Re: [PATCH RFC 11/14] arm64: Move the ASID allocator code in a separate file

[Guo Ren]

Hi Julien,

You forgot CCing C-SKY folks :P

Move arm asid allocator code in a generic one is a agood idea, I've
made a patchset for C-SKY and test is on processing, See:
https://lore.kernel.org/linux-csky/1560930553-26502-1-git-send-email-guoren@xxxxxxxxxx/

If you plan to seperate it into generic one, I could co-work with you.
Or I'll bring asid code into csky subsystem first and you can cleanup
them later.

Best Regards
 Guo Ren

ML: linux-csky@xxxxxxxxxxxxxxx

On Thu, Jun 6, 2019 at 12:56 AM Julien Grall <julien.grall@xxxxxxx> wrote:
>
> Hi,
>
> I am CCing RISC-V folks to see if there are an interest to share the code.
>
> @RISC-V: I noticed you are discussing about importing a version of ASID
> allocator in RISC-V. At a first look, the code looks quite similar. Would the
> library below helps you?
>
> Cheers,
>
> On 21/03/2019 16:36, Julien Grall wrote:
> > We will want to re-use the ASID allocator in a separate context (e.g
> > allocating VMID). So move the code in a new file.
> >
> > The function asid_check_context has been moved in the header as a static
> > inline function because we want to avoid add a branch when checking if the
> > ASID is still valid.
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> >
> > ---
> >
> > This code will be used in the virt code for allocating VMID. I am not
> > entirely sure where to place it. Lib could potentially be a good place but I
> > am not entirely convinced the algo as it is could be used by other
> > architecture.
> >
> > Looking at x86, it seems that it will not be possible to re-use because
> > the number of PCID (aka ASID) could be smaller than the number of CPUs.
> > See commit message 10af6235e0d327d42e1bad974385197817923dc1 "x86/mm:
> > Implement PCID based optimization: try to preserve old TLB entries using
> > PCI".
> > ---
> >   arch/arm64/include/asm/asid.h |  77 ++++++++++++++
> >   arch/arm64/lib/Makefile       |   2 +
> >   arch/arm64/lib/asid.c         | 185 +++++++++++++++++++++++++++++++++
> >   arch/arm64/mm/context.c       | 235 +-----------------------------------------
> >   4 files changed, 267 insertions(+), 232 deletions(-)
> >   create mode 100644 arch/arm64/include/asm/asid.h
> >   create mode 100644 arch/arm64/lib/asid.c
> >
> > diff --git a/arch/arm64/include/asm/asid.h b/arch/arm64/include/asm/asid.h
> > new file mode 100644
> > index 000000000000..bb62b587f37f
> > --- /dev/null
> > +++ b/arch/arm64/include/asm/asid.h
> > @@ -0,0 +1,77 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef __ASM_ASM_ASID_H
> > +#define __ASM_ASM_ASID_H
> > +
> > +#include <linux/atomic.h>
> > +#include <linux/compiler.h>
> > +#include <linux/cpumask.h>
> > +#include <linux/percpu.h>
> > +#include <linux/spinlock.h>
> > +
> > +struct asid_info
> > +{
> > +     atomic64_t      generation;
> > +     unsigned long   *map;
> > +     atomic64_t __percpu     *active;
> > +     u64 __percpu            *reserved;
> > +     u32                     bits;
> > +     /* Lock protecting the structure */
> > +     raw_spinlock_t          lock;
> > +     /* Which CPU requires context flush on next call */
> > +     cpumask_t               flush_pending;
> > +     /* Number of ASID allocated by context (shift value) */
> > +     unsigned int            ctxt_shift;
> > +     /* Callback to locally flush the context. */
> > +     void                    (*flush_cpu_ctxt_cb)(void);
> > +};
> > +
> > +#define NUM_ASIDS(info)                      (1UL << ((info)->bits))
> > +#define NUM_CTXT_ASIDS(info)         (NUM_ASIDS(info) >> (info)->ctxt_shift)
> > +
> > +#define active_asid(info, cpu)       *per_cpu_ptr((info)->active, cpu)
> > +
> > +void asid_new_context(struct asid_info *info, atomic64_t *pasid,
> > +                   unsigned int cpu);
> > +
> > +/*
> > + * Check the ASID is still valid for the context. If not generate a new ASID.
> > + *
> > + * @pasid: Pointer to the current ASID batch
> > + * @cpu: current CPU ID. Must have been acquired throught get_cpu()
> > + */
> > +static inline void asid_check_context(struct asid_info *info,
> > +                                   atomic64_t *pasid, unsigned int cpu)
> > +{
> > +     u64 asid, old_active_asid;
> > +
> > +     asid = atomic64_read(pasid);
> > +
> > +     /*
> > +      * The memory ordering here is subtle.
> > +      * If our active_asid is non-zero and the ASID matches the current
> > +      * generation, then we update the active_asid entry with a relaxed
> > +      * cmpxchg. Racing with a concurrent rollover means that either:
> > +      *
> > +      * - We get a zero back from the cmpxchg and end up waiting on the
> > +      *   lock. Taking the lock synchronises with the rollover and so
> > +      *   we are forced to see the updated generation.
> > +      *
> > +      * - We get a valid ASID back from the cmpxchg, which means the
> > +      *   relaxed xchg in flush_context will treat us as reserved
> > +      *   because atomic RmWs are totally ordered for a given location.
> > +      */
> > +     old_active_asid = atomic64_read(&active_asid(info, cpu));
> > +     if (old_active_asid &&
> > +         !((asid ^ atomic64_read(&info->generation)) >> info->bits) &&
> > +         atomic64_cmpxchg_relaxed(&active_asid(info, cpu),
> > +                                  old_active_asid, asid))
> > +             return;
> > +
> > +     asid_new_context(info, pasid, cpu);
> > +}
> > +
> > +int asid_allocator_init(struct asid_info *info,
> > +                     u32 bits, unsigned int asid_per_ctxt,
> > +                     void (*flush_cpu_ctxt_cb)(void));
> > +
> > +#endif
> > diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile
> > index 5540a1638baf..720df5ee2aa2 100644
> > --- a/arch/arm64/lib/Makefile
> > +++ b/arch/arm64/lib/Makefile
> > @@ -5,6 +5,8 @@ lib-y         := clear_user.o delay.o copy_from_user.o                \
> >                  memcmp.o strcmp.o strncmp.o strlen.o strnlen.o       \
> >                  strchr.o strrchr.o tishift.o
> >
> > +lib-y                += asid.o
> > +
> >   ifeq ($(CONFIG_KERNEL_MODE_NEON), y)
> >   obj-$(CONFIG_XOR_BLOCKS)    += xor-neon.o
> >   CFLAGS_REMOVE_xor-neon.o    += -mgeneral-regs-only
> > diff --git a/arch/arm64/lib/asid.c b/arch/arm64/lib/asid.c
> > new file mode 100644
> > index 000000000000..72b71bfb32be
> > --- /dev/null
> > +++ b/arch/arm64/lib/asid.c
> > @@ -0,0 +1,185 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Generic ASID allocator.
> > + *
> > + * Based on arch/arm/mm/context.c
> > + *
> > + * Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
> > + * Copyright (C) 2012 ARM Ltd.
> > + */
> > +
> > +#include <linux/slab.h>
> > +
> > +#include <asm/asid.h>
> > +
> > +#define reserved_asid(info, cpu) *per_cpu_ptr((info)->reserved, cpu)
> > +
> > +#define ASID_MASK(info)                      (~GENMASK((info)->bits - 1, 0))
> > +#define ASID_FIRST_VERSION(info)     (1UL << ((info)->bits))
> > +
> > +#define asid2idx(info, asid)         (((asid) & ~ASID_MASK(info)) >> (info)->ctxt_shift)
> > +#define idx2asid(info, idx)          (((idx) << (info)->ctxt_shift) & ~ASID_MASK(info))
> > +
> > +static void flush_context(struct asid_info *info)
> > +{
> > +     int i;
> > +     u64 asid;
> > +
> > +     /* Update the list of reserved ASIDs and the ASID bitmap. */
> > +     bitmap_clear(info->map, 0, NUM_CTXT_ASIDS(info));
> > +
> > +     for_each_possible_cpu(i) {
> > +             asid = atomic64_xchg_relaxed(&active_asid(info, i), 0);
> > +             /*
> > +              * If this CPU has already been through a
> > +              * rollover, but hasn't run another task in
> > +              * the meantime, we must preserve its reserved
> > +              * ASID, as this is the only trace we have of
> > +              * the process it is still running.
> > +              */
> > +             if (asid == 0)
> > +                     asid = reserved_asid(info, i);
> > +             __set_bit(asid2idx(info, asid), info->map);
> > +             reserved_asid(info, i) = asid;
> > +     }
> > +
> > +     /*
> > +      * Queue a TLB invalidation for each CPU to perform on next
> > +      * context-switch
> > +      */
> > +     cpumask_setall(&info->flush_pending);
> > +}
> > +
> > +static bool check_update_reserved_asid(struct asid_info *info, u64 asid,
> > +                                    u64 newasid)
> > +{
> > +     int cpu;
> > +     bool hit = false;
> > +
> > +     /*
> > +      * Iterate over the set of reserved ASIDs looking for a match.
> > +      * If we find one, then we can update our mm to use newasid
> > +      * (i.e. the same ASID in the current generation) but we can't
> > +      * exit the loop early, since we need to ensure that all copies
> > +      * of the old ASID are updated to reflect the mm. Failure to do
> > +      * so could result in us missing the reserved ASID in a future
> > +      * generation.
> > +      */
> > +     for_each_possible_cpu(cpu) {
> > +             if (reserved_asid(info, cpu) == asid) {
> > +                     hit = true;
> > +                     reserved_asid(info, cpu) = newasid;
> > +             }
> > +     }
> > +
> > +     return hit;
> > +}
> > +
> > +static u64 new_context(struct asid_info *info, atomic64_t *pasid)
> > +{
> > +     static u32 cur_idx = 1;
> > +     u64 asid = atomic64_read(pasid);
> > +     u64 generation = atomic64_read(&info->generation);
> > +
> > +     if (asid != 0) {
> > +             u64 newasid = generation | (asid & ~ASID_MASK(info));
> > +
> > +             /*
> > +              * If our current ASID was active during a rollover, we
> > +              * can continue to use it and this was just a false alarm.
> > +              */
> > +             if (check_update_reserved_asid(info, asid, newasid))
> > +                     return newasid;
> > +
> > +             /*
> > +              * We had a valid ASID in a previous life, so try to re-use
> > +              * it if possible.
> > +              */
> > +             if (!__test_and_set_bit(asid2idx(info, asid), info->map))
> > +                     return newasid;
> > +     }
> > +
> > +     /*
> > +      * Allocate a free ASID. If we can't find one, take a note of the
> > +      * currently active ASIDs and mark the TLBs as requiring flushes.  We
> > +      * always count from ASID #2 (index 1), as we use ASID #0 when setting
> > +      * a reserved TTBR0 for the init_mm and we allocate ASIDs in even/odd
> > +      * pairs.
> > +      */
> > +     asid = find_next_zero_bit(info->map, NUM_CTXT_ASIDS(info), cur_idx);
> > +     if (asid != NUM_CTXT_ASIDS(info))
> > +             goto set_asid;
> > +
> > +     /* We're out of ASIDs, so increment the global generation count */
> > +     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_CTXT_ASIDS(info), 1);
> > +
> > +set_asid:
> > +     __set_bit(asid, info->map);
> > +     cur_idx = asid;
> > +     return idx2asid(info, asid) | generation;
> > +}
> > +
> > +/*
> > + * Generate a new ASID for the context.
> > + *
> > + * @pasid: Pointer to the current ASID batch allocated. It will be updated
> > + * with the new ASID batch.
> > + * @cpu: current CPU ID. Must have been acquired through get_cpu()
> > + */
> > +void asid_new_context(struct asid_info *info, atomic64_t *pasid,
> > +                   unsigned int cpu)
> > +{
> > +     unsigned long flags;
> > +     u64 asid;
> > +
> > +     raw_spin_lock_irqsave(&info->lock, flags);
> > +     /* Check that our ASID belongs to the current generation. */
> > +     asid = atomic64_read(pasid);
> > +     if ((asid ^ atomic64_read(&info->generation)) >> info->bits) {
> > +             asid = new_context(info, pasid);
> > +             atomic64_set(pasid, asid);
> > +     }
> > +
> > +     if (cpumask_test_and_clear_cpu(cpu, &info->flush_pending))
> > +             info->flush_cpu_ctxt_cb();
> > +
> > +     atomic64_set(&active_asid(info, cpu), asid);
> > +     raw_spin_unlock_irqrestore(&info->lock, flags);
> > +}
> > +
> > +/*
> > + * Initialize the ASID allocator
> > + *
> > + * @info: Pointer to the asid allocator structure
> > + * @bits: Number of ASIDs available
> > + * @asid_per_ctxt: Number of ASIDs to allocate per-context. ASIDs are
> > + * allocated contiguously for a given context. This value should be a power of
> > + * 2.
> > + */
> > +int asid_allocator_init(struct asid_info *info,
> > +                     u32 bits, unsigned int asid_per_ctxt,
> > +                     void (*flush_cpu_ctxt_cb)(void))
> > +{
> > +     info->bits = bits;
> > +     info->ctxt_shift = ilog2(asid_per_ctxt);
> > +     info->flush_cpu_ctxt_cb = flush_cpu_ctxt_cb;
> > +     /*
> > +      * Expect allocation after rollover to fail if we don't have at least
> > +      * one more ASID than CPUs. ASID #0 is always reserved.
> > +      */
> > +     WARN_ON(NUM_CTXT_ASIDS(info) - 1 <= num_possible_cpus());
> > +     atomic64_set(&info->generation, ASID_FIRST_VERSION(info));
> > +     info->map = kcalloc(BITS_TO_LONGS(NUM_CTXT_ASIDS(info)),
> > +                         sizeof(*info->map), GFP_KERNEL);
> > +     if (!info->map)
> > +             return -ENOMEM;
> > +
> > +     raw_spin_lock_init(&info->lock);
> > +
> > +     return 0;
> > +}
> > diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
> > index 678a57b77c91..95ee7711a2ef 100644
> > --- a/arch/arm64/mm/context.c
> > +++ b/arch/arm64/mm/context.c
> > @@ -22,47 +22,22 @@
> >   #include <linux/slab.h>
> >   #include <linux/mm.h>
> >
> > +#include <asm/asid.h>
> >   #include <asm/cpufeature.h>
> >   #include <asm/mmu_context.h>
> >   #include <asm/smp.h>
> >   #include <asm/tlbflush.h>
> >
> > -struct asid_info
> > -{
> > -     atomic64_t      generation;
> > -     unsigned long   *map;
> > -     atomic64_t __percpu     *active;
> > -     u64 __percpu            *reserved;
> > -     u32                     bits;
> > -     raw_spinlock_t          lock;
> > -     /* Which CPU requires context flush on next call */
> > -     cpumask_t               flush_pending;
> > -     /* Number of ASID allocated by context (shift value) */
> > -     unsigned int            ctxt_shift;
> > -     /* Callback to locally flush the context. */
> > -     void                    (*flush_cpu_ctxt_cb)(void);
> > -} asid_info;
> > -
> > -#define active_asid(info, cpu)       *per_cpu_ptr((info)->active, cpu)
> > -#define reserved_asid(info, cpu) *per_cpu_ptr((info)->reserved, cpu)
> > -
> >   static DEFINE_PER_CPU(atomic64_t, active_asids);
> >   static DEFINE_PER_CPU(u64, reserved_asids);
> >
> > -#define ASID_MASK(info)                      (~GENMASK((info)->bits - 1, 0))
> > -#define NUM_ASIDS(info)                      (1UL << ((info)->bits))
> > -
> > -#define ASID_FIRST_VERSION(info)     NUM_ASIDS(info)
> > -
> >   #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
> >   #define ASID_PER_CONTEXT            2
> >   #else
> >   #define ASID_PER_CONTEXT            1
> >   #endif
> >
> > -#define NUM_CTXT_ASIDS(info)         (NUM_ASIDS(info) >> (info)->ctxt_shift)
> > -#define asid2idx(info, asid)         (((asid) & ~ASID_MASK(info)) >> (info)->ctxt_shift)
> > -#define idx2asid(info, idx)          (((idx) << (info)->ctxt_shift) & ~ASID_MASK(info))
> > +struct asid_info asid_info;
> >
> >   /* Get the ASIDBits supported by the current CPU */
> >   static u32 get_cpu_asid_bits(void)
> > @@ -102,178 +77,6 @@ void verify_cpu_asid_bits(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(info->map, 0, NUM_CTXT_ASIDS(info));
> > -
> > -     for_each_possible_cpu(i) {
> > -             asid = atomic64_xchg_relaxed(&active_asid(info, i), 0);
> > -             /*
> > -              * If this CPU has already been through a
> > -              * rollover, but hasn't run another task in
> > -              * the meantime, we must preserve its reserved
> > -              * ASID, as this is the only trace we have of
> > -              * the process it is still running.
> > -              */
> > -             if (asid == 0)
> > -                     asid = reserved_asid(info, i);
> > -             __set_bit(asid2idx(info, asid), info->map);
> > -             reserved_asid(info, i) = asid;
> > -     }
> > -
> > -     /*
> > -      * Queue a TLB invalidation for each CPU to perform on next
> > -      * context-switch
> > -      */
> > -     cpumask_setall(&info->flush_pending);
> > -}
> > -
> > -static bool check_update_reserved_asid(struct asid_info *info, u64 asid,
> > -                                    u64 newasid)
> > -{
> > -     int cpu;
> > -     bool hit = false;
> > -
> > -     /*
> > -      * Iterate over the set of reserved ASIDs looking for a match.
> > -      * If we find one, then we can update our mm to use newasid
> > -      * (i.e. the same ASID in the current generation) but we can't
> > -      * exit the loop early, since we need to ensure that all copies
> > -      * of the old ASID are updated to reflect the mm. Failure to do
> > -      * so could result in us missing the reserved ASID in a future
> > -      * generation.
> > -      */
> > -     for_each_possible_cpu(cpu) {
> > -             if (reserved_asid(info, cpu) == asid) {
> > -                     hit = true;
> > -                     reserved_asid(info, cpu) = newasid;
> > -             }
> > -     }
> > -
> > -     return hit;
> > -}
> > -
> > -static u64 new_context(struct asid_info *info, atomic64_t *pasid)
> > -{
> > -     static u32 cur_idx = 1;
> > -     u64 asid = atomic64_read(pasid);
> > -     u64 generation = atomic64_read(&info->generation);
> > -
> > -     if (asid != 0) {
> > -             u64 newasid = generation | (asid & ~ASID_MASK(info));
> > -
> > -             /*
> > -              * If our current ASID was active during a rollover, we
> > -              * can continue to use it and this was just a false alarm.
> > -              */
> > -             if (check_update_reserved_asid(info, asid, newasid))
> > -                     return newasid;
> > -
> > -             /*
> > -              * We had a valid ASID in a previous life, so try to re-use
> > -              * it if possible.
> > -              */
> > -             if (!__test_and_set_bit(asid2idx(info, asid), info->map))
> > -                     return newasid;
> > -     }
> > -
> > -     /*
> > -      * Allocate a free ASID. If we can't find one, take a note of the
> > -      * currently active ASIDs and mark the TLBs as requiring flushes.  We
> > -      * always count from ASID #2 (index 1), as we use ASID #0 when setting
> > -      * a reserved TTBR0 for the init_mm and we allocate ASIDs in even/odd
> > -      * pairs.
> > -      */
> > -     asid = find_next_zero_bit(info->map, NUM_CTXT_ASIDS(info), cur_idx);
> > -     if (asid != NUM_CTXT_ASIDS(info))
> > -             goto set_asid;
> > -
> > -     /* We're out of ASIDs, so increment the global generation count */
> > -     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_CTXT_ASIDS(info), 1);
> > -
> > -set_asid:
> > -     __set_bit(asid, info->map);
> > -     cur_idx = asid;
> > -     return idx2asid(info, asid) | generation;
> > -}
> > -
> > -static void asid_new_context(struct asid_info *info, atomic64_t *pasid,
> > -                          unsigned int cpu);
> > -
> > -/*
> > - * Check the ASID is still valid for the context. If not generate a new ASID.
> > - *
> > - * @pasid: Pointer to the current ASID batch
> > - * @cpu: current CPU ID. Must have been acquired throught get_cpu()
> > - */
> > -static void asid_check_context(struct asid_info *info,
> > -                            atomic64_t *pasid, unsigned int cpu)
> > -{
> > -     u64 asid, old_active_asid;
> > -
> > -     asid = atomic64_read(pasid);
> > -
> > -     /*
> > -      * The memory ordering here is subtle.
> > -      * If our active_asid is non-zero and the ASID matches the current
> > -      * generation, then we update the active_asid entry with a relaxed
> > -      * cmpxchg. Racing with a concurrent rollover means that either:
> > -      *
> > -      * - We get a zero back from the cmpxchg and end up waiting on the
> > -      *   lock. Taking the lock synchronises with the rollover and so
> > -      *   we are forced to see the updated generation.
> > -      *
> > -      * - We get a valid ASID back from the cmpxchg, which means the
> > -      *   relaxed xchg in flush_context will treat us as reserved
> > -      *   because atomic RmWs are totally ordered for a given location.
> > -      */
> > -     old_active_asid = atomic64_read(&active_asid(info, cpu));
> > -     if (old_active_asid &&
> > -         !((asid ^ atomic64_read(&info->generation)) >> info->bits) &&
> > -         atomic64_cmpxchg_relaxed(&active_asid(info, cpu),
> > -                                  old_active_asid, asid))
> > -             return;
> > -
> > -     asid_new_context(info, pasid, cpu);
> > -}
> > -
> > -/*
> > - * Generate a new ASID for the context.
> > - *
> > - * @pasid: Pointer to the current ASID batch allocated. It will be updated
> > - * with the new ASID batch.
> > - * @cpu: current CPU ID. Must have been acquired through get_cpu()
> > - */
> > -static void asid_new_context(struct asid_info *info, atomic64_t *pasid,
> > -                          unsigned int cpu)
> > -{
> > -     unsigned long flags;
> > -     u64 asid;
> > -
> > -     raw_spin_lock_irqsave(&info->lock, flags);
> > -     /* Check that our ASID belongs to the current generation. */
> > -     asid = atomic64_read(pasid);
> > -     if ((asid ^ atomic64_read(&info->generation)) >> info->bits) {
> > -             asid = new_context(info, pasid);
> > -             atomic64_set(pasid, asid);
> > -     }
> > -
> > -     if (cpumask_test_and_clear_cpu(cpu, &info->flush_pending))
> > -             info->flush_cpu_ctxt_cb();
> > -
> > -     atomic64_set(&active_asid(info, cpu), asid);
> > -     raw_spin_unlock_irqrestore(&info->lock, flags);
> > -}
> > -
> >   void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
> >   {
> >       if (system_supports_cnp())
> > @@ -305,38 +108,6 @@ static void asid_flush_cpu_ctxt(void)
> >       local_flush_tlb_all();
> >   }
> >
> > -/*
> > - * Initialize the ASID allocator
> > - *
> > - * @info: Pointer to the asid allocator structure
> > - * @bits: Number of ASIDs available
> > - * @asid_per_ctxt: Number of ASIDs to allocate per-context. ASIDs are
> > - * allocated contiguously for a given context. This value should be a power of
> > - * 2.
> > - */
> > -static int asid_allocator_init(struct asid_info *info,
> > -                            u32 bits, unsigned int asid_per_ctxt,
> > -                            void (*flush_cpu_ctxt_cb)(void))
> > -{
> > -     info->bits = bits;
> > -     info->ctxt_shift = ilog2(asid_per_ctxt);
> > -     info->flush_cpu_ctxt_cb = flush_cpu_ctxt_cb;
> > -     /*
> > -      * Expect allocation after rollover to fail if we don't have at least
> > -      * one more ASID than CPUs. ASID #0 is always reserved.
> > -      */
> > -     WARN_ON(NUM_CTXT_ASIDS(info) - 1 <= num_possible_cpus());
> > -     atomic64_set(&info->generation, ASID_FIRST_VERSION(info));
> > -     info->map = kcalloc(BITS_TO_LONGS(NUM_CTXT_ASIDS(info)),
> > -                         sizeof(*info->map), GFP_KERNEL);
> > -     if (!info->map)
> > -             return -ENOMEM;
> > -
> > -     raw_spin_lock_init(&info->lock);
> > -
> > -     return 0;
> > -}
> > -
> >   static int asids_init(void)
> >   {
> >       u32 bits = get_cpu_asid_bits();
> > @@ -344,7 +115,7 @@ static int asids_init(void)
> >       if (!asid_allocator_init(&asid_info, bits, ASID_PER_CONTEXT,
> >                                asid_flush_cpu_ctxt))
> >               panic("Unable to initialize ASID allocator for %lu ASIDs\n",
> > -                   1UL << bits);
> > +                   NUM_ASIDS(&asid_info));
> >
> >       asid_info.active = &active_asids;
> >       asid_info.reserved = &reserved_asids;
> >
>
> --
> Julien Grall
>
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