From 1f4d2e79b0aaef6a9be08b01a97fe7b40b398ae7 Mon Sep 17 00:00:00 2001 From: Dmitriy Vyukov Date: Wed, 12 Mar 2014 10:21:34 +0400 Subject: [PATCH] runtime: efence support for growable stacks 1. Fix the bug that shrinkstack returns memory to heap. This causes growslice to misbehave (it manually initialized blocks, and in efence mode shrinkstack's free leads to partially-initialized blocks coming out of growslice. Which in turn causes GC to crash while treating the garbage as Eface/Iface. 2. Enable efence for stack segments. LGTM=rsc R=golang-codereviews, rsc CC=golang-codereviews, khr https://golang.org/cl/74080043 --- src/pkg/runtime/stack.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/src/pkg/runtime/stack.c b/src/pkg/runtime/stack.c index 4d699f1101..4bdc24107c 100644 --- a/src/pkg/runtime/stack.c +++ b/src/pkg/runtime/stack.c @@ -102,7 +102,7 @@ runtime·stackalloc(G *gp, uint32 n) runtime·printf("stackalloc %d\n", n); gp->stacksize += n; - if(StackFromSystem) + if(runtime·debug.efence || StackFromSystem) return runtime·SysAlloc(ROUND(n, PageSize), &mstats.stacks_sys); // Minimum-sized stacks are allocated with a fixed-size free-list allocator, @@ -143,8 +143,8 @@ runtime·stackfree(G *gp, void *v, Stktop *top) if(StackDebug >= 1) runtime·printf("stackfree %p %d\n", v, (int32)n); gp->stacksize -= n; - if(StackFromSystem) { - if(StackFaultOnFree) + if(runtime·debug.efence || StackFromSystem) { + if(runtime·debug.efence || StackFaultOnFree) runtime·SysFault(v, n); else runtime·SysFree(v, n, &mstats.stacks_sys); @@ -819,7 +819,15 @@ runtime·shrinkstack(G *gp) gp->stack0 = (uintptr)oldstk + newsize; gp->stacksize -= oldsize - newsize; - // Free bottom half of the stack. First, we trick malloc into thinking + // Free bottom half of the stack. + if(runtime·debug.efence || StackFromSystem) { + if(runtime·debug.efence || StackFaultOnFree) + runtime·SysFault(oldstk, newsize); + else + runtime·SysFree(oldstk, newsize, &mstats.stacks_sys); + return; + } + // First, we trick malloc into thinking // we allocated the stack as two separate half-size allocs. Then the // free() call does the rest of the work for us. if(oldsize == PageSize) { -- 2.50.0