Message-ID: <CA+icZUUpxh=99JP5K_R1KpxouqDW4KY5BjCn5VTcmyByEb0R5w@mail.gmail.com>
Date:   Tue, 24 Apr 2018 13:54:29 +0200
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Matthias Kaehlcke <mka@...omium.org>
Cc:     lkml <linux-kernel@...r.kernel.org>, Arnd Bergmann <arnd@...db.de>,
        Nick Desaulniers <nick.desaulniers@...il.com>
Subject: Re: Clang patch stacks for LTS kernels (v4.4 and v4.9) and status update

Hi Matthias,

a big thank you for giving all the informations!

I used your mka/llvm/v4.14_ext Git tree...

https://chromium.googlesource.com/chromiumos/third_party/kernel/+log/sandbox/mka/llvm/v4.14_ext

...and was able to compile with clang-6.0 from Debian/buster64 with...

...reverting the clang-3/clang-4 patches...

user$ for p in 69e44656ae43 222b88977a00 cdfcf1e45537 26f14c9225a6
0385a18e9995 68dab143c9b4 ; do echo [ $p ] ; LC_ALL=C git revert
--no-edit $p ; done

0001-Revert-CLANG3-core-clang-work-around-x86-regparm-int.patch
0002-Revert-CLANG4-futex-don-t-optimize-futex_detect_cmpx.patch
0003-Revert-CLANG4-Disable-lkdtm-when-ftrace-is-enabled.patch
0004-Revert-CLANG4-arm64-prefetch-Use-__builtin_arm_prefe.patch
0005-Revert-CLANG4-kbuild-Add-meabi-gnu-to-the-clang-para.patch
0006-Revert-CLANG4-crypto-arm64-aes-ce-Explicitly-pass-th.patch

...and needed two additional patches from upstream:

0007-kbuild-clang-remove-crufty-HOSTCFLAGS.patch <--- Label with
BACKPORT (XXX: Backported; Required when using HOSTCC in make-line,
see below)
0008-x86-xen-remove-the-use-of-VLAIS.patch <--- Label with UPSTREAM
(XXX: cherry-picked)

These 3 patches in your Git branch are in Linux v4.14.36...

9af5ddf981ed BACKPORT: kbuild: disable clang's default use of
-fmerge-all-constants
f24088a3842c BACKPORT: kbuild: Set KBUILD_CFLAGS before incl. arch Makefile
d4dfe384346d UPSTREAM: kbuild: fix linker feature test macros when
cross compiling with Clang

...and can be dropped.
I do not know your work-flow/policy: Maybe you want to keep your
patch-stack against vanilla Linux v4.14 - without stables from
linux-stable-4.14.y.

For easy switching "mycompiler" I use a wrapper-script:

root# cat /usr/bin/mycompiler
#!/bin/bash

clang-6.0 "$@"
- EOF -

user$ cp -v /boot/config-4.14.35-1-iniza-amd64 .config
user$ MAKE="make V=1" ; COMPILER="mycompiler" ;
MAKE_OPTS="CC=$COMPILER HOSTCC=$COMPILER"
user$ yes "" | $MAKE $MAKE_OPTS oldconfig && $MAKE $MAKE_OPTS
silentoldconfig < /dev/null

The diffconfig to my current kernel-config-4.14 looks like this...

user$ ./scripts/diffconfig /boot/config-4.14.35-1-iniza-amd64 .config
-ARCH_HAS_REFCOUNT y
-BPF_JIT_ALWAYS_ON n
-EXOFS_DEBUG n
-EXOFS_FS m
-GENERIC_CPU_VULNERABILITIES y
-KASAN n
-ORE m
-PAGE_TABLE_ISOLATION y
-RETPOLINE y
-UNWINDER_FRAME_POINTER n
-UNWINDER_GUESS n
-UNWINDER_ORC y
+FRAME_POINTER y
+FRAME_POINTER_UNWINDER y
+GUESS_UNWINDER n
+HAVE_ARCH_KMEMCHECK y
+HAVE_RELIABLE_STACKTRACE y
+ORC_UNWINDER n

Unfortunately, I cannot boot into the generated kernel on bare metal.

Checking with QEMU (version: 2.12~rc3) and catching earlyprintk, I see this...

user$ echo $KPATH
$HOME/src/linux-kernel/important-files

user$ ls -al
insgesamt 344916
drwxr-xr-x  2 sdi sdi      4096 Apr 24 13:15 .
drwxr-xr-x 20 sdi sdi      4096 Apr 24 13:13 ..
-rw-r--r--  1 sdi sdi   4528416 Apr 24 12:42 bzImage
lrwxrwxrwx  1 sdi sdi        35 Apr 24 13:15 initrd.img ->
initrd.img-4.14.0-1-iniza-llvmlinux
-rw-r--r--  1 sdi sdi  25572955 Apr 24 13:08
initrd.img-4.14.0-1-iniza-llvmlinux
-rw-r--r--  1 sdi sdi   2887195 Apr 24 12:42 System.map
-rwxr-xr-x  1 sdi sdi 326116744 Apr 24 12:42 vmlinux

user$ sudo qemu-system-x86_64 -enable-kvm -M pc -kernel $KPATH/bzImage
-initrd $KPATH/initrd.img -m 512 -net none -serial stdio -append
"root=/dev/ram0 console=ttyS0 hung_task_panic=1
earlyprintk=ttyS0,115200"

Probing EDD (edd=off to disable)... ok
[    0.000000] Linux version 4.14.0-1-iniza-llvmlinux
(sedat.dilek@...il.com@...za) (clang version 6.0.0-1
(tags/RELEASE_600/final)) #1 SMP Tue Apr 24 12:42:21 CEST 2018
[    0.000000] Command line: root=/dev/ram0 console=ttyS0
hung_task_panic=1 earlyprintk=ttyS0,115200
[    0.000000] x86/fpu: x87 FPU will use FXSAVE
[    0.000000] e820: BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
[    0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000001ffdffff] usable
[    0.000000] BIOS-e820: [mem 0x000000001ffe0000-0x000000001fffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved
[    0.000000] bootconsole [earlyser0] enabled
[    0.000000] NX (Execute Disable) protection: active
[    0.000000] random: fast init done
[    0.000000] SMBIOS 2.8 present.
[    0.000000] DMI: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.11.1-1 04/01/2014
[    0.000000] Hypervisor detected: KVM
[    0.000000] tsc: Fast TSC calibration using PIT
[    0.000000] e820: last_pfn = 0x1ffe0 max_arch_pfn = 0x400000000
[    0.000000] x86/PAT: PAT not supported by CPU.
[    0.000000] x86/PAT: Configuration [0-7]: WB  WT  UC- UC  WB  WT  UC- UC
Memory KASLR using RDTSC...
[    0.000000] found SMP MP-table at [mem 0x000f5d60-0x000f5d6f]
mapped at [ffffffffff000d60]
[    0.000000] RAMDISK: [mem 0x1e77c000-0x1ffdffff]
[    0.000000] ACPI: Early table checksum verification disabled
[    0.000000] ACPI: RSDP 0x00000000000F5B90 000014 (v00 BOCHS )
[    0.000000] ACPI: RSDT 0x000000001FFE157C 000030 (v01 BOCHS
BXPCRSDT 00000001 BXPC 00000001)
[    0.000000] ACPI: FACP 0x000000001FFE1458 000074 (v01 BOCHS
BXPCFACP 00000001 BXPC 00000001)
[    0.000000] ACPI: DSDT 0x000000001FFE0040 001418 (v01 BOCHS
BXPCDSDT 00000001 BXPC 00000001)
[    0.000000] ACPI: FACS 0x000000001FFE0000 000040
[    0.000000] ACPI: APIC 0x000000001FFE14CC 000078 (v01 BOCHS
BXPCAPIC 00000001 BXPC 00000001)
[    0.000000] ACPI: HPET 0x000000001FFE1544 000038 (v01 BOCHS
BXPCHPET 00000001 BXPC 00000001)
[    0.000000] No NUMA configuration found
[    0.000000] Faking a node at [mem 0x0000000000000000-0x000000001ffdffff]
[    0.000000] NODE_DATA(0) allocated [mem 0x1e777000-0x1e77bfff]
[    0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00
[    0.000000] kvm-clock: cpu 0, msr 0:1e76f001, primary cpu clock
[    0.000000] kvm-clock: using sched offset of 528742140 cycles
[    0.000000] clocksource: kvm-clock: mask: 0xffffffffffffffff
max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000000001000-0x0000000000ffffff]
[    0.000000]   DMA32    [mem 0x0000000001000000-0x000000001ffdffff]
[    0.000000]   Normal   empty
[    0.000000]   Device   empty
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000000001000-0x000000000009efff]
[    0.000000]   node   0: [mem 0x0000000000100000-0x000000001ffdffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000000001000-0x000000001ffdffff]
[    0.000000] ACPI: PM-Timer IO Port: 0x608
[    0.000000] ACPI: LAPIC_NMI (acpi_id[0xff] dfl dfl lint[0x1])
[    0.000000] IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23
[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 5 global_irq 5 high level)
[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 10 global_irq 10 high level)
[    0.000000] ACPI: INT_SRC_OVR (bus 0 bus_irq 11 global_irq 11 high level)
[    0.000000] Using ACPI (MADT) for SMP configuration information
[    0.000000] ACPI: HPET id: 0x8086a201 base: 0xfed00000
[    0.000000] smpboot: Allowing 1 CPUs, 0 hotplug CPUs
[    0.000000] PM: Registered nosave memory: [mem 0x00000000-0x00000fff]
[    0.000000] PM: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
[    0.000000] PM: Registered nosave memory: [mem 0x000a0000-0x000effff]
[    0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]
[    0.000000] e820: [mem 0x20000000-0xfeffbfff] available for PCI devices
[    0.000000] Booting paravirtualized kernel on KVM
[    0.000000] clocksource: refined-jiffies: mask: 0xffffffff
max_cycles: 0xffffffff, max_idle_ns: 7645519600211568 ns
[    0.000000] setup_percpu: NR_CPUS:512 nr_cpumask_bits:512
nr_cpu_ids:1 nr_node_ids:1
[    0.000000] percpu: Embedded 37 pages/cpu @ffff96dd9e400000 s114392
r8192 d28968 u2097152
[    0.000000] KVM setup async PF for cpu 0
[    0.000000] kvm-stealtime: cpu 0, msr 1e40d900
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 128872
[    0.000000] Policy zone: DMA32
[    0.000000] Kernel command line: root=/dev/ram0 console=ttyS0
hung_task_panic=1 earlyprintk=ttyS0,115200
[    0.000000] PID hash table entries: 2048 (order: 2, 16384 bytes)
[    0.000000] Memory: 474480K/523768K available (7639K kernel code,
1005K rwdata, 2936K rodata, 1636K init, 688K bss, 49288K reserved, 0K
cma-reserved)
[    0.000000] ftrace: allocating 27586 entries in 108 pages
[    0.004000] Hierarchical RCU implementation.
[    0.004000]  RCU restricting CPUs from NR_CPUS=512 to nr_cpu_ids=1.
[    0.004000] RCU: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[    0.004000] NR_IRQS: 33024, nr_irqs: 256, preallocated irqs: 16
[    0.004000] Console: colour VGA+ 80x25
[    0.004000] console [ttyS0] enabled
[    0.004000] console [ttyS0] enabled
[    0.004000] bootconsole [earlyser0] disabled
[    0.004000] bootconsole [earlyser0] disabled
[    0.004000] clocksource: hpet: mask: 0xffffffff max_cycles:
0xffffffff, max_idle_ns: 19112604467 ns
[    0.004000] general protection fault: 0000 [#1] SMP
[    0.004000] Modules linked in:
[    0.004000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted
4.14.0-1-iniza-llvmlinux #1
[    0.004000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.11.1-1 04/01/2014
[    0.004000] task: ffffffffaa610480 task.stack: ffffffffaa600000
[    0.004000] RIP: 0010:irq_work_tick+0x9d/0x110
[    0.004000] RSP: 0000:ffff96dd9e403e58 EFLAGS: 00010046
[    0.004000] RAX: 0000000000000082 RBX: ffff96dd9e411d80 RCX: adecc9cc04e2ca00
[    0.004000] RDX: 000000000001ba00 RSI: fffffffffffffed4 RDI: ffff96dd9e41ba38
[    0.004000] RBP: ffff96dd9e403e78 R08: 0000000000000000 R09: 0000000000000018
[    0.004000] R10: 0000000000000000 R11: 0000000000000018 R12: ffffffffaa61bd40
[    0.004000] R13: 0000000000000000 R14: ffffffffaa610480 R15: 0000000000000000
[    0.004000] FS:  0000000000000000(0000) GS:ffff96dd9e400000(0000)
knlGS:0000000000000000
[    0.004000] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.004000] CR2: 00000000ffffffff CR3: 0000000008a09000 CR4: 00000000000006b0
[    0.004000] Call Trace:
[    0.004000]  <IRQ>
[    0.004000]  update_process_times+0x6e/0xa0
[    0.004000]  tick_periodic+0x78/0x90
[    0.004000]  tick_handle_periodic+0x26/0x80
[    0.004000]  timer_interrupt+0x13/0x20
[    0.004000]  __handle_irq_event_percpu+0x106/0x230
[    0.004000]  handle_irq_event+0x5a/0xc0
[    0.004000]  handle_level_irq+0x11a/0x190
[    0.004000]  handle_irq+0x1f/0x30
[    0.004000]  do_IRQ+0x4b/0xd0
[    0.004000]  common_interrupt+0x93/0x93
[    0.004000]  </IRQ>
[    0.004000] RIP: 0010:native_restore_fl+0x12/0x20
[    0.004000] RSP: 0000:ffffffffaa603e10 EFLAGS: 00000286 ORIG_RAX:
ffffffffffffffcf
[    0.004000] RAX: 0000000000000001 RBX: ffff96dd9d0c0608 RCX: 0000000000000000
[    0.004000] RDX: ffff96dd9d0c0400 RSI: 0000000000000286 RDI: 0000000000000286
[    0.004000] RBP: ffffffffaa603e18 R08: 0000000000000001 R09: 000000000000003f
[    0.004000] R10: 0000000000000286 R11: 0000000000000007 R12: ffff96dd9d0c0514
[    0.004000] R13: ffff96dd9d0c04e0 R14: ffffffffaa61bd40 R15: ffff96dd9d0c0400
[    0.004000]  _raw_spin_unlock_irqrestore+0x1a/0x20
[    0.004000]  __setup_irq+0x5d9/0x780
[    0.004000]  setup_irq+0x5c/0x90
[    0.004000]  hpet_time_init+0x32/0x40
[    0.004000]  x86_late_time_init+0x10/0x20
[    0.004000]  start_kernel+0x45d/0x580
[    0.004000]  x86_64_start_kernel+0x30f/0x320
[    0.004000]  secondary_startup_64+0xa5/0xa5
[    0.004000] Code: f0 f0 4c 0f b1 7b f8 4c 89 e3 4d 85 e4 75 cf 48
c7 c1 88 5b 01 00 65 48 03 0c 25 d8 a1 00 00 ff 14 25 10 08 62 aa f6
c4 02 75 4d <48> 83 39 00 74 3e 31 db 48 87 19 48 85 db 74 34 0f 1f 00
48 8d
[    0.004000] RIP: irq_work_tick+0x9d/0x110 RSP: ffff96dd9e403e58
[    0.004000] ---[ end trace 8c7851007fbc6b6f ]---
[    0.004000] Kernel panic - not syncing: Fatal exception in interrupt
[    0.004000] ---[ end Kernel panic - not syncing: Fatal exception in interrupt

Is this saying someting to you?

I am attaching my kernel-config file and the two additional patches.

Do you need further informations?

Thanks.

Regards,
- Sedat -

Download attachment "config-4.14.0-1-iniza-llvmlinux" of type "application/octet-stream" (197072 bytes)

View attachment "0007-kbuild-clang-remove-crufty-HOSTCFLAGS.patch" of type "text/x-patch" (1639 bytes)

View attachment "0008-x86-xen-remove-the-use-of-VLAIS.patch" of type "text/x-patch" (1921 bytes)

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