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Linux/arch/x86/include/asm/debugreg.h

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  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 */
135 

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