[PATCH 2/7] riscv: mm: Introduce cntx2asid/cntx2version helper macros

From: Samuel Holland <samuel@sholland.org>
To: Palmer Dabbelt <palmer@dabbelt.com>,
	Alexandre Ghiti <alexghiti@rivosinc.com>,
	linux-riscv@lists.infradead.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Samuel Holland <samuel@sholland.org>
Subject: [PATCH 2/7] riscv: mm: Introduce cntx2asid/cntx2version helper macros
Date: Sat,  9 Sep 2023 15:16:30 -0500	[thread overview]
Message-ID: <20230909201727.10909-3-samuel@sholland.org> (raw)
In-Reply-To: <20230909201727.10909-1-samuel@sholland.org>

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@sholland.org>
---

 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 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(&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 115d617d16c9..54c3e70ccd81 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -73,7 +73,7 @@ static void __flush_tlb_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) & asid_mask;
+		unsigned long asid = cntx2asid(atomic_long_read(&mm->context.id));
 
 		if (broadcast) {
 			if (riscv_use_ipi_for_rfence()) {
-- 
2.41.0

