kitten/arch/x86_64/lib/thunk.S

   1         /*
   2          * Save registers before calling assembly functions. This avoids
   3          * disturbance of register allocation in some inline assembly constructs.
   4          * Copyright 2001,2002 by Andi Kleen, SuSE Labs.
   5          * Subject to the GNU public license, v.2. No warranty of any kind.
   6          * $Id: thunk.S,v 1.2 2002/03/13 20:06:58 ak Exp $
   7          */
   8
   9         #include <lwk/linkage.h>
  10         #include <arch/dwarf2.h>
  11         #include <arch/calling.h>
  12         #include <arch/rwlock.h>
  13
  14         /* rdi: arg1 ... normal C conventions. rax is saved/restored. */
  15         .macro thunk name,func
  16         .globl \name
  17 \name:
  18         CFI_STARTPROC
  19         SAVE_ARGS
  20         call \func
  21         jmp  restore
  22         CFI_ENDPROC
  23         .endm
  24
  25         /* rdi: arg1 ... normal C conventions. rax is passed from C. */
  26         .macro thunk_retrax name,func
  27         .globl \name
  28 \name:
  29         CFI_STARTPROC
  30         SAVE_ARGS
  31         call \func
  32         jmp  restore_norax
  33         CFI_ENDPROC
  34         .endm
  35
  36
  37 #if 0
  38         .section .sched.text
  39 #ifdef CONFIG_RWSEM_XCHGADD_ALGORITHM
  40         thunk rwsem_down_read_failed_thunk,rwsem_down_read_failed
  41         thunk rwsem_down_write_failed_thunk,rwsem_down_write_failed
  42         thunk rwsem_wake_thunk,rwsem_wake
  43         thunk rwsem_downgrade_thunk,rwsem_downgrade_wake
  44 #endif
  45
  46         thunk __down_failed,__down
  47         thunk_retrax __down_failed_interruptible,__down_interruptible
  48         thunk_retrax __down_failed_trylock,__down_trylock
  49         thunk __up_wakeup,__up
  50 #endif
  51
  52         /* SAVE_ARGS below is used only for the .cfi directives it contains. */
  53         CFI_STARTPROC
  54         SAVE_ARGS
  55 restore:
  56         RESTORE_ARGS
  57         ret
  58         CFI_ENDPROC
  59
  60         CFI_STARTPROC
  61         SAVE_ARGS
  62 restore_norax:
  63         RESTORE_ARGS 1
  64         ret
  65         CFI_ENDPROC
  66
  67 /* Support for read/write spinlocks. */
  68         .text
  69 /* rax: pointer to rwlock_t */
  70 ENTRY(__write_lock_failed)
  71         lock
  72         addl $RW_LOCK_BIAS,(%rax)
  73 1:      rep
  74         nop
  75         cmpl $RW_LOCK_BIAS,(%rax)
  76         jne 1b
  77         lock
  78         subl $RW_LOCK_BIAS,(%rax)
  79         jnz  __write_lock_failed
  80         ret
  81
  82 /* rax: pointer to rwlock_t */
  83 ENTRY(__read_lock_failed)
  84         lock
  85         incl (%rax)
  86 1:      rep
  87         nop
  88         cmpl $1,(%rax)
  89         js 1b
  90         lock
  91         decl (%rax)
  92         js __read_lock_failed
  93         ret