On 12/18/2017 03:07 PM, Kevin Darbyshire-Bryant wrote: > > >> On 18 Dec 2017, at 10:12, Felix Fietkau <n...@nbd.name> wrote: >> >> On 2017-12-18 11:07, Kevin Darbyshire-Bryant wrote: >>> Hi Felix, >>> >>> Thanks for explaining that. I suspect you’re right that there’s an >>> underlying bug in gcc mips. So ideally we need some code that exposes the >>> bug when using -O2 (or even just -funroll_loops) Looking at FS 814 there’s >>> a hint in there that uhttpd was similarly affected…and not solved by the >>> patch drop. So what to do if there’s a bug just lurking to bite us? >> >> If possible, reproduce it on uhttpd with an unmodified upstream version >> of GCC and open up a bug report. >> >> - Felix > > Sadly I’m unable to reproduce the uhttpd issue - frustrating. > > Cheers, > > Kevin D-B
Hi, The attached patch also made the problem disappear. This patch builds the code with -funroll-loops in addition, otherwise only the default settings are used. Hauke
From 2b58f2cac799c4eca511b12d068bd043c7f8b014 Mon Sep 17 00:00:00 2001 From: Hauke Mehrtens <ha...@hauke-m.de> Date: Sun, 17 Dec 2017 14:43:28 +0100 Subject: [PATCH] dropbear: fix libtommath for GCC 7 This adds a workaround needef for GCC 7 into the libtommath. With this workaorund dropbear is able to generate a RSA key, otherwise not. Size before: ipk: 86.469 dropbear: 172.405 Size with this cahnge on MIPS BE 24KEc ipk: 87.660 dropbear: 172.405 Signed-off-by: Hauke Mehrtens <ha...@hauke-m.de> --- .../patches/700-use-unroll-loops-for-gcc7.patch | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 package/network/services/dropbear/patches/700-use-unroll-loops-for-gcc7.patch diff --git a/package/network/services/dropbear/patches/700-use-unroll-loops-for-gcc7.patch b/package/network/services/dropbear/patches/700-use-unroll-loops-for-gcc7.patch new file mode 100644 index 0000000000..7d30f10db9 --- /dev/null +++ b/package/network/services/dropbear/patches/700-use-unroll-loops-for-gcc7.patch @@ -0,0 +1,18 @@ +When we compile the libtommath math library without -funroll-loops for +MIPS BE 24KEc with GCC 7.2 the math library will not work correctly. +This was not seen on older gcc versions. +You can test it with "/usr/bin/dropbearkey -t rsa -f /tmp/rsa-key" on a +MIPS BE 24KEc CPU, if it returns in about 1 minute it is ok otherwise +you hit the bug. The If C is too low check in the mp_invmod_slow() +function will never finish. + +--- a/libtommath/Makefile.in ++++ b/libtommath/Makefile.in +@@ -11,6 +11,7 @@ srcdir=@srcdir@ + # So that libtommath can include Dropbear headers for options and m_burn() + CFLAGS += -I. -I$(srcdir) -I../libtomcrypt/src/headers/ -I$(srcdir)/../libtomcrypt/src/headers/ -I../ -I$(srcdir)/../ + ++CFLAGS += -funroll-loops -Wall + ifndef IGNORE_SPEED + + #for speed -- 2.11.0
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