Pass the new stack pointer by value into the swap trampoline

src/arch/or1k.rs

@@ -42,7 +42,7 @@ use stack::Stack;
 
 pub const STACK_ALIGNMENT: usize = 4;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy)]
 pub struct StackPointer(*mut usize);
 
 pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackPointer {
@@ -107,7 +107,7 @@ pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackP
 }
 
 #[inline(always)]
-pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPointer,
+pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: StackPointer,
                    new_stack: &Stack) -> usize {
   // Address of the topmost CFA stack slot.
   let new_cfa = (new_stack.base() as *mut usize).offset(-1);
@@ -124,12 +124,10 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
         # the call instruction that invoked the trampoline.
         l.sw    -8(r1), r2
 
-        # Remember stack pointer of the old context, in case r5==r4.
-        l.or    r13, r0, r1
-        # Load stack pointer of the new context.
-        l.lwz   r1, 0(r5)
         # Save stack pointer of the old context.
-        l.sw    0(r4), r13
+        l.sw    0(r4), r1
+        # Load stack pointer of the new context.
+        l.or    r1, r0, r5
 
         # Restore frame pointer of the new context.
         l.lwz   r2, -8(r1)
@@ -156,7 +154,7 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
     : "s" (trampoline as usize)
       "{r3}" (arg)
       "{r4}" (old_sp)
-      "{r5}" (new_sp)
+      "{r5}" (new_sp.0)
       "{r6}" (new_cfa)
     :/*"r0", "r1",  "r2",  "r3",*/"r4",  "r5",  "r6",  "r7",
       "r8",  "r9",  "r10", "r11", "r12", "r13", "r14", "r15",

src/arch/x86.rs

@@ -43,7 +43,7 @@ use stack::Stack;
 
 pub const STACK_ALIGNMENT: usize = 16;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy)]
 pub struct StackPointer(*mut usize);
 
 pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackPointer {
@@ -106,7 +106,7 @@ pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackP
 }
 
 #[inline(always)]
-pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPointer,
+pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: StackPointer,
                    new_stack: &Stack) -> usize {
   // Address of the topmost CFA stack slot.
   let new_cfa = (new_stack.base() as *mut usize).offset(-1);
@@ -120,12 +120,10 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
         # the call instruction that invoked the trampoline.
         pushl   %ebp
 
-        # Remember stack pointer of the old context, in case %edx==%esi.
-        movl    %esp, %ebx
-        # Load stack pointer of the new context.
-        movl    (%edx), %esp
         # Save stack pointer of the old context.
-        movl    %ebx, (%esi)
+        movl    %esp, (%esi)
+        # Load stack pointer of the new context.
+        movl    %edx, %esp
 
         # Restore frame pointer of the new context.
         popl    %ebp
@@ -151,7 +149,7 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
     : "s" (trampoline as usize)
       "{eax}" (arg)
       "{esi}" (old_sp)
-      "{edx}" (new_sp)
+      "{edx}" (new_sp.0)
       "{edi}" (new_cfa)
     :/*"eax",*/"ebx", "ecx",  "edx",  "esi",  "edi",/*"ebp",  "esp",*/
       "mm0",  "mm1",  "mm2",  "mm3",  "mm4",  "mm5",  "mm6",  "mm7",

src/arch/x86_64.rs

@@ -47,7 +47,7 @@ use stack::Stack;
 
 pub const STACK_ALIGNMENT: usize = 16;
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, Copy)]
 pub struct StackPointer(*mut usize);
 
 pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackPointer {
@@ -133,7 +133,7 @@ pub unsafe fn init(stack: &Stack, f: unsafe extern "C" fn(usize) -> !) -> StackP
 }
 
 #[inline(always)]
-pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPointer,
+pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: StackPointer,
                    new_stack: &Stack) -> usize {
   // Address of the topmost CFA stack slot.
   let new_cfa = (new_stack.base() as *mut usize).offset(-1);
@@ -147,12 +147,10 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
         # the call instruction that invoked the trampoline.
         pushq   %rbp
 
-        # Remember stack pointer of the old context, in case %rdx==%rsi.
-        movq    %rsp, %rbx
-        # Load stack pointer of the new context.
-        movq    (%rdx), %rsp
         # Save stack pointer of the old context.
-        movq    %rbx, (%rsi)
+        movq    %rsp, (%rsi)
+        # Load stack pointer of the new context.
+        movq    %rdx, %rsp
 
         # Restore frame pointer of the new context.
         popq    %rbp
@@ -178,7 +176,7 @@ pub unsafe fn swap(arg: usize, old_sp: *mut StackPointer, new_sp: *const StackPo
     : "s" (trampoline as usize)
       "{rdi}" (arg)
       "{rsi}" (old_sp)
-      "{rdx}" (new_sp)
+      "{rdx}" (new_sp.0)
       "{rcx}" (new_cfa)
     : "rax",   "rbx",   "rcx",   "rdx",   "rsi", /*"rdi",   "rbp",   "rsp",*/
       "r8",    "r9",    "r10",   "r11",   "r12",   "r13",   "r14",   "r15",

src/context.rs

@@ -52,7 +52,7 @@ impl<OldStack> Context<OldStack> where OldStack: stack::Stack {
                                new_ctx: *const Context<NewStack>,
                                arg: usize) -> usize
       where NewStack: stack::Stack {
-    arch::swap(arg, &mut (*old_ctx).stack_ptr, &(*new_ctx).stack_ptr, &(*new_ctx).stack)
+    arch::swap(arg, &mut (*old_ctx).stack_ptr, (*new_ctx).stack_ptr, &(*new_ctx).stack)
   }
 }