Use fibers on windows

Cargo.toml

@@ -19,8 +19,18 @@ doctest = false
 test = false
 
 [dependencies]
-cfg-if = "0.1"
-libc = "0.2"
+cfg-if = "0.1.6"
+libc = "0.2.45"
+
+[target.'cfg(windows)'.dependencies.winapi]
+version = "0.3.6"
+features = [
+  'memoryapi',
+  'winbase',
+  'fibersapi',
+  'processthreadsapi',
+  'minwindef',
+]
 
 [build-dependencies]
 cc = "1.0"

README.md

@@ -7,7 +7,7 @@
 
 A stack-growth library for Rust. Enables annotating fixed points in programs
 where the stack may want to grow larger. Spills over to the heap if the stack
-has it its limit.
+has hit its limit.
 
 This library is intended on helping implement recursive algorithms.
 

build.rs

@@ -14,6 +14,7 @@ fn main() {
         cfg.define("APPLE", None);
     } else if target.contains("windows") {
         cfg.define("WINDOWS", None);
+        cfg.file("src/arch/windows.c");
     } else {
         panic!("\n\nusing currently unsupported target triple with \
                 stacker: {}\n\n", target);

src/arch/i686.S

@@ -2,26 +2,25 @@
 
 .text
 
-GLOBAL(__stacker_black_box):
-    ret
-
 GLOBAL(__stacker_stack_pointer):
     mov %esp, %eax
     ret
 
-#if defined(WINDOWS)
-GLOBAL(__stacker_get_tib_32):
-    mov %fs:0x18, %eax
-    ret
-#endif
-
 GLOBAL(__stacker_switch_stacks):
+    // CFI instructions tells the unwinder how to unwind this function
+    // This enables unwinding through our extended stacks and also
+    // backtrackes
+    .cfi_startproc
     push %ebp
+    .cfi_def_cfa_offset 8 // restore esp by adding 8
+    .cfi_offset ebp, -8   // restore ebp from the stack
     mov %esp, %ebp
-    mov 8(%ebp), %esp   // switch to our new stack
+    .cfi_def_cfa_register ebp // restore esp from ebp
+    mov 16(%ebp), %esp  // switch to our new stack
     mov 12(%ebp), %eax  // load function we're going to call
-    push 16(%ebp)       // push argument to first function
+    push 8(%ebp)        // push argument to first function
     call *%eax          // call our function pointer
     mov %ebp, %esp      // restore the old stack pointer
     pop %ebp
     ret
+    .cfi_endproc

src/arch/i686.asm

@@ -2,32 +2,9 @@
 .MODEL FLAT, C
 .CODE
 
-__stacker_black_box PROC
-    RET
-__stacker_black_box ENDP
-
 __stacker_stack_pointer PROC
     MOV EAX, ESP
     RET
 __stacker_stack_pointer ENDP
 
-__stacker_get_tib_32 PROC
-    ASSUME FS:NOTHING
-    MOV EAX, FS:[24]
-    ASSUME FS:ERROR
-    RET
-__stacker_get_tib_32 ENDP
-
-__stacker_switch_stacks PROC
-    PUSH EBP
-    MOV EBP, ESP
-    MOV ESP, [EBP + 8]      ; switch stacks
-    MOV EAX, [EBP + 12]     ; load the function we're going to call
-    PUSH [EBP + 16]         ; push the argument to this function
-    CALL EAX                ; call the next function
-    MOV ESP, EBP            ; restore the old stack pointer
-    POP EBP
-    RET
-__stacker_switch_stacks ENDP
-
 END

src/arch/windows.c

@@ -0,0 +1,5 @@
+#include <windows.h>
+
+PVOID __stacker_get_current_fiber() {
+    return GetCurrentFiber();
+}

src/arch/x86_64.S

@@ -2,35 +2,23 @@
 
 .text
 
-GLOBAL(__stacker_black_box):
-    ret
-
 GLOBAL(__stacker_stack_pointer):
     movq %rsp, %rax
     ret
 
-#if defined(WINDOWS)
-#define ARG1 %rcx
-#define ARG2 %rdx
-#define ARG3 %r8
-#else
-#define ARG1 %rdi
-#define ARG2 %rsi
-#define ARG3 %rdx
-#endif
-
-#if defined(WINDOWS)
-GLOBAL(__stacker_get_tib_64):
-    mov %gs:0x30, %rax
-    ret
-#endif
-
 GLOBAL(__stacker_switch_stacks):
+    // CFI instructions tells the unwinder how to unwind this function
+    // This enables unwinding through our extended stacks and also
+    // backtrackes
+    .cfi_startproc
     push %rbp
+    .cfi_def_cfa_offset 16 // restore rsp by adding 16
+    .cfi_offset rbp, -16   // restore rbp from the stack
     mov %rsp, %rbp
-    mov ARG1, %rsp      // switch to our new stack
-    mov ARG3, ARG1      // move the data pointer to the first argument
-    call *ARG2          // call our function pointer
+    .cfi_def_cfa_register rbp // restore rsp from rbp
+    mov %rdx, %rsp      // switch to our new stack
+    call *%rsi          // call our function pointer, data argument in %rdi
     mov %rbp, %rsp      // restore the old stack pointer
     pop %rbp
     ret
+    .cfi_endproc

src/arch/x86_64.asm

@@ -1,23 +1,8 @@
 _text SEGMENT
 
-__stacker_black_box PROC
-    RET
-__stacker_black_box ENDP
-
 __stacker_stack_pointer PROC
     MOV RAX, RSP
     RET
 __stacker_stack_pointer ENDP
 
-__stacker_switch_stacks PROC
-    PUSH RBP
-    MOV RBP, RSP
-    MOV RSP, RCX            ; switch to our new stack
-    MOV RCX, R8             ; move the data pointer to the first argument
-    CALL RDX                ; call our function pointer
-    MOV RSP, RBP            ; restore the old stack pointer
-    POP RBP
-    RET
-__stacker_switch_stacks ENDP
-
-END
+END