qemu

FORK: QEMU emulator
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signal_save_restore_xer.c (909B)

      1 #include <assert.h>
      2 #include <stdint.h>
      3 #include <signal.h>
      4 #include <sys/user.h>
      5 
      6 #define XER_SO   (1 << 31)
      7 #define XER_OV   (1 << 30)
      8 #define XER_CA   (1 << 29)
      9 #define XER_OV32 (1 << 19)
     10 #define XER_CA32 (1 << 18)
     11 
     12 uint64_t saved;
     13 
     14 void sigtrap_handler(int sig, siginfo_t *si, void *ucontext)
     15 {
     16     ucontext_t *uc = ucontext;
     17     uc->uc_mcontext.regs->nip += 4;
     18     saved = uc->uc_mcontext.regs->xer;
     19     uc->uc_mcontext.regs->xer |= XER_OV | XER_OV32;
     20 }
     21 
     22 int main(void)
     23 {
     24     uint64_t initial = XER_CA | XER_CA32, restored;
     25     struct sigaction sa = {
     26         .sa_sigaction = sigtrap_handler,
     27         .sa_flags = SA_SIGINFO
     28     };
     29 
     30     sigaction(SIGTRAP, &sa, NULL);
     31 
     32     asm("mtspr 1, %1\n\t"
     33         "trap\n\t"
     34         "mfspr %0, 1\n\t"
     35         : "=r" (restored)
     36         : "r" (initial));
     37 
     38     assert(saved == initial);
     39     assert(restored == (XER_OV | XER_OV32 | XER_CA | XER_CA32));
     40 
     41     return 0;
     42 }