Messages in this thread | | | From | Damien Le Moal <> | Subject | Re: [PATCH] RISC-V: Check clint_time_val before use | Date | Sat, 26 Sep 2020 10:01:22 +0000 |
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On Sat, 2020-09-26 at 15:27 +0530, Anup Patel wrote: > On Sat, Sep 26, 2020 at 3:16 PM Damien Le Moal <Damien.LeMoal@wdc.com> wrote: > > On Sat, 2020-09-26 at 09:31 +0000, Anup Patel wrote: > > > > -----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. > > > > With this applied in addition to your patch, it works. > > > > diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer- > > clint.c > > index d17367dee02c..8dbec85979fd 100644 > > --- a/drivers/clocksource/timer-clint.c > > +++ b/drivers/clocksource/timer-clint.c > > @@ -37,7 +37,7 @@ static unsigned long clint_timer_freq; > > static unsigned int clint_timer_irq; > > > > #ifdef CONFIG_RISCV_M_MODE > > -u64 __iomem *clint_time_val; > > +u64 __iomem *clint_time_val = NULL; > > #endif > > > > static void clint_send_ipi(const struct cpumask *target) > > Ahh, clint_time_val is an uninitialized variable. > > I will send a v2 with your SoB.
No need for my sob. Just merge that in your patch.
> > Regards, > Anup > > > -- > > Damien Le Moal > > Western Digital
-- Damien Le Moal Western Digital
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