2 files changed, 173 insertions, 0 deletions
diff --git a/coroutine/amd64/Context.S b/coroutine/amd64/Context.S
new file mode 100644
index 0000000000..4b94d31f30
--- /dev/null
+++ b/coroutine/amd64/Context.S
@@ -0,0 +1,88 @@
+##
+##  This file is part of the "Coroutine" project and released under the MIT License.
+##
+##  Created by Samuel Williams on 10/5/2018.
+##  Copyright, 2018, by Samuel Williams.
+##
+
+/* Important - do _not_ include <cet.h> in this file; doing so will
+ * cause an incorrect .note.gnu.property section to be emitted. We have
+ * one at the bottom of this file */
+
+#define TOKEN_PASTE(x,y) x##y
+
+.text
+
+.globl PREFIXED_SYMBOL(coroutine_transfer)
+PREFIXED_SYMBOL(coroutine_transfer):
+
+#if defined(__CET__) && (__CET__ & 0x01) != 0
+        /* IBT landing pad */
+        endbr64
+#endif
+
+	# Make space on the stack for 6 registers:
+	subq $48, %rsp
+
+	# Save caller state:
+	movq %rbp, 40(%rsp)
+	movq %rbx, 32(%rsp)
+	movq %r12, 24(%rsp)
+	movq %r13, 16(%rsp)
+	movq %r14, 8(%rsp)
+	movq %r15, (%rsp)
+
+	# Save caller stack pointer:
+	movq %rsp, (%rdi)
+
+	# Restore callee stack pointer:
+	movq (%rsi), %rsp
+
+	# Restore callee state
+	movq 40(%rsp), %rbp
+	movq 32(%rsp), %rbx
+	movq 24(%rsp), %r12
+	movq 16(%rsp), %r13
+	movq 8(%rsp), %r14
+	movq (%rsp), %r15
+
+	# Adjust stack pointer back:
+	addq $48, %rsp
+
+	# Put the first argument into the return value:
+	movq %rdi, %rax
+
+	# We pop the return address and jump to it
+	ret
+
+#if (defined(__linux__) || defined(__FreeBSD__)) && defined(__ELF__)
+.section .note.GNU-stack,"",%progbits
+#endif
+
+#if defined(__ELF__)
+
+#if defined(__CET__) && (__CET__ & 0x01) != 0
+# define IBT_FLAG 0x01
+#else
+# define IBT_FLAG 0x00
+#endif
+
+/* We do _NOT_ support CET shadow-stack. Do _not_ add the property for
+ * this to the Context.o object. If you require CET shadow-stack support,
+ * for now, consider building with --with-coroutine=ucontext */
+#define SHSTK_FLAG 0x00
+
+.pushsection .note.gnu.property, "a"
+.p2align 3
+.long 0x4        /* Name size ("GNU\0") */
+.long 0x10       /* Descriptor size */
+.long 0x5        /* Type: NT_GNU_PROPERTY_TYPE_0 */
+.asciz "GNU"     /* Name */
+# Begin descriptor
+.long 0xc0000002 /* Property type: GNU_PROPERTY_X86_FEATURE_1_AND */
+.long 0x4        /* Property size */
+.long (IBT_FLAG | SHSTK_FLAG)
+.long 0x0        /* 8-byte alignment padding */
+/* End descriptor */
+.popsection
+#endif
diff --git a/coroutine/amd64/Context.h b/coroutine/amd64/Context.h
new file mode 100644
index 0000000000..65aa638304
--- /dev/null
+++ b/coroutine/amd64/Context.h
@@ -0,0 +1,85 @@
+#ifndef COROUTINE_AMD64_CONTEXT_H
+#define COROUTINE_AMD64_CONTEXT_H 1
+
+/*
+ *  This file is part of the "Coroutine" project and released under the MIT License.
+ *
+ *  Created by Samuel Williams on 10/5/2018.
+ *  Copyright, 2018, by Samuel Williams.
+*/
+
+#pragma once
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#define COROUTINE __attribute__((noreturn)) void
+
+enum {COROUTINE_REGISTERS = 6};
+
+#if defined(__SANITIZE_ADDRESS__)
+    #define COROUTINE_SANITIZE_ADDRESS
+#elif defined(__has_feature)
+    #if __has_feature(address_sanitizer)
+        #define COROUTINE_SANITIZE_ADDRESS
+    #endif
+#endif
+
+#if defined(COROUTINE_SANITIZE_ADDRESS)
+#include <sanitizer/common_interface_defs.h>
+#include <sanitizer/asan_interface.h>
+#endif
+
+struct coroutine_context
+{
+    void **stack_pointer;
+    void *argument;
+
+#if defined(COROUTINE_SANITIZE_ADDRESS)
+    void *fake_stack;
+    void *stack_base;
+    size_t stack_size;
+#endif
+};
+
+typedef COROUTINE(* coroutine_start)(struct coroutine_context *from, struct coroutine_context *self);
+
+static inline void coroutine_initialize_main(struct coroutine_context * context) {
+    context->stack_pointer = NULL;
+}
+
+static inline void coroutine_initialize(
+    struct coroutine_context *context,
+    coroutine_start start,
+    void *stack,
+    size_t size
+) {
+    assert(start && stack && size >= 1024);
+
+#if defined(COROUTINE_SANITIZE_ADDRESS)
+    context->fake_stack = NULL;
+    context->stack_base = stack;
+    context->stack_size = size;
+#endif
+
+    // Stack grows down. Force 16-byte alignment.
+    char * top = (char*)stack + size;
+    context->stack_pointer = (void**)((uintptr_t)top & ~0xF);
+
+    *--context->stack_pointer = NULL;
+    *--context->stack_pointer = (void*)(uintptr_t)start;
+
+    context->stack_pointer -= COROUTINE_REGISTERS;
+    memset(context->stack_pointer, 0, sizeof(void*) * COROUTINE_REGISTERS);
+}
+
+struct coroutine_context * coroutine_transfer(struct coroutine_context * current, struct coroutine_context * target);
+
+static inline void coroutine_destroy(struct coroutine_context * context)
+{
+    context->stack_pointer = NULL;
+}
+
+#endif /* COROUTINE_AMD64_CONTEXT_H */