LXR linux/arch/powerpc/kernel/optprobes

   1/*
   2 * Code to prepare detour buffer for optprobes in Kernel.
   3 *
   4 * Copyright 2017, Anju T, IBM Corp.
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#include <asm/ppc_asm.h>
  13#include <asm/ptrace.h>
  14#include <asm/asm-offsets.h>
  15
  16#define OPT_SLOT_SIZE   65536
  17
  18        .balign 4
  19
  20        /*
  21         * Reserve an area to allocate slots for detour buffer.
  22         * This is part of .text section (rather than vmalloc area)
  23         * as this needs to be within 32MB of the probed address.
  24         */
  25        .global optinsn_slot
  26optinsn_slot:
  27        .space  OPT_SLOT_SIZE
  28
  29        /*
  30         * Optprobe template:
  31         * This template gets copied into one of the slots in optinsn_slot
  32         * and gets fixed up with real optprobe structures et al.
  33         */
  34        .global optprobe_template_entry
  35optprobe_template_entry:
  36        /* Create an in-memory pt_regs */
  37        stdu    r1,-INT_FRAME_SIZE(r1)
  38        SAVE_GPR(0,r1)
  39        /* Save the previous SP into stack */
  40        addi    r0,r1,INT_FRAME_SIZE
  41        std     r0,GPR1(r1)
  42        SAVE_10GPRS(2,r1)
  43        SAVE_10GPRS(12,r1)
  44        SAVE_10GPRS(22,r1)
  45        /* Save SPRS */
  46        mfmsr   r5
  47        std     r5,_MSR(r1)
  48        li      r5,0x700
  49        std     r5,_TRAP(r1)
  50        li      r5,0
  51        std     r5,ORIG_GPR3(r1)
  52        std     r5,RESULT(r1)
  53        mfctr   r5
  54        std     r5,_CTR(r1)
  55        mflr    r5
  56        std     r5,_LINK(r1)
  57        mfspr   r5,SPRN_XER
  58        std     r5,_XER(r1)
  59        mfcr    r5
  60        std     r5,_CCR(r1)
  61        lbz     r5,PACAIRQSOFTMASK(r13)
  62        std     r5,SOFTE(r1)
  63
  64        /*
  65         * We may get here from a module, so load the kernel TOC in r2.
  66         * The original TOC gets restored when pt_regs is restored
  67         * further below.
  68         */
  69        ld      r2,PACATOC(r13)
  70
  71        .global optprobe_template_op_address
  72optprobe_template_op_address:
  73        /*
  74         * Parameters to optimized_callback():
  75         * 1. optimized_kprobe structure in r3
  76         */
  77        nop
  78        nop
  79        nop
  80        nop
  81        nop
  82        /* 2. pt_regs pointer in r4 */
  83        addi    r4,r1,STACK_FRAME_OVERHEAD
  84
  85        .global optprobe_template_call_handler
  86optprobe_template_call_handler:
  87        /* Branch to optimized_callback() */
  88        nop
  89
  90        /*
  91         * Parameters for instruction emulation:
  92         * 1. Pass SP in register r3.
  93         */
  94        addi    r3,r1,STACK_FRAME_OVERHEAD
  95
  96        .global optprobe_template_insn
  97optprobe_template_insn:
  98        /* 2, Pass instruction to be emulated in r4 */
  99        nop
 100        nop
 101
 102        .global optprobe_template_call_emulate
 103optprobe_template_call_emulate:
 104        /* Branch to emulate_step()  */
 105        nop
 106
 107        /*
 108         * All done.
 109         * Now, restore the registers...
 110         */
 111        ld      r5,_MSR(r1)
 112        mtmsr   r5
 113        ld      r5,_CTR(r1)
 114        mtctr   r5
 115        ld      r5,_LINK(r1)
 116        mtlr    r5
 117        ld      r5,_XER(r1)
 118        mtxer   r5
 119        ld      r5,_CCR(r1)
 120        mtcr    r5
 121        REST_GPR(0,r1)
 122        REST_10GPRS(2,r1)
 123        REST_10GPRS(12,r1)
 124        REST_10GPRS(22,r1)
 125        /* Restore the previous SP */
 126        addi    r1,r1,INT_FRAME_SIZE
 127
 128        .global optprobe_template_ret
 129optprobe_template_ret:
 130        /* ... and jump back from trampoline */
 131        nop
 132
 133        .global optprobe_template_end
 134optprobe_template_end:
 135