Messages in this thread | | | Date | Sat, 28 May 2022 10:03:23 +0200 | Subject | Re: [syzbot] riscv/fixes test error: lost connection to test machine | From | Alexandre Ghiti <> |
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On 5/27/22 19:04, Dmitry Vyukov 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
Thank you for that, I'll pull that into Ubuntu when merged. Do you know if any other programming language does the same and would need a fix too?
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