Mikael Pettersson writes: > Anatoly Pugachev writes: > > On Fri, Jul 28, 2017 at 11:45 AM, Mikael Pettersson > > <[email protected]> wrote: > > > It's an rpmbuild --rebuild of Fedora's strace-4.18-1.fc24.src.rpm, but > according to the > > > build log the following should do it: > > > > > > export CFLAGS='-O2 -g -pipe -Wall -Werror=format-security > -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector > --param=ssp-buffer-size=4 -grecord-gcc-switches -m32 -mcpu=ultrasparc' > > > ./configure --build=sparcv9-unknown-linux-gnu > --host=sparcv9-unknown-linux-gnu --program-prefix= > --disable-dependency-tracking --prefix=/usr --exec-prefix=/u > > > sr --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc > --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib > --libexecdir=/usr/libexec --local > > > statedir=/var --sharedstatedir=/var/lib --mandir=/usr/share/man > --infodir=/usr/share/info > > > make -j2 > > > make -j2 -k check VERBOSE=1 > > > > cant' reproduce it here on debian sparc64 LDOM: > > DaveM was also unable to reproduce it. > > I'll be investigating a possible kernel miscompile next.
I don't think it's a miscompile. First I recompiled 4.13-rc2 with each of gcc-7, gcc-6, and gcc-5, each bootstrapped and regtested from the head of the respective FSF GCC branch: no change, kernel 4.11 works while kernels >= 4.12 OOPS. So a miscompile seems unlikely. Then I ran a git bisect between v4.11 (good) and v4.12 (bad), booting each kernel and trying the problematic strace test binaries. That identified the following as the first bad commit: commit 31af2f36d50e3b9b2fb7f17aa430c11c91f946c4 Author: Al Viro <[email protected]> Date: Tue Mar 21 17:04:45 2017 -0400 sparc: switch to RAW_COPY_USER ... and drop zeroing in sparc32. Signed-off-by: Al Viro <[email protected]> That touches the CPU model specific assembly code in arch/sparc/lib/ for copy_{to,from}_user and changes how it's wired into the rest of the kernel. There's different code for different UltraSPARC and Niagara generations, so if there is a bug in e.g. the USIII code, you won't see it on Niagara. Unfortunately I don't see anything obviously wrong in Al's patch... /Mikael
