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    Contents of /trunk/kernel26-xen/patches-2.6.25-r1/1116-2.6.25-xen-Hack-to-implement-return-to-userspace-without-SWAPGS.patch

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    Revision 606 - (show annotations) (download)
    Thu May 22 23:13:13 2008 UTC (16 years ago) by niro
    File size: 2211 byte(s) 
    -ver bump to 2.6.25-magellan-r1:
- linux-2.6.25.4
- fbcondecor-0.9.4
- squashfs-3.3
- unionfs-2.3.3
- tuxonice-3.0-rc7
- linux-phc-0.3.0
- acpi-dstd-0.9a
- reiser4
- xen-3.2.0
. ipw3945-1.2.2
    1 From 0ad8cf63312ab9eaf02efdd148eed9151894ef0f Mon Sep 17 00:00:00 2001
    2 From: Eduardo Habkost <ehabkost@redhat.com>
    3 Date: Fri, 18 Jan 2008 17:12:43 -0200
    4 Subject: [PATCH] Hack to implement return to userspace without SWAPGS (CLEANME)
    5
    6 Implementing SWAPGS as nop wouldn't be good, because code using it may
    7 really expect a swapgs operation to be done. It is better to make each
    8 operation that use swapgs to be a paravirt op.
    9
    10 Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
    11 ---
    12 arch/x86/kernel/entry_64.S | 15 ++++++++++++++-
    13 arch/x86/xen/entry_64.S | 10 ++++++++++
    14 2 files changed, 24 insertions(+), 1 deletions(-)
    15
    16 diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
    17 index 9952c3f..1182250 100644
    18 --- a/arch/x86/kernel/entry_64.S
    19 +++ b/arch/x86/kernel/entry_64.S
    20 @@ -66,6 +66,17 @@ ENTRY(native_irq_enable_syscall_ret)
    21 #endif /* CONFIG_PARAVIRT */
    22
    23
    24 +/*FIXME: implement this as a paravirt op */
    25 +#ifdef CONFIG_XEN
    26 +#define retint_swapgs xen_retint_swapgs
    27 +#define error_userspace error_sti
    28 +#else
    29 +#define retint_swapgs native_retint_swapgs
    30 +#define error_userspace error_swapgs
    31 +#endif
    32 +
    33 +
    34 +
    35 .macro TRACE_IRQS_IRETQ offset=ARGOFFSET
    36 #ifdef CONFIG_TRACE_IRQFLAGS
    37 bt $9,EFLAGS-\offset(%rsp) /* interrupts off? */
    38 @@ -564,8 +575,9 @@ retint_check:
    39 andl %edi,%edx
    40 CFI_REMEMBER_STATE
    41 jnz retint_careful
    42 + jmp retint_swapgs
    43
    44 -retint_swapgs: /* return to user-space */
    45 +native_retint_swapgs: /* return to user-space */
    46 /*
    47 * The iretq could re-enable interrupts:
    48 */
    49 @@ -912,6 +924,7 @@ KPROBE_ENTRY(error_entry)
    50 xorl %ebx,%ebx
    51 testl $3,CS(%rsp)
    52 je error_kernelspace
    53 + jmp error_userspace
    54 error_swapgs:
    55 SWAPGS
    56 error_sti:
    57 diff --git a/arch/x86/xen/entry_64.S b/arch/x86/xen/entry_64.S
    58 index 927108c..2a2a0a0 100644
    59 --- a/arch/x86/xen/entry_64.S
    60 +++ b/arch/x86/xen/entry_64.S
    61 @@ -41,3 +41,13 @@ ENTRY(do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
    62 jmp error_exit
    63 CFI_ENDPROC
    64 END(do_hypervisor_callback)
    65 +
    66 +
    67 +ENTRY(xen_retint_swapgs) /* return to user-space */
    68 + /*
    69 + * The iretq could re-enable interrupts:
    70 + */
    71 + DISABLE_INTERRUPTS(CLBR_ANY)
    72 + TRACE_IRQS_IRETQ
    73 + jmp restore_args
    74 +END(xen_retint_swapgs)
    75 --
    76 1.5.4.1
    77