root/arch/powerpc/kernel/optprobes_head.S

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Code to prepare detour buffer for optprobes in Kernel.
   4  *
   5  * Copyright 2017, Anju T, IBM Corp.
   6  */
   7 
   8 #include <asm/ppc_asm.h>
   9 #include <asm/ptrace.h>
  10 #include <asm/asm-offsets.h>
  11 
  12 #define OPT_SLOT_SIZE   65536
  13 
  14         .balign 4
  15 
  16         /*
  17          * Reserve an area to allocate slots for detour buffer.
  18          * This is part of .text section (rather than vmalloc area)
  19          * as this needs to be within 32MB of the probed address.
  20          */
  21         .global optinsn_slot
  22 optinsn_slot:
  23         .space  OPT_SLOT_SIZE
  24 
  25         /*
  26          * Optprobe template:
  27          * This template gets copied into one of the slots in optinsn_slot
  28          * and gets fixed up with real optprobe structures et al.
  29          */
  30         .global optprobe_template_entry
  31 optprobe_template_entry:
  32         /* Create an in-memory pt_regs */
  33         stdu    r1,-INT_FRAME_SIZE(r1)
  34         SAVE_GPR(0,r1)
  35         /* Save the previous SP into stack */
  36         addi    r0,r1,INT_FRAME_SIZE
  37         std     r0,GPR1(r1)
  38         SAVE_10GPRS(2,r1)
  39         SAVE_10GPRS(12,r1)
  40         SAVE_10GPRS(22,r1)
  41         /* Save SPRS */
  42         mfmsr   r5
  43         std     r5,_MSR(r1)
  44         li      r5,0x700
  45         std     r5,_TRAP(r1)
  46         li      r5,0
  47         std     r5,ORIG_GPR3(r1)
  48         std     r5,RESULT(r1)
  49         mfctr   r5
  50         std     r5,_CTR(r1)
  51         mflr    r5
  52         std     r5,_LINK(r1)
  53         mfspr   r5,SPRN_XER
  54         std     r5,_XER(r1)
  55         mfcr    r5
  56         std     r5,_CCR(r1)
  57         lbz     r5,PACAIRQSOFTMASK(r13)
  58         std     r5,SOFTE(r1)
  59 
  60         /*
  61          * We may get here from a module, so load the kernel TOC in r2.
  62          * The original TOC gets restored when pt_regs is restored
  63          * further below.
  64          */
  65         ld      r2,PACATOC(r13)
  66 
  67         .global optprobe_template_op_address
  68 optprobe_template_op_address:
  69         /*
  70          * Parameters to optimized_callback():
  71          * 1. optimized_kprobe structure in r3
  72          */
  73         nop
  74         nop
  75         nop
  76         nop
  77         nop
  78         /* 2. pt_regs pointer in r4 */
  79         addi    r4,r1,STACK_FRAME_OVERHEAD
  80 
  81         .global optprobe_template_call_handler
  82 optprobe_template_call_handler:
  83         /* Branch to optimized_callback() */
  84         nop
  85 
  86         /*
  87          * Parameters for instruction emulation:
  88          * 1. Pass SP in register r3.
  89          */
  90         addi    r3,r1,STACK_FRAME_OVERHEAD
  91 
  92         .global optprobe_template_insn
  93 optprobe_template_insn:
  94         /* 2, Pass instruction to be emulated in r4 */
  95         nop
  96         nop
  97 
  98         .global optprobe_template_call_emulate
  99 optprobe_template_call_emulate:
 100         /* Branch to emulate_step()  */
 101         nop
 102 
 103         /*
 104          * All done.
 105          * Now, restore the registers...
 106          */
 107         ld      r5,_MSR(r1)
 108         mtmsr   r5
 109         ld      r5,_CTR(r1)
 110         mtctr   r5
 111         ld      r5,_LINK(r1)
 112         mtlr    r5
 113         ld      r5,_XER(r1)
 114         mtxer   r5
 115         ld      r5,_CCR(r1)
 116         mtcr    r5
 117         REST_GPR(0,r1)
 118         REST_10GPRS(2,r1)
 119         REST_10GPRS(12,r1)
 120         REST_10GPRS(22,r1)
 121         /* Restore the previous SP */
 122         addi    r1,r1,INT_FRAME_SIZE
 123 
 124         .global optprobe_template_ret
 125 optprobe_template_ret:
 126         /* ... and jump back from trampoline */
 127         nop
 128 
 129         .global optprobe_template_end
 130 optprobe_template_end: