[PATCH RFC 03/14] arm64/mm: Move bits to asid_info

From: Julien Grall
Date: Thu Mar 21 2019 - 12:37:56 EST

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Previous message: Julien Grall: "[PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending to asid_info"
In reply to: Julien Grall: "[PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending to asid_info"
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The variable bits hold information for a given ASID allocator. So move
it to the asid_info structure.

Because most of the macros were relying on bits, they are now taking an
extra parameter that is a pointer to the asid_info structure.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
arch/arm64/mm/context.c | 59 +++++++++++++++++++++++++------------------------
1 file changed, 30 insertions(+), 29 deletions(-)

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index cfe4c5f7abf3..da17ed6c7117 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -27,7 +27,6 @@
#include <asm/smp.h>
#include <asm/tlbflush.h>

-static u32 asid_bits;
static DEFINE_RAW_SPINLOCK(cpu_asid_lock);

struct asid_info
@@ -36,6 +35,7 @@ struct asid_info
unsigned long *map;
atomic64_t __percpu *active;
u64 __percpu *reserved;
+ u32 bits;
} asid_info;

#define active_asid(info, cpu) *per_cpu_ptr((info)->active, cpu)
@@ -46,17 +46,17 @@ static DEFINE_PER_CPU(u64, reserved_asids);

static cpumask_t tlb_flush_pending;

-#define ASID_MASK (~GENMASK(asid_bits - 1, 0))
-#define ASID_FIRST_VERSION (1UL << asid_bits)
+#define ASID_MASK(info) (~GENMASK((info)->bits - 1, 0))
+#define ASID_FIRST_VERSION(info) (1UL << ((info)->bits))

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
-#define NUM_USER_ASIDS (ASID_FIRST_VERSION >> 1)
-#define asid2idx(asid) (((asid) & ~ASID_MASK) >> 1)
-#define idx2asid(idx) (((idx) << 1) & ~ASID_MASK)
+#define NUM_USER_ASIDS(info) (ASID_FIRST_VERSION(info) >> 1)
+#define asid2idx(info, asid) (((asid) & ~ASID_MASK(info)) >> 1)
+#define idx2asid(info, idx) (((idx) << 1) & ~ASID_MASK(info))
#else
-#define NUM_USER_ASIDS (ASID_FIRST_VERSION)
-#define asid2idx(asid) ((asid) & ~ASID_MASK)
-#define idx2asid(idx) asid2idx(idx)
+#define NUM_USER_ASIDS(info) (ASID_FIRST_VERSION(info))
+#define asid2idx(info, asid) ((asid) & ~ASID_MASK(info))
+#define idx2asid(info, idx) asid2idx(info, idx)
#endif

/* Get the ASIDBits supported by the current CPU */
@@ -86,13 +86,13 @@ void verify_cpu_asid_bits(void)
{
u32 asid = get_cpu_asid_bits();

- if (asid < asid_bits) {
+ if (asid < asid_info.bits) {
/*
* We cannot decrease the ASID size at runtime, so panic if we support
* fewer ASID bits than the boot CPU.
*/
pr_crit("CPU%d: smaller ASID size(%u) than boot CPU (%u)\n",
- smp_processor_id(), asid, asid_bits);
+ smp_processor_id(), asid, asid_info.bits);
cpu_panic_kernel();
}
}
@@ -103,7 +103,7 @@ static void flush_context(struct asid_info *info)
u64 asid;

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

for_each_possible_cpu(i) {
asid = atomic64_xchg_relaxed(&active_asid(info, i), 0);
@@ -116,7 +116,7 @@ static void flush_context(struct asid_info *info)
*/
if (asid == 0)
asid = reserved_asid(info, i);
- __set_bit(asid2idx(asid), info->map);
+ __set_bit(asid2idx(info, asid), info->map);
reserved_asid(info, i) = asid;
}

@@ -159,7 +159,7 @@ static u64 new_context(struct asid_info *info, struct mm_struct *mm)
u64 generation = atomic64_read(&info->generation);

if (asid != 0) {
- u64 newasid = generation | (asid & ~ASID_MASK);
+ u64 newasid = generation | (asid & ~ASID_MASK(info));

/*
* If our current ASID was active during a rollover, we
@@ -172,7 +172,7 @@ static u64 new_context(struct asid_info *info, 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), info->map))
+ if (!__test_and_set_bit(asid2idx(info, asid), info->map))
return newasid;
}

@@ -183,22 +183,22 @@ static u64 new_context(struct asid_info *info, struct mm_struct *mm)
* a reserved TTBR0 for the init_mm and we allocate ASIDs in even/odd
* pairs.
*/
- asid = find_next_zero_bit(info->map, NUM_USER_ASIDS, cur_idx);
- if (asid != NUM_USER_ASIDS)
+ asid = find_next_zero_bit(info->map, NUM_USER_ASIDS(info), cur_idx);
+ if (asid != NUM_USER_ASIDS(info))
goto set_asid;

/* We're out of ASIDs, so increment the global generation count */
- generation = atomic64_add_return_relaxed(ASID_FIRST_VERSION,
+ generation = atomic64_add_return_relaxed(ASID_FIRST_VERSION(info),
&info->generation);
flush_context(info);

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

set_asid:
__set_bit(asid, info->map);
cur_idx = asid;
- return idx2asid(asid) | generation;
+ return idx2asid(info, asid) | generation;
}

void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
@@ -228,7 +228,7 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
*/
old_active_asid = atomic64_read(&active_asid(info, cpu));
if (old_active_asid &&
- !((asid ^ atomic64_read(&info->generation)) >> asid_bits) &&
+ !((asid ^ atomic64_read(&info->generation)) >> info->bits) &&
atomic64_cmpxchg_relaxed(&active_asid(info, cpu),
old_active_asid, asid))
goto switch_mm_fastpath;
@@ -236,7 +236,7 @@ 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(&info->generation)) >> asid_bits) {
+ if ((asid ^ atomic64_read(&info->generation)) >> info->bits) {
asid = new_context(info, mm);
atomic64_set(&mm->context.id, asid);
}
@@ -272,23 +272,24 @@ static int asids_init(void)
{
struct asid_info *info = &asid_info;

- asid_bits = get_cpu_asid_bits();
+ info->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(&info->generation, ASID_FIRST_VERSION);
- info->map = kcalloc(BITS_TO_LONGS(NUM_USER_ASIDS), sizeof(*info->map),
- GFP_KERNEL);
+ WARN_ON(NUM_USER_ASIDS(info) - 1 <= num_possible_cpus());
+ atomic64_set(&info->generation, ASID_FIRST_VERSION(info));
+ info->map = kcalloc(BITS_TO_LONGS(NUM_USER_ASIDS(info)),
+ sizeof(*info->map), GFP_KERNEL);
if (!info->map)
panic("Failed to allocate bitmap for %lu ASIDs\n",
- NUM_USER_ASIDS);
+ NUM_USER_ASIDS(info));

info->active = &active_asids;
info->reserved = &reserved_asids;

- pr_info("ASID allocator initialised with %lu entries\n", NUM_USER_ASIDS);
+ pr_info("ASID allocator initialised with %lu entries\n",
+ NUM_USER_ASIDS(info));
return 0;
}
early_initcall(asids_init);
--
2.11.0

Next message: Kees Cook: "Re: mount.nfs: Protocol error after upgrade to linux/master"
Previous message: Julien Grall: "[PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending to asid_info"
In reply to: Julien Grall: "[PATCH RFC 04/14] arm64/mm: Move the variable lock and tlb_flush_pending to asid_info"
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