lkml.org 
[lkml]   [2019]   [Mar]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH RFC 01/14] arm64/mm: Introduce asid_info structure and move asid_generation/asid_map to it
Date
In an attempt to make the ASID allocator generic, create a new structure
asid_info to store all the information necessary for the allocator.

For now, move the variables asid_generation and asid_map to the new structure
asid_info. Follow-up patches will move more variables.

Note to avoid more renaming aftwards, a local variable 'info' has been
created and is a pointer to the ASID allocator structure.

Signed-off-by: Julien Grall <julien.grall@arm.com>
---
arch/arm64/mm/context.c | 46 ++++++++++++++++++++++++++--------------------
1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 1f0ea2facf24..34db54f1a39a 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -30,8 +30,11 @@
static u32 asid_bits;
static DEFINE_RAW_SPINLOCK(cpu_asid_lock);

-static atomic64_t asid_generation;
-static unsigned long *asid_map;
+struct asid_info
+{
+ atomic64_t generation;
+ unsigned long *map;
+} asid_info;

static DEFINE_PER_CPU(atomic64_t, active_asids);
static DEFINE_PER_CPU(u64, reserved_asids);
@@ -88,13 +91,13 @@ void verify_cpu_asid_bits(void)
}
}

-static void flush_context(void)
+static void flush_context(struct asid_info *info)
{
int i;
u64 asid;

/* Update the list of reserved ASIDs and the ASID bitmap. */
- bitmap_clear(asid_map, 0, NUM_USER_ASIDS);
+ bitmap_clear(info->map, 0, NUM_USER_ASIDS);

for_each_possible_cpu(i) {
asid = atomic64_xchg_relaxed(&per_cpu(active_asids, i), 0);
@@ -107,7 +110,7 @@ static void flush_context(void)
*/
if (asid == 0)
asid = per_cpu(reserved_asids, i);
- __set_bit(asid2idx(asid), asid_map);
+ __set_bit(asid2idx(asid), info->map);
per_cpu(reserved_asids, i) = asid;
}

@@ -142,11 +145,11 @@ static bool check_update_reserved_asid(u64 asid, u64 newasid)
return hit;
}

-static u64 new_context(struct mm_struct *mm)
+static u64 new_context(struct asid_info *info, struct mm_struct *mm)
{
static u32 cur_idx = 1;
u64 asid = atomic64_read(&mm->context.id);
- u64 generation = atomic64_read(&asid_generation);
+ u64 generation = atomic64_read(&info->generation);

if (asid != 0) {
u64 newasid = generation | (asid & ~ASID_MASK);
@@ -162,7 +165,7 @@ static u64 new_context(struct mm_struct *mm)
* We had a valid ASID in a previous life, so try to re-use
* it if possible.
*/
- if (!__test_and_set_bit(asid2idx(asid), asid_map))
+ if (!__test_and_set_bit(asid2idx(asid), info->map))
return newasid;
}

@@ -173,20 +176,20 @@ static u64 new_context(struct mm_struct *mm)
* a reserved TTBR0 for the init_mm and we allocate ASIDs in even/odd
* pairs.
*/
- asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, cur_idx);
+ asid = find_next_zero_bit(info->map, NUM_USER_ASIDS, cur_idx);
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();
+ &info->generation);
+ flush_context(info);

/* We have more ASIDs than CPUs, so this will always succeed */
- asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, 1);
+ asid = find_next_zero_bit(info->map, NUM_USER_ASIDS, 1);

set_asid:
- __set_bit(asid, asid_map);
+ __set_bit(asid, info->map);
cur_idx = asid;
return idx2asid(asid) | generation;
}
@@ -195,6 +198,7 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
{
unsigned long flags;
u64 asid, old_active_asid;
+ struct asid_info *info = &asid_info;

if (system_supports_cnp())
cpu_set_reserved_ttbr0();
@@ -217,7 +221,7 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
*/
old_active_asid = atomic64_read(&per_cpu(active_asids, cpu));
if (old_active_asid &&
- !((asid ^ atomic64_read(&asid_generation)) >> asid_bits) &&
+ !((asid ^ atomic64_read(&info->generation)) >> asid_bits) &&
atomic64_cmpxchg_relaxed(&per_cpu(active_asids, cpu),
old_active_asid, asid))
goto switch_mm_fastpath;
@@ -225,8 +229,8 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
raw_spin_lock_irqsave(&cpu_asid_lock, flags);
/* Check that our ASID belongs to the current generation. */
asid = atomic64_read(&mm->context.id);
- if ((asid ^ atomic64_read(&asid_generation)) >> asid_bits) {
- asid = new_context(mm);
+ if ((asid ^ atomic64_read(&info->generation)) >> asid_bits) {
+ asid = new_context(info, mm);
atomic64_set(&mm->context.id, asid);
}

@@ -259,16 +263,18 @@ asmlinkage void post_ttbr_update_workaround(void)

static int asids_init(void)
{
+ struct asid_info *info = &asid_info;
+
asid_bits = get_cpu_asid_bits();
/*
* Expect allocation after rollover to fail if we don't have at least
* one more ASID than CPUs. ASID #0 is reserved for init_mm.
*/
WARN_ON(NUM_USER_ASIDS - 1 <= num_possible_cpus());
- atomic64_set(&asid_generation, ASID_FIRST_VERSION);
- asid_map = kcalloc(BITS_TO_LONGS(NUM_USER_ASIDS), sizeof(*asid_map),
- GFP_KERNEL);
- if (!asid_map)
+ atomic64_set(&info->generation, ASID_FIRST_VERSION);
+ info->map = kcalloc(BITS_TO_LONGS(NUM_USER_ASIDS), sizeof(*info->map),
+ GFP_KERNEL);
+ if (!info->map)
panic("Failed to allocate bitmap for %lu ASIDs\n",
NUM_USER_ASIDS);

--
2.11.0
\
 
 \ /
  Last update: 2019-03-21 17:38    [W:0.106 / U:9.252 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site