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xen64: save lots of registers
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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@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Jeremy Fitzhardinge authored and Ingo Molnar committed Jul 16, 2008
1 parent c05f1cf commit c24481e
Showing 1 changed file with 22 additions and 4 deletions.
26 changes: 22 additions & 4 deletions include/asm-x86/paravirt.h
Original file line number Diff line number Diff line change
Expand Up @@ -1396,8 +1396,8 @@ extern struct paravirt_patch_site __parainstructions[],
* 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

Expand Down Expand Up @@ -1489,8 +1489,26 @@ static inline unsigned long __raw_local_irq_save(void)


#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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