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SubjectRe: [PATCH 5/5] x86: entry_64.S - trivial: space, comments fixup
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On Wed, 26 Nov 2008 22:17:04 +0300, gorcunov@gmail.com said:
> From: Cyrill Gorcunov <gorcunov@gmail.com>
>
> Impact: cleanup
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>

Acked-by: Alexander van Heukelum <heukelum@fastmail.fm>


> arch/x86/kernel/entry_64.S | 92
> ++++++++++++++++++++++---------------------
> 1 files changed, 47 insertions(+), 45 deletions(-)
>
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index a21be86..5ccf410 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -1119,8 +1119,8 @@ paranoidzeroentry machine_check do_machine_check
> zeroentry simd_coprocessor_error do_simd_coprocessor_error
>
> /*
> - * "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
> @@ -1225,7 +1225,7 @@ 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
> KPROBE_END(error_entry)
>
> @@ -1249,36 +1249,36 @@ KPROBE_ENTRY(error_exit)
> CFI_ENDPROC
> KPROBE_END(error_exit)
>
> - /* 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.
> @@ -1313,7 +1313,7 @@ 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
> @@ -1420,7 +1420,7 @@ nmi_schedule:
> CFI_ENDPROC
> #else
> jmp paranoid_exit
> - CFI_ENDPROC
> + CFI_ENDPROC
> #endif
> KPROBE_END(nmi)
>
> @@ -1455,22 +1455,24 @@ KPROBE_END(ignore_sysret)
> 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
> @@ -1488,18 +1490,18 @@ 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*/
> --
> 1.6.0.4.603.gbc9c0
>
--
Alexander van Heukelum
heukelum@fastmail.fm

--
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