arch/sparc/kernel/ftrace.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/spinlock.h>
   3 #include <linux/hardirq.h>
   4 #include <linux/ftrace.h>
   5 #include <linux/percpu.h>
   6 #include <linux/init.h>
   7 #include <linux/list.h>
   8 #include <trace/syscall.h>
   9
  10 #include <asm/ftrace.h>
  11
  12 #ifdef CONFIG_DYNAMIC_FTRACE
  13 static const u32 ftrace_nop = 0x01000000;
  14
  15 static u32 ftrace_call_replace(unsigned long ip, unsigned long addr)
  16 {
  17         u32 call;
  18         s32 off;
  19
  20         off = ((s32)addr - (s32)ip);
  21         call = 0x40000000 | ((u32)off >> 2);
  22
  23         return call;
  24 }
  25
  26 static int ftrace_modify_code(unsigned long ip, u32 old, u32 new)
  27 {
  28         u32 replaced;
  29         int faulted;
  30
  31         __asm__ __volatile__(
  32         "1:     cas     [%[ip]], %[old], %[new]\n"
  33         "       flush   %[ip]\n"
  34         "       mov     0, %[faulted]\n"
  35         "2:\n"
  36         "       .section .fixup,#alloc,#execinstr\n"
  37         "       .align  4\n"
  38         "3:     sethi   %%hi(2b), %[faulted]\n"
  39         "       jmpl    %[faulted] + %%lo(2b), %%g0\n"
  40         "        mov    1, %[faulted]\n"
  41         "       .previous\n"
  42         "       .section __ex_table,\"a\"\n"
  43         "       .align  4\n"
  44         "       .word   1b, 3b\n"
  45         "       .previous\n"
  46         : "=r" (replaced), [faulted] "=r" (faulted)
  47         : [new] "0" (new), [old] "r" (old), [ip] "r" (ip)
  48         : "memory");
  49
  50         if (replaced != old && replaced != new)
  51                 faulted = 2;
  52
  53         return faulted;
  54 }
  55
  56 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
  57 {
  58         unsigned long ip = rec->ip;
  59         u32 old, new;
  60
  61         old = ftrace_call_replace(ip, addr);
  62         new = ftrace_nop;
  63         return ftrace_modify_code(ip, old, new);
  64 }
  65
  66 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
  67 {
  68         unsigned long ip = rec->ip;
  69         u32 old, new;
  70
  71         old = ftrace_nop;
  72         new = ftrace_call_replace(ip, addr);
  73         return ftrace_modify_code(ip, old, new);
  74 }
  75
  76 int ftrace_update_ftrace_func(ftrace_func_t func)
  77 {
  78         unsigned long ip = (unsigned long)(&ftrace_call);
  79         u32 old, new;
  80
  81         old = *(u32 *) &ftrace_call;
  82         new = ftrace_call_replace(ip, (unsigned long)func);
  83         return ftrace_modify_code(ip, old, new);
  84 }
  85 #endif
  86
  87 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  88
  89 #ifdef CONFIG_DYNAMIC_FTRACE
  90 extern void ftrace_graph_call(void);
  91
  92 int ftrace_enable_ftrace_graph_caller(void)
  93 {
  94         unsigned long ip = (unsigned long)(&ftrace_graph_call);
  95         u32 old, new;
  96
  97         old = *(u32 *) &ftrace_graph_call;
  98         new = ftrace_call_replace(ip, (unsigned long) &ftrace_graph_caller);
  99         return ftrace_modify_code(ip, old, new);
 100 }
 101
 102 int ftrace_disable_ftrace_graph_caller(void)
 103 {
 104         unsigned long ip = (unsigned long)(&ftrace_graph_call);
 105         u32 old, new;
 106
 107         old = *(u32 *) &ftrace_graph_call;
 108         new = ftrace_call_replace(ip, (unsigned long) &ftrace_stub);
 109
 110         return ftrace_modify_code(ip, old, new);
 111 }
 112
 113 #endif /* !CONFIG_DYNAMIC_FTRACE */
 114
 115 /*
 116  * Hook the return address and push it in the stack of return addrs
 117  * in current thread info.
 118  */
 119 unsigned long prepare_ftrace_return(unsigned long parent,
 120                                     unsigned long self_addr,
 121                                     unsigned long frame_pointer)
 122 {
 123         unsigned long return_hooker = (unsigned long) &return_to_handler;
 124
 125         if (unlikely(atomic_read(&current->tracing_graph_pause)))
 126                 return parent + 8UL;
 127
 128         if (function_graph_enter(parent, self_addr, frame_pointer, NULL))
 129                 return parent + 8UL;
 130
 131         return return_hooker;
 132 }
 133 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */