1 files changed, 282 insertions, 0 deletions
diff --git a/src/pkg/runtime/stack.c b/src/pkg/runtime/stack.c
new file mode 100644
index 000000000..e9a35672f
--- /dev/null
+++ b/src/pkg/runtime/stack.c
@@ -0,0 +1,282 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+#include "arch_GOARCH.h"
+#include "malloc.h"
+#include "stack.h"
+
+typedef struct StackCacheNode StackCacheNode;
+struct StackCacheNode
+{
+	StackCacheNode *next;
+	void*	batch[StackCacheBatch-1];
+};
+
+static StackCacheNode *stackcache;
+static Lock stackcachemu;
+
+// stackcacherefill/stackcacherelease implement a global cache of stack segments.
+// The cache is required to prevent unlimited growth of per-thread caches.
+static void
+stackcacherefill(void)
+{
+	StackCacheNode *n;
+	int32 i, pos;
+
+	runtime·lock(&stackcachemu);
+	n = stackcache;
+	if(n)
+		stackcache = n->next;
+	runtime·unlock(&stackcachemu);
+	if(n == nil) {
+		n = (StackCacheNode*)runtime·SysAlloc(FixedStack*StackCacheBatch);
+		if(n == nil)
+			runtime·throw("out of memory (stackcacherefill)");
+		runtime·xadd64(&mstats.stacks_sys, FixedStack*StackCacheBatch);
+		for(i = 0; i < StackCacheBatch-1; i++)
+			n->batch[i] = (byte*)n + (i+1)*FixedStack;
+	}
+	pos = m->stackcachepos;
+	for(i = 0; i < StackCacheBatch-1; i++) {
+		m->stackcache[pos] = n->batch[i];
+		pos = (pos + 1) % StackCacheSize;
+	}
+	m->stackcache[pos] = n;
+	pos = (pos + 1) % StackCacheSize;
+	m->stackcachepos = pos;
+	m->stackcachecnt += StackCacheBatch;
+}
+
+static void
+stackcacherelease(void)
+{
+	StackCacheNode *n;
+	uint32 i, pos;
+
+	pos = (m->stackcachepos - m->stackcachecnt) % StackCacheSize;
+	n = (StackCacheNode*)m->stackcache[pos];
+	pos = (pos + 1) % StackCacheSize;
+	for(i = 0; i < StackCacheBatch-1; i++) {
+		n->batch[i] = m->stackcache[pos];
+		pos = (pos + 1) % StackCacheSize;
+	}
+	m->stackcachecnt -= StackCacheBatch;
+	runtime·lock(&stackcachemu);
+	n->next = stackcache;
+	stackcache = n;
+	runtime·unlock(&stackcachemu);
+}
+
+void*
+runtime·stackalloc(uint32 n)
+{
+	uint32 pos;
+	void *v;
+
+	// Stackalloc must be called on scheduler stack, so that we
+	// never try to grow the stack during the code that stackalloc runs.
+	// Doing so would cause a deadlock (issue 1547).
+	if(g != m->g0)
+		runtime·throw("stackalloc not on scheduler stack");
+
+	// Stack allocator uses malloc/free most of the time,
+	// but if we're in the middle of malloc and need stack,
+	// we have to do something else to avoid deadlock.
+	// In that case, we fall back on a fixed-size free-list
+	// allocator, assuming that inside malloc all the stack
+	// frames are small, so that all the stack allocations
+	// will be a single size, the minimum (right now, 5k).
+	if(n == FixedStack || m->mallocing || m->gcing) {
+		if(n != FixedStack) {
+			runtime·printf("stackalloc: in malloc, size=%d want %d\n", FixedStack, n);
+			runtime·throw("stackalloc");
+		}
+		if(m->stackcachecnt == 0)
+			stackcacherefill();
+		pos = m->stackcachepos;
+		pos = (pos - 1) % StackCacheSize;
+		v = m->stackcache[pos];
+		m->stackcachepos = pos;
+		m->stackcachecnt--;
+		m->stackinuse++;
+		return v;
+	}
+	return runtime·mallocgc(n, FlagNoProfiling|FlagNoGC, 0, 0);
+}
+
+void
+runtime·stackfree(void *v, uintptr n)
+{
+	uint32 pos;
+
+	if(n == FixedStack || m->mallocing || m->gcing) {
+		if(m->stackcachecnt == StackCacheSize)
+			stackcacherelease();
+		pos = m->stackcachepos;
+		m->stackcache[pos] = v;
+		m->stackcachepos = (pos + 1) % StackCacheSize;
+		m->stackcachecnt++;
+		m->stackinuse--;
+		return;
+	}
+	runtime·free(v);
+}
+
+// Called from runtime·lessstack when returning from a function which
+// allocated a new stack segment.  The function's return value is in
+// m->cret.
+void
+runtime·oldstack(void)
+{
+	Stktop *top;
+	Gobuf label;
+	uint32 argsize;
+	uintptr cret;
+	byte *sp, *old;
+	uintptr *src, *dst, *dstend;
+	G *gp;
+	int64 goid;
+
+//printf("oldstack m->cret=%p\n", m->cret);
+
+	gp = m->curg;
+	top = (Stktop*)gp->stackbase;
+	old = (byte*)gp->stackguard - StackGuard;
+	sp = (byte*)top;
+	argsize = top->argsize;
+	if(argsize > 0) {
+		sp -= argsize;
+		dst = (uintptr*)top->argp;
+		dstend = dst + argsize/sizeof(*dst);
+		src = (uintptr*)sp;
+		while(dst < dstend)
+			*dst++ = *src++;
+	}
+	goid = top->gobuf.g->goid;	// fault if g is bad, before gogo
+	USED(goid);
+
+	label = top->gobuf;
+	gp->stackbase = (uintptr)top->stackbase;
+	gp->stackguard = (uintptr)top->stackguard;
+	if(top->free != 0)
+		runtime·stackfree(old, top->free);
+
+	cret = m->cret;
+	m->cret = 0;  // drop reference
+	runtime·gogo(&label, cret);
+}
+
+// Called from reflect·call or from runtime·morestack when a new
+// stack segment is needed.  Allocate a new stack big enough for
+// m->moreframesize bytes, copy m->moreargsize bytes to the new frame,
+// and then act as though runtime·lessstack called the function at
+// m->morepc.
+void
+runtime·newstack(void)
+{
+	int32 framesize, minalloc, argsize;
+	Stktop *top;
+	byte *stk, *sp;
+	uintptr *src, *dst, *dstend;
+	G *gp;
+	Gobuf label;
+	bool reflectcall;
+	uintptr free;
+
+	framesize = m->moreframesize;
+	argsize = m->moreargsize;
+	gp = m->curg;
+
+	if(m->morebuf.sp < gp->stackguard - StackGuard) {
+		runtime·printf("runtime: split stack overflow: %p < %p\n", m->morebuf.sp, gp->stackguard - StackGuard);
+		runtime·throw("runtime: split stack overflow");
+	}
+	if(argsize % sizeof(uintptr) != 0) {
+		runtime·printf("runtime: stack split with misaligned argsize %d\n", argsize);
+		runtime·throw("runtime: stack split argsize");
+	}
+
+	minalloc = 0;
+	reflectcall = framesize==1;
+	if(reflectcall) {
+		framesize = 0;
+		// moreframesize_minalloc is only set in runtime·gc(),
+		// that calls newstack via reflect·call().
+		minalloc = m->moreframesize_minalloc;
+		m->moreframesize_minalloc = 0;
+		if(framesize < minalloc)
+			framesize = minalloc;
+	}
+
+	if(reflectcall && minalloc == 0 && m->morebuf.sp - sizeof(Stktop) - argsize - 32 > gp->stackguard) {
+		// special case: called from reflect.call (framesize==1)
+		// to call code with an arbitrary argument size,
+		// and we have enough space on the current stack.
+		// the new Stktop* is necessary to unwind, but
+		// we don't need to create a new segment.
+		top = (Stktop*)(m->morebuf.sp - sizeof(*top));
+		stk = (byte*)gp->stackguard - StackGuard;
+		free = 0;
+	} else {
+		// allocate new segment.
+		framesize += argsize;
+		framesize += StackExtra;	// room for more functions, Stktop.
+		if(framesize < StackMin)
+			framesize = StackMin;
+		framesize += StackSystem;
+		stk = runtime·stackalloc(framesize);
+		top = (Stktop*)(stk+framesize-sizeof(*top));
+		free = framesize;
+	}
+
+	if(0) {
+		runtime·printf("newstack framesize=%d argsize=%d morepc=%p moreargp=%p gobuf=%p, %p top=%p old=%p\n",
+			framesize, argsize, m->morepc, m->moreargp, m->morebuf.pc, m->morebuf.sp, top, gp->stackbase);
+	}
+
+	top->stackbase = (byte*)gp->stackbase;
+	top->stackguard = (byte*)gp->stackguard;
+	top->gobuf = m->morebuf;
+	top->argp = m->moreargp;
+	top->argsize = argsize;
+	top->free = free;
+	m->moreargp = nil;
+	m->morebuf.pc = nil;
+	m->morebuf.sp = (uintptr)nil;
+
+	// copy flag from panic
+	top->panic = gp->ispanic;
+	gp->ispanic = false;
+
+	gp->stackbase = (uintptr)top;
+	gp->stackguard = (uintptr)stk + StackGuard;
+
+	sp = (byte*)top;
+	if(argsize > 0) {
+		sp -= argsize;
+		dst = (uintptr*)sp;
+		dstend = dst + argsize/sizeof(*dst);
+		src = (uintptr*)top->argp;
+		while(dst < dstend)
+			*dst++ = *src++;
+	}
+	if(thechar == '5') {
+		// caller would have saved its LR below args.
+		sp -= sizeof(void*);
+		*(void**)sp = nil;
+	}
+
+	// Continue as if lessstack had just called m->morepc
+	// (the PC that decided to grow the stack).
+	label.sp = (uintptr)sp;
+	label.pc = (byte*)runtime·lessstack;
+	label.g = m->curg;
+	if(reflectcall)
+		runtime·gogocallfn(&label, (FuncVal*)m->morepc);
+	else
+		runtime·gogocall(&label, m->morepc, m->cret);
+
+	*(int32*)345 = 123;	// never return
+}