linux-kernel - [PATCH 50 of 55] xen64: save lots of registers

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Date:	Tue, 08 Jul 2008 15:07:12 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
	Stephen Tweedie <sct@...hat.com>,
	Eduardo Habkost <ehabkost@...hat.com>,
	Mark McLoughlin <markmc@...hat.com>, x86@...nel.org
Subject: [PATCH 50 of 55] xen64: save lots of registers

The Xen hypercall interface is allowed to trash any or all of the
argument registers, so we need to be careful that the kernel state
isn't damaged.  On 32-bit kernels, the hypercall parameter registers
same as a regparm function call, so we've got away without explicit
clobbering so far.  The 64-bit ABI defines lots of caller-save
registers, so save them all for safety.  We can trim this set later by
re-distributing the responsibility for saving all these registers.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
 include/asm-x86/paravirt.h |   26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -1396,8 +1396,8 @@
  * caller saved registers but the argument parameter */
 #define PV_SAVE_REGS "pushq %%rdi;"
 #define PV_RESTORE_REGS "popq %%rdi;"
-#define PV_EXTRA_CLOBBERS EXTRA_CLOBBERS, "rcx" , "rdx"
-#define PV_VEXTRA_CLOBBERS EXTRA_CLOBBERS, "rdi", "rcx" , "rdx"
+#define PV_EXTRA_CLOBBERS EXTRA_CLOBBERS, "rcx" , "rdx", "rsi"
+#define PV_VEXTRA_CLOBBERS EXTRA_CLOBBERS, "rdi", "rcx" , "rdx", "rsi"
 #define PV_FLAGS_ARG "D"
 #endif
 
@@ -1489,8 +1489,26 @@
 
 
 #ifdef CONFIG_X86_64
-#define PV_SAVE_REGS   pushq %rax; pushq %rdi; pushq %rcx; pushq %rdx
-#define PV_RESTORE_REGS popq %rdx; popq %rcx; popq %rdi; popq %rax
+#define PV_SAVE_REGS				\
+	push %rax;				\
+	push %rcx;				\
+	push %rdx;				\
+	push %rsi;				\
+	push %rdi;				\
+	push %r8;				\
+	push %r9;				\
+	push %r10;				\
+	push %r11
+#define PV_RESTORE_REGS				\
+	pop %r11;				\
+	pop %r10;				\
+	pop %r9;				\
+	pop %r8;				\
+	pop %rdi;				\
+	pop %rsi;				\
+	pop %rdx;				\
+	pop %rcx;				\
+	pop %rax
 #define PARA_PATCH(struct, off)        ((PARAVIRT_PATCH_##struct + (off)) / 8)
 #define PARA_SITE(ptype, clobbers, ops) _PVSITE(ptype, clobbers, ops, .quad, 8)
 #define PARA_INDIRECT(addr)	*addr(%rip)


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