root/arch/csky/abiv2/mcount.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
   3 
   4 #include <linux/linkage.h>
   5 #include <asm/ftrace.h>
   6 
   7 /*
   8  * csky-gcc with -pg will put the following asm after prologue:
   9  *      push    r15
  10  *      jsri    _mcount
  11  *
  12  * stack layout after mcount_enter in _mcount():
  13  *
  14  * current sp => 0:+-------+
  15  *                 | a0-a3 | -> must save all argument regs
  16  *             +16:+-------+
  17  *                 | lr    | -> _mcount lr (instrumente function's pc)
  18  *             +20:+-------+
  19  *                 | fp=r8 | -> instrumented function fp
  20  *             +24:+-------+
  21  *                 | plr   | -> instrumented function lr (parent's pc)
  22  *                 +-------+
  23  */
  24 
  25 .macro mcount_enter
  26         subi    sp, 24
  27         stw     a0, (sp, 0)
  28         stw     a1, (sp, 4)
  29         stw     a2, (sp, 8)
  30         stw     a3, (sp, 12)
  31         stw     lr, (sp, 16)
  32         stw     r8, (sp, 20)
  33 .endm
  34 
  35 .macro mcount_exit
  36         ldw     a0, (sp, 0)
  37         ldw     a1, (sp, 4)
  38         ldw     a2, (sp, 8)
  39         ldw     a3, (sp, 12)
  40         ldw     t1, (sp, 16)
  41         ldw     r8, (sp, 20)
  42         ldw     lr, (sp, 24)
  43         addi    sp, 28
  44         jmp     t1
  45 .endm
  46 
  47 .macro save_return_regs
  48         subi    sp, 16
  49         stw     a0, (sp, 0)
  50         stw     a1, (sp, 4)
  51         stw     a2, (sp, 8)
  52         stw     a3, (sp, 12)
  53 .endm
  54 
  55 .macro restore_return_regs
  56         mov     lr, a0
  57         ldw     a0, (sp, 0)
  58         ldw     a1, (sp, 4)
  59         ldw     a2, (sp, 8)
  60         ldw     a3, (sp, 12)
  61         addi    sp, 16
  62 .endm
  63 
  64 .macro nop32_stub
  65         nop32
  66         nop32
  67         nop32
  68 .endm
  69 
  70 ENTRY(ftrace_stub)
  71         jmp     lr
  72 END(ftrace_stub)
  73 
  74 #ifndef CONFIG_DYNAMIC_FTRACE
  75 ENTRY(_mcount)
  76         mcount_enter
  77 
  78         /* r26 is link register, only used with jsri translation */
  79         lrw     r26, ftrace_trace_function
  80         ldw     r26, (r26, 0)
  81         lrw     a1, ftrace_stub
  82         cmpne   r26, a1
  83         bf      skip_ftrace
  84 
  85         mov     a0, lr
  86         subi    a0, 4
  87         ldw     a1, (sp, 24)
  88 
  89         jsr     r26
  90 
  91 #ifndef CONFIG_FUNCTION_GRAPH_TRACER
  92 skip_ftrace:
  93         mcount_exit
  94 #else
  95 skip_ftrace:
  96         lrw     a0, ftrace_graph_return
  97         ldw     a0, (a0, 0)
  98         lrw     a1, ftrace_stub
  99         cmpne   a0, a1
 100         bt      ftrace_graph_caller
 101 
 102         lrw     a0, ftrace_graph_entry
 103         ldw     a0, (a0, 0)
 104         lrw     a1, ftrace_graph_entry_stub
 105         cmpne   a0, a1
 106         bt      ftrace_graph_caller
 107 
 108         mcount_exit
 109 #endif
 110 END(_mcount)
 111 #else /* CONFIG_DYNAMIC_FTRACE */
 112 ENTRY(_mcount)
 113         mov     t1, lr
 114         ldw     lr, (sp, 0)
 115         addi    sp, 4
 116         jmp     t1
 117 ENDPROC(_mcount)
 118 
 119 ENTRY(ftrace_caller)
 120         mcount_enter
 121 
 122         ldw     a0, (sp, 16)
 123         subi    a0, 4
 124         ldw     a1, (sp, 24)
 125 
 126         nop
 127 GLOBAL(ftrace_call)
 128         nop32_stub
 129 
 130 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 131         nop
 132 GLOBAL(ftrace_graph_call)
 133         nop32_stub
 134 #endif
 135 
 136         mcount_exit
 137 ENDPROC(ftrace_caller)
 138 #endif /* CONFIG_DYNAMIC_FTRACE */
 139 
 140 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 141 ENTRY(ftrace_graph_caller)
 142         mov     a0, sp
 143         addi    a0, 24
 144         ldw     a1, (sp, 16)
 145         subi    a1, 4
 146         mov     a2, r8
 147         lrw     r26, prepare_ftrace_return
 148         jsr     r26
 149         mcount_exit
 150 END(ftrace_graph_caller)
 151 
 152 ENTRY(return_to_handler)
 153         save_return_regs
 154         mov     a0, r8
 155         jsri    ftrace_return_to_handler
 156         restore_return_regs
 157         jmp     lr
 158 END(return_to_handler)
 159 #endif