Messages in this thread | | | Date | Fri, 11 Nov 2005 17:39:39 +0800 | From | Coywolf Qi Hunt <> | Subject | Re: [patch 02/02] Debug option to write-protect rodata: the write protect logic and config option |
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2005/11/7, Arjan van de Ven <arjan@infradead.org>: > On Mon, 2005-11-07 at 08:06 -0600, Josh Boyer wrote: > > On Mon, 2005-11-07 at 10:58 +0000, arjan@infradead.org wrote: > > > Hi, > > > > > > I've been working on a patch that turns the kernel's .rodata section to be > > > actually read only, eg any write attempts to it cause a segmentation fault. > > > > > > This patch introduces the actual debug option to catch any writes to rodata > > > > Why a debug option? From what I can tell, it doesn't impact runtime > > performance much and it provides good protection. Any reason not to > > make it an always-on feature? > > personally I'd like that but there is a chance of a tiny perf regression > and usually there are people objecting to that. > > (It's not clear cut: while the last bit of the kernel no longer is > covered by a 2Mb tlb, most intel cpus have very few of such tlbs in the > first place and this would free up one such tlb for other things (say > the stack data) or even the userspace database), so it's not all that > clear cut what the cost of this is)
I'm dumb. But how is "the last bit of the kernel no longer is covered by a 2Mb tlb"? Could you explain a bit more? -- Coywolf Qi Hunt http://sosdg.org/~coywolf/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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