| Message ID | 20220330214358.3409766-1-alistair.francis@opensource.wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] riscv: Ensure only ASIDLEN is used for sfence.vma | expand |
On 3/31/22 06:43, Alistair Francis 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. > > Fixes: 3f1e782998cd ("riscv: add ASID-based tlbflushing methods") > Signed-off-by: Alistair Francis <alistair.francis@wdc.com> > --- > arch/riscv/mm/context.c | 2 +- > arch/riscv/mm/tlbflush.c | 2 +- > include/linux/mm_types.h | 2 ++ > 3 files changed, 4 insertions(+), 2 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..ef701fa83f36 100644 > --- a/arch/riscv/mm/tlbflush.c > +++ b/arch/riscv/mm/tlbflush.c > @@ -42,7 +42,7 @@ 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; It would be a lot nicer and less error prone to have a small helper function for this, no ? > > if (broadcast) { > sbi_remote_sfence_vma_asid(cmask, start, size, asid); > 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) > {
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..ef701fa83f36 100644 --- a/arch/riscv/mm/tlbflush.c +++ b/arch/riscv/mm/tlbflush.c @@ -42,7 +42,7 @@ 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; if (broadcast) { sbi_remote_sfence_vma_asid(cmask, start, size, asid); 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) {