linux/arch/x86/include/asm/msr.h
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   1#ifndef _ASM_X86_MSR_H
   2#define _ASM_X86_MSR_H
   3
   4#include "msr-index.h"
   5
   6#ifndef __ASSEMBLY__
   7
   8#include <asm/asm.h>
   9#include <asm/errno.h>
  10#include <asm/cpumask.h>
  11#include <uapi/asm/msr.h>
  12
  13struct msr {
  14        union {
  15                struct {
  16                        u32 l;
  17                        u32 h;
  18                };
  19                u64 q;
  20        };
  21};
  22
  23struct msr_info {
  24        u32 msr_no;
  25        struct msr reg;
  26        struct msr *msrs;
  27        int err;
  28};
  29
  30struct msr_regs_info {
  31        u32 *regs;
  32        int err;
  33};
  34
  35static inline unsigned long long native_read_tscp(unsigned int *aux)
  36{
  37        unsigned long low, high;
  38        asm volatile(".byte 0x0f,0x01,0xf9"
  39                     : "=a" (low), "=d" (high), "=c" (*aux));
  40        return low | ((u64)high << 32);
  41}
  42
  43/*
  44 * both i386 and x86_64 returns 64-bit value in edx:eax, but gcc's "A"
  45 * constraint has different meanings. For i386, "A" means exactly
  46 * edx:eax, while for x86_64 it doesn't mean rdx:rax or edx:eax. Instead,
  47 * it means rax *or* rdx.
  48 */
  49#ifdef CONFIG_X86_64
  50#define DECLARE_ARGS(val, low, high)    unsigned low, high
  51#define EAX_EDX_VAL(val, low, high)     ((low) | ((u64)(high) << 32))
  52#define EAX_EDX_ARGS(val, low, high)    "a" (low), "d" (high)
  53#define EAX_EDX_RET(val, low, high)     "=a" (low), "=d" (high)
  54#else
  55#define DECLARE_ARGS(val, low, high)    unsigned long long val
  56#define EAX_EDX_VAL(val, low, high)     (val)
  57#define EAX_EDX_ARGS(val, low, high)    "A" (val)
  58#define EAX_EDX_RET(val, low, high)     "=A" (val)
  59#endif
  60
  61static __always_inline unsigned long long native_read_msr(unsigned int msr)
  62{
  63        DECLARE_ARGS(val, low, high);
  64
  65        asm volatile("rdmsr" : EAX_EDX_RET(val, low, high) : "c" (msr));
  66        return EAX_EDX_VAL(val, low, high);
  67}
  68
  69static inline unsigned long long native_read_msr_safe(unsigned int msr,
  70                                                      int *err)
  71{
  72        DECLARE_ARGS(val, low, high);
  73
  74        asm volatile("2: rdmsr ; xor %[err],%[err]\n"
  75                     "1:\n\t"
  76                     ".section .fixup,\"ax\"\n\t"
  77                     "3:  mov %[fault],%[err] ; jmp 1b\n\t"
  78                     ".previous\n\t"
  79                     _ASM_EXTABLE(2b, 3b)
  80                     : [err] "=r" (*err), EAX_EDX_RET(val, low, high)
  81                     : "c" (msr), [fault] "i" (-EIO));
  82        return EAX_EDX_VAL(val, low, high);
  83}
  84
  85static __always_inline void native_write_msr(unsigned int msr,
  86                                    unsigned low, unsigned high)
  87{
  88        asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high) : "memory");
  89}
  90
  91/* Can be uninlined because referenced by paravirt */
  92notrace static inline int native_write_msr_safe(unsigned int msr,
  93                                        unsigned low, unsigned high)
  94{
  95        int err;
  96        asm volatile("2: wrmsr ; xor %[err],%[err]\n"
  97                     "1:\n\t"
  98                     ".section .fixup,\"ax\"\n\t"
  99                     "3:  mov %[fault],%[err] ; jmp 1b\n\t"
 100                     ".previous\n\t"
 101                     _ASM_EXTABLE(2b, 3b)
 102                     : [err] "=a" (err)
 103                     : "c" (msr), "0" (low), "d" (high),
 104                       [fault] "i" (-EIO)
 105                     : "memory");
 106        return err;
 107}
 108
 109extern int rdmsr_safe_regs(u32 regs[8]);
 110extern int wrmsr_safe_regs(u32 regs[8]);
 111
 112/**
 113 * rdtsc() - returns the current TSC without ordering constraints
 114 *
 115 * rdtsc() returns the result of RDTSC as a 64-bit integer.  The
 116 * only ordering constraint it supplies is the ordering implied by
 117 * "asm volatile": it will put the RDTSC in the place you expect.  The
 118 * CPU can and will speculatively execute that RDTSC, though, so the
 119 * results can be non-monotonic if compared on different CPUs.
 120 */
 121static __always_inline unsigned long long rdtsc(void)
 122{
 123        DECLARE_ARGS(val, low, high);
 124
 125        asm volatile("rdtsc" : EAX_EDX_RET(val, low, high));
 126
 127        return EAX_EDX_VAL(val, low, high);
 128}
 129
 130/*
 131 * RHEL7: This is only defined to maintain KABI.  New code in the kernel should
 132 * not use this function.
 133 */
 134extern unsigned long long native_read_tsc(void);
 135
 136/**
 137 * rdtsc_ordered() - read the current TSC in program order
 138 *
 139 * rdtsc_ordered() returns the result of RDTSC as a 64-bit integer.
 140 * It is ordered like a load to a global in-memory counter.  It should
 141 * be impossible to observe non-monotonic rdtsc_unordered() behavior
 142 * across multiple CPUs as long as the TSC is synced.
 143 */
 144static __always_inline unsigned long long rdtsc_ordered(void)
 145{
 146        /*
 147         * The RDTSC instruction is not ordered relative to memory
 148         * access.  The Intel SDM and the AMD APM are both vague on this
 149         * point, but empirically an RDTSC instruction can be
 150         * speculatively executed before prior loads.  An RDTSC
 151         * immediately after an appropriate barrier appears to be
 152         * ordered as a normal load, that is, it provides the same
 153         * ordering guarantees as reading from a global memory location
 154         * that some other imaginary CPU is updating continuously with a
 155         * time stamp.
 156         */
 157        barrier_nospec();
 158        return rdtsc();
 159}
 160
 161/* Deprecated, keep it for a cycle for easier merging: */
 162#define rdtscll(now)    do { (now) = rdtsc_ordered(); } while (0)
 163
 164static inline unsigned long long native_read_pmc(int counter)
 165{
 166        DECLARE_ARGS(val, low, high);
 167
 168        asm volatile("rdpmc" : EAX_EDX_RET(val, low, high) : "c" (counter));
 169        return EAX_EDX_VAL(val, low, high);
 170}
 171
 172#ifdef CONFIG_PARAVIRT
 173#include <asm/paravirt.h>
 174#else
 175#include <linux/errno.h>
 176/*
 177 * Access to machine-specific registers (available on 586 and better only)
 178 * Note: the rd* operations modify the parameters directly (without using
 179 * pointer indirection), this allows gcc to optimize better
 180 */
 181
 182#define rdmsr(msr, low, high)                                   \
 183do {                                                            \
 184        u64 __val = native_read_msr((msr));                     \
 185        (void)((low) = (u32)__val);                             \
 186        (void)((high) = (u32)(__val >> 32));                    \
 187} while (0)
 188
 189static inline void wrmsr(unsigned msr, unsigned low, unsigned high)
 190{
 191        native_write_msr(msr, low, high);
 192}
 193
 194#define rdmsrl(msr, val)                        \
 195        ((val) = native_read_msr((msr)))
 196
 197#define wrmsrl(msr, val)                                                \
 198        native_write_msr((msr), (u32)((u64)(val)), (u32)((u64)(val) >> 32))
 199
 200/* wrmsr with exception handling */
 201static inline int wrmsr_safe(unsigned msr, unsigned low, unsigned high)
 202{
 203        return native_write_msr_safe(msr, low, high);
 204}
 205
 206/* rdmsr with exception handling */
 207#define rdmsr_safe(msr, low, high)                              \
 208({                                                              \
 209        int __err;                                              \
 210        u64 __val = native_read_msr_safe((msr), &__err);        \
 211        (*low) = (u32)__val;                                    \
 212        (*high) = (u32)(__val >> 32);                           \
 213        __err;                                                  \
 214})
 215
 216static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
 217{
 218        int err;
 219
 220        *p = native_read_msr_safe(msr, &err);
 221        return err;
 222}
 223
 224#define rdpmc(counter, low, high)                       \
 225do {                                                    \
 226        u64 _l = native_read_pmc((counter));            \
 227        (low)  = (u32)_l;                               \
 228        (high) = (u32)(_l >> 32);                       \
 229} while (0)
 230
 231#define rdpmcl(counter, val) ((val) = native_read_pmc(counter))
 232
 233#endif  /* !CONFIG_PARAVIRT */
 234
 235#define wrmsrl_safe(msr, val) wrmsr_safe((msr), (u32)(val),             \
 236                                             (u32)((val) >> 32))
 237
 238#define write_tsc(low, high) wrmsr(MSR_IA32_TSC, (low), (high))
 239
 240#define write_rdtscp_aux(val) wrmsr(MSR_TSC_AUX, (val), 0)
 241
 242struct msr *msrs_alloc(void);
 243void msrs_free(struct msr *msrs);
 244int msr_set_bit(u32 msr, u8 bit);
 245int msr_clear_bit(u32 msr, u8 bit);
 246
 247#ifdef CONFIG_SMP
 248int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
 249int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
 250int rdmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 *q);
 251int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q);
 252void rdmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr *msrs);
 253void wrmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr *msrs);
 254int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
 255int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
 256int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q);
 257int wrmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 q);
 258int rdmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]);
 259int wrmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]);
 260#else  /*  CONFIG_SMP  */
 261static inline int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
 262{
 263        rdmsr(msr_no, *l, *h);
 264        return 0;
 265}
 266static inline int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
 267{
 268        wrmsr(msr_no, l, h);
 269        return 0;
 270}
 271static inline int rdmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
 272{
 273        rdmsrl(msr_no, *q);
 274        return 0;
 275}
 276static inline int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q)
 277{
 278        wrmsrl(msr_no, q);
 279        return 0;
 280}
 281static inline void rdmsr_on_cpus(const struct cpumask *m, u32 msr_no,
 282                                struct msr *msrs)
 283{
 284       rdmsr_on_cpu(0, msr_no, &(msrs[0].l), &(msrs[0].h));
 285}
 286static inline void wrmsr_on_cpus(const struct cpumask *m, u32 msr_no,
 287                                struct msr *msrs)
 288{
 289       wrmsr_on_cpu(0, msr_no, msrs[0].l, msrs[0].h);
 290}
 291static inline int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no,
 292                                    u32 *l, u32 *h)
 293{
 294        return rdmsr_safe(msr_no, l, h);
 295}
 296static inline int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
 297{
 298        return wrmsr_safe(msr_no, l, h);
 299}
 300static inline int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
 301{
 302        return rdmsrl_safe(msr_no, q);
 303}
 304static inline int wrmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 q)
 305{
 306        return wrmsrl_safe(msr_no, q);
 307}
 308static inline int rdmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8])
 309{
 310        return rdmsr_safe_regs(regs);
 311}
 312static inline int wrmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8])
 313{
 314        return wrmsr_safe_regs(regs);
 315}
 316#endif  /* CONFIG_SMP */
 317#endif /* __ASSEMBLY__ */
 318#endif /* _ASM_X86_MSR_H */
 319