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
  35struct saved_msr {
  36        bool valid;
  37        struct msr_info info;
  38};
  39
  40struct saved_msrs {
  41        unsigned int num;
  42        struct saved_msr *array;
  43};
  44
  45/*
  46 * both i386 and x86_64 returns 64-bit value in edx:eax, but gcc's "A"
  47 * constraint has different meanings. For i386, "A" means exactly
  48 * edx:eax, while for x86_64 it doesn't mean rdx:rax or edx:eax. Instead,
  49 * it means rax *or* rdx.
  50 */
  51#ifdef CONFIG_X86_64
  52/* Using 64-bit values saves one instruction clearing the high half of low */
  53#define DECLARE_ARGS(val, low, high)    unsigned long low, high
  54#define EAX_EDX_VAL(val, low, high)     ((low) | (high) << 32)
  55#define EAX_EDX_RET(val, low, high)     "=a" (low), "=d" (high)
  56#else
  57#define DECLARE_ARGS(val, low, high)    unsigned long long val
  58#define EAX_EDX_VAL(val, low, high)     (val)
  59#define EAX_EDX_RET(val, low, high)     "=A" (val)
  60#endif
  61
  62#ifdef CONFIG_TRACEPOINTS
  63/*
  64 * Be very careful with includes. This header is prone to include loops.
  65 */
  66#include <asm/atomic.h>
  67#include <linux/tracepoint-defs.h>
  68
  69extern struct tracepoint __tracepoint_read_msr;
  70extern struct tracepoint __tracepoint_write_msr;
  71extern struct tracepoint __tracepoint_rdpmc;
  72#define msr_tracepoint_active(t) static_key_false(&(t).key)
  73extern void do_trace_write_msr(unsigned msr, u64 val, int failed);
  74extern void do_trace_read_msr(unsigned msr, u64 val, int failed);
  75extern void do_trace_rdpmc(unsigned msr, u64 val, int failed);
  76#else
  77#define msr_tracepoint_active(t) false
  78static inline void do_trace_write_msr(unsigned msr, u64 val, int failed) {}
  79static inline void do_trace_read_msr(unsigned msr, u64 val, int failed) {}
  80static inline void do_trace_rdpmc(unsigned msr, u64 val, int failed) {}
  81#endif
  82
  83static inline unsigned long long native_read_msr(unsigned int msr)
  84{
  85        DECLARE_ARGS(val, low, high);
  86
  87        asm volatile("1: rdmsr\n"
  88                     "2:\n"
  89                     _ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_rdmsr_unsafe)
  90                     : EAX_EDX_RET(val, low, high) : "c" (msr));
  91        if (msr_tracepoint_active(__tracepoint_read_msr))
  92                do_trace_read_msr(msr, EAX_EDX_VAL(val, low, high), 0);
  93        return EAX_EDX_VAL(val, low, high);
  94}
  95
  96static inline unsigned long long native_read_msr_safe(unsigned int msr,
  97                                                      int *err)
  98{
  99        DECLARE_ARGS(val, low, high);
 100
 101        asm volatile("2: rdmsr ; xor %[err],%[err]\n"
 102                     "1:\n\t"
 103                     ".section .fixup,\"ax\"\n\t"
 104                     "3: mov %[fault],%[err]\n\t"
 105                     "xorl %%eax, %%eax\n\t"
 106                     "xorl %%edx, %%edx\n\t"
 107                     "jmp 1b\n\t"
 108                     ".previous\n\t"
 109                     _ASM_EXTABLE(2b, 3b)
 110                     : [err] "=r" (*err), EAX_EDX_RET(val, low, high)
 111                     : "c" (msr), [fault] "i" (-EIO));
 112        if (msr_tracepoint_active(__tracepoint_read_msr))
 113                do_trace_read_msr(msr, EAX_EDX_VAL(val, low, high), *err);
 114        return EAX_EDX_VAL(val, low, high);
 115}
 116
 117/* Can be uninlined because referenced by paravirt */
 118notrace static inline void native_write_msr(unsigned int msr,
 119                                            unsigned low, unsigned high)
 120{
 121        asm volatile("1: wrmsr\n"
 122                     "2:\n"
 123                     _ASM_EXTABLE_HANDLE(1b, 2b, ex_handler_wrmsr_unsafe)
 124                     : : "c" (msr), "a"(low), "d" (high) : "memory");
 125        if (msr_tracepoint_active(__tracepoint_write_msr))
 126                do_trace_write_msr(msr, ((u64)high << 32 | low), 0);
 127}
 128
 129/* Can be uninlined because referenced by paravirt */
 130notrace static inline int native_write_msr_safe(unsigned int msr,
 131                                        unsigned low, unsigned high)
 132{
 133        int err;
 134        asm volatile("2: wrmsr ; xor %[err],%[err]\n"
 135                     "1:\n\t"
 136                     ".section .fixup,\"ax\"\n\t"
 137                     "3:  mov %[fault],%[err] ; jmp 1b\n\t"
 138                     ".previous\n\t"
 139                     _ASM_EXTABLE(2b, 3b)
 140                     : [err] "=a" (err)
 141                     : "c" (msr), "0" (low), "d" (high),
 142                       [fault] "i" (-EIO)
 143                     : "memory");
 144        if (msr_tracepoint_active(__tracepoint_write_msr))
 145                do_trace_write_msr(msr, ((u64)high << 32 | low), err);
 146        return err;
 147}
 148
 149extern int rdmsr_safe_regs(u32 regs[8]);
 150extern int wrmsr_safe_regs(u32 regs[8]);
 151
 152/**
 153 * rdtsc() - returns the current TSC without ordering constraints
 154 *
 155 * rdtsc() returns the result of RDTSC as a 64-bit integer.  The
 156 * only ordering constraint it supplies is the ordering implied by
 157 * "asm volatile": it will put the RDTSC in the place you expect.  The
 158 * CPU can and will speculatively execute that RDTSC, though, so the
 159 * results can be non-monotonic if compared on different CPUs.
 160 */
 161static __always_inline unsigned long long rdtsc(void)
 162{
 163        DECLARE_ARGS(val, low, high);
 164
 165        asm volatile("rdtsc" : EAX_EDX_RET(val, low, high));
 166
 167        return EAX_EDX_VAL(val, low, high);
 168}
 169
 170/**
 171 * rdtsc_ordered() - read the current TSC in program order
 172 *
 173 * rdtsc_ordered() returns the result of RDTSC as a 64-bit integer.
 174 * It is ordered like a load to a global in-memory counter.  It should
 175 * be impossible to observe non-monotonic rdtsc_unordered() behavior
 176 * across multiple CPUs as long as the TSC is synced.
 177 */
 178static __always_inline unsigned long long rdtsc_ordered(void)
 179{
 180        /*
 181         * The RDTSC instruction is not ordered relative to memory
 182         * access.  The Intel SDM and the AMD APM are both vague on this
 183         * point, but empirically an RDTSC instruction can be
 184         * speculatively executed before prior loads.  An RDTSC
 185         * immediately after an appropriate barrier appears to be
 186         * ordered as a normal load, that is, it provides the same
 187         * ordering guarantees as reading from a global memory location
 188         * that some other imaginary CPU is updating continuously with a
 189         * time stamp.
 190         */
 191        alternative_2("", "mfence", X86_FEATURE_MFENCE_RDTSC,
 192                          "lfence", X86_FEATURE_LFENCE_RDTSC);
 193        return rdtsc();
 194}
 195
 196/* Deprecated, keep it for a cycle for easier merging: */
 197#define rdtscll(now)    do { (now) = rdtsc_ordered(); } while (0)
 198
 199static inline unsigned long long native_read_pmc(int counter)
 200{
 201        DECLARE_ARGS(val, low, high);
 202
 203        asm volatile("rdpmc" : EAX_EDX_RET(val, low, high) : "c" (counter));
 204        if (msr_tracepoint_active(__tracepoint_rdpmc))
 205                do_trace_rdpmc(counter, EAX_EDX_VAL(val, low, high), 0);
 206        return EAX_EDX_VAL(val, low, high);
 207}
 208
 209#ifdef CONFIG_PARAVIRT
 210#include <asm/paravirt.h>
 211#else
 212#include <linux/errno.h>
 213/*
 214 * Access to machine-specific registers (available on 586 and better only)
 215 * Note: the rd* operations modify the parameters directly (without using
 216 * pointer indirection), this allows gcc to optimize better
 217 */
 218
 219#define rdmsr(msr, low, high)                                   \
 220do {                                                            \
 221        u64 __val = native_read_msr((msr));                     \
 222        (void)((low) = (u32)__val);                             \
 223        (void)((high) = (u32)(__val >> 32));                    \
 224} while (0)
 225
 226static inline void wrmsr(unsigned msr, unsigned low, unsigned high)
 227{
 228        native_write_msr(msr, low, high);
 229}
 230
 231#define rdmsrl(msr, val)                        \
 232        ((val) = native_read_msr((msr)))
 233
 234static inline void wrmsrl(unsigned msr, u64 val)
 235{
 236        native_write_msr(msr, (u32)(val & 0xffffffffULL), (u32)(val >> 32));
 237}
 238
 239/* wrmsr with exception handling */
 240static inline int wrmsr_safe(unsigned msr, unsigned low, unsigned high)
 241{
 242        return native_write_msr_safe(msr, low, high);
 243}
 244
 245/* rdmsr with exception handling */
 246#define rdmsr_safe(msr, low, high)                              \
 247({                                                              \
 248        int __err;                                              \
 249        u64 __val = native_read_msr_safe((msr), &__err);        \
 250        (*low) = (u32)__val;                                    \
 251        (*high) = (u32)(__val >> 32);                           \
 252        __err;                                                  \
 253})
 254
 255static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
 256{
 257        int err;
 258
 259        *p = native_read_msr_safe(msr, &err);
 260        return err;
 261}
 262
 263#define rdpmc(counter, low, high)                       \
 264do {                                                    \
 265        u64 _l = native_read_pmc((counter));            \
 266        (low)  = (u32)_l;                               \
 267        (high) = (u32)(_l >> 32);                       \
 268} while (0)
 269
 270#define rdpmcl(counter, val) ((val) = native_read_pmc(counter))
 271
 272#endif  /* !CONFIG_PARAVIRT */
 273
 274/*
 275 * 64-bit version of wrmsr_safe():
 276 */
 277static inline int wrmsrl_safe(u32 msr, u64 val)
 278{
 279        return wrmsr_safe(msr, (u32)val,  (u32)(val >> 32));
 280}
 281
 282#define write_tsc(low, high) wrmsr(MSR_IA32_TSC, (low), (high))
 283
 284#define write_rdtscp_aux(val) wrmsr(MSR_TSC_AUX, (val), 0)
 285
 286struct msr *msrs_alloc(void);
 287void msrs_free(struct msr *msrs);
 288int msr_set_bit(u32 msr, u8 bit);
 289int msr_clear_bit(u32 msr, u8 bit);
 290
 291#ifdef CONFIG_SMP
 292int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
 293int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
 294int rdmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 *q);
 295int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q);
 296void rdmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr *msrs);
 297void wrmsr_on_cpus(const struct cpumask *mask, u32 msr_no, struct msr *msrs);
 298int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h);
 299int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h);
 300int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q);
 301int wrmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 q);
 302int rdmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]);
 303int wrmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]);
 304#else  /*  CONFIG_SMP  */
 305static inline int rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
 306{
 307        rdmsr(msr_no, *l, *h);
 308        return 0;
 309}
 310static inline int wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
 311{
 312        wrmsr(msr_no, l, h);
 313        return 0;
 314}
 315static inline int rdmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
 316{
 317        rdmsrl(msr_no, *q);
 318        return 0;
 319}
 320static inline int wrmsrl_on_cpu(unsigned int cpu, u32 msr_no, u64 q)
 321{
 322        wrmsrl(msr_no, q);
 323        return 0;
 324}
 325static inline void rdmsr_on_cpus(const struct cpumask *m, u32 msr_no,
 326                                struct msr *msrs)
 327{
 328       rdmsr_on_cpu(0, msr_no, &(msrs[0].l), &(msrs[0].h));
 329}
 330static inline void wrmsr_on_cpus(const struct cpumask *m, u32 msr_no,
 331                                struct msr *msrs)
 332{
 333       wrmsr_on_cpu(0, msr_no, msrs[0].l, msrs[0].h);
 334}
 335static inline int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no,
 336                                    u32 *l, u32 *h)
 337{
 338        return rdmsr_safe(msr_no, l, h);
 339}
 340static inline int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
 341{
 342        return wrmsr_safe(msr_no, l, h);
 343}
 344static inline int rdmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 *q)
 345{
 346        return rdmsrl_safe(msr_no, q);
 347}
 348static inline int wrmsrl_safe_on_cpu(unsigned int cpu, u32 msr_no, u64 q)
 349{
 350        return wrmsrl_safe(msr_no, q);
 351}
 352static inline int rdmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8])
 353{
 354        return rdmsr_safe_regs(regs);
 355}
 356static inline int wrmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8])
 357{
 358        return wrmsr_safe_regs(regs);
 359}
 360#endif  /* CONFIG_SMP */
 361#endif /* __ASSEMBLY__ */
 362#endif /* _ASM_X86_MSR_H */
 363