arch/x86/include/asm/debugreg.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_DEBUGREG_H
   3 #define _ASM_X86_DEBUGREG_H
   4
   5
   6 #include <linux/bug.h>
   7 #include <uapi/asm/debugreg.h>
   8
   9 DECLARE_PER_CPU(unsigned long, cpu_dr7);
  10
  11 #ifndef CONFIG_PARAVIRT_XXL
  12 /*
  13  * These special macros can be used to get or set a debugging register
  14  */
  15 #define get_debugreg(var, register)                             \
  16         (var) = native_get_debugreg(register)
  17 #define set_debugreg(value, register)                           \
  18         native_set_debugreg(register, value)
  19 #endif
  20
  21 static __always_inline unsigned long native_get_debugreg(int regno)
  22 {
  23         unsigned long val = 0;  /* Damn you, gcc! */
  24
  25         switch (regno) {
  26         case 0:
  27                 asm("mov %%db0, %0" :"=r" (val));
  28                 break;
  29         case 1:
  30                 asm("mov %%db1, %0" :"=r" (val));
  31                 break;
  32         case 2:
  33                 asm("mov %%db2, %0" :"=r" (val));
  34                 break;
  35         case 3:
  36                 asm("mov %%db3, %0" :"=r" (val));
  37                 break;
  38         case 6:
  39                 asm("mov %%db6, %0" :"=r" (val));
  40                 break;
  41         case 7:
  42                 asm("mov %%db7, %0" :"=r" (val));
  43                 break;
  44         default:
  45                 BUG();
  46         }
  47         return val;
  48 }
  49
  50 static __always_inline void native_set_debugreg(int regno, unsigned long value)
  51 {
  52         switch (regno) {
  53         case 0:
  54                 asm("mov %0, %%db0"     ::"r" (value));
  55                 break;
  56         case 1:
  57                 asm("mov %0, %%db1"     ::"r" (value));
  58                 break;
  59         case 2:
  60                 asm("mov %0, %%db2"     ::"r" (value));
  61                 break;
  62         case 3:
  63                 asm("mov %0, %%db3"     ::"r" (value));
  64                 break;
  65         case 6:
  66                 asm("mov %0, %%db6"     ::"r" (value));
  67                 break;
  68         case 7:
  69                 asm("mov %0, %%db7"     ::"r" (value));
  70                 break;
  71         default:
  72                 BUG();
  73         }
  74 }
  75
  76 static inline void hw_breakpoint_disable(void)
  77 {
  78         /* Zero the control register for HW Breakpoint */
  79         set_debugreg(0UL, 7);
  80
  81         /* Zero-out the individual HW breakpoint address registers */
  82         set_debugreg(0UL, 0);
  83         set_debugreg(0UL, 1);
  84         set_debugreg(0UL, 2);
  85         set_debugreg(0UL, 3);
  86 }
  87
  88 static __always_inline bool hw_breakpoint_active(void)
  89 {
  90         return __this_cpu_read(cpu_dr7) & DR_GLOBAL_ENABLE_MASK;
  91 }
  92
  93 extern void hw_breakpoint_restore(void);
  94
  95 static __always_inline unsigned long local_db_save(void)
  96 {
  97         unsigned long dr7;
  98
  99         if (static_cpu_has(X86_FEATURE_HYPERVISOR) && !hw_breakpoint_active())
 100                 return 0;
 101
 102         get_debugreg(dr7, 7);
 103         dr7 &= ~0x400; /* architecturally set bit */
 104         if (dr7)
 105                 set_debugreg(0, 7);
 106         /*
 107          * Ensure the compiler doesn't lower the above statements into
 108          * the critical section; disabling breakpoints late would not
 109          * be good.
 110          */
 111         barrier();
 112
 113         return dr7;
 114 }
 115
 116 static __always_inline void local_db_restore(unsigned long dr7)
 117 {
 118         /*
 119          * Ensure the compiler doesn't raise this statement into
 120          * the critical section; enabling breakpoints early would
 121          * not be good.
 122          */
 123         barrier();
 124         if (dr7)
 125                 set_debugreg(dr7, 7);
 126 }
 127
 128 #ifdef CONFIG_CPU_SUP_AMD
 129 extern void set_dr_addr_mask(unsigned long mask, int dr);
 130 #else
 131 static inline void set_dr_addr_mask(unsigned long mask, int dr) { }
 132 #endif
 133
 134 #endif /* _ASM_X86_DEBUGREG_H */