On 08.01.21 10:44, David Hildenbrand wrote: > On 08.01.21 03:20, Nick Desaulniers wrote: >> On Thu, Jan 7, 2021 at 3:27 PM David Hildenbrand <dhild...@redhat.com> wrote: >>> >>> >>>> Am 08.01.2021 um 00:21 schrieb Nick Desaulniers <ndesaulni...@google.com>: >>>> >>>> On Thu, Jan 7, 2021 at 3:13 PM David Hildenbrand <da...@redhat.com> wrote: >>>>> >>>>> RISBHG is broken and currently hinders clang builds of upstream kernels >>>>> from booting: the kernel crashes early, while decompressing the image. >>>>> >>>>> [...] >>>>> Kernel fault: interruption code 0005 ilc:2 >>>>> Kernel random base: 0000000000000000 >>>>> PSW : 0000200180000000 0000000000017a1e >>>>> R:0 T:0 IO:0 EX:0 Key:0 M:0 W:0 P:0 AS:0 CC:2 PM:0 RI:0 EA:3 >>>>> GPRS: 0000000000000001 0000000c00000000 00000003fffffff4 >>>>> 00000000fffffff0 >>>>> 0000000000000000 00000000fffffff4 000000000000000c >>>>> 00000000fffffff0 >>>>> 00000000fffffffc 0000000000000000 00000000fffffff8 >>>>> 00000000008e25a8 >>>>> 0000000000000009 0000000000000002 0000000000000008 >>>>> 000000000000bce0 >>>>> >>>>> One example of a buggy instruction is: >>>>> >>>>> 17dde: ec 1e 00 9f 20 5d risbhg %r1,%r14,0,159,32 >>>>> >>>>> With %r14 = 0x9 and %r1 = 0x7 should result in %r1 = 0x900000007, however, >>>>> results in %r1 = 0. >>>>> >>>>> Let's interpret values of i3/i4 as documented in the PoP and make >>>>> computation of "mask" only based on i3 and i4 and use "pmask" only at the >>>>> very end to make sure wrapping is only applied to the high/low doubleword. >>>>> >>>>> With this patch, I can successfully boot a v5.10 kernel built with >>>>> clang, and gcc builds keep on working. >>>>> >>>>> Fixes: 2d6a869833d9 ("target-s390: Implement RISBG") >>>>> Reported-by: Nick Desaulniers <ndesaulni...@google.com> >>>>> Cc: Guenter Roeck <li...@roeck-us.net> >>>>> Cc: Christian Borntraeger <borntrae...@de.ibm.com> >>>>> Signed-off-by: David Hildenbrand <da...@redhat.com> >>>>> --- >>>>> >>>>> This BUG was a nightmare to debug and the code a nightmare to understand. >>>>> >>>>> To make clang/gcc builds boot, the following fix is required as well on >>>>> top of current master: "[PATCH] target/s390x: Fix ALGSI" >>>>> https://lkml.kernel.org/r/20210107202135.52379-1-da...@redhat.com >>>> >>>> In that case, a huge thank you!!! for this work! ++beers_owed. >>>> >>> >>> :) a kernel build for z13 should work with the (default) „-cpu qemu“ cpu >>> type. >> >> Hmm...so I don't think clang can build a Linux kernel image with >> CONFIG_MARCH_Z13=y just yet; just defconfig. Otherwise looks like >> clang barfs on some of the inline asm constraints. >> > > Ah, right. I overwrote my manual config by a temporary defconfig :) > > > So, I'm on x86-64 F33. > > clang version 11.0.0 (Fedora 11.0.0-2.fc33) > LLVM version 11.0.0 > > I cannot directly use "LLVM=1" for cross-compilation, as I keep getting > "error: unknown emulation: elf64_s390" from ld.lld and "error: invalid > output format: 'elf64-s390'" from llvm-objcopy. I assume that's fixed in > llvm12? > > 1. I patch around it (strange, I remember CC= .. used to work, but it no > longer does) > > --- > > index e30cf02da8b8..89c57062ed5d 100644 > --- a/Makefile > +++ b/Makefile > @@ -427,13 +427,13 @@ KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS) $(HOSTLDLIBS) > CPP = $(CC) -E > ifneq ($(LLVM),) > CC = clang > -LD = ld.lld > -AR = llvm-ar > -NM = llvm-nm > -OBJCOPY = llvm-objcopy > -OBJDUMP = llvm-objdump > -READELF = llvm-readelf > -STRIP = llvm-strip > +LD = $(CROSS_COMPILE)ld > +AR = $(CROSS_COMPILE)ar > +NM = $(CROSS_COMPILE)nm > +OBJCOPY = $(CROSS_COMPILE)objcopy > +OBJDUMP = $(CROSS_COMPILE)objdump > +READELF = $(CROSS_COMPILE)readelf > +STRIP = $(CROSS_COMPILE)strip > else > CC = $(CROSS_COMPILE)gcc > LD = $(CROSS_COMPILE)ld > > --- > > 2. Compile using clang > > > Using latest linux-next (1c925d2030afd354a02c23500386e620e662622b) + > above patch > > --- > > #!/bin/bash > export ARCH=s390; > export CROSS_COMPILE=s390x-linux-gnu- > export LLVM=1 > make distclean > make defconfig > > # Make F32 initrd boot without inserting modules > ./scripts/config -e CONFIG_SCSI_ISCSI_ATTRS > ./scripts/config -e CONFIG_ISCSI_TCP > > make -j40 > /dev/null > > --- > > 3. Run it via QEMU. I boot a full Fedora 32 using the cloud-image + > initrd from Fedora 32 (tried to stick to your cmdline where possible) > > ./build/qemu-system-s390x \ > -m 512M \ > -cpu qemu \ > -display none \ > -nodefaults \ > -kernel ../linux-cross/arch/s390/boot/bzImage \ > -append "root=/dev/vda1 conmode=sclp console=ttyS0" \ > -initrd ../Fedora-Cloud-Base-32-1.6.x86_64-initrd.img \ > -hda ../Fedora-Cloud-Base-32-1.6.x86_64-initrd.img \
^ -hda ../Fedora-Cloud-Base-32-1.6.x86_64.qcow2 \ -- Thanks, David / dhildenb