RISCV panic due to stackprotector support

[nathanchance]

On next-20200715:

$ make -skj"$(nproc)" ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- LD=riscv64-linux-gnu-ld LLVM=1 LLVM_IAS=1 O=out/riscv distclean defconfig Image.gz

$ ../../cbl/github/boot-utils/boot-qemu.sh -a riscv -k out/riscv -t 20s
...
+ timeout --foreground 20s unbuffer qemu-system-riscv64 -bios default -M virt -append '' -display none -initrd /home/nathan/cbl/github/boot-utils/images/riscv/rootfs.cpio -kernel /home/nathan/src/linux-next/out/riscv/arch/riscv/boot/Image -m 512m -nodefaults -serial mon:stdio

OpenSBI v0.5 (Oct  9 2019 12:03:04)
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|

Platform Name          : QEMU Virt Machine
Platform HART Features : RV64ACDFIMSU
Platform Max HARTs     : 8
Current Hart           : 0
Firmware Base          : 0x80000000
Firmware Size          : 116 KB
Runtime SBI Version    : 0.2

PMP0: 0x0000000080000000-0x000000008001ffff (A)
PMP1: 0x0000000000000000-0xffffffffffffffff (A,R,W,X)
[    0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
[    0.000000] Linux version 5.8.0-rc5-next-20200715 (nathan@ubuntu-n2-xlarge-x86) (ClangBuiltLinux clang version 11.0.0 (https://github.com/llvm/llvm-project.git 05a21b7b6da853090628bcaa57c1ac26bc6bbc63), GNU ld (GNU Binutils) 2.34) #1 SMP Wed Jul 15 15:56:16 MST 2020
[    0.000000] Initial ramdisk at: 0x(____ptrval____) (5446144 bytes)
[    0.000000] Zone ranges:
[    0.000000]   DMA32    [mem 0x0000000080200000-0x000000009fffffff]
[    0.000000]   Normal   empty
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000080200000-0x000000009fffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000080200000-0x000000009fffffff]
[    0.000000] software IO TLB: mapped [mem 0x9b8fb000-0x9f8fb000] (64MB)
[    0.000000] SBI specification v0.2 detected
[    0.000000] SBI implementation ID=0x1 Version=0x5
[    0.000000] riscv: ISA extensions acdfimsu
[    0.000000] riscv: ELF capabilities acdfim
[    0.000000] percpu: Embedded 17 pages/cpu s32104 r8192 d29336 u69632
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 128775
[    0.000000] Kernel command line: 
[    0.000000] Dentry cache hash table entries: 65536 (order: 7, 524288 bytes, linear)
[    0.000000] Inode-cache hash table entries: 32768 (order: 6, 262144 bytes, linear)
[    0.000000] Sorting __ex_table...
[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[    0.000000] Memory: 427412K/522240K available (9425K kernel code, 3460K rwdata, 2048K rodata, 279K init, 448K bss, 94828K reserved, 0K cma-reserved)
[    0.000000] Virtual kernel memory layout:
[    0.000000]       fixmap : 0xffffffcefee00000 - 0xffffffceff000000   (2048 kB)
[    0.000000]       pci io : 0xffffffceff000000 - 0xffffffcf00000000   (  16 MB)
[    0.000000]      vmemmap : 0xffffffcf00000000 - 0xffffffcfffffffff   (4095 MB)
[    0.000000]      vmalloc : 0xffffffd000000000 - 0xffffffdfffffffff   (65535 MB)
[    0.000000]       lowmem : 0xffffffe000000000 - 0xffffffe01fe00000   ( 510 MB)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000] rcu: 	RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=1.
[    0.000000] rcu: 	RCU debug extended QS entry/exit.
[    0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
[    0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[    0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
[    0.000000] riscv-intc: 64 local interrupts mapped
[    0.000000] plic: interrupt-controller@c000000: mapped 53 interrupts with 1 handlers for 2 contexts.
[    0.000000] random: get_random_bytes called from start_kernel+0x1de/0x39e with crng_init=0
[    0.000000] riscv_timer_init_dt: Registering clocksource cpuid [0] hartid [0]
[    0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x24e6a1710, max_idle_ns: 440795202120 ns
[    0.000279] sched_clock: 64 bits at 10MHz, resolution 100ns, wraps every 4398046511100ns
[    0.011410] Console: colour dummy device 80x25
[    0.015569] printk: console [tty0] enabled
[    0.018971] Calibrating delay loop (skipped), value calculated using timer frequency.. 20.00 BogoMIPS (lpj=40000)
[    0.019380] pid_max: default: 32768 minimum: 301
[    0.021979] Mount-cache hash table entries: 1024 (order: 1, 8192 bytes, linear)
[    0.022226] Mountpoint-cache hash table entries: 1024 (order: 1, 8192 bytes, linear)
[    0.075176] rcu: Hierarchical SRCU implementation.
[    0.086244] smp: Bringing up secondary CPUs ...
[    0.086587] smp: Brought up 1 node, 1 CPU
[    0.105053] devtmpfs: initialized
[    0.118558] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[    0.119042] futex hash table entries: 256 (order: 2, 16384 bytes, linear)
[    0.130528] NET: Registered protocol family 16
[    0.240428] vgaarb: loaded
[    0.246714] SCSI subsystem initialized
[    0.251171] usbcore: registered new interface driver usbfs
[    0.251983] usbcore: registered new interface driver hub
[    0.252552] usbcore: registered new device driver usb
[    0.272405] clocksource: Switched to clocksource riscv_clocksource
[    0.334606] NET: Registered protocol family 2
[    0.344512] tcp_listen_portaddr_hash hash table entries: 256 (order: 1, 10240 bytes, linear)
[    0.344985] TCP established hash table entries: 4096 (order: 3, 32768 bytes, linear)
[    0.345565] TCP bind hash table entries: 4096 (order: 5, 131072 bytes, linear)
[    0.346957] TCP: Hash tables configured (established 4096 bind 4096)
[    0.349422] UDP hash table entries: 256 (order: 2, 24576 bytes, linear)
[    0.350128] UDP-Lite hash table entries: 256 (order: 2, 24576 bytes, linear)
[    0.353213] NET: Registered protocol family 1
[    0.360602] RPC: Registered named UNIX socket transport module.
[    0.360854] RPC: Registered udp transport module.
[    0.361015] RPC: Registered tcp transport module.
[    0.361156] RPC: Registered tcp NFSv4.1 backchannel transport module.
[    0.361535] PCI: CLS 0 bytes, default 64
[    0.370406] Unpacking initramfs...
[    0.760888] Freeing initrd memory: 5316K
[    0.765466] workingset: timestamp_bits=62 max_order=17 bucket_order=0
[    0.791745] NFS: Registering the id_resolver key type
[    0.793340] Key type id_resolver registered
[    0.793557] Key type id_legacy registered
[    0.793889] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[    0.796000] 9p: Installing v9fs 9p2000 file system support
[    0.798862] NET: Registered protocol family 38
[    0.799518] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252)
[    0.799809] io scheduler mq-deadline registered
[    0.800043] io scheduler kyber registered
[    0.817068] pci-host-generic 30000000.pci: host bridge /soc/pci@30000000 ranges:
[    0.818667] pci-host-generic 30000000.pci:       IO 0x0003000000..0x000300ffff -> 0x0000000000
[    0.820086] pci-host-generic 30000000.pci:      MEM 0x0040000000..0x007fffffff -> 0x0040000000
[    0.824088] pci-host-generic 30000000.pci: ECAM at [mem 0x30000000-0x3fffffff] for [bus 00-ff]
[    0.825787] pci-host-generic 30000000.pci: PCI host bridge to bus 0000:00
[    0.826257] pci_bus 0000:00: root bus resource [bus 00-ff]
[    0.826542] pci_bus 0000:00: root bus resource [io  0x0000-0xffff]
[    0.826699] pci_bus 0000:00: root bus resource [mem 0x40000000-0x7fffffff]
[    0.828808] pci 0000:00:00.0: [1b36:0008] type 00 class 0x060000
[    1.117635] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[    1.134577] 10000000.uart: ttyS0 at MMIO 0x10000000 (irq = 1, base_baud = 230400) is a 16550A
[    1.181374] printk: console [ttyS0] enabled
[    1.186602] [drm] radeon kernel modesetting enabled.
[    1.225551] loop: module loaded
[    1.232481] libphy: Fixed MDIO Bus: probed
[    1.235595] e1000e: Intel(R) PRO/1000 Network Driver
[    1.236100] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.
[    1.237215] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[    1.237862] ehci-pci: EHCI PCI platform driver
[    1.238594] ehci-platform: EHCI generic platform driver
[    1.239764] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[    1.240475] ohci-pci: OHCI PCI platform driver
[    1.241230] ohci-platform: OHCI generic platform driver
[    1.244348] usbcore: registered new interface driver uas
[    1.245172] usbcore: registered new interface driver usb-storage
[    1.247481] mousedev: PS/2 mouse device common for all mice
[    1.250422] usbcore: registered new interface driver usbhid
[    1.250812] usbhid: USB HID core driver
[    1.252990] NET: Registered protocol family 10
[    1.262964] Segment Routing with IPv6
[    1.264284] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[    1.267898] NET: Registered protocol family 17
[    1.269926] 9pnet: Installing 9P2000 support
[    1.270551] Key type dns_resolver registered
[    1.315658] Freeing unused kernel memory: 276K
[    1.322375] Run /init as init process
[    1.565710] init[38]: unhandled signal 11 code 0x1 at 0x0000000000000000
[    1.566457] CPU: 0 PID: 38 Comm: init Not tainted 5.8.0-rc5-next-20200715 #1
[    1.567300] epc: 0000003fde11b980 ra : 0000003fde04f92c sp : 0000003ffff08880
[    1.567840]  gp : 00000000000e8528 tp : 0000003fde11a820 t0 : 000000000000001e
[    1.568389]  t1 : 000000000000000a t2 : 0000003ffff0881e s0 : 0000003ffff088a0
[    1.568922]  s1 : 0000000000000000 a0 : 0000003ffff088c0 a1 : 0000000000000000
[    1.569482]  a2 : 0000000000000000 a3 : 0000000000000000 a4 : fffffffffbad8000
[    1.569868]  a5 : 0000003fde11b970 a6 : 0000000000000000 a7 : 0000000000000000
[    1.570415]  s2 : 0000000000000001 s3 : 0000003fde10012c s4 : 0000000000000010
[    1.570982]  s5 : 0000000000000016 s6 : 00000000000d0e38 s7 : 0000003ffff089f0
[    1.571736]  s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000003ffff088e0
[    1.572271]  s11: 00000000000e1637 t3 : 0000000000000000 t4 : 0000003ffff08820
[    1.572655]  t5 : 0000000000000000 t6 : 0000000000000000
[    1.572948] status: 8000000000006020 badaddr: 0000000000000000 cause: 000000000000000d
[    1.574739] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    1.575293] CPU: 0 PID: 1 Comm: init Not tainted 5.8.0-rc5-next-20200715 #1
[    1.575685] Call Trace:
[    1.575970] [<ffffffe000202934>] walk_stackframe+0x0/0xba
[    1.576313] [<ffffffe0004d26e8>] dump_stack+0x9c/0xd8
[    1.576607] [<ffffffe000209442>] panic+0x11c/0x2cc
[    1.576891] [<ffffffe00020bb1a>] exit_mm+0x0/0x134
[    1.577171] [<ffffffe00020bcfa>] do_group_exit+0x70/0x86
[    1.577485] [<ffffffe000215864>] get_signal+0x4ec/0x636
[    1.577779] [<ffffffe000201fea>] do_notify_resume+0x42/0x388
[    1.578086] [<ffffffe0002014a2>] ret_from_exception+0x0/0xc
[    1.578987] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---
+ RET=124
+ set +x

I have done no additional triage beyond the initial bisect and I probably won't have time to do so for quite a while:

$ git bisect log
# bad: [ca0e494af5edb59002665bf12871e94b4163a257] Add linux-next specific files for 20200715
# good: [e9919e11e219eaa5e8041b7b1a196839143e9125] Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
git bisect start 'ca0e494af5edb59002665bf12871e94b4163a257' 'e9919e11e219eaa5e8041b7b1a196839143e9125'
# bad: [8a21074e4724ce86b4e1a8fdc271081a86303014] Merge remote-tracking branch 'crypto/master'
git bisect bad 8a21074e4724ce86b4e1a8fdc271081a86303014
# bad: [4f6c452675e5480e108acf31214280b8362155ec] Merge remote-tracking branch 'hid/for-next'
git bisect bad 4f6c452675e5480e108acf31214280b8362155ec
# good: [074074965e19f8c1a4e5474ec4c210821feb0353] Merge remote-tracking branch 'uniphier/for-next'
git bisect good 074074965e19f8c1a4e5474ec4c210821feb0353
# bad: [585fcbb07daf35b82cded52a779d6c5bfe2e3572] Merge remote-tracking branch 'nfsd/nfsd-next'
git bisect bad 585fcbb07daf35b82cded52a779d6c5bfe2e3572
# bad: [93d7381b4ca61b47c498a2303a8e28dd1f2530a3] Merge remote-tracking branch 'fscrypt/master'
git bisect bad 93d7381b4ca61b47c498a2303a8e28dd1f2530a3
# good: [a9d57272c89ef176b6d4c5b185ef3d8e2806d8f9] Merge remote-tracking branch 'h8300/h8300-next'
git bisect good a9d57272c89ef176b6d4c5b185ef3d8e2806d8f9
# good: [7dbea40fff2de5157ab828c9f4326fd6cdcdcef4] Merge remote-tracking branch 'powerpc/next'
git bisect good 7dbea40fff2de5157ab828c9f4326fd6cdcdcef4
# good: [6589c93f99894e007a1260f009018effc958ab69] s390: add trace events for idle enter/exit
git bisect good 6589c93f99894e007a1260f009018effc958ab69
# good: [41e8333123e25f54476c0d62f0e612f328eefb38] riscv: Add kmemleak support
git bisect good 41e8333123e25f54476c0d62f0e612f328eefb38
# bad: [dcadb5c0f1056114f2d205ac725199faf3a8d899] Merge remote-tracking branch 'sh/for-next'
git bisect bad dcadb5c0f1056114f2d205ac725199faf3a8d899
# bad: [94efd6d16a1bc5a711ac6902a2de7606b739b971] Merge remote-tracking branch 's390/features'
git bisect bad 94efd6d16a1bc5a711ac6902a2de7606b739b971
# bad: [375e2bad2f8c6b7292f5ebf3d43dd4fdfc5baf34] riscv: Add STACKPROTECTOR supported
git bisect bad 375e2bad2f8c6b7292f5ebf3d43dd4fdfc5baf34
# good: [7f2d2223169f596d91dac975574e04669988f17a] riscv: Fix typo in asm/hwcap.h uapi header
git bisect good 7f2d2223169f596d91dac975574e04669988f17a
# first bad commit: [375e2bad2f8c6b7292f5ebf3d43dd4fdfc5baf34] riscv: Add STACKPROTECTOR supported

[nathanchance]

Fixed by https://git.kernel.org/linus/40284a072c42f6177184fb1f62ba94c69e0c0277.