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Date: Thu, 9 Oct 2014 16:10:15 -0700 From: Leonid Yegoshin <Leonid.Yegoshin@...tec.com> To: James Hogan <james.hogan@...tec.com> CC: <linux-mips@...ux-mips.org>, <Zubair.Kakakhel@...tec.com>, <geert+renesas@...der.be>, <david.daney@...ium.com>, <peterz@...radead.org>, <paul.gortmaker@...driver.com>, <davidlohr@...com>, <macro@...ux-mips.org>, <chenhc@...ote.com>, <richard@....at>, <zajec5@...il.com>, <keescook@...omium.org>, <alex@...x-smith.me.uk>, <tglx@...utronix.de>, <blogic@...nwrt.org>, <jchandra@...adcom.com>, <paul.burton@...tec.com>, <qais.yousef@...tec.com>, <linux-kernel@...r.kernel.org>, <ralf@...ux-mips.org>, <markos.chandras@...tec.com>, <dengcheng.zhu@...tec.com>, <manuel.lauss@...il.com>, <akpm@...ux-foundation.org>, <lars.persson@...s.com> Subject: Re: [PATCH v2 2/3] MIPS: Setup an instruction emulation in VDSO protected page instead of user stack >> Small stack of emulation blocks is supported because nested traps are possible >> in MIPS32/64 R6 emulation mix with FPU emulation. > Could you please clarify how this nesting of emulation blocks could > happen now that signals are handled more cleanly. > > I.e. isn't the emuframe stuff only required for instructions in branch > delay slots, and branches shouldn't be in branch delay slots anyway, so > I don't get how they could nest. > It may be a case for mix of FPU and MIPS R6 emulations. I just keep both emulators separate as much as possible but I assume that without prove it may be stackable - some rollback is needed to join both and it may (probably) cause a double emulation setup - dsemul may be called twice for the same pair of instructions. I didn't see that yet, honestly and you may be right. And as for signals - it is a different issue, some signal may happen before or after emulated instruction in emulation block and I see that. But I see it only before because of probability for it is a lot of higher. Unwinding is need because signal handler may not return but longjump to somewhere. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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