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Diffstat (limited to 'arch/alpha/include/asm/mmu_context.h')
| -rw-r--r-- | arch/alpha/include/asm/mmu_context.h | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/arch/alpha/include/asm/mmu_context.h b/arch/alpha/include/asm/mmu_context.h new file mode 100644 index 000000000..4eea7c616 --- /dev/null +++ b/arch/alpha/include/asm/mmu_context.h @@ -0,0 +1,259 @@ +/* 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(); +} + +#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 + +#define init_new_context init_new_context +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; +} + +#define enter_lazy_tlb enter_lazy_tlb +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; +} + +#include <asm-generic/mmu_context.h> + +#ifdef __MMU_EXTERN_INLINE +#undef __EXTERN_INLINE +#undef __MMU_EXTERN_INLINE +#endif + +#endif /* __ALPHA_MMU_CONTEXT_H */ |