[PATCH v6 09/13] riscv: mm: Introduce cntx2asid/cntx2version helper macros

From: Samuel Holland
Date: Wed Mar 27 2024 - 00:52:27 EST


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.

Reviewed-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
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)
+
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 ba8eb3944687..b562b3c44487 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(&current_version)) &&
+ (cntx2version(cntx) == atomic_long_read(&current_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(&current_version)) {
+ if (cntx2version(cntx) != atomic_long_read(&current_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 18af7b5053af..35266dd9a9a2 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -110,7 +110,7 @@ static void __flush_tlb_range(struct cpumask *cmask, unsigned long asid,
static inline unsigned long get_mm_asid(struct mm_struct *mm)
{
return static_branch_unlikely(&use_asid_allocator) ?
- atomic_long_read(&mm->context.id) & asid_mask : FLUSH_TLB_NO_ASID;
+ cntx2asid(atomic_long_read(&mm->context.id)) : FLUSH_TLB_NO_ASID;
}

void flush_tlb_mm(struct mm_struct *mm)
--
2.43.1