arch/x86/lib/rwsem_64.S

   1 /*
   2  * x86-64 rwsem wrappers
   3  *
   4  * This interfaces the inline asm code to the slow-path
   5  * C routines. We need to save the call-clobbered regs
   6  * that the asm does not mark as clobbered, and move the
   7  * argument from %rax to %rdi.
   8  *
   9  * NOTE! We don't need to save %rax, because the functions
  10  * will always return the semaphore pointer in %rax (which
  11  * is also the input argument to these helpers)
  12  *
  13  * The following can clobber %rdx because the asm clobbers it:
  14  *   call_rwsem_down_write_failed
  15  *   call_rwsem_wake
  16  * but %rdi, %rsi, %rcx, %r8-r11 always need saving.
  17  */
  18
  19 #include <linux/linkage.h>
  20 #include <asm/rwlock.h>
  21 #include <asm/alternative-asm.h>
  22 #include <asm/frame.h>
  23 #include <asm/dwarf2.h>
  24
  25 #define save_common_regs \
  26         pushq %rdi; \
  27         pushq %rsi; \
  28         pushq %rcx; \
  29         pushq %r8; \
  30         pushq %r9; \
  31         pushq %r10; \
  32         pushq %r11
  33
  34 #define restore_common_regs \
  35         popq %r11; \
  36         popq %r10; \
  37         popq %r9; \
  38         popq %r8; \
  39         popq %rcx; \
  40         popq %rsi; \
  41         popq %rdi
  42
  43 /* Fix up special calling conventions */
  44 ENTRY(call_rwsem_down_read_failed)
  45         save_common_regs
  46         pushq %rdx
  47         movq %rax,%rdi
  48         call rwsem_down_read_failed
  49         popq %rdx
  50         restore_common_regs
  51         ret
  52         ENDPROC(call_rwsem_down_read_failed)
  53
  54 ENTRY(call_rwsem_down_write_failed)
  55         save_common_regs
  56         movq %rax,%rdi
  57         call rwsem_down_write_failed
  58         restore_common_regs
  59         ret
  60         ENDPROC(call_rwsem_down_write_failed)
  61
  62 ENTRY(call_rwsem_wake)
  63         decw %dx    /* do nothing if still outstanding active readers */
  64         jnz 1f
  65         save_common_regs
  66         movq %rax,%rdi
  67         call rwsem_wake
  68         restore_common_regs
  69 1:      ret
  70         ENDPROC(call_rwsem_wake)
  71
  72 /* Fix up special calling conventions */
  73 ENTRY(call_rwsem_downgrade_wake)
  74         save_common_regs
  75         pushq %rdx
  76         movq %rax,%rdi
  77         call rwsem_downgrade_wake
  78         popq %rdx
  79         restore_common_regs
  80         ret
  81         ENDPROC(call_rwsem_downgrade_wake)