src/include/cpu/x86/cache.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #ifndef CPU_X86_CACHE
   4 #define CPU_X86_CACHE
   5
   6 #include <cpu/x86/cr.h>
   7
   8 #define CR0_CacheDisable        (CR0_CD)
   9 #define CR0_NoWriteThrough      (CR0_NW)
  10
  11 #define CPUID_FEATURE_CLFLUSH_BIT 19
  12 #define CPUID_FEATURE_SELF_SNOOP_BIT 27
  13
  14 #if !defined(__ASSEMBLER__)
  15
  16 #include <arch/cpuid.h>
  17 #include <stdbool.h>
  18 #include <stddef.h>
  19
  20 static inline void wbinvd(void)
  21 {
  22         asm volatile ("wbinvd" ::: "memory");
  23 }
  24
  25 static inline void invd(void)
  26 {
  27         asm volatile("invd" ::: "memory");
  28 }
  29
  30 static inline void clflush(void *addr)
  31 {
  32         asm volatile ("clflush (%0)"::"r" (addr));
  33 }
  34
  35 bool clflush_supported(void);
  36 void clflush_region(const uintptr_t start, const size_t size);
  37
  38 /* The following functions require the __always_inline due to AMD
  39  * function STOP_CAR_AND_CPU that disables cache as
  40  * RAM, the cache as RAM stack can no longer be used. Called
  41  * functions must be inlined to avoid stack usage. Also, the
  42  * compiler must keep local variables register based and not
  43  * allocated them from the stack. With gcc 4.5.0, some functions
  44  * declared as inline are not being inlined. This patch forces
  45  * these functions to always be inlined by adding the qualifier
  46  * __always_inline to their declaration.
  47  */
  48 static __always_inline void enable_cache(void)
  49 {
  50         write_cr0(read_cr0() & ~(CR0_CD | CR0_NW));
  51 }
  52
  53 /*
  54  * Cache flushing is the most time-consuming step when programming the MTRRs.
  55  * However, if the processor supports cache self-snooping (ss), we can skip
  56  * this step and save time.
  57  */
  58 static __always_inline bool self_snooping_supported(void)
  59 {
  60         return (cpuid_edx(1) >> CPUID_FEATURE_SELF_SNOOP_BIT) & 1;
  61 }
  62
  63 static __always_inline void disable_cache(void)
  64 {
  65         /* Disable and write back the cache */
  66         write_cr0(read_cr0() | CR0_CD);
  67         if (!self_snooping_supported())
  68                 wbinvd();
  69 }
  70
  71 #endif /* !__ASSEMBLER__ */
  72 #endif /* CPU_X86_CACHE */