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

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  1 /* SPDX-License-Identifier: GPL-2.0 */
  2 #ifndef _ASM_X86_CPUFEATURE_H
  3 #define _ASM_X86_CPUFEATURE_H
  4 
  5 #include <asm/processor.h>
  6 
  7 #if defined(__KERNEL__) && !defined(__ASSEMBLY__)
  8 
  9 #include <asm/asm.h>
 10 #include <linux/bitops.h>
 11 #include <asm/alternative.h>
 12 
 13 enum cpuid_leafs
 14 {
 15         CPUID_1_EDX             = 0,
 16         CPUID_8000_0001_EDX,
 17         CPUID_8086_0001_EDX,
 18         CPUID_LNX_1,
 19         CPUID_1_ECX,
 20         CPUID_C000_0001_EDX,
 21         CPUID_8000_0001_ECX,
 22         CPUID_LNX_2,
 23         CPUID_LNX_3,
 24         CPUID_7_0_EBX,
 25         CPUID_D_1_EAX,
 26         CPUID_LNX_4,
 27         CPUID_7_1_EAX,
 28         CPUID_8000_0008_EBX,
 29         CPUID_6_EAX,
 30         CPUID_8000_000A_EDX,
 31         CPUID_7_ECX,
 32         CPUID_8000_0007_EBX,
 33         CPUID_7_EDX,
 34         CPUID_8000_001F_EAX,
 35 };
 36 
 37 #ifdef CONFIG_X86_FEATURE_NAMES
 38 extern const char * const x86_cap_flags[NCAPINTS*32];
 39 extern const char * const x86_power_flags[32];
 40 #define X86_CAP_FMT "%s"
 41 #define x86_cap_flag(flag) x86_cap_flags[flag]
 42 #else
 43 #define X86_CAP_FMT "%d:%d"
 44 #define x86_cap_flag(flag) ((flag) >> 5), ((flag) & 31)
 45 #endif
 46 
 47 /*
 48  * In order to save room, we index into this array by doing
 49  * X86_BUG_<name> - NCAPINTS*32.
 50  */
 51 extern const char * const x86_bug_flags[NBUGINTS*32];
 52 
 53 #define test_cpu_cap(c, bit)                                            \
 54          test_bit(bit, (unsigned long *)((c)->x86_capability))
 55 
 56 /*
 57  * There are 32 bits/features in each mask word.  The high bits
 58  * (selected with (bit>>5) give us the word number and the low 5
 59  * bits give us the bit/feature number inside the word.
 60  * (1UL<<((bit)&31) gives us a mask for the feature_bit so we can
 61  * see if it is set in the mask word.
 62  */
 63 #define CHECK_BIT_IN_MASK_WORD(maskname, word, bit)     \
 64         (((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word ))
 65 
 66 /*
 67  * {REQUIRED,DISABLED}_MASK_CHECK below may seem duplicated with the
 68  * following BUILD_BUG_ON_ZERO() check but when NCAPINTS gets changed, all
 69  * header macros which use NCAPINTS need to be changed. The duplicated macro
 70  * use causes the compiler to issue errors for all headers so that all usage
 71  * sites can be corrected.
 72  */
 73 #define REQUIRED_MASK_BIT_SET(feature_bit)              \
 74          ( CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  0, feature_bit) ||    \
 75            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  1, feature_bit) ||    \
 76            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  2, feature_bit) ||    \
 77            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  3, feature_bit) ||    \
 78            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  4, feature_bit) ||    \
 79            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  5, feature_bit) ||    \
 80            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  6, feature_bit) ||    \
 81            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  7, feature_bit) ||    \
 82            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  8, feature_bit) ||    \
 83            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  9, feature_bit) ||    \
 84            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 10, feature_bit) ||    \
 85            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 11, feature_bit) ||    \
 86            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 12, feature_bit) ||    \
 87            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 13, feature_bit) ||    \
 88            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 14, feature_bit) ||    \
 89            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 15, feature_bit) ||    \
 90            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 16, feature_bit) ||    \
 91            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 17, feature_bit) ||    \
 92            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 18, feature_bit) ||    \
 93            CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK, 19, feature_bit) ||    \
 94            REQUIRED_MASK_CHECK                                    ||    \
 95            BUILD_BUG_ON_ZERO(NCAPINTS != 20))
 96 
 97 #define DISABLED_MASK_BIT_SET(feature_bit)                              \
 98          ( CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  0, feature_bit) ||    \
 99            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  1, feature_bit) ||    \
100            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  2, feature_bit) ||    \
101            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  3, feature_bit) ||    \
102            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  4, feature_bit) ||    \
103            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  5, feature_bit) ||    \
104            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  6, feature_bit) ||    \
105            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  7, feature_bit) ||    \
106            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  8, feature_bit) ||    \
107            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK,  9, feature_bit) ||    \
108            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 10, feature_bit) ||    \
109            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 11, feature_bit) ||    \
110            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 12, feature_bit) ||    \
111            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 13, feature_bit) ||    \
112            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 14, feature_bit) ||    \
113            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 15, feature_bit) ||    \
114            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 16, feature_bit) ||    \
115            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 17, feature_bit) ||    \
116            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 18, feature_bit) ||    \
117            CHECK_BIT_IN_MASK_WORD(DISABLED_MASK, 19, feature_bit) ||    \
118            DISABLED_MASK_CHECK                                    ||    \
119            BUILD_BUG_ON_ZERO(NCAPINTS != 20))
120 
121 #define cpu_has(c, bit)                                                 \
122         (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 :  \
123          test_cpu_cap(c, bit))
124 
125 #define this_cpu_has(bit)                                               \
126         (__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 :  \
127          x86_this_cpu_test_bit(bit,                                     \
128                 (unsigned long __percpu *)&cpu_info.x86_capability))
129 
130 /*
131  * This macro is for detection of features which need kernel
132  * infrastructure to be used.  It may *not* directly test the CPU
133  * itself.  Use the cpu_has() family if you want true runtime
134  * testing of CPU features, like in hypervisor code where you are
135  * supporting a possible guest feature where host support for it
136  * is not relevant.
137  */
138 #define cpu_feature_enabled(bit)        \
139         (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit))
140 
141 #define boot_cpu_has(bit)       cpu_has(&boot_cpu_data, bit)
142 
143 #define set_cpu_cap(c, bit)     set_bit(bit, (unsigned long *)((c)->x86_capability))
144 
145 extern void setup_clear_cpu_cap(unsigned int bit);
146 extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit);
147 
148 #define setup_force_cpu_cap(bit) do { \
149         set_cpu_cap(&boot_cpu_data, bit);       \
150         set_bit(bit, (unsigned long *)cpu_caps_set);    \
151 } while (0)
152 
153 #define setup_force_cpu_bug(bit) setup_force_cpu_cap(bit)
154 
155 #if defined(__clang__) && !defined(CONFIG_CC_HAS_ASM_GOTO)
156 
157 /*
158  * Workaround for the sake of BPF compilation which utilizes kernel
159  * headers, but clang does not support ASM GOTO and fails the build.
160  */
161 #ifndef __BPF_TRACING__
162 #warning "Compiler lacks ASM_GOTO support. Add -D __BPF_TRACING__ to your compiler arguments"
163 #endif
164 
165 #define static_cpu_has(bit)            boot_cpu_has(bit)
166 
167 #else
168 
169 /*
170  * Static testing of CPU features. Used the same as boot_cpu_has(). It
171  * statically patches the target code for additional performance. Use
172  * static_cpu_has() only in fast paths, where every cycle counts. Which
173  * means that the boot_cpu_has() variant is already fast enough for the
174  * majority of cases and you should stick to using it as it is generally
175  * only two instructions: a RIP-relative MOV and a TEST.
176  *
177  * Do not use an "m" constraint for [cap_byte] here: gcc doesn't know
178  * that this is only used on a fallback path and will sometimes cause
179  * it to manifest the address of boot_cpu_data in a register, fouling
180  * the mainline (post-initialization) code.
181  */
182 static __always_inline bool _static_cpu_has(u16 bit)
183 {
184         asm_volatile_goto(
185                 ALTERNATIVE_TERNARY("jmp 6f", %P[feature], "", "jmp %l[t_no]")
186                 ".pushsection .altinstr_aux,\"ax\"\n"
187                 "6:\n"
188                 " testb %[bitnum]," _ASM_RIP(%P[cap_byte]) "\n"
189                 " jnz %l[t_yes]\n"
190                 " jmp %l[t_no]\n"
191                 ".popsection\n"
192                  : : [feature]  "i" (bit),
193                      [bitnum]   "i" (1 << (bit & 7)),
194                      [cap_byte] "i" (&((const char *)boot_cpu_data.x86_capability)[bit >> 3])
195                  : : t_yes, t_no);
196 t_yes:
197         return true;
198 t_no:
199         return false;
200 }
201 
202 #define static_cpu_has(bit)                                     \
203 (                                                               \
204         __builtin_constant_p(boot_cpu_has(bit)) ?               \
205                 boot_cpu_has(bit) :                             \
206                 _static_cpu_has(bit)                            \
207 )
208 #endif
209 
210 #define cpu_has_bug(c, bit)             cpu_has(c, (bit))
211 #define set_cpu_bug(c, bit)             set_cpu_cap(c, (bit))
212 #define clear_cpu_bug(c, bit)           clear_cpu_cap(c, (bit))
213 
214 #define static_cpu_has_bug(bit)         static_cpu_has((bit))
215 #define boot_cpu_has_bug(bit)           cpu_has_bug(&boot_cpu_data, (bit))
216 #define boot_cpu_set_bug(bit)           set_cpu_cap(&boot_cpu_data, (bit))
217 
218 #define MAX_CPU_FEATURES                (NCAPINTS * 32)
219 #define cpu_have_feature                boot_cpu_has
220 
221 #define CPU_FEATURE_TYPEFMT             "x86,ven%04Xfam%04Xmod%04X"
222 #define CPU_FEATURE_TYPEVAL             boot_cpu_data.x86_vendor, boot_cpu_data.x86, \
223                                         boot_cpu_data.x86_model
224 
225 #endif /* defined(__KERNEL__) && !defined(__ASSEMBLY__) */
226 #endif /* _ASM_X86_CPUFEATURE_H */
227 

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