixup, "ax"
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2: movw $0, (%esp)
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jmp 1b
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.popsection
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_ASM_EXTABLE(1b,2b)
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.endm
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ENTRY(xen_iret)
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/* test eflags for special cases */
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testl $(X86_EFLAGS_VM | XEN_EFLAGS_NMI), 8(%esp)
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@ -83,15 +94,13 @@ ENTRY(xen_iret)
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push %eax
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ESP_OFFSET=4 # bytes pushed onto stack
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/*
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* Store vcpu_info pointer for easy access. Do it this way to
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* avoid having to reload %fs
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*/
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/* Store vcpu_info pointer for easy access */
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#ifdef CONFIG_SMP
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GET_THREAD_INFO(%eax)
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movl %ss:TI_cpu(%eax), %eax
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movl %ss:__per_cpu_offset(,%eax,4), %eax
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mov %ss:xen_vcpu(%eax), %eax
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pushw %fs
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movl $(__KERNEL_PERCPU), %eax
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movl %eax, %fs
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movl %fs:xen_vcpu, %eax
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POP_FS
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#else
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movl %ss:xen_vcpu, %eax
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#endif
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