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References: <20230614013018.2168426-1-guoren@kernel.org> <20230614013018.2168426-2-guoren@kernel.org>
 <ZM1tGgcJg0silFaJ@zx2c4.com>
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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Fri, 4 Aug 2023 23:28:17 +0200
Message-ID: <CAHmME9p3VoZco0+io6pZDnzKVdnP4vr4XWNaAPXGew+1RmfVig@mail.gmail.com>
Subject: Re: [PATCH -next V13 1/3] riscv: stack: Support HAVE_IRQ_EXIT_ON_IRQ_STACK
To:     guoren@kernel.org
Cc:     arnd@arndb.de, palmer@rivosinc.com, conor.dooley@microchip.com,
        heiko@sntech.de, jszhang@kernel.org, bjorn@kernel.org,
        cleger@rivosinc.com, linux-arch@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
        Guo Ren <guoren@linux.alibaba.com>
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On Fri, Aug 4, 2023 at 11:28=E2=80=AFPM Jason A. Donenfeld <Jason@zx2c4.com=
> wrote:
>
> Hi Guo,
>
> On Tue, Jun 13, 2023 at 09:30:16PM -0400, guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > Add independent irq stacks for percpu to prevent kernel stack overflows=
.
> > It is also compatible with VMAP_STACK by arch_alloc_vmap_stack.
> >
> > Tested-by: Jisheng Zhang <jszhang@kernel.org>
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Signed-off-by: Guo Ren <guoren@kernel.org>
> > Cc: Cl=C3=A9ment L=C3=A9ger <cleger@rivosinc.com>
>
> This patch broke the WireGuard test suite. I've attached the .config
> file that it uses. I'm able to fix it by setting CONFIG_EXPERT=3Dy and
> CONFIG_IRQ_STACKS=3Dn to essentially reverse the effect of this patch. Bu=
t
> I'd rather not do that.
>
> Any idea what's up?
>
> Thanks,
> Jason

And, err, I guess I failed to describe what's broken exactly. Here's
what happens:

timeout --foreground 20m qemu-system-riscv64 \
       -nodefaults \
       -nographic \
       -smp 4 \
       -cpu rv64 -machine virt \
       -m 256M \
       -serial stdio \
       -chardev
file,path=3D/home/zx2c4/Projects/wireguard-linux/tools/testing/selftests/wi=
reguard/qemu/build/riscv64/result,id=3Dresult
\
       -device virtio-serial-device -device virtserialport,chardev=3Dresult=
 \
       -no-reboot \
       -monitor none \
       -kernel /home/zx2c4/Projects/wireguard-linux/tools/testing/selftests=
/wireguard/qemu/build/riscv64/kernel/arch/riscv/boot/Image

OpenSBI v1.2
  ____                    _____ ____ _____
 / __ \                  / ____|  _ \_   _|
| |  | |_ __   ___ _ __ | (___ | |_) || |
| |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
| |__| | |_) |  __/ | | |____) | |_) || |_
 \____/| .__/ \___|_| |_|_____/|____/_____|
       | |
       |_|

Platform Name             : riscv-virtio,qemu
Platform Features         : medeleg
Platform HART Count       : 4
Platform IPI Device       : aclint-mswi
Platform Timer Device     : aclint-mtimer @ 10000000Hz
Platform Console Device   : uart8250
Platform HSM Device       : ---
Platform PMU Device       : ---
Platform Reboot Device    : sifive_test
Platform Shutdown Device  : sifive_test
Firmware Base             : 0x80000000
Firmware Size             : 236 KB
Runtime SBI Version       : 1.0

Domain0 Name              : root
Domain0 Boot HART         : 0
Domain0 HARTs             : 0*,1*,2*,3*
Domain0 Region00          : 0x0000000002000000-0x000000000200ffff (I)
Domain0 Region01          : 0x0000000080000000-0x000000008003ffff ()
Domain0 Region02          : 0x0000000000000000-0xffffffffffffffff (R,W,X)
Domain0 Next Address      : 0x0000000080200000
Domain0 Next Arg1         : 0x000000008fe00000
Domain0 Next Mode         : S-mode
Domain0 SysReset          : yes

Boot HART ID              : 0
Boot HART Domain          : root
Boot HART Priv Version    : v1.12
Boot HART Base ISA        : rv64imafdch
Boot HART ISA Extensions  : time,sstc
Boot HART PMP Count       : 16
Boot HART PMP Granularity : 4
Boot HART PMP Address Bits: 54
Boot HART MHPM Count      : 16
Boot HART MIDELEG         : 0x0000000000001666
Boot HART MEDELEG         : 0x0000000000f0b509
[terminates/hangs here]