Date: Mon, 01 Dec 2003 20:07:01 -0800 From: Peter Wemm <peter@wemm.org> To: James Van Artsdalen <james-freebsd-amd64@jrv.org> Cc: freebsd-amd64@freebsd.org Subject: Re: Varargs issues Message-ID: <20031202040701.753912A7EA@canning.wemm.org> In-Reply-To: <20031202020159.2897C2A8DA@canning.wemm.org>
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Peter Wemm wrote: > James Van Artsdalen wrote: > > I looked at the example I was suspicious of and realized that I had > > overlooked that the caller implicitly allocates 8 bytes in the stack > > due to the CALL opcode. It's perfectly reasonable for a function to > > start with something like: > > > > doo: > > push (64 bit) val > > call z > > > > since the return address + the push makes an even 16 bytes. > > > > There are two different pthread_create () functions. The one in > > /usr/src/lib/libc_r/uthread/uthread_create.c does this to ensure that > > the stack starts off right: > > > > SET_STACK_JB(new_thread->ctx.jb, > > (long)new_thread->stack + pattr->stacksize_attr > > - sizeof(double)); > > > > sizeof (double) isn't really portable - sizeof (&_pthread_create) would > > be better - but it clearly leaves the stack with a value that gcc expects, > > i.e., an "odd" value in 8-byte units (0xfff8 instead of 0xfff0). > > This stuff is all pretty broken for amd64. I'm amazed that it even remotely > works. The situation right now is that if a pthread_create()ed thread > tries to do floating point, it'll blow up sooner or later. If its not > in varargs, it'll be in the function prologue/epilogue when it saves and > restores the xmm registers. This patch seems to fix it for me so far. Now to find the same problems in the libkse code... http://people.freebsd.org/~peter/libc_r.diff Index: libc_r/uthread/uthread_create.c =================================================================== RCS file: /home/ncvs/src/lib/libc_r/uthread/uthread_create.c,v retrieving revision 1.37 diff -u -r1.37 uthread_create.c --- libc_r/uthread/uthread_create.c 6 Jan 2003 00:56:23 -0000 1.37 +++ libc_r/uthread/uthread_create.c 2 Dec 2003 04:00:20 -0000 @@ -73,6 +73,9 @@ pthread_t new_thread; pthread_attr_t pattr; void *stack; +#if !defined(__ia64__) + u_long stackp; +#endif if (thread == NULL) return(EINVAL); @@ -145,10 +148,12 @@ SET_RETURN_ADDR_JB(new_thread->ctx.jb, _thread_start); #if !defined(__ia64__) + stackp = (long)new_thread->stack + pattr->stacksize_attr - sizeof(double); +#if defined(__amd64__) + stackp &= ~0xFUL; +#endif /* The stack starts high and builds down: */ - SET_STACK_JB(new_thread->ctx.jb, - (long)new_thread->stack + pattr->stacksize_attr - - sizeof(double)); + SET_STACK_JB(new_thread->ctx.jb, stackp); #else SET_STACK_JB(new_thread->ctx.jb, (long)new_thread->stack, pattr->stacksize_attr); Index: libc_r/uthread/uthread_init.c =================================================================== RCS file: /home/ncvs/src/lib/libc_r/uthread/uthread_init.c,v retrieving revision 1.45 diff -u -r1.45 uthread_init.c --- libc_r/uthread/uthread_init.c 11 Jan 2003 00:43:20 -0000 1.45 +++ libc_r/uthread/uthread_init.c 2 Dec 2003 04:00:20 -0000 @@ -208,6 +208,9 @@ size_t len; int mib[2]; int sched_stack_size; /* Size of scheduler stack. */ +#if !defined(__ia64__) + u_long stackp; +#endif struct clockinfo clockinfo; struct sigaction act; @@ -374,8 +377,11 @@ /* Setup the context for the scheduler: */ _setjmp(_thread_kern_sched_jb); #if !defined(__ia64__) - SET_STACK_JB(_thread_kern_sched_jb, _thread_kern_sched_stack + - sched_stack_size - sizeof(double)); + stackp = (long)_thread_kern_sched_stack + sched_stack_size - sizeof(double); +#if defined(__amd64__) + stackp &= ~0xFUL; +#endif + SET_STACK_JB(_thread_kern_sched_jb, stackp); #else SET_STACK_JB(_thread_kern_sched_jb, _thread_kern_sched_stack, sched_stack_size); Index: libc_r/uthread/uthread_sig.c =================================================================== RCS file: /home/ncvs/src/lib/libc_r/uthread/uthread_sig.c,v retrieving revision 1.45 diff -u -r1.45 uthread_sig.c --- libc_r/uthread/uthread_sig.c 5 Mar 2003 04:28:08 -0000 1.45 +++ libc_r/uthread/uthread_sig.c 2 Dec 2003 04:00:20 -0000 @@ -1048,13 +1048,20 @@ * Leave a little space on the stack and round down to the * nearest aligned word: */ +#if defined(__amd64__) + stackp -= 128; /* Skip over 128 byte red-zone */ +#endif stackp -= sizeof(double); +#if defined(__amd64__) + stackp &= ~0xFUL; +#else stackp &= ~0x3UL; #endif +#endif /* Allocate room on top of the stack for a new signal frame: */ stackp -= sizeof(struct pthread_signal_frame); -#if defined(__ia64__) +#if defined(__ia64__) || defined(__amd64__) stackp &= ~0xFUL; #endif @@ -1087,6 +1094,9 @@ */ #if !defined(__ia64__) stackp -= sizeof(double); +#if defined(__amd64__) + stackp &= ~0xFUL; +#endif #endif _setjmp(thread->ctx.jb); #if !defined(__ia64__) Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5home | help
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