Date: Sun, 23 Jul 2017 09:47:14 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Don Lewis <truckman@FreeBSD.org> Cc: pz-freebsd-stable@ziemba.us, freebsd-stable@FreeBSD.org Subject: Re: stable/11 r321349 crashing immediately Message-ID: <20170723064714.GW1935@kib.kiev.ua> In-Reply-To: <201707230551.v6N5pgdZ082546@gw.catspoiler.org> References: <201707230543.v6N5gwwH082362@gw.catspoiler.org> <201707230551.v6N5pgdZ082546@gw.catspoiler.org>
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On Sat, Jul 22, 2017 at 10:51:42PM -0700, Don Lewis wrote: > > The stack is aligned to a 4096 (0x1000) boundary. The first access to a > > local variable below 0xfffffe085cfa5000 is what triggered the trap. The > > other end of the stack must be at 0xfffffe085cfa9000 less a bit. I don't > > know why the first stack pointer value in the trace is > > 0xfffffe085cfa8a10. That would seem to indicate that amd64_syscall is > > using ~1500 bytes of stack space. > > Actually there could be quite a bit of CPU context that gets saved. That > could be sizeable on amd64. Yes, the usermode trap frame is located on the kernel stack. Also, pcb and usermode FPU save area (FPU == all non-general purpose x86 registers, including XMM/AVX/AVX512 as implemented by CPU) are on the stack.
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