Messages in this thread | | | From | Dmitry Vyukov <> | Date | Sat, 28 May 2022 10:31:16 +0200 | Subject | Re: [syzbot] riscv/fixes test error: lost connection to test machine |
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On Sat, 28 May 2022 at 10:09, Alexandre Ghiti <alex@ghiti.fr> wrote: > > On 5/27/22 19:12, Dmitry Vyukov wrote: > > On Fri, 27 May 2022 at 19:04, Dmitry Vyukov <dvyukov@google.com> wrote: > >> On Fri, 27 May 2022 at 16:01, Alexandre Ghiti > >> <alexandre.ghiti@canonical.com> wrote: > >>> On Friday, May 27, 2022 at 3:55:24 PM UTC+2 Dmitry Vyukov wrote: > >>>> On Fri, 27 May 2022 at 15:50, Alexandre Ghiti > >>>> <alexand...@canonical.com> wrote: > >>>>> On Friday, May 27, 2022 at 3:02:01 PM UTC+2 Dmitry Vyukov wrote: > >>>>>> On Fri, 27 May 2022 at 14:55, syzbot > >>>>>> <syzbot+2c5da6...@syzkaller.appspotmail.com> wrote: > >>>>>>> Hello, > >>>>>>> > >>>>>>> syzbot found the following issue on: > >>>>>>> > >>>>>>> HEAD commit: c932edeaf6d6 riscv: dts: microchip: fix gpio1 reg property.. > >>>>>>> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes > >>>>>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1418add5f00000 > >>>>>>> kernel config: https://syzkaller.appspot.com/x/.config?x=aa6b5702bdf14a17 > >>>>>>> dashboard link: https://syzkaller.appspot.com/bug?extid=2c5da6a0a16a0c4f34aa > >>>>>>> compiler: riscv64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > >>>>>>> userspace arch: riscv64 > >>>>>>> > >>>>>>> IMPORTANT: if you fix the issue, please add the following tag to the commit: > >>>>>>> Reported-by: syzbot+2c5da6...@syzkaller.appspotmail.com > >>>>>> The CONFIG_KASAN_VMALLOC allows riscv kernel to boot, but now Go > >>>>>> processes started crashing with: > >>>>>> > >>>>>> 1970/01/01 00:06:55 fuzzer started > >>>>>> runtime: lfstack.push invalid packing: node=0xffffff5908a940 cnt=0x1 > >>>>>> packed=0xffff5908a9400001 -> node=0xffff5908a940 > >>>>>> fatal error: lfstack.push > >>>>>> runtime stack: > >>>>>> runtime.throw({0x30884c, 0xc}) > >>>>>> /usr/local/go/src/runtime/panic.go:1198 +0x60 > >>>>>> runtime.(*lfstack).push(0xdb3850, 0xffffff5908a940) > >>>>>> /usr/local/go/src/runtime/lfstack.go:30 +0x1a8 > >>>>>> > >>>>>> Go runtime tries to shove some data into the upper 16 bits of pointers > >>>>>> assuming they are unused. > >>>>>> However, the original pointer node=0xffffff5908a940 suggest riscv now > >>>>>> has 56-bit users-space address space? > >>>>> > >>>>> Yes, sv57 was merged recently. > >>>>> > >>>>>> Documentation/riscv/vm-layout.rst claims 48-bit pointers: > >>>>>> " > >>>>>> The RISC-V privileged architecture document states that the 64bit addresses > >>>>>> "must have bits 63–48 all equal to bit 47, or else a page-fault exception will > >>>>>> occur.": > >>>>> > >>>>> Thanks for pointing that, I extracted that from the specification before sv57 was specified, I'll fix that. > >>>>> > >>>>> The current kernel code will use sv57 as it is supported and advertised by qemu, and to my knowledge, you can't downgrade to sv48 unless by re-compiling qemu using the following: > >>>>> > >>>>> diff --git a/target/riscv/csr.c b/target/riscv/csr.c > >>>>> index 6dbe9b541f..a64b50ed75 100644 > >>>>> --- a/target/riscv/csr.c > >>>>> +++ b/target/riscv/csr.c > >>>>> @@ -637,7 +637,7 @@ static const char valid_vm_1_10_64[16] = { > >>>>> [VM_1_10_MBARE] = 1, > >>>>> [VM_1_10_SV39] = 1, > >>>>> [VM_1_10_SV48] = 1, > >>>>> - [VM_1_10_SV57] = 1 > >>>>> + [VM_1_10_SV57] = 0 > >>>>> }; > >>>>> > >>>>> /* Machine Information Registers */ > >>>>> > >>>>>> ... > >>>>>> 0000000000000000 | 0 | 0000003fffffffff | 256 GB | > >>>>>> user-space virtual memory, different per mm > >>>>>> " > >>>> There is no kernel config to force SV48/39, right? > >>> > >>> No, we rely on what the hardware advertises, if it supports sv57, we'll go for sv57, if not, we'll try sv48...etc. I had some patches to force the downgrade by using the device tree but they never got merged though. > >> +original CC list > >> > >> FTR sent Go runtime change to support SV57: > >> https://go-review.googlesource.com/c/go/+/409055 > > > > > > Is CONFIG_CMDLINE broken on riscv? > > I am running with: > > > > CONFIG_CMDLINE="earlyprintk=serial net.ifnames=0 > > sysctl.kernel.hung_task_all_cpu_backtrace=1 ima_policy=tcb > > nf-conntrack-ftp.ports=20000 nf-conntrack-tftp.ports=20000 > > nf-conntrack-sip.ports=20000 nf-conntrack-irc.ports=20000 > > nf-conntrack-sane.ports=20000 binder.debug_mask=0 > > rcupdate.rcu_expedited=1 no_hash_pointers page_owner=on > > sysctl.vm.nr_hugepages=4 sysctl.vm.nr_overcommit_hugepages=4 > > secretmem.enable=1 sysctl.max_rcu_stall_to_panic=1 > > msr.allow_writes=off dummy_hcd.num=2 smp.csd_lock_timeout=300000 > > watchdog_thresh=165 workqueue.watchdog_thresh=420 > > sysctl.net.core.netdev_unregister_timeout_secs=420 panic_on_warn=1" > > > This command line is 608-character long, but we are still stuck with the > default COMMAND_LINE_SIZE to 512, I imagine that it is the problem. I > had proposed a patch last year to bump that to 1024, but it never got > merged > https://lore.kernel.org/lkml/CAEn-LTqTXCEC=bXTvGyo8SNL0JMWRKtiSwQB7R=Pc4uhxZUruA@mail.gmail.com/T/#m4b45019dc0f5573f2a50c1f6007c5109fa35efff
risc-v maintainers, please merge it now. I would even suggest 2048:
git grep "define COMMAND_LINE_SIZE" arch/ arch/alpha/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/arc/include/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/arm/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 1024 arch/arm64/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 2048 arch/ia64/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 2048 arch/m68k/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/microblaze/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256 arch/mips/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 4096 arch/parisc/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 1024 arch/powerpc/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 2048 arch/s390/include/asm/setup.h:#define COMMAND_LINE_SIZE CONFIG_COMMAND_LINE_SIZE arch/sparc/include/uapi/asm/setup.h:# define COMMAND_LINE_SIZE 2048 arch/sparc/include/uapi/asm/setup.h:# define COMMAND_LINE_SIZE 256 arch/um/include/asm/setup.h:#define COMMAND_LINE_SIZE 4096 arch/x86/include/asm/setup.h:#define COMMAND_LINE_SIZE 2048 arch/xtensa/include/uapi/asm/setup.h:#define COMMAND_LINE_SIZE 256
It's also interesting how the kernel handles overflow. Imagine one adds that_critical_security_feature=1 to the end of an existing long line.
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