[PATCH 19 of 36] paravirt_ops: define PARA_INDIRECT for indirect asm calls

Jeremy Fitzhardinge
2008-06-25T04:46:22Z

On 32-bit it's best to use a %cs: prefix to access memory where the
other segments may not bet set up properly yet. On 64-bit it's best
to use a rip-relative addressing mode. Define PARA_INDIRECT() to
abstract this and generate the proper addressing mode in each case.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
include/asm-x86/paravirt.h | 30 ++++++++++++++++--------------
1 file changed, 16 insertions(+), 14 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
@@ -1456,55 +1456,57 @@
#define PV_RESTORE_REGS popq %rdx; popq %rcx; popq %rdi; popq %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)
#else
#define PV_SAVE_REGS pushl %eax; pushl %edi; pushl %ecx; pushl %edx
#define PV_RESTORE_REGS popl %edx; popl %ecx; popl %edi; popl %eax
#define PARA_PATCH(struct, off) ((PARAVIRT_PATCH_##struct + (off)) / 4)
#define PARA_SITE(ptype, clobbers, ops) _PVSITE(ptype, clobbers, ops, .long, 4)
+#define PARA_INDIRECT(addr) *%cs:addr
#endif

#define INTERRUPT_RETURN \
PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_iret), CLBR_NONE, \
- jmp *%cs:pv_cpu_ops+PV_CPU_iret)
+ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_iret))

#define INTERRUPT_RETURN_NMI_SAFE \
PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_nmi_return), CLBR_NONE, \
- jmp *%cs:pv_cpu_ops+PV_CPU_nmi_return)
+ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_nmi_return))

#define DISABLE_INTERRUPTS(clobbers) \
PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_irq_disable), clobbers, \
- PV_SAVE_REGS; \
- call *%cs:pv_irq_ops+PV_IRQ_irq_disable; \
+ PV_SAVE_REGS; \
+ call PARA_INDIRECT(pv_irq_ops+PV_IRQ_irq_disable); \
PV_RESTORE_REGS;) \

#define ENABLE_INTERRUPTS(clobbers) \
PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_irq_enable), clobbers, \
- PV_SAVE_REGS; \
- call *%cs:pv_irq_ops+PV_IRQ_irq_enable; \
+ PV_SAVE_REGS; \
+ call PARA_INDIRECT(pv_irq_ops+PV_IRQ_irq_enable); \
PV_RESTORE_REGS;)

#define ENABLE_INTERRUPTS_SYSCALL_RET \
PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_irq_enable_syscall_ret),\
CLBR_NONE, \
- jmp *%cs:pv_cpu_ops+PV_CPU_irq_enable_syscall_ret)
+ jmp PARA_INDIRECT(pv_cpu_ops+PV_CPU_irq_enable_syscall_ret))

#ifdef CONFIG_X86_32
-#define GET_CR0_INTO_EAX \
- push %ecx; push %edx; \
- call *pv_cpu_ops+PV_CPU_read_cr0; \
+#define GET_CR0_INTO_EAX \
+ push %ecx; push %edx; \
+ call PARA_INDIRECT(pv_cpu_ops+PV_CPU_read_cr0); \
pop %edx; pop %ecx
#else
#define SWAPGS \
PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_swapgs), CLBR_NONE, \
PV_SAVE_REGS; \
- call *pv_cpu_ops+PV_CPU_swapgs; \
+ call PARA_INDIRECT(pv_cpu_ops+PV_CPU_swapgs); \
PV_RESTORE_REGS \
)

-#define GET_CR2_INTO_RCX \
- call *pv_mmu_ops+PV_MMU_read_cr2; \
- movq %rax, %rcx; \
+#define GET_CR2_INTO_RCX \
+ call PARA_INDIRECT(pv_mmu_ops+PV_MMU_read_cr2); \
+ movq %rax, %rcx; \
xorq %rax, %rax;

#endif