cregit-Linux how code gets into the kernel

Release 4.15 arch/x86/kernel/cpu/cpuid-deps.c

/* Declare dependencies between CPUIDs */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <asm/cpufeature.h>


struct cpuid_dep {
	
unsigned int	feature;
	
unsigned int	depends;
};

/*
 * Table of CPUID features that depend on others.
 *
 * This only includes dependencies that can be usefully disabled, not
 * features part of the base set (like FPU).
 *
 * Note this all is not __init / __initdata because it can be
 * called from cpu hotplug. It shouldn't do anything in this case,
 * but it's difficult to tell that to the init reference checker.
 */

const static struct cpuid_dep cpuid_deps[] = {
	{ X86_FEATURE_XSAVEOPT,		X86_FEATURE_XSAVE     },
	{ X86_FEATURE_XSAVEC,		X86_FEATURE_XSAVE     },
	{ X86_FEATURE_XSAVES,		X86_FEATURE_XSAVE     },
	{ X86_FEATURE_AVX,		X86_FEATURE_XSAVE     },
	{ X86_FEATURE_PKU,		X86_FEATURE_XSAVE     },
	{ X86_FEATURE_MPX,		X86_FEATURE_XSAVE     },
	{ X86_FEATURE_XGETBV1,		X86_FEATURE_XSAVE     },
	{ X86_FEATURE_FXSR_OPT,		X86_FEATURE_FXSR      },
	{ X86_FEATURE_XMM,		X86_FEATURE_FXSR      },
	{ X86_FEATURE_XMM2,		X86_FEATURE_XMM       },
	{ X86_FEATURE_XMM3,		X86_FEATURE_XMM2      },
	{ X86_FEATURE_XMM4_1,		X86_FEATURE_XMM2      },
	{ X86_FEATURE_XMM4_2,		X86_FEATURE_XMM2      },
	{ X86_FEATURE_XMM3,		X86_FEATURE_XMM2      },
	{ X86_FEATURE_PCLMULQDQ,	X86_FEATURE_XMM2      },
	{ X86_FEATURE_SSSE3,		X86_FEATURE_XMM2,     },
	{ X86_FEATURE_F16C,		X86_FEATURE_XMM2,     },
	{ X86_FEATURE_AES,		X86_FEATURE_XMM2      },
	{ X86_FEATURE_SHA_NI,		X86_FEATURE_XMM2      },
	{ X86_FEATURE_FMA,		X86_FEATURE_AVX       },
	{ X86_FEATURE_AVX2,		X86_FEATURE_AVX,      },
	{ X86_FEATURE_AVX512F,		X86_FEATURE_AVX,      },
	{ X86_FEATURE_AVX512IFMA,	X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512PF,		X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512ER,		X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512CD,		X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512DQ,		X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512BW,		X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512VL,		X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512VBMI,	X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512_VBMI2,	X86_FEATURE_AVX512VL  },
	{ X86_FEATURE_GFNI,		X86_FEATURE_AVX512VL  },
	{ X86_FEATURE_VAES,		X86_FEATURE_AVX512VL  },
	{ X86_FEATURE_VPCLMULQDQ,	X86_FEATURE_AVX512VL  },
	{ X86_FEATURE_AVX512_VNNI,	X86_FEATURE_AVX512VL  },
	{ X86_FEATURE_AVX512_BITALG,	X86_FEATURE_AVX512VL  },
	{ X86_FEATURE_AVX512_4VNNIW,	X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512_4FMAPS,	X86_FEATURE_AVX512F   },
	{ X86_FEATURE_AVX512_VPOPCNTDQ, X86_FEATURE_AVX512F   },
	{}
};


static inline void clear_feature(struct cpuinfo_x86 *c, unsigned int feature) { /* * Note: This could use the non atomic __*_bit() variants, but the * rest of the cpufeature code uses atomics as well, so keep it for * consistency. Cleanup all of it separately. */ if (!c) { clear_cpu_cap(&boot_cpu_data, feature); set_bit(feature, (unsigned long *)cpu_caps_cleared); } else { clear_bit(feature, (unsigned long *)c->x86_capability); } }

Contributors

PersonTokensPropCommitsCommitProp
Andi Kleen3557.38%150.00%
Thomas Gleixner2642.62%150.00%
Total61100.00%2100.00%

/* Take the capabilities and the BUG bits into account */ #define MAX_FEATURE_BITS ((NCAPINTS + NBUGINTS) * sizeof(u32) * 8)
static void do_clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature) { DECLARE_BITMAP(disable, MAX_FEATURE_BITS); const struct cpuid_dep *d; bool changed; if (WARN_ON(feature >= MAX_FEATURE_BITS)) return; clear_feature(c, feature); /* Collect all features to disable, handling dependencies */ memset(disable, 0, sizeof(disable)); __set_bit(feature, disable); /* Loop until we get a stable state. */ do { changed = false; for (d = cpuid_deps; d->feature; d++) { if (!test_bit(d->depends, disable)) continue; if (__test_and_set_bit(d->feature, disable)) continue; changed = true; clear_feature(c, d->feature); } } while (changed); }

Contributors

PersonTokensPropCommitsCommitProp
Andi Kleen12089.55%150.00%
Thomas Gleixner1410.45%150.00%
Total134100.00%2100.00%


void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature) { do_clear_cpu_cap(c, feature); }

Contributors

PersonTokensPropCommitsCommitProp
Andi Kleen21100.00%1100.00%
Total21100.00%1100.00%


void setup_clear_cpu_cap(unsigned int feature) { do_clear_cpu_cap(NULL, feature); }

Contributors

PersonTokensPropCommitsCommitProp
Andi Kleen16100.00%1100.00%
Total16100.00%1100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Andi Kleen42884.09%125.00%
Thomas Gleixner458.84%250.00%
Gayatri Kammela367.07%125.00%
Total509100.00%4100.00%
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