On Tue, Jan 2, 2024 at 11:01 PM Samuel Holland
<samuel.holland@xxxxxxxxxx> wrote:
>
> When using the ASID allocator, the MM context ID contains two values:
> the ASID in the lower bits, and the allocator version number in the
> remaining bits. Use macros to make this separation more obvious.
>
> Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
> ---
>
> (no changes since v1)
>
> arch/riscv/include/asm/mmu.h | 3 +++
> arch/riscv/mm/context.c | 12 ++++++------
> arch/riscv/mm/tlbflush.c | 2 +-
> 3 files changed, 10 insertions(+), 7 deletions(-)
>
> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
> index 355504b37f8e..a550fbf770be 100644
> --- a/arch/riscv/include/asm/mmu.h
> +++ b/arch/riscv/include/asm/mmu.h
> @@ -26,6 +26,9 @@ typedef struct {
> #endif
> } mm_context_t;
>
> +#define cntx2asid(cntx) ((cntx) & asid_mask)
> +#define cntx2version(cntx) ((cntx) & ~asid_mask)
Not a big fan of the naming, I would have something like
get_asid_from_context() and get_version_from_context() or something
like that, but up to you of course.
> +
> void __init create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa,
> phys_addr_t sz, pgprot_t prot);
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
> index 217fd4de6134..43d005f63253 100644
> --- a/arch/riscv/mm/context.c
> +++ b/arch/riscv/mm/context.c
> @@ -81,7 +81,7 @@ static void __flush_context(void)
> if (cntx == 0)
> cntx = per_cpu(reserved_context, i);
>
> - __set_bit(cntx & asid_mask, context_asid_map);
> + __set_bit(cntx2asid(cntx), context_asid_map);
> per_cpu(reserved_context, i) = cntx;
> }
>
> @@ -102,7 +102,7 @@ static unsigned long __new_context(struct mm_struct *mm)
> lockdep_assert_held(&context_lock);
>
> if (cntx != 0) {
> - unsigned long newcntx = ver | (cntx & asid_mask);
> + unsigned long newcntx = ver | cntx2asid(cntx);
>
> /*
> * If our current CONTEXT was active during a rollover, we
> @@ -115,7 +115,7 @@ static unsigned long __new_context(struct mm_struct *mm)
> * We had a valid CONTEXT in a previous life, so try to
> * re-use it if possible.
> */
> - if (!__test_and_set_bit(cntx & asid_mask, context_asid_map))
> + if (!__test_and_set_bit(cntx2asid(cntx), context_asid_map))
> return newcntx;
> }
>
> @@ -168,7 +168,7 @@ static void set_mm_asid(struct mm_struct *mm, unsigned int cpu)
> */
> old_active_cntx = atomic_long_read(&per_cpu(active_context, cpu));
> if (old_active_cntx &&
> - ((cntx & ~asid_mask) == atomic_long_read(¤t_version)) &&
> + (cntx2version(cntx) == atomic_long_read(¤t_version)) &&
> atomic_long_cmpxchg_relaxed(&per_cpu(active_context, cpu),
> old_active_cntx, cntx))
> goto switch_mm_fast;
> @@ -177,7 +177,7 @@ static void set_mm_asid(struct mm_struct *mm, unsigned int cpu)
>
> /* Check that our ASID belongs to the current_version. */
> cntx = atomic_long_read(&mm->context.id);
> - if ((cntx & ~asid_mask) != atomic_long_read(¤t_version)) {
> + if (cntx2version(cntx) != atomic_long_read(¤t_version)) {
> cntx = __new_context(mm);
> atomic_long_set(&mm->context.id, cntx);
> }
> @@ -191,7 +191,7 @@ static void set_mm_asid(struct mm_struct *mm, unsigned int cpu)
>
> switch_mm_fast:
> csr_write(CSR_SATP, virt_to_pfn(mm->pgd) |
> - ((cntx & asid_mask) << SATP_ASID_SHIFT) |
> + (cntx2asid(cntx) << SATP_ASID_SHIFT) |
> satp_mode);
>
> if (need_flush_tlb)
> diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
> index 76b24d4ed4ab..5ec621545c69 100644
> --- a/arch/riscv/mm/tlbflush.c
> +++ b/arch/riscv/mm/tlbflush.c
> @@ -85,7 +85,7 @@ static void __flush_tlb_range(struct mm_struct *mm, unsigned long start,
> return;
>
> if (static_branch_unlikely(&use_asid_allocator))
> - asid = atomic_long_read(&mm->context.id) & asid_mask;
> + asid = cntx2asid(atomic_long_read(&mm->context.id));
> } else {
> cmask = cpu_online_mask;
> }
> --
> 2.42.0
>
You can add:
Reviewed-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
Thanks,
Alex
