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 2008-11-27 21:10:08 +03:00 committed by Ingo Molnar
parent 5ae3a139cf
commit 9f1e87ea3e

View File

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