arch/xtensa/include/asm/mmu_context.h

Source file repositories/reference/linux-study-clean/arch/xtensa/include/asm/mmu_context.h

File Facts

System
Linux kernel
Corpus path
arch/xtensa/include/asm/mmu_context.h
Extension
.h
Size
3624 bytes
Lines
155
Domain
Architecture Layer
Bucket
arch/xtensa
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _XTENSA_MMU_CONTEXT_H
#define _XTENSA_MMU_CONTEXT_H

#ifndef CONFIG_MMU
#include <asm/nommu_context.h>
#else

#include <linux/stringify.h>
#include <linux/sched.h>
#include <linux/mm_types.h>
#include <linux/pgtable.h>

#include <asm/vectors.h>

#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm-generic/mm_hooks.h>
#include <asm-generic/percpu.h>

#if (XCHAL_HAVE_TLBS != 1)
# error "Linux must have an MMU!"
#endif

DECLARE_PER_CPU(unsigned long, asid_cache);
#define cpu_asid_cache(cpu) per_cpu(asid_cache, cpu)

/*
 * NO_CONTEXT is the invalid ASID value that we don't ever assign to
 * any user or kernel context.  We use the reserved values in the
 * ASID_INSERT macro below.
 *
 * 0 invalid
 * 1 kernel
 * 2 reserved
 * 3 reserved
 * 4...255 available
 */

#define NO_CONTEXT	0
#define ASID_USER_FIRST	4
#define ASID_MASK	((1 << XCHAL_MMU_ASID_BITS) - 1)
#define ASID_INSERT(x)	(0x03020001 | (((x) & ASID_MASK) << 8))

void init_mmu(void);
void init_kio(void);

static inline void set_rasid_register (unsigned long val)
{
	__asm__ __volatile__ (" wsr %0, rasid\n\t"
			      " isync\n" : : "a" (val));
}

static inline unsigned long get_rasid_register (void)
{
	unsigned long tmp;
	__asm__ __volatile__ (" rsr %0, rasid\n\t" : "=a" (tmp));
	return tmp;
}

static inline void get_new_mmu_context(struct mm_struct *mm, unsigned int cpu)
{
	unsigned long asid = cpu_asid_cache(cpu);
	if ((++asid & ASID_MASK) == 0) {
		/*
		 * Start new asid cycle; continue counting with next
		 * incarnation bits; skipping over 0, 1, 2, 3.
		 */
		local_flush_tlb_all();
		asid += ASID_USER_FIRST;
	}
	cpu_asid_cache(cpu) = asid;
	mm->context.asid[cpu] = asid;
	mm->context.cpu = cpu;
}

static inline void get_mmu_context(struct mm_struct *mm, unsigned int cpu)
{
	/*
	 * Check if our ASID is of an older version and thus invalid.
	 */

	if (mm) {
		unsigned long asid = mm->context.asid[cpu];

		if (asid == NO_CONTEXT ||
				((asid ^ cpu_asid_cache(cpu)) & ~ASID_MASK))
			get_new_mmu_context(mm, cpu);
	}
}

Annotation

Implementation Notes