root/tools/perf/arch/arm/tests/regs_load.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <linux/linkage.h>
   3 
   4 #define R0 0x00
   5 #define R1 0x08
   6 #define R2 0x10
   7 #define R3 0x18
   8 #define R4 0x20
   9 #define R5 0x28
  10 #define R6 0x30
  11 #define R7 0x38
  12 #define R8 0x40
  13 #define R9 0x48
  14 #define SL 0x50
  15 #define FP 0x58
  16 #define IP 0x60
  17 #define SP 0x68
  18 #define LR 0x70
  19 #define PC 0x78
  20 
  21 /*
  22  * Implementation of void perf_regs_load(u64 *regs);
  23  *
  24  * This functions fills in the 'regs' buffer from the actual registers values,
  25  * in the way the perf built-in unwinding test expects them:
  26  * - the PC at the time at the call to this function. Since this function
  27  *   is called using a bl instruction, the PC value is taken from LR.
  28  * The built-in unwinding test then unwinds the call stack from the dwarf
  29  * information in unwind__get_entries.
  30  *
  31  * Notes:
  32  * - the 8 bytes stride in the registers offsets comes from the fact
  33  * that the registers are stored in an u64 array (u64 *regs),
  34  * - the regs buffer needs to be zeroed before the call to this function,
  35  * in this case using a calloc in dwarf-unwind.c.
  36  */
  37 
  38 .text
  39 .type perf_regs_load,%function
  40 ENTRY(perf_regs_load)
  41         str r0, [r0, #R0]
  42         str r1, [r0, #R1]
  43         str r2, [r0, #R2]
  44         str r3, [r0, #R3]
  45         str r4, [r0, #R4]
  46         str r5, [r0, #R5]
  47         str r6, [r0, #R6]
  48         str r7, [r0, #R7]
  49         str r8, [r0, #R8]
  50         str r9, [r0, #R9]
  51         str sl, [r0, #SL]
  52         str fp, [r0, #FP]
  53         str ip, [r0, #IP]
  54         str sp, [r0, #SP]
  55         str lr, [r0, #LR]
  56         str lr, [r0, #PC]       // store pc as lr in order to skip the call
  57                                 //  to this function
  58         mov pc, lr
  59 ENDPROC(perf_regs_load)