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List:       uclinux-dev
Subject:    Re: [uClinux-dev] [PATCH] FDPIC: respect PT_GNU_STACK exec markings
From:       Mike Frysinger <vapier.adi () gmail ! com>
Date:       2009-11-28 18:47:26
Message-ID: 8bd0f97a0911281047i25626fc5q622e06fa1d306441 () mail ! gmail ! com
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On Sat, Nov 28, 2009 at 10:24, Mike Frysinger wrote:
> The current code will load the stack size and markings, but then only use
> the markings in the MMU code path.  The NOMMU code path always passes EXEC
> to the mmap() call.  While this doesn't matter to most people during the
> run of the code, it causes a pointless icache flush when starting every
> FDPIC application and by default, that tends to be 128kB of waste.

for some raw numbers:
with my default FDPIC boot (inetd/syslog/watchdog), we icache flush
18,562,124 bytes.  with this stack fix, we cut off 3,538,944 bytes
(19% shrinkage).
-mike
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