Am Wed, 3 Jan 2018 13:05:38 +0100 (CET) schrieb Thomas Gleixner <[email protected]>:
> On Wed, 3 Jan 2018, Thomas Gleixner wrote: > > On Wed, 3 Jan 2018, Lars Wendler wrote: > > Thanks for the report. > > > > > I already had a conversation with Thomas Gleixner about this > > > issue and he asked me to post it here. > > > > > > After upgrading my system to vanilla 4.14.11 kernel with > > > CONFIG_PAGE_TABLE_ISOLATION=y I could no longer build any 32bit > > > binaries because gcc (7.2.0) segfaults. > > > > That's a 64bit binary, right? Yes it is. > > > This only happens with CONFIG_PAGE_TABLE_ISOLATION=y > > > I can get rid of this issue by setting > > > CONFIG_PAGE_TABLE_ISOLATION=n _or_ adding pti=off to the kernel > > > command line (the latter was suggested by Thomas). > > > > > > Please find attached the kernel's config together with the dmesg > > > output of the kernel that produces segfaults and the one with > > > pti=off. I also attached a config.log file from a build where gcc > > > segfaulted. > > > > > > If you need more information, please don't hesitate to ask. > > > > will do. > > Here you go. > > Is this anything special you are trying to build or is a simple > > gcc -m32 -o hello hello.c A simple hello world compiles as 32bit binary but running it causes a segfault. Compiling the same hello world as 64bit does not cause any segfaults. Switching off pti resolves the issue and I can run the 32bit hello world. I first found this issue while trying to emerge gdbm-1.14 as 32bit. Running configure failed and the config.log file said that gcc produced a segfault while compiling a test binary called "conftest" (see the gdbm-1.14-abi_x86_32.x86_config.log attachment in my initial report). > Also can you please try Linus v4.15-rc6 with PTI enabled so we can see > whether that's a backport issue or a general one? Same problem with 4.15-rc6. So I suppose that means it's a general issue. > Thanks, > > tglx Kind regards Lars
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