lkml.org 
[lkml]   [2020]   [Sep]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH] RISC-V: Check clint_time_val before use
Date


> -----Original Message-----
> From: Damien Le Moal <Damien.LeMoal@wdc.com>
> Sent: 26 September 2020 14:55
> To: paul.walmsley@sifive.com; palmer@dabbelt.com;
> palmerdabbelt@google.com; Anup Patel <Anup.Patel@wdc.com>;
> aou@eecs.berkeley.edu
> Cc: anup@brainfault.org; linux-riscv@lists.infradead.org; Atish Patra
> <Atish.Patra@wdc.com>; Alistair Francis <Alistair.Francis@wdc.com>; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH] RISC-V: Check clint_time_val before use
>
> On Sat, 2020-09-26 at 12:57 +0530, Anup Patel wrote:
> > The NoMMU kernel is broken for QEMU virt machine from Linux-5.9-rc6
> > because the get_cycles() and friends are called very early from
> > rand_initialize() before CLINT driver is probed. To fix this, we
> > should check clint_time_val before use in get_cycles() and friends.
> >
> > Fixes: d5be89a8d118 ("RISC-V: Resurrect the MMIO timer implementation
> > for M-mode systems")
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > ---
> > arch/riscv/include/asm/timex.h | 12 +++++++++---
> > 1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/timex.h
> > b/arch/riscv/include/asm/timex.h index 7f659dda0032..52b42bb1602c
> > 100644
> > --- a/arch/riscv/include/asm/timex.h
> > +++ b/arch/riscv/include/asm/timex.h
> > @@ -17,18 +17,24 @@ typedef unsigned long cycles_t; #ifdef
> > CONFIG_64BIT static inline cycles_t get_cycles(void) {
> > - return readq_relaxed(clint_time_val);
> > + if (clint_time_val)
> > + return readq_relaxed(clint_time_val);
> > + return 0;
> > }
> > #else /* !CONFIG_64BIT */
> > static inline u32 get_cycles(void)
> > {
> > - return readl_relaxed(((u32 *)clint_time_val));
> > + if (clint_time_val)
> > + return readl_relaxed(((u32 *)clint_time_val));
> > + return 0;
> > }
> > #define get_cycles get_cycles
> >
> > static inline u32 get_cycles_hi(void) {
> > - return readl_relaxed(((u32 *)clint_time_val) + 1);
> > + if (clint_time_val)
> > + return readl_relaxed(((u32 *)clint_time_val) + 1);
> > + return 0
> > }
> > #define get_cycles_hi get_cycles_hi
> > #endif /* CONFIG_64BIT */
>
> Applying this on top of rc6, I now get a hang on Kendryte boot...
> No problems without the patch on the other hand.

Not sure about the issue with Kendryte but I get a crash on
QEMU virt machine without this patch.

Regards,
Anup
\
 
 \ /
  Last update: 2020-09-26 11:32    [W:0.053 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site