| Message ID | 20220330073347.3898802-1-alistair.francis@opensource.wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | riscv: Ensure only ASIDLEN is used for sfence.vma | expand |
On Wed, Mar 30, 2022 at 1:04 PM Alistair Francis <alistair.francis@opensource.wdc.com> wrote: > > From: Alistair Francis <alistair.francis@wdc.com> > > When we set the value of context.id using __new_context() we set both > the asid and the current_version with this return statement in > __new_context(): > > return asid | ver; > > This means that when local_flush_tlb_all_asid() is called with the asid > specified from context.id we can write the incorrect value. > > We get away with this as hardware ignores the extra bits, as the RISC-V > specification states: > > "bits SXLEN-1:ASIDMAX of the value held in rs2 are reserved for future > standard use. Until their use is defined by a standard extension, they > should be zeroed by software and ignored by current implementations." > > but it is still a bug and worth addressing as we are incorrectly setting > extra bits. > > This patch uses asid_mask when calling sfence.vma to ensure the asid is > always the correct len (ASIDLEN). This is similar to what we do in > arch/riscv/mm/context.c. > > Signed-off-by: Alistair Francis <alistair.francis@wdc.com> Instead of fixing various local_flush_tlb_xyz() functions, I suggest fixing the __sbi_tlb_flush_range() in tlbflush.c which passes incorrect ASID. (Refer line 45, "unsigned long asid = atomic_long_read(&mm->context.id);") Also, please add the "Fixes: " tag. Regards, Anup > --- > arch/riscv/mm/context.c | 2 +- > arch/riscv/mm/tlbflush.c | 4 ++-- > include/linux/mm_types.h | 2 ++ > 3 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c > index 7acbfbd14557..4329fe54176b 100644 > --- a/arch/riscv/mm/context.c > +++ b/arch/riscv/mm/context.c > @@ -22,7 +22,7 @@ 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; > > static atomic_long_t current_version; > > diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c > index 37ed760d007c..4469615aa07f 100644 > --- a/arch/riscv/mm/tlbflush.c > +++ b/arch/riscv/mm/tlbflush.c > @@ -10,7 +10,7 @@ static inline void local_flush_tlb_all_asid(unsigned long asid) > { > __asm__ __volatile__ ("sfence.vma x0, %0" > : > - : "r" (asid) > + : "r" (asid & asid_mask) > : "memory"); > } > > @@ -19,7 +19,7 @@ static inline void local_flush_tlb_page_asid(unsigned long addr, > { > __asm__ __volatile__ ("sfence.vma %0, %1" > : > - : "r" (addr), "r" (asid) > + : "r" (addr), "r" (asid & asid_mask) > : "memory"); > } > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 8834e38c06a4..5fa7cc0af853 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -666,6 +666,8 @@ struct mm_struct { > > extern struct mm_struct init_mm; > > +extern unsigned long asid_mask; > + > /* Pointer magic because the dynamic array size confuses some compilers. */ > static inline void mm_init_cpumask(struct mm_struct *mm) > { > -- > 2.35.1 >
diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c index 7acbfbd14557..4329fe54176b 100644 --- a/arch/riscv/mm/context.c +++ b/arch/riscv/mm/context.c @@ -22,7 +22,7 @@ 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; static atomic_long_t current_version; diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c index 37ed760d007c..4469615aa07f 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -10,7 +10,7 @@ static inline void local_flush_tlb_all_asid(unsigned long asid) { __asm__ __volatile__ ("sfence.vma x0, %0" : - : "r" (asid) + : "r" (asid & asid_mask) : "memory"); } @@ -19,7 +19,7 @@ static inline void local_flush_tlb_page_asid(unsigned long addr, { __asm__ __volatile__ ("sfence.vma %0, %1" : - : "r" (addr), "r" (asid) + : "r" (addr), "r" (asid & asid_mask) : "memory"); } diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 8834e38c06a4..5fa7cc0af853 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -666,6 +666,8 @@ struct mm_struct { extern struct mm_struct init_mm; +extern unsigned long asid_mask; + /* Pointer magic because the dynamic array size confuses some compilers. */ static inline void mm_init_cpumask(struct mm_struct *mm) {