kernel/fiasco/src/kern/arm/spin_lock-arm.cpp

   1 //---------------------------------------------------------------------------
   2 INTERFACE [arm && mp]:
   3
   4 EXTENSION class Spin_lock
   5 {
   6 public:
   7   enum { Arch_lock = 2 };
   8 };
   9 //---------------------------------------------------------------------------
  10 IMPLEMENTATION [arm && mp]:
  11
  12 #include "processor.h"
  13
  14 PRIVATE template<typename Lock_t> inline NEEDS["processor.h"]
  15 void
  16 Spin_lock<Lock_t>::lock_arch()
  17 {
  18   Lock_t dummy, tmp;
  19
  20 #define L(z) \
  21   __asm__ __volatile__ ( \
  22       "1: ldr" #z "     %[d], [%[lock]]           \n" \
  23       "   tst     %[d], #2                  \n" /* Arch_lock == #2 */ \
  24       "   wfene                             \n" \
  25       "   bne     1b                        \n" \
  26       "   ldrex"#z"   %[d], [%[lock]]           \n" \
  27       "   tst     %[d], #2                  \n" \
  28       "   orr     %[tmp], %[d], #2          \n" \
  29       "   strex"#z"eq %[d], %[tmp], [%[lock]]   \n" \
  30       "   teqeq   %[d], #0                  \n" \
  31       "   bne     1b                        \n" \
  32       : [d] "=&r" (dummy), [tmp] "=&r"(tmp), "+m" (_lock) \
  33       : [lock] "r" (&_lock) \
  34       : "cc" \
  35       )
  36   if (sizeof(Lock_t) == sizeof(char))
  37     L(b);
  38   else if (sizeof(Lock_t) == sizeof(short))
  39     L(h);
  40   else
  41     L();
  42
  43 #undef L
  44 }
  45
  46 PRIVATE template<typename Lock_t> inline
  47 void
  48 Spin_lock<Lock_t>::unlock_arch()
  49 {
  50   Lock_t tmp;
  51 #define UNL(z) \
  52   __asm__ __volatile__( \
  53       "ldr"#z " %[tmp], %[lock]             \n" \
  54       "bic %[tmp], %[tmp], #2          \n" /* Arch_lock == #2 */ \
  55       "str"#z " %[tmp], %[lock]             \n" \
  56       "mcr p15, 0, %[tmp], c7, c10, 4  \n" /* drain write buffer */ \
  57       "sev                             \n" \
  58       : [lock] "=m" (_lock), [tmp] "=&r" (tmp))
  59   if (sizeof(Lock_t) == sizeof(char))
  60     UNL(b);
  61   else if (sizeof(Lock_t) == sizeof(short))
  62     UNL(h);
  63   else
  64     UNL();
  65 #undef UNL
  66 }