guest/linux/hvm-ros/v3_hvm_ros_user_low_level.S

   1 .section .text
   2
   3 .extern __v3_hvm_ros_signal_handler
   4
   5 /*
   6    This is the entry point for signal dispatch
   7    from the VMM.
   8
   9    VMM invokes this stub when a user signal is
  10    raised and:  the relevant address space
  11    is active, and we are at user-level.
  12    It will be invoked  on exactly one core,
  13    although there are  no guarantees on which one.
  14
  15 */
  16
  17
  18 #define GPR_SAVE()                                               \
  19         pushq %rbp              ;                                \
  20         pushq %rax              ;                                \
  21         pushq %rbx              ;                                \
  22         pushq %rcx              ;                                \
  23         pushq %rdx              ;                                \
  24         pushq %rsi              ;                                \
  25         pushq %rdi              ;                                \
  26         pushq %r8               ;                                \
  27         pushq %r9               ;                                \
  28         pushq %r10              ;                                \
  29         pushq %r11              ;                                \
  30         pushq %r12              ;                                \
  31         pushq %r13              ;                                \
  32         pushq %r14              ;                                \
  33         pushq %r15              ;                                \
  34
  35 #define GPR_LOAD()                       \
  36         popq %r15               ;                                \
  37         popq %r14               ;                                \
  38         popq %r13               ;                                \
  39         popq %r12               ;                                \
  40         popq %r11               ;                                \
  41         popq %r10               ;                                \
  42         popq %r9                ;                                \
  43         popq %r8                ;                                \
  44         popq %rdi               ;                                \
  45         popq %rsi               ;                                \
  46         popq %rdx               ;                                \
  47         popq %rcx               ;                                \
  48         popq %rbx               ;                                \
  49         popq %rax               ;                                \
  50         popq %rbp               ;
  51
  52
  53 /*
  54    The VMM puts us here with what looks like a long mode
  55    interrupt dispatch, but it's from CPL 3 to CPL 3 and
  56    it's not done as an interrupt injection per se, so
  57    we can be interrupted, and deliverable interrupts
  58    automatically prioritize over us.
  59
  60         48bitsblank | return SS (16 bits)
  61         Return RSP
  62         Return RFLAGS
  63         48bitsblank | return CS (16 bits)
  64         Return RIP
  65         ERROR CODE (HVM-specific non-zero number here)  <- RSP on entry
  66
  67         We then need simply to do this:
  68
  69         save regs
  70         call the handler (if installed)
  71         restore regs
  72         iret
  73
  74 */
  75
  76 .global __v3_hvm_ros_signal_handler_stub
  77 __v3_hvm_ros_signal_handler_stub:
  78         GPR_SAVE()
  79         movabs __v3_hvm_ros_signal_handler, %rax
  80         testq %rax, %rax
  81         jz skip_handler
  82         movq 120(%rsp), %rdi /* error code becomes argument */
  83         callq *%rax
  84 skip_handler:
  85         GPR_LOAD()
  86         addq $8, %rsp /* nuke the error code */
  87         iretq
  88