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hc
2023-12-08 01573e231f18eb2d99162747186f59511f56b64d 
 kernel/arch/x86/include/asm/cpufeature.h
....@@ -8,6 +8,7 @@
88 
99 #include <asm/asm.h>
1010 #include <linux/bitops.h>
11
+#include <asm/alternative.h>
1112 
1213 enum cpuid_leafs
1314 {
....@@ -23,7 +24,7 @@
2324 	CPUID_7_0_EBX,
2425 	CPUID_D_1_EAX,
2526 	CPUID_LNX_4,
26
-	CPUID_DUMMY,
27
+	CPUID_7_1_EAX,
2728 	CPUID_8000_0008_EBX,
2829 	CPUID_6_EAX,
2930 	CPUID_8000_000A_EDX,
....@@ -49,7 +50,7 @@
4950 extern const char * const x86_bug_flags[NBUGINTS*32];
5051 
5152 #define test_cpu_cap(c, bit)						\
52
-	 test_bit(bit, (unsigned long *)((c)->x86_capability))
53
+	 arch_test_bit(bit, (unsigned long *)((c)->x86_capability))
5354 
5455 /*
5556  * There are 32 bits/features in each mask word.  The high bits
....@@ -61,6 +62,13 @@
6162 #define CHECK_BIT_IN_MASK_WORD(maskname, word, bit)	\
6263 	(((bit)>>5)==(word) && (1UL<<((bit)&31) & maskname##word ))
6364 
65
+/*
66
+ * {REQUIRED,DISABLED}_MASK_CHECK below may seem duplicated with the
67
+ * following BUILD_BUG_ON_ZERO() check but when NCAPINTS gets changed, all
68
+ * header macros which use NCAPINTS need to be changed. The duplicated macro
69
+ * use causes the compiler to issue errors for all headers so that all usage
70
+ * sites can be corrected.
71
+ */
6472 #define REQUIRED_MASK_BIT_SET(feature_bit)		\
6573 	 ( CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  0, feature_bit) ||	\
6674 	   CHECK_BIT_IN_MASK_WORD(REQUIRED_MASK,  1, feature_bit) ||	\
....@@ -112,8 +120,9 @@
112120 	 test_cpu_cap(c, bit))
113121 
114122 #define this_cpu_has(bit)						\
115
-	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 : 	\
116
-	 x86_this_cpu_test_bit(bit, (unsigned long *)&cpu_info.x86_capability))
123
+	(__builtin_constant_p(bit) && REQUIRED_MASK_BIT_SET(bit) ? 1 :	\
124
+	 x86_this_cpu_test_bit(bit,					\
125
+		(unsigned long __percpu *)&cpu_info.x86_capability))
117126 
118127 /*
119128  * This macro is for detection of features which need kernel
....@@ -146,51 +155,33 @@
146155  * Workaround for the sake of BPF compilation which utilizes kernel
147156  * headers, but clang does not support ASM GOTO and fails the build.
148157  */
158
+#ifndef __BPF_TRACING__
159
+#warning "Compiler lacks ASM_GOTO support. Add -D __BPF_TRACING__ to your compiler arguments"
160
+#endif
149161 
150162 #define static_cpu_has(bit)            boot_cpu_has(bit)
151163 
152164 #else
153165 
154166 /*
155
- * Static testing of CPU features.  Used the same as boot_cpu_has().
156
- * These will statically patch the target code for additional
157
- * performance.
167
+ * Static testing of CPU features. Used the same as boot_cpu_has(). It
168
+ * statically patches the target code for additional performance. Use
169
+ * static_cpu_has() only in fast paths, where every cycle counts. Which
170
+ * means that the boot_cpu_has() variant is already fast enough for the
171
+ * majority of cases and you should stick to using it as it is generally
172
+ * only two instructions: a RIP-relative MOV and a TEST.
158173  */
159
-static __always_inline __pure bool _static_cpu_has(u16 bit)
174
+static __always_inline bool _static_cpu_has(u16 bit)
160175 {
161
-	asm_volatile_goto("1: jmp 6f\n"
162
-		 "2:\n"
163
-		 ".skip -(((5f-4f) - (2b-1b)) > 0) * "
164
-			 "((5f-4f) - (2b-1b)),0x90\n"
165
-		 "3:\n"
166
-		 ".section .altinstructions,\"a\"\n"
167
-		 " .long 1b - .\n"		/* src offset */
168
-		 " .long 4f - .\n"		/* repl offset */
169
-		 " .word %P[always]\n"		/* always replace */
170
-		 " .byte 3b - 1b\n"		/* src len */
171
-		 " .byte 5f - 4f\n"		/* repl len */
172
-		 " .byte 3b - 2b\n"		/* pad len */
173
-		 ".previous\n"
174
-		 ".section .altinstr_replacement,\"ax\"\n"
175
-		 "4: jmp %l[t_no]\n"
176
-		 "5:\n"
177
-		 ".previous\n"
178
-		 ".section .altinstructions,\"a\"\n"
179
-		 " .long 1b - .\n"		/* src offset */
180
-		 " .long 0\n"			/* no replacement */
181
-		 " .word %P[feature]\n"		/* feature bit */
182
-		 " .byte 3b - 1b\n"		/* src len */
183
-		 " .byte 0\n"			/* repl len */
184
-		 " .byte 0\n"			/* pad len */
185
-		 ".previous\n"
186
-		 ".section .altinstr_aux,\"ax\"\n"
187
-		 "6:\n"
188
-		 " testb %[bitnum],%[cap_byte]\n"
189
-		 " jnz %l[t_yes]\n"
190
-		 " jmp %l[t_no]\n"
191
-		 ".previous\n"
176
+	asm_volatile_goto(
177
+		ALTERNATIVE_TERNARY("jmp 6f", %P[feature], "", "jmp %l[t_no]")
178
+		".section .altinstr_aux,\"ax\"\n"
179
+		"6:\n"
180
+		" testb %[bitnum],%[cap_byte]\n"
181
+		" jnz %l[t_yes]\n"
182
+		" jmp %l[t_no]\n"
183
+		".previous\n"
192184 		 : : [feature]  "i" (bit),
193
-		     [always]   "i" (X86_FEATURE_ALWAYS),
194185 		     [bitnum]   "i" (1 << (bit & 7)),
195186 		     [cap_byte] "m" (((const char *)boot_cpu_data.x86_capability)[bit >> 3])
196187 		 : : t_yes, t_no);