amd64 processor low level functions

[zos] / cpu.s

diff --git a/cpu.s b/cpu.s
new file mode 100644 (file)
index 0000000..30ca25e
--- /dev/null
+++ b/cpu.s
@@ -0,0 +1,70 @@
+global readtsc:function
+global readmsr:function
+global writemsr:function
+global enable_syscall:function
+global disable_syscall:function
+global setdr0:function
+global setdr1:function
+global setdr2:function
+global setdr3:function
+global nextrip:function
+
+setdr0:
+       mov rax, dr0
+       mov dr0, rdi
+       ret
+
+setdr1:
+       mov rax, dr1
+       mov dr1, rdi
+       ret
+setdr2:
+       mov rax, dr2
+       mov dr2, rdi
+       ret
+setdr3:
+       mov rax, dr3
+       mov dr3, rdi
+       ret
+
+nextrip:
+       pop rax
+       push rax
+       ret
+       
+readtsc:
+       rdtsc
+       shl rdx, 32
+       or rax, rdx
+       ret
+
+writemsr:
+       ; rdi is msr, rsi is value to write
+       mov ecx, edi
+       ; edx is high order bits, eax is low order bits to write
+       mov eax, esi
+       shr rsi, 32
+       mov edx, esi
+       wrmsr
+       ret
+
+readmsr:
+       mov ecx, edi
+       rdmsr
+       shl rdx, 32
+       or rax, rdx
+
+%define EFER 0xc0000080
+enable_syscall:
+       mov ecx, EFER
+       rdmsr
+       or eax, 0x1
+       wrmsr
+       ret
+
+disable_syscall:
+       mov ecx, EFER
+       rdmsr
+       and eax, DWORD ~0x1
+       wrmsr
+       ret