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x86: entry_64.S - trivial: space, comments fixup
Impact: cleanup Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Cyrill Gorcunov
Ingo Molnar
parent
5ae3a139cf
commit
9f1e87ea3e
@ -1020,7 +1020,7 @@ END(\sym)
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.macro paranoidzeroentry_ist sym do_sym ist
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ENTRY(\sym)
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INTR_FRAME
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INTR_FRAME
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PARAVIRT_ADJUST_EXCEPTION_FRAME
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pushq $-1 /* ORIG_RAX: no syscall to restart */
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CFI_ADJUST_CFA_OFFSET 8
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@ -1088,36 +1088,36 @@ zeroentry coprocessor_error do_coprocessor_error
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errorentry alignment_check do_alignment_check
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zeroentry simd_coprocessor_error do_simd_coprocessor_error
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/* Reload gs selector with exception handling */
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/* edi: new selector */
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/* Reload gs selector with exception handling */
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/* edi: new selector */
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ENTRY(native_load_gs_index)
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CFI_STARTPROC
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pushf
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CFI_ADJUST_CFA_OFFSET 8
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DISABLE_INTERRUPTS(CLBR_ANY | ~(CLBR_RDI))
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SWAPGS
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SWAPGS
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gs_change:
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movl %edi,%gs
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movl %edi,%gs
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2: mfence /* workaround */
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SWAPGS
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popf
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popf
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CFI_ADJUST_CFA_OFFSET -8
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ret
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ret
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CFI_ENDPROC
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END(native_load_gs_index)
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.section __ex_table,"a"
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.align 8
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.quad gs_change,bad_gs
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.previous
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.section .fixup,"ax"
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.section __ex_table,"a"
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.align 8
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.quad gs_change,bad_gs
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.previous
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.section .fixup,"ax"
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/* running with kernelgs */
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bad_gs:
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SWAPGS /* switch back to user gs */
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xorl %eax,%eax
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movl %eax,%gs
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jmp 2b
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.previous
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movl %eax,%gs
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jmp 2b
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.previous
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/*
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* Create a kernel thread.
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@ -1152,7 +1152,7 @@ ENTRY(kernel_thread)
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* so internally to the x86_64 port you can rely on kernel_thread()
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* not to reschedule the child before returning, this avoids the need
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* of hacks for example to fork off the per-CPU idle tasks.
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* [Hopefully no generic code relies on the reschedule -AK]
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* [Hopefully no generic code relies on the reschedule -AK]
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*/
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RESTORE_ALL
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UNFAKE_STACK_FRAME
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@ -1231,22 +1231,24 @@ END(call_softirq)
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zeroentry xen_hypervisor_callback xen_do_hypervisor_callback
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/*
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# A note on the "critical region" in our callback handler.
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# We want to avoid stacking callback handlers due to events occurring
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# during handling of the last event. To do this, we keep events disabled
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# until we've done all processing. HOWEVER, we must enable events before
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# popping the stack frame (can't be done atomically) and so it would still
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# be possible to get enough handler activations to overflow the stack.
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# Although unlikely, bugs of that kind are hard to track down, so we'd
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# like to avoid the possibility.
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# So, on entry to the handler we detect whether we interrupted an
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# existing activation in its critical region -- if so, we pop the current
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# activation and restart the handler using the previous one.
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*/
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* A note on the "critical region" in our callback handler.
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* We want to avoid stacking callback handlers due to events occurring
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* during handling of the last event. To do this, we keep events disabled
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* until we've done all processing. HOWEVER, we must enable events before
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* popping the stack frame (can't be done atomically) and so it would still
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* be possible to get enough handler activations to overflow the stack.
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* Although unlikely, bugs of that kind are hard to track down, so we'd
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* like to avoid the possibility.
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* So, on entry to the handler we detect whether we interrupted an
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* existing activation in its critical region -- if so, we pop the current
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* activation and restart the handler using the previous one.
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*/
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ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
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CFI_STARTPROC
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/* Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
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see the correct pointer to the pt_regs */
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/*
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* Since we don't modify %rdi, evtchn_do_upall(struct *pt_regs) will
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* see the correct pointer to the pt_regs
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*/
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movq %rdi, %rsp # we don't return, adjust the stack frame
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CFI_ENDPROC
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DEFAULT_FRAME
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@ -1264,18 +1266,18 @@ ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
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END(do_hypervisor_callback)
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/*
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# Hypervisor uses this for application faults while it executes.
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# We get here for two reasons:
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# 1. Fault while reloading DS, ES, FS or GS
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# 2. Fault while executing IRET
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# Category 1 we do not need to fix up as Xen has already reloaded all segment
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# registers that could be reloaded and zeroed the others.
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# Category 2 we fix up by killing the current process. We cannot use the
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# normal Linux return path in this case because if we use the IRET hypercall
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# to pop the stack frame we end up in an infinite loop of failsafe callbacks.
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# We distinguish between categories by comparing each saved segment register
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# with its current contents: any discrepancy means we in category 1.
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*/
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* Hypervisor uses this for application faults while it executes.
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* We get here for two reasons:
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* 1. Fault while reloading DS, ES, FS or GS
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* 2. Fault while executing IRET
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* Category 1 we do not need to fix up as Xen has already reloaded all segment
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* registers that could be reloaded and zeroed the others.
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* Category 2 we fix up by killing the current process. We cannot use the
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* normal Linux return path in this case because if we use the IRET hypercall
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* to pop the stack frame we end up in an infinite loop of failsafe callbacks.
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* We distinguish between categories by comparing each saved segment register
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* with its current contents: any discrepancy means we in category 1.
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*/
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ENTRY(xen_failsafe_callback)
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INTR_FRAME 1 (6*8)
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/*CFI_REL_OFFSET gs,GS*/
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@ -1339,8 +1341,8 @@ paranoidzeroentry machine_check do_machine_check
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#endif
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/*
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* "Paranoid" exit path from exception stack.
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* Paranoid because this is used by NMIs and cannot take
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* "Paranoid" exit path from exception stack.
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* Paranoid because this is used by NMIs and cannot take
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* any kernel state for granted.
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* We don't do kernel preemption checks here, because only
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* NMI should be common and it does not enable IRQs and
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@ -1445,7 +1447,7 @@ error_kernelspace:
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cmpq %rcx,RIP+8(%rsp)
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je error_swapgs
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cmpq $gs_change,RIP+8(%rsp)
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je error_swapgs
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je error_swapgs
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jmp error_sti
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END(error_entry)
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@ -1521,7 +1523,7 @@ nmi_schedule:
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CFI_ENDPROC
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#else
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jmp paranoid_exit
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CFI_ENDPROC
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CFI_ENDPROC
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#endif
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END(nmi)
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