arch/parisc/kernel/ftrace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Code for tracing calls in Linux kernel.
   4  * Copyright (C) 2009-2016 Helge Deller <deller@gmx.de>
   5  *
   6  * based on code for x86 which is:
   7  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   8  *
   9  * future possible enhancements:
  10  *      - add CONFIG_STACK_TRACER
  11  */
  12
  13 #include <linux/init.h>
  14 #include <linux/ftrace.h>
  15 #include <linux/uaccess.h>
  16
  17 #include <asm/assembly.h>
  18 #include <asm/sections.h>
  19 #include <asm/ftrace.h>
  20 #include <asm/patch.h>
  21
  22 #define __hot __attribute__ ((__section__ (".text.hot")))
  23
  24 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  25 /*
  26  * Hook the return address and push it in the stack of return addrs
  27  * in current thread info.
  28  */
  29 static void __hot prepare_ftrace_return(unsigned long *parent,
  30                                         unsigned long self_addr)
  31 {
  32         unsigned long old;
  33         extern int parisc_return_to_handler;
  34
  35         if (unlikely(ftrace_graph_is_dead()))
  36                 return;
  37
  38         if (unlikely(atomic_read(&current->tracing_graph_pause)))
  39                 return;
  40
  41         old = *parent;
  42
  43         if (!function_graph_enter(old, self_addr, 0, NULL))
  44                 /* activate parisc_return_to_handler() as return point */
  45                 *parent = (unsigned long) &parisc_return_to_handler;
  46 }
  47 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
  48
  49 void notrace __hot ftrace_function_trampoline(unsigned long parent,
  50                                 unsigned long self_addr,
  51                                 unsigned long org_sp_gr3)
  52 {
  53 #ifndef CONFIG_DYNAMIC_FTRACE
  54         extern ftrace_func_t ftrace_trace_function;
  55 #endif
  56         if (ftrace_trace_function != ftrace_stub)
  57                 ftrace_trace_function(self_addr, parent, NULL, NULL);
  58
  59 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  60         if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub ||
  61                 ftrace_graph_entry != ftrace_graph_entry_stub) {
  62                 unsigned long *parent_rp;
  63
  64                 /* calculate pointer to %rp in stack */
  65                 parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET);
  66                 /* sanity check: parent_rp should hold parent */
  67                 if (*parent_rp != parent)
  68                         return;
  69
  70                 prepare_ftrace_return(parent_rp, self_addr);
  71                 return;
  72         }
  73 #endif
  74 }
  75
  76 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  77 int ftrace_enable_ftrace_graph_caller(void)
  78 {
  79         return 0;
  80 }
  81
  82 int ftrace_disable_ftrace_graph_caller(void)
  83 {
  84         return 0;
  85 }
  86 #endif
  87
  88 #ifdef CONFIG_DYNAMIC_FTRACE
  89
  90 int __init ftrace_dyn_arch_init(void)
  91 {
  92         return 0;
  93 }
  94 int ftrace_update_ftrace_func(ftrace_func_t func)
  95 {
  96         return 0;
  97 }
  98
  99 unsigned long ftrace_call_adjust(unsigned long addr)
 100 {
 101         return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4;
 102 }
 103
 104 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 105 {
 106         u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
 107         u32 *tramp;
 108         int size, ret, i;
 109         void *ip;
 110
 111 #ifdef CONFIG_64BIT
 112         unsigned long addr2 =
 113                 (unsigned long)dereference_function_descriptor((void *)addr);
 114
 115         u32 ftrace_trampoline[] = {
 116                 0x73c10208, /* std,ma r1,100(sp) */
 117                 0x0c2110c1, /* ldd -10(r1),r1 */
 118                 0xe820d002, /* bve,n (r1) */
 119                 addr2 >> 32,
 120                 addr2 & 0xffffffff,
 121                 0xe83f1fd7, /* b,l,n .-14,r1 */
 122         };
 123
 124         u32 ftrace_trampoline_unaligned[] = {
 125                 addr2 >> 32,
 126                 addr2 & 0xffffffff,
 127                 0x37de0200, /* ldo 100(sp),sp */
 128                 0x73c13e01, /* std r1,-100(sp) */
 129                 0x34213ff9, /* ldo -4(r1),r1 */
 130                 0x50213fc1, /* ldd -20(r1),r1 */
 131                 0xe820d002, /* bve,n (r1) */
 132                 0xe83f1fcf, /* b,l,n .-20,r1 */
 133         };
 134
 135         BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) >
 136                                 FTRACE_PATCHABLE_FUNCTION_SIZE);
 137 #else
 138         u32 ftrace_trampoline[] = {
 139                 (u32)addr,
 140                 0x6fc10080, /* stw,ma r1,40(sp) */
 141                 0x48213fd1, /* ldw -18(r1),r1 */
 142                 0xe820c002, /* bv,n r0(r1) */
 143                 0xe83f1fdf, /* b,l,n .-c,r1 */
 144         };
 145 #endif
 146
 147         BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) >
 148                                 FTRACE_PATCHABLE_FUNCTION_SIZE);
 149
 150         size = sizeof(ftrace_trampoline);
 151         tramp = ftrace_trampoline;
 152
 153 #ifdef CONFIG_64BIT
 154         if (rec->ip & 0x4) {
 155                 size = sizeof(ftrace_trampoline_unaligned);
 156                 tramp = ftrace_trampoline_unaligned;
 157         }
 158 #endif
 159
 160         ip = (void *)(rec->ip + 4 - size);
 161
 162         ret = probe_kernel_read(insn, ip, size);
 163         if (ret)
 164                 return ret;
 165
 166         for (i = 0; i < size / 4; i++) {
 167                 if (insn[i] != INSN_NOP)
 168                         return -EINVAL;
 169         }
 170
 171         __patch_text_multiple(ip, tramp, size);
 172         return 0;
 173 }
 174
 175 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 176                     unsigned long addr)
 177 {
 178         u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
 179         int i;
 180
 181         for (i = 0; i < ARRAY_SIZE(insn); i++)
 182                 insn[i] = INSN_NOP;
 183
 184         __patch_text((void *)rec->ip, INSN_NOP);
 185         __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn),
 186                               insn, sizeof(insn)-4);
 187         return 0;
 188 }
 189 #endif