cregit-Linux how code gets into the kernel

Release 4.11 arch/x86/include/asm/special_insns.h

#ifndef _ASM_X86_SPECIAL_INSNS_H

#define _ASM_X86_SPECIAL_INSNS_H


#ifdef __KERNEL__

#include <asm/nops.h>

/*
 * Volatile isn't enough to prevent the compiler from reordering the
 * read/write functions for the control registers and messing everything up.
 * A memory clobber would solve the problem, but would prevent reordering of
 * all loads stores around it, which can hurt performance. Solution is to
 * use a variable and mimic reads and writes to it to enforce serialization
 */
extern unsigned long __force_order;


static inline unsigned long native_read_cr0(void) { unsigned long val; asm volatile("mov %%cr0,%0\n\t" : "=r" (val), "=m" (__force_order)); return val; }

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David Howells20100.00%1100.00%
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static inline void native_write_cr0(unsigned long val) { asm volatile("mov %0,%%cr0": : "r" (val), "m" (__force_order)); }

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David Howells14100.00%1100.00%
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static inline unsigned long native_read_cr2(void) { unsigned long val; asm volatile("mov %%cr2,%0\n\t" : "=r" (val), "=m" (__force_order)); return val; }

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David Howells20100.00%1100.00%
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static inline void native_write_cr2(unsigned long val) { asm volatile("mov %0,%%cr2": : "r" (val), "m" (__force_order)); }

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David Howells14100.00%1100.00%
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static inline unsigned long native_read_cr3(void) { unsigned long val; asm volatile("mov %%cr3,%0\n\t" : "=r" (val), "=m" (__force_order)); return val; }

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David Howells20100.00%1100.00%
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static inline void native_write_cr3(unsigned long val) { asm volatile("mov %0,%%cr3": : "r" (val), "m" (__force_order)); }

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David Howells14100.00%1100.00%
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static inline unsigned long native_read_cr4(void) { unsigned long val; #ifdef CONFIG_X86_32 /* * This could fault if CR4 does not exist. Non-existent CR4 * is functionally equivalent to CR4 == 0. Keep it simple and pretend * that CR4 == 0 on CPUs that don't have CR4. */ asm volatile("1: mov %%cr4, %0\n" "2:\n" _ASM_EXTABLE(1b, 2b) : "=r" (val), "=m" (__force_order) : "0" (0)); #else /* CR4 always exists on x86_64. */ asm volatile("mov %%cr4,%0\n\t" : "=r" (val), "=m" (__force_order)); #endif return val; }

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David Howells2784.38%150.00%
Andrew Lutomirski515.62%150.00%
Total32100.00%2100.00%


static inline void native_write_cr4(unsigned long val) { asm volatile("mov %0,%%cr4": : "r" (val), "m" (__force_order)); }

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David Howells14100.00%1100.00%
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#ifdef CONFIG_X86_64
static inline unsigned long native_read_cr8(void) { unsigned long cr8; asm volatile("movq %%cr8,%0" : "=r" (cr8)); return cr8; }

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David Howells20100.00%1100.00%
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static inline void native_write_cr8(unsigned long val) { asm volatile("movq %0,%%cr8" :: "r" (val) : "memory"); }

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David Howells14100.00%1100.00%
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#endif #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
static inline u32 __read_pkru(void) { u32 ecx = 0; u32 edx, pkru; /* * "rdpkru" instruction. Places PKRU contents in to EAX, * clears EDX and requires that ecx=0. */ asm volatile(".byte 0x0f,0x01,0xee\n\t" : "=a" (pkru), "=d" (edx) : "c" (ecx)); return pkru; }

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Dave Hansen26100.00%1100.00%
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static inline void __write_pkru(u32 pkru) { u32 ecx = 0, edx = 0; /* * "wrpkru" instruction. Loads contents in EAX to PKRU, * requires that ecx = edx = 0. */ asm volatile(".byte 0x0f,0x01,0xef\n\t" : : "a" (pkru), "c"(ecx), "d"(edx)); }

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Xiao Guangrong23100.00%1100.00%
Total23100.00%1100.00%

#else
static inline u32 __read_pkru(void) { return 0; }

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Dave Hansen12100.00%1100.00%
Total12100.00%1100.00%


static inline void __write_pkru(u32 pkru) { }

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Xiao Guangrong9100.00%1100.00%
Total9100.00%1100.00%

#endif
static inline void native_wbinvd(void) { asm volatile("wbinvd": : :"memory"); }

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David Howells12100.00%1100.00%
Total12100.00%1100.00%

extern asmlinkage void native_load_gs_index(unsigned); #ifdef CONFIG_PARAVIRT #include <asm/paravirt.h> #else
static inline unsigned long read_cr0(void) { return native_read_cr0(); }

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David Howells14100.00%1100.00%
Total14100.00%1100.00%


static inline void write_cr0(unsigned long x) { native_write_cr0(x); }

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David Howells16100.00%1100.00%
Total16100.00%1100.00%


static inline unsigned long read_cr2(void) { return native_read_cr2(); }

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David Howells14100.00%1100.00%
Total14100.00%1100.00%


static inline void write_cr2(unsigned long x) { native_write_cr2(x); }

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David Howells16100.00%1100.00%
Total16100.00%1100.00%


static inline unsigned long read_cr3(void) { return native_read_cr3(); }

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David Howells14100.00%1100.00%
Total14100.00%1100.00%


static inline void write_cr3(unsigned long x) { native_write_cr3(x); }

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David Howells16100.00%1100.00%
Total16100.00%1100.00%


static inline unsigned long __read_cr4(void) { return native_read_cr4(); }

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David Howells1392.86%150.00%
Andrew Lutomirski17.14%150.00%
Total14100.00%2100.00%


static inline void __write_cr4(unsigned long x) { native_write_cr4(x); }

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David Howells1593.75%150.00%
Andrew Lutomirski16.25%150.00%
Total16100.00%2100.00%


static inline void wbinvd(void) { native_wbinvd(); }

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David Howells12100.00%1100.00%
Total12100.00%1100.00%

#ifdef CONFIG_X86_64
static inline unsigned long read_cr8(void) { return native_read_cr8(); }

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David Howells14100.00%1100.00%
Total14100.00%1100.00%


static inline void write_cr8(unsigned long x) { native_write_cr8(x); }

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PersonTokensPropCommitsCommitProp
David Howells16100.00%1100.00%
Total16100.00%1100.00%


static inline void load_gs_index(unsigned selector) { native_load_gs_index(selector); }

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David Howells15100.00%1100.00%
Total15100.00%1100.00%

#endif #endif/* CONFIG_PARAVIRT */
static inline void clflush(volatile void *__p) { asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p)); }

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David Howells15100.00%1100.00%
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static inline void clflushopt(volatile void *__p) { alternative_io(".byte " __stringify(NOP_DS_PREFIX) "; clflush %P0", ".byte 0x66; clflush %P0", X86_FEATURE_CLFLUSHOPT, "+m" (*(volatile char __force *)__p)); }

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Ross Zwisler38100.00%1100.00%
Total38100.00%1100.00%


static inline void clwb(volatile void *__p) { volatile struct { char x[64]; } *p = __p; asm volatile(ALTERNATIVE_2( ".byte " __stringify(NOP_DS_PREFIX) "; clflush (%[pax])", ".byte 0x66; clflush (%[pax])", /* clflushopt (%%rax) */ X86_FEATURE_CLFLUSHOPT, ".byte 0x66, 0x0f, 0xae, 0x30", /* clwb (%%rax) */ X86_FEATURE_CLWB) : [p] "+m" (*p) : [pax] "a" (p)); }

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Ross Zwisler34100.00%1100.00%
Total34100.00%1100.00%

#define nop() asm volatile ("nop") #endif /* __KERNEL__ */ #endif /* _ASM_X86_SPECIAL_INSNS_H */

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David Howells43272.85%110.00%
Ross Zwisler7512.65%330.00%
Dave Hansen457.59%110.00%
Xiao Guangrong325.40%110.00%
Andrew Lutomirski71.18%220.00%
Jan Beulich10.17%110.00%
Andi Kleen10.17%110.00%
Total593100.00%10100.00%
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