64-bit swtch.S

d9545e8b · Silas Boyd-Wickizer · 6ed206c5 · d9545e8b · d9545e8b · d9545e8b
--- a/proc.h
+++ b/proc.h
@@ -40,9 +40,16 @@ struct vmap {
 };
 // Saved registers for kernel context switches.
+// (also implicitly defined in swtch.S)
 struct context {
+  u64 r15;
+  u64 r14;
+  u64 r13;
+  u64 r12;
+  u64 rbp;
+  u64 rbx;
  u64 rip;
-};
+} __attribute__((packed));
 // Per-process, per-stack meta data for mtrace
 #define MTRACE_NSTACKS 16

--- a/swtch.S
+++ b/swtch.S
@@ -4,29 +4,23 @@
 # 
 # Save current register context in old
 # and then load register context from new.
+# %rdi holds old, %rsi holds new.
 .globl swtch
 swtch:
-        jmp swtch
+        pushq %rbx
-#if 0
+        pushq %rbp
-  movl 4(%esp), %eax
+        pushq %r12
-  movl 8(%esp), %edx
+        pushq %r13
+        pushq %r14
-  # Save old callee-save registers
+        pushq %r15
-  pushl %ebp
-  pushl %ebx
-  pushl %esi
-  pushl %edi
-  # Switch stacks
+        movq %rsp, (%rdi)
-  movl %esp, (%eax)
+        movq %rsi, %rsp
-  movl %edx, %esp
-  # Load new callee-save registers
+        popq %r15
-  popl %edi
+        popq %r14
-  popl %esi
+        popq %r13
-  popl %ebx
+        popq %r12
-  popl %ebp
+        popq %rbp
+        popq %rbx
        ret
-#endif
\ No newline at end of file
--- a/x86.h
+++ b/x86.h
@@ -130,6 +130,7 @@ static inline void lcr3(u64 val)
 // Layout of the trap frame built on the stack by the
 // hardware and by trapasm.S, and passed to trap().
 struct trapframe {
+  // amd64 ABI callee saved registers
  u64 r15;
  u64 r14;
  u64 r13;
@@ -137,7 +138,7 @@ struct trapframe {
  u64 rbp;
  u64 rbx;
-  // amd64 ABI callee saved registers
+  // amd64 ABI caller saved registers
  u64 r11;
  u64 r10;
  u64 r9;