diff mbox series

target/riscv: Bugfix reserved bits in PTE for RV64

Message ID 1569301232-7128-1-git-send-email-guoren@kernel.org
State New
Headers show
Series target/riscv: Bugfix reserved bits in PTE for RV64 | expand

Commit Message

Guo Ren Sept. 24, 2019, 5 a.m. UTC 
From: Guo Ren <ren_guo@c-sky.com>

Highest 10 bits of PTE are reserved in riscv-privileged, ref: [1], so we
need to ignore them. They can not be a part of ppn.

1: The RISC-V Instruction Set Manual, Volume II: Privileged Architecture
   4.4 Sv39: Page-Based 39-bit Virtual-Memory System
   4.5 Sv48: Page-Based 48-bit Virtual-Memory System

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Liu Zhiwei <zhiwei_liu@c-sky.com>
---
 target/riscv/cpu_helper.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Alistair Francis Sept. 24, 2019, 5:03 a.m. UTC | #1 
On Mon, Sep 23, 2019 at 10:01 PM <guoren@kernel.org> wrote:
>
> From: Guo Ren <ren_guo@c-sky.com>
>
> Highest 10 bits of PTE are reserved in riscv-privileged, ref: [1], so we
> need to ignore them. They can not be a part of ppn.
>
> 1: The RISC-V Instruction Set Manual, Volume II: Privileged Architecture
>    4.4 Sv39: Page-Based 39-bit Virtual-Memory System
>    4.5 Sv48: Page-Based 48-bit Virtual-Memory System
>
> Signed-off-by: Guo Ren <ren_guo@c-sky.com>
> Reviewed-by: Liu Zhiwei <zhiwei_liu@c-sky.com>
> ---
>  target/riscv/cpu_helper.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 87dd6a6..3c5e8f6 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -260,6 +260,7 @@ restart:
>          target_ulong pte = ldl_phys(cs->as, pte_addr);
>  #elif defined(TARGET_RISCV64)
>          target_ulong pte = ldq_phys(cs->as, pte_addr);
> +        pte = pte << 10 >> 10;

You can just AND with a mask instead of shifting both directions.

Alistair

>  #endif
>          hwaddr ppn = pte >> PTE_PPN_SHIFT;
>
> --
> 2.7.4
>
Guo Ren Sept. 24, 2019, 7:43 a.m. UTC | #2 
Ok, In fact it's wrong patch, don't try it. pte is destroyed.

Sorry for that, I'll send V2.

On Tue, Sep 24, 2019 at 1:03 PM Alistair Francis <alistair23@gmail.com> wrote:
>
> On Mon, Sep 23, 2019 at 10:01 PM <guoren@kernel.org> wrote:
> >
> > From: Guo Ren <ren_guo@c-sky.com>
> >
> > Highest 10 bits of PTE are reserved in riscv-privileged, ref: [1], so we
> > need to ignore them. They can not be a part of ppn.
> >
> > 1: The RISC-V Instruction Set Manual, Volume II: Privileged Architecture
> >    4.4 Sv39: Page-Based 39-bit Virtual-Memory System
> >    4.5 Sv48: Page-Based 48-bit Virtual-Memory System
> >
> > Signed-off-by: Guo Ren <ren_guo@c-sky.com>
> > Reviewed-by: Liu Zhiwei <zhiwei_liu@c-sky.com>
> > ---
> >  target/riscv/cpu_helper.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> > index 87dd6a6..3c5e8f6 100644
> > --- a/target/riscv/cpu_helper.c
> > +++ b/target/riscv/cpu_helper.c
> > @@ -260,6 +260,7 @@ restart:
> >          target_ulong pte = ldl_phys(cs->as, pte_addr);
> >  #elif defined(TARGET_RISCV64)
> >          target_ulong pte = ldq_phys(cs->as, pte_addr);
> > +        pte = pte << 10 >> 10;
>
> You can just AND with a mask instead of shifting both directions.
>
> Alistair
>
> >  #endif
> >          hwaddr ppn = pte >> PTE_PPN_SHIFT;
> >
> > --
> > 2.7.4
> >
diff mbox series

Patch

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 87dd6a6..3c5e8f6 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -260,6 +260,7 @@  restart:
         target_ulong pte = ldl_phys(cs->as, pte_addr);
 #elif defined(TARGET_RISCV64)
         target_ulong pte = ldq_phys(cs->as, pte_addr);
+        pte = pte << 10 >> 10;
 #endif
         hwaddr ppn = pte >> PTE_PPN_SHIFT;