x86/paravirt: define PARA_INDIRECT for indirect asm calls

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>
Cc: xen-devel <xen-devel@lists.xensource.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>

1 files changed, 15 insertions, 13 deletions

diff --git a/include/asm-x86/paravirt.h b/include/asm-x86/paravirt.h
index 198293bed46f..82cdcde4b222 100644
--- a/include/asm-x86/paravirt.h
+++ b/include/asm-x86/paravirt.h
@@ -1455,51 +1455,53 @@ static inline unsigned long __raw_local_irq_save(void)
 #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 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