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Contents of /trunk/kernel26-xen/patches-2.6.25-r1/1087-2.6.25-xen-64-xen_iret-use-iretq-directly-if-returning-t.patch
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Revision Log
Revision 606 -
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Thu May 22 23:13:13 2008 UTC (15 years, 11 months ago) by niro
File size: 2568 byte(s)
Thu May 22 23:13:13 2008 UTC (15 years, 11 months ago) by niro
File size: 2568 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 22cc94bb97f4c9ae3fcd3d3c751db935c8c594a2 Mon Sep 17 00:00:00 2001 |
| 2 | From: Eduardo Habkost <ehabkost@redhat.com> |
| 3 | Date: Fri, 4 Jan 2008 11:54:37 -0200 |
| 4 | Subject: [PATCH] xen-64: xen_iret() use iretq directly if returning to kernel-space |
| 5 | |
| 6 | Optimization pulled from upstream Xen. |
| 7 | |
| 8 | Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> |
| 9 | --- |
| 10 | arch/x86/xen/xen-asm.S | 5 ++++ |
| 11 | arch/x86/xen/xen-asm_64.S | 49 +++++++++++++++++++++++++++++++++++++++++++++ |
| 12 | 2 files changed, 54 insertions(+), 0 deletions(-) |
| 13 | |
| 14 | diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S |
| 15 | index 1c3c0ac..c7356c0 100644 |
| 16 | --- a/arch/x86/xen/xen-asm.S |
| 17 | +++ b/arch/x86/xen/xen-asm.S |
| 18 | @@ -21,6 +21,11 @@ |
| 19 | #include <asm/asm-hack.h> |
| 20 | |
| 21 | #include <xen/interface/xen.h> |
| 22 | +#include <xen/interface/features.h> |
| 23 | + |
| 24 | +#include <asm/calling.h> |
| 25 | +#include <asm/processor-flags.h> |
| 26 | + |
| 27 | |
| 28 | #define RELOC(x, v) .globl x##_reloc; x##_reloc=v |
| 29 | #define ENDPATCH(x) .globl x##_end; x##_end=. |
| 30 | diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S |
| 31 | index 8f28a91..85c235c 100644 |
| 32 | --- a/arch/x86/xen/xen-asm_64.S |
| 33 | +++ b/arch/x86/xen/xen-asm_64.S |
| 34 | @@ -7,7 +7,56 @@ ENTRY(xen_iret_direct) |
| 35 | /*FIXME: implement me! */ |
| 36 | ud2a |
| 37 | |
| 38 | +//FIXME: move to calling.h? |
| 39 | +#define IRETOFFSET RIP |
| 40 | + |
| 41 | ENTRY(xen_iret) |
| 42 | + /* Are we returning to kernel space? */ |
| 43 | + testb $3,CS-IRETOFFSET(%rsp) |
| 44 | + jnz xen_iret_slow |
| 45 | + |
| 46 | +#if 0 |
| 47 | + /*FIXME: handle NMI callbacks */ |
| 48 | + testl $NMI_MASK,EFLAGS-IRETOFFSET(%rsp) |
| 49 | + jnz xen_iret_slow |
| 50 | +#endif |
| 51 | + |
| 52 | + /* If we are going to restore interrupts, we need to |
| 53 | + * return through the hypervisor, too. |
| 54 | + * |
| 55 | + * We may set evtchn_upcall_mask ourselves, but things get complicated |
| 56 | + * because we would need to avoid a stack overflow if we get |
| 57 | + * interrupts between upcall_mask being cleared and iret being |
| 58 | + * executed. |
| 59 | + */ |
| 60 | + testl $X86_EFLAGS_IF,EFLAGS-IRETOFFSET(%rsp) |
| 61 | + jnz xen_iret_slow |
| 62 | + |
| 63 | + |
| 64 | + |
| 65 | + /* Returning to kernel (RING0). |
| 66 | + * Use direct iret to kernel space after correcting CS and SS |
| 67 | + */ |
| 68 | + |
| 69 | + cmpb $0,(xen_features+XENFEAT_supervisor_mode_kernel)(%rip) |
| 70 | + /* supervisor_mode_kernel -> no need to correct CS and SS */ |
| 71 | + jne xen_iretq |
| 72 | + |
| 73 | + /* Direct iret to kernel space. Correct CS and SS. */ |
| 74 | + orl $3,CS-IRETOFFSET(%rsp) |
| 75 | + orl $3,SS-IRETOFFSET(%rsp) |
| 76 | +xen_iretq: |
| 77 | + iretq |
| 78 | + |
| 79 | +xen_iret_slow: |
| 80 | + /* Slow iret via hypervisor */ |
| 81 | + |
| 82 | +#if 0 |
| 83 | + /*FIXME: handle NMI callbacks */ |
| 84 | + andl $~NMI_MASK, 2*8(%rsp) |
| 85 | +#endif |
| 86 | + |
| 87 | + /* Xen has an additional value in the stack for iret */ |
| 88 | /*FIXME: the VGCF_in_syscall flag need to be handled here */ |
| 89 | pushq $0 |
| 90 | jmp hypercall_page + (__HYPERVISOR_iret * 32) |
| 91 | -- |
| 92 | 1.5.4.1 |
| 93 |