linux-kernel - [PATCH 2/5] arm64: mm: Extract the processing of asid

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Message-ID: <20221017083203.3690346-3-yeyunfeng@huawei.com>
Date:   Mon, 17 Oct 2022 16:32:00 +0800
From:   Yunfeng Ye <yeyunfeng@...wei.com>
To:     <catalin.marinas@....com>, <will@...nel.org>,
        <wangkefeng.wang@...wei.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <yeyunfeng@...wei.com>
CC:     <linfeilong@...wei.com>
Subject: [PATCH 2/5] arm64: mm: Extract the processing of asid_generation

To prepare for supporting ASID isolation feature, extract the processing
of asid_generation. it is convenient to modify the asid_generation
centrally.

By the way, It is clearer to put flush_generation() into flush_context().

Signed-off-by: Yunfeng Ye <yeyunfeng@...wei.com>
---
 arch/arm64/mm/context.c | 39 ++++++++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 8549b5f30352..380c7b05c36b 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -102,14 +102,40 @@ static void set_reserved_asid_bits(void)
 		bitmap_clear(asid_map, 0, NUM_USER_ASIDS);
 }
 
-#define asid_gen_match(asid) \
-	(!(((asid) ^ atomic64_read(&asid_generation)) >> asid_bits))
+static void asid_generation_init(void)
+{
+	atomic64_set(&asid_generation, ASID_FIRST_VERSION);
+}
+
+static void flush_generation(void)
+{
+	/* We're out of ASIDs, so increment the global generation count */
+	atomic64_add_return_relaxed(ASID_FIRST_VERSION,
+					&asid_generation);
+}
+
+static inline u64 asid_read_generation(void)
+{
+	return atomic64_read(&asid_generation);
+}
+
+static inline bool asid_match(u64 asid, u64 genid)
+{
+	return (!(((asid) ^ (genid)) >> asid_bits));
+}
+
+static inline bool asid_gen_match(u64 asid)
+{
+	return asid_match(asid, asid_read_generation());
+}
 
 static void flush_context(void)
 {
 	int i;
 	u64 asid;
 
+	flush_generation();
+
 	/* Update the list of reserved ASIDs and the ASID bitmap. */
 	set_reserved_asid_bits();
 
@@ -163,7 +189,7 @@ static u64 new_context(struct mm_struct *mm)
 {
 	static u32 cur_idx = 1;
 	u64 asid = atomic64_read(&mm->context.id);
-	u64 generation = atomic64_read(&asid_generation);
+	u64 generation = asid_read_generation();
 
 	if (asid != 0) {
 		u64 newasid = asid2ctxid(ctxid2asid(asid), generation);
@@ -202,14 +228,12 @@ static u64 new_context(struct mm_struct *mm)
 	if (asid != NUM_USER_ASIDS)
 		goto set_asid;
 
-	/* We're out of ASIDs, so increment the global generation count */
-	generation = atomic64_add_return_relaxed(ASID_FIRST_VERSION,
-						 &asid_generation);
 	flush_context();
 
 	/* We have more ASIDs than CPUs, so this will always succeed */
 	asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, 1);
 
+	generation = asid_read_generation();
 set_asid:
 	__set_bit(asid, asid_map);
 	cur_idx = asid;
@@ -405,7 +429,8 @@ arch_initcall(asids_update_limit);
 static int asids_init(void)
 {
 	asid_bits = get_cpu_asid_bits();
-	atomic64_set(&asid_generation, ASID_FIRST_VERSION);
+	asid_generation_init();
+
 	asid_map = bitmap_zalloc(NUM_USER_ASIDS, GFP_KERNEL);
 	if (!asid_map)
 		panic("Failed to allocate bitmap for %lu ASIDs\n",
-- 
2.27.0