2023-03-10 10:32:24

by Dylan Jhong

Subject: [PATCH] riscv: mm: Fix incorrect ASID argument when flushing TLB

Currently, we pass the CONTEXTID instead of the ASID to the TLB flush
function. We should only take the ASID field to prevent from touching
the reserved bit field.

Fixes: 3f1e782998cd ("riscv: add ASID-based tlbflushing methods")
Signed-off-by: Dylan Jhong <[email protected]>
---
arch/riscv/include/asm/tlbflush.h | 2 ++
arch/riscv/mm/context.c | 3 ++-
arch/riscv/mm/tlbflush.c | 2 +-
3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index 907b9efd39a8..597d6d8aec28 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -12,6 +12,8 @@
#include <asm/errata_list.h>

#ifdef CONFIG_MMU
+extern unsigned long asid_mask;
+
static inline void local_flush_tlb_all(void)
{
__asm__ __volatile__ ("sfence.vma" : : : "memory");
diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
index 80ce9caba8d2..a6b76b33e377 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -22,7 +22,8 @@ DEFINE_STATIC_KEY_FALSE(use_asid_allocator);

static unsigned long asid_bits;
static unsigned long num_asids;
-static unsigned long asid_mask;
+unsigned long asid_mask;
+EXPORT_SYMBOL(asid_mask);

static atomic_long_t current_version;

diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index ce7dfc81bb3f..ba4c27187c95 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -27,7 +27,7 @@ static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start,
/* check if the tlbflush needs to be sent to other CPUs */
broadcast = cpumask_any_but(cmask, cpuid) < nr_cpu_ids;
if (static_branch_unlikely(&use_asid_allocator)) {
- unsigned long asid = atomic_long_read(&mm->context.id);
+ unsigned long asid = atomic_long_read(&mm->context.id) & asid_mask;

/*
* TLB will be immediately flushed on harts concurrently
--
2.34.1

2023-03-12 12:41:29

by Guo Ren

Subject: Re: [PATCH] riscv: mm: Fix incorrect ASID argument when flushing TLB

On Fri, Mar 10, 2023 at 6:32 PM Dylan Jhong <[email protected]> wrote:
>
> Currently, we pass the CONTEXTID instead of the ASID to the TLB flush
> function. We should only take the ASID field to prevent from touching
> the reserved bit field.
>
> Fixes: 3f1e782998cd ("riscv: add ASID-based tlbflushing methods")
> Signed-off-by: Dylan Jhong <[email protected]>
> ---
> arch/riscv/include/asm/tlbflush.h | 2 ++
> arch/riscv/mm/context.c | 3 ++-
> arch/riscv/mm/tlbflush.c | 2 +-
> 3 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
> index 907b9efd39a8..597d6d8aec28 100644
> --- a/arch/riscv/include/asm/tlbflush.h
> +++ b/arch/riscv/include/asm/tlbflush.h
> @@ -12,6 +12,8 @@
> #include <asm/errata_list.h>
>
> #ifdef CONFIG_MMU
> +extern unsigned long asid_mask;
> +
> static inline void local_flush_tlb_all(void)
> {
> __asm__ __volatile__ ("sfence.vma" : : : "memory");
> diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
> index 80ce9caba8d2..a6b76b33e377 100644
> --- a/arch/riscv/mm/context.c
> +++ b/arch/riscv/mm/context.c
> @@ -22,7 +22,8 @@ DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
>
> static unsigned long asid_bits;
> static unsigned long num_asids;
> -static unsigned long asid_mask;
> +unsigned long asid_mask;
> +EXPORT_SYMBOL(asid_mask);
Why EXPORT_SYMBOL? (No module would use it by your patch.)

>
> static atomic_long_t current_version;
>
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index ce7dfc81bb3f..ba4c27187c95 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -27,7 +27,7 @@ static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start,
> /* check if the tlbflush needs to be sent to other CPUs */
> broadcast = cpumask_any_but(cmask, cpuid) < nr_cpu_ids;
> if (static_branch_unlikely(&use_asid_allocator)) {
> - unsigned long asid = atomic_long_read(&mm->context.id);
> + unsigned long asid = atomic_long_read(&mm->context.id) & asid_mask;
>
> /*
> * TLB will be immediately flushed on harts concurrently
> --
> 2.34.1
>


--
Best Regards
Guo Ren

2023-03-13 03:32:22

by Dylan Jhong

Subject: Re: [PATCH] riscv: mm: Fix incorrect ASID argument when flushing TLB

On Sun, Mar 12, 2023 at 08:40:59PM +0800, Guo Ren wrote:
> On Fri, Mar 10, 2023 at 6:32 PM Dylan Jhong <[email protected]> wrote:
> >
> > Currently, we pass the CONTEXTID instead of the ASID to the TLB flush
> > function. We should only take the ASID field to prevent from touching
> > the reserved bit field.
> >
> > Fixes: 3f1e782998cd ("riscv: add ASID-based tlbflushing methods")
> > Signed-off-by: Dylan Jhong <[email protected]>
> > ---
> > arch/riscv/include/asm/tlbflush.h | 2 ++
> > arch/riscv/mm/context.c | 3 ++-
> > arch/riscv/mm/tlbflush.c | 2 +-
> > 3 files changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
> > index 907b9efd39a8..597d6d8aec28 100644
> > --- a/arch/riscv/include/asm/tlbflush.h
> > +++ b/arch/riscv/include/asm/tlbflush.h
> > @@ -12,6 +12,8 @@
> > #include <asm/errata_list.h>
> >
> > #ifdef CONFIG_MMU
> > +extern unsigned long asid_mask;
> > +
> > static inline void local_flush_tlb_all(void)
> > {
> > __asm__ __volatile__ ("sfence.vma" : : : "memory");
> > diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
> > index 80ce9caba8d2..a6b76b33e377 100644
> > --- a/arch/riscv/mm/context.c
> > +++ b/arch/riscv/mm/context.c
> > @@ -22,7 +22,8 @@ DEFINE_STATIC_KEY_FALSE(use_asid_allocator);
> >
> > static unsigned long asid_bits;
> > static unsigned long num_asids;
> > -static unsigned long asid_mask;
> > +unsigned long asid_mask;
> > +EXPORT_SYMBOL(asid_mask);
> Why EXPORT_SYMBOL? (No module would use it by your patch.)
>
OK. I'll remove EXPORT_SYMBOL in v2.
Thanks.

> >
> > static atomic_long_t current_version;
> >
> > diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> > index ce7dfc81bb3f..ba4c27187c95 100644
> > --- a/arch/riscv/mm/tlbflush.c
> > +++ b/arch/riscv/mm/tlbflush.c
> > @@ -27,7 +27,7 @@ static void __sbi_tlb_flush_range(struct mm_struct *mm, unsigned long start,
> > /* check if the tlbflush needs to be sent to other CPUs */
> > broadcast = cpumask_any_but(cmask, cpuid) < nr_cpu_ids;
> > if (static_branch_unlikely(&use_asid_allocator)) {
> > - unsigned long asid = atomic_long_read(&mm->context.id);
> > + unsigned long asid = atomic_long_read(&mm->context.id) & asid_mask;
> >
> > /*
> > * TLB will be immediately flushed on harts concurrently
> > --
> > 2.34.1
> >
>
>
> --
> Best Regards
> Guo Ren