/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ALPHA_MMU_CONTEXT_H
#define __ALPHA_MMU_CONTEXT_H
/*
* get a new mmu context..
*
* Copyright (C) 1996, Linus Torvalds
*/
#include <linux/mm_types.h>
#include <linux/sched.h>
#include <asm/machvec.h>
#include <asm/compiler.h>
#include <asm-generic/mm_hooks.h>
/*
* Force a context reload. This is needed when we change the page
* table pointer or when we update the ASN of the current process.
*/
/* Don't get into trouble with dueling __EXTERN_INLINEs. */
#ifndef __EXTERN_INLINE
#include <asm/io.h>
#endif
static inline unsigned long
__reload_thread(struct pcb_struct *pcb)
{
register unsigned long a0 __asm__("$16");
register unsigned long v0 __asm__("$0");
a0 = virt_to_phys(pcb);
__asm__ __volatile__(
"call_pal %2 #__reload_thread"
: "=r"(v0), "=r"(a0)
: "i"(PAL_swpctx), "r"(a0)
: "$1", "$22", "$23", "$24", "$25");
return v0;
}
/*
* The maximum ASN's the processor supports. On the EV4 this is 63
* but the PAL-code doesn't actually use this information. On the
* EV5 this is 127, and EV6 has 255.
*
* On the EV4, the ASNs are more-or-less useless anyway, as they are
* only used as an icache tag, not for TB entries. On the EV5 and EV6,
* ASN's also validate the TB entries, and thus make a lot more sense.
*
* The EV4 ASN's don't even match the architecture manual, ugh. And
* I quote: "If a processor implements address space numbers (ASNs),
* and the old PTE has the Address Space Match (ASM) bit clear (ASNs
* in use) and the Valid bit set, then entries can also effectively be
* made coherent by assigning a new, unused ASN to the currently
* running process and not reusing the previous ASN before calling the
* appropriate PALcode routine to invalidate the translation buffer (TB)".
*
* In short, the EV4 has a "kind of" ASN capability, but it doesn't actually
* work correctly and can thus not be used (explaining the lack of PAL-code
* support).
*/
#define EV4_MAX_ASN 63
#define EV5_MAX_ASN 127
#define EV6_MAX_ASN 255
#ifdef CONFIG_ALPHA_GENERIC
# define MAX_ASN (alpha_mv.max_asn)
#else
# ifdef CONFIG_ALPHA_EV4
# define MAX_ASN EV4_MAX_ASN
# elif defined(CONFIG_ALPHA_EV5)
# define MAX_ASN EV5_MAX_ASN
# else
# define MAX_ASN EV6_MAX_ASN
# endif
#endif
/*
* cpu_last_asn(processor):
* 63 0
* +-------------+----------------+--------------+
* | asn version | this processor | hardware asn |
* +-------------+----------------+--------------+
*/
#include <asm/smp.h>
#ifdef CONFIG_SMP
#define cpu_last_asn(cpuid) (cpu_data[cpuid].last_asn)
#else
extern unsigned long last_asn;
#define cpu_last_asn(cpuid) last_asn
#endif /* CONFIG_SMP */
#define WIDTH_HARDWARE_ASN 8
#define ASN_FIRST_VERSION (1UL << WIDTH_HARDWARE_ASN)
#define HARDWARE_ASN_MASK ((1UL << WIDTH_HARDWARE_ASN) - 1)
/*
* NOTE! The way this is set up, the high bits of the "asn_cache" (and
* the "mm->context") are the ASN _version_ code. A version of 0 is
* always considered invalid, so to invalidate another process you only
* need to do "p->mm->context = 0".
*
* If we need more ASN's than the processor has, we invalidate the old
* user TLB's (tbiap()) and start a new ASN version. That will automatically
* force a new asn for any other processes the next time they want to
* run.
*/
#ifndef __EXTERN_INLINE
#define __EXTERN_INLINE extern inline
#define __MMU_EXTERN_INLINE
#endif
extern inline unsigned long
__get_new_mm_context(struct mm_struct *mm, long cpu)
{
unsigned long asn = cpu_last_asn(cpu);
unsigned long next = asn + 1;
if ((asn & HARDWARE_ASN_MASK) >= MAX_ASN) {
tbiap();
imb();
next = (asn & ~HARDWARE_ASN_MASK) + ASN_FIRST_VERSION;
}
cpu_last_asn(cpu) = next;
return next;
}
__EXTERN_INLINE void
ev5_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm,
struct task_struct *next)
{
/* Check if our ASN is of an older version, and thus invalid. */
unsigned long asn;
unsigned long mmc;
long cpu = smp_processor_id();
#ifdef CONFIG_SMP
cpu_data[cpu].asn_lock = 1;
barrier();
#endif
asn = cpu_last_asn(cpu);
mmc = next_mm->context[cpu];
if ((mmc ^ asn) & ~HARDWARE_ASN_MASK) {
mmc = __get_new_mm_context(next_mm, cpu);
next_mm->context[cpu] = mmc;
}
#ifdef CONFIG_SMP
else
cpu_data[cpu].need_new_asn = 1;
#endif
/* Always update the PCB ASN. Another thread may have allocated
a new mm->context (via flush_tlb_mm) without the ASN serial
number wrapping. We have no way to detect when this is needed. */
task_thread_info(next)->pcb.asn = mmc & HARDWARE_ASN_MASK;
}
__EXTERN_INLINE void
ev4_switch_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm,
struct task_struct *next)
{
/* As described, ASN's are broken for TLB usage. But we can
optimize for switching between threads -- if the mm is
unchanged from current we needn't flush. */
/* ??? May not be needed because EV4 PALcode recognizes that
ASN's are broken and does a tbiap itself on swpctx, under
the "Must set ASN or flush" rule. At least this is true
for a 1992 SRM, reports Joseph Martin (jmartin@hlo.dec.com).
I'm going to leave this here anyway, just to Be Sure. -- r~ */
if (prev_mm != next_mm)
tbiap();
/* Do continue to allocate ASNs, because we can still use them
to avoid flushing the icache. */
ev5_switch_mm(prev_mm, next_mm, next);
}
extern void __load_new_mm_context(struct mm_struct *);
#ifdef CONFIG_SMP
#define check_mmu_context() \
do { \
int cpu = smp_processor_id(); \
cpu_data[cpu].asn_lock = 0; \
barrier(); \
if (cpu_data[cpu].need_new_asn) { \
struct mm_struct * mm = current->active_mm; \
cpu_data[cpu].need_new_asn = 0; \
if (!mm->context[cpu]) \
__load_new_mm_context(mm); \
} \
} while(0)
#else
#define check_mmu_context() do { } while(0)
#endif
__EXTERN_INLINE void
ev5_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm)
{
__load_new_mm_context(next_mm);
}
__EXTERN_INLINE void
ev4_activate_mm(struct mm_struct *prev_mm, struct mm_struct *next_mm)
{
__load_new_mm_context(next_mm);
tbiap();
}
#define deactivate_mm(tsk,mm) do { } while (0)
#ifdef CONFIG_ALPHA_GENERIC
# define switch_mm(a,b,c) alpha_mv.mv_switch_mm((a),(b),(c))
# define activate_mm(x,y) alpha_mv.mv_activate_mm((x),(y))
#else
# ifdef CONFIG_ALPHA_EV4
# define switch_mm(a,b,c) ev4_switch_mm((a),(b),(c))
# define activate_mm(x,y) ev4_activate_mm((x),(y))
# else
# define switch_mm(a,b,c) ev5_switch_mm((a),(b),(c))
# define activate_mm(x,y) ev5_activate_mm((x),(y))
# endif
#endif
static inline int
init_new_context(struct task_struct *tsk, struct mm_struct *mm)
{
int i;
for_each_online_cpu(i)
mm->context[i] = 0;
if (tsk != current)
task_thread_info(tsk)->pcb.ptbr
= ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
return 0;
}
extern inline void
destroy_context(struct mm_struct *mm)
{
/* Nothing to do. */
}
static inline void
enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
task_thread_info(tsk)->pcb.ptbr
= ((unsigned long)mm->pgd - IDENT_ADDR) >> PAGE_SHIFT;
}
#ifdef __MMU_EXTERN_INLINE
#undef __EXTERN_INLINE
#undef __MMU_EXTERN_INLINE
#endif
#endif /* __ALPHA_MMU_CONTEXT_H */
