android_kernel_xiaomi_sm8350/arch/powerpc/mm/stab.c
Paul Mackerras 1189be6508 [POWERPC] Use 1TB segments
This makes the kernel use 1TB segments for all kernel mappings and for
user addresses of 1TB and above, on machines which support them
(currently POWER5+, POWER6 and PA6T).

We detect that the machine supports 1TB segments by looking at the
ibm,processor-segment-sizes property in the device tree.

We don't currently use 1TB segments for user addresses < 1T, since
that would effectively prevent 32-bit processes from using huge pages
unless we also had a way to revert to using 256MB segments.  That
would be possible but would involve extra complications (such as
keeping track of which segment size was used when HPTEs were inserted)
and is not addressed here.

Parts of this patch were originally written by Ben Herrenschmidt.

Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-10-12 14:05:17 +10:00

285 lines
7.3 KiB
C

/*
* PowerPC64 Segment Translation Support.
*
* Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
* Copyright (c) 2001 Dave Engebretsen
*
* Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/paca.h>
#include <asm/cputable.h>
#include <asm/lmb.h>
#include <asm/abs_addr.h>
#include <asm/firmware.h>
struct stab_entry {
unsigned long esid_data;
unsigned long vsid_data;
};
#define NR_STAB_CACHE_ENTRIES 8
DEFINE_PER_CPU(long, stab_cache_ptr);
DEFINE_PER_CPU(long, stab_cache[NR_STAB_CACHE_ENTRIES]);
/*
* Create a segment table entry for the given esid/vsid pair.
*/
static int make_ste(unsigned long stab, unsigned long esid, unsigned long vsid)
{
unsigned long esid_data, vsid_data;
unsigned long entry, group, old_esid, castout_entry, i;
unsigned int global_entry;
struct stab_entry *ste, *castout_ste;
unsigned long kernel_segment = (esid << SID_SHIFT) >= PAGE_OFFSET;
vsid_data = vsid << STE_VSID_SHIFT;
esid_data = esid << SID_SHIFT | STE_ESID_KP | STE_ESID_V;
if (! kernel_segment)
esid_data |= STE_ESID_KS;
/* Search the primary group first. */
global_entry = (esid & 0x1f) << 3;
ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
/* Find an empty entry, if one exists. */
for (group = 0; group < 2; group++) {
for (entry = 0; entry < 8; entry++, ste++) {
if (!(ste->esid_data & STE_ESID_V)) {
ste->vsid_data = vsid_data;
eieio();
ste->esid_data = esid_data;
return (global_entry | entry);
}
}
/* Now search the secondary group. */
global_entry = ((~esid) & 0x1f) << 3;
ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
}
/*
* Could not find empty entry, pick one with a round robin selection.
* Search all entries in the two groups.
*/
castout_entry = get_paca()->stab_rr;
for (i = 0; i < 16; i++) {
if (castout_entry < 8) {
global_entry = (esid & 0x1f) << 3;
ste = (struct stab_entry *)(stab | ((esid & 0x1f) << 7));
castout_ste = ste + castout_entry;
} else {
global_entry = ((~esid) & 0x1f) << 3;
ste = (struct stab_entry *)(stab | (((~esid) & 0x1f) << 7));
castout_ste = ste + (castout_entry - 8);
}
/* Dont cast out the first kernel segment */
if ((castout_ste->esid_data & ESID_MASK) != PAGE_OFFSET)
break;
castout_entry = (castout_entry + 1) & 0xf;
}
get_paca()->stab_rr = (castout_entry + 1) & 0xf;
/* Modify the old entry to the new value. */
/* Force previous translations to complete. DRENG */
asm volatile("isync" : : : "memory");
old_esid = castout_ste->esid_data >> SID_SHIFT;
castout_ste->esid_data = 0; /* Invalidate old entry */
asm volatile("sync" : : : "memory"); /* Order update */
castout_ste->vsid_data = vsid_data;
eieio(); /* Order update */
castout_ste->esid_data = esid_data;
asm volatile("slbie %0" : : "r" (old_esid << SID_SHIFT));
/* Ensure completion of slbie */
asm volatile("sync" : : : "memory");
return (global_entry | (castout_entry & 0x7));
}
/*
* Allocate a segment table entry for the given ea and mm
*/
static int __ste_allocate(unsigned long ea, struct mm_struct *mm)
{
unsigned long vsid;
unsigned char stab_entry;
unsigned long offset;
/* Kernel or user address? */
if (is_kernel_addr(ea)) {
vsid = get_kernel_vsid(ea, MMU_SEGSIZE_256M);
} else {
if ((ea >= TASK_SIZE_USER64) || (! mm))
return 1;
vsid = get_vsid(mm->context.id, ea, MMU_SEGSIZE_256M);
}
stab_entry = make_ste(get_paca()->stab_addr, GET_ESID(ea), vsid);
if (!is_kernel_addr(ea)) {
offset = __get_cpu_var(stab_cache_ptr);
if (offset < NR_STAB_CACHE_ENTRIES)
__get_cpu_var(stab_cache[offset++]) = stab_entry;
else
offset = NR_STAB_CACHE_ENTRIES+1;
__get_cpu_var(stab_cache_ptr) = offset;
/* Order update */
asm volatile("sync":::"memory");
}
return 0;
}
int ste_allocate(unsigned long ea)
{
return __ste_allocate(ea, current->mm);
}
/*
* Do the segment table work for a context switch: flush all user
* entries from the table, then preload some probably useful entries
* for the new task
*/
void switch_stab(struct task_struct *tsk, struct mm_struct *mm)
{
struct stab_entry *stab = (struct stab_entry *) get_paca()->stab_addr;
struct stab_entry *ste;
unsigned long offset = __get_cpu_var(stab_cache_ptr);
unsigned long pc = KSTK_EIP(tsk);
unsigned long stack = KSTK_ESP(tsk);
unsigned long unmapped_base;
/* Force previous translations to complete. DRENG */
asm volatile("isync" : : : "memory");
if (offset <= NR_STAB_CACHE_ENTRIES) {
int i;
for (i = 0; i < offset; i++) {
ste = stab + __get_cpu_var(stab_cache[i]);
ste->esid_data = 0; /* invalidate entry */
}
} else {
unsigned long entry;
/* Invalidate all entries. */
ste = stab;
/* Never flush the first entry. */
ste += 1;
for (entry = 1;
entry < (HW_PAGE_SIZE / sizeof(struct stab_entry));
entry++, ste++) {
unsigned long ea;
ea = ste->esid_data & ESID_MASK;
if (!is_kernel_addr(ea)) {
ste->esid_data = 0;
}
}
}
asm volatile("sync; slbia; sync":::"memory");
__get_cpu_var(stab_cache_ptr) = 0;
/* Now preload some entries for the new task */
if (test_tsk_thread_flag(tsk, TIF_32BIT))
unmapped_base = TASK_UNMAPPED_BASE_USER32;
else
unmapped_base = TASK_UNMAPPED_BASE_USER64;
__ste_allocate(pc, mm);
if (GET_ESID(pc) == GET_ESID(stack))
return;
__ste_allocate(stack, mm);
if ((GET_ESID(pc) == GET_ESID(unmapped_base))
|| (GET_ESID(stack) == GET_ESID(unmapped_base)))
return;
__ste_allocate(unmapped_base, mm);
/* Order update */
asm volatile("sync" : : : "memory");
}
/*
* Allocate segment tables for secondary CPUs. These must all go in
* the first (bolted) segment, so that do_stab_bolted won't get a
* recursive segment miss on the segment table itself.
*/
void __init stabs_alloc(void)
{
int cpu;
if (cpu_has_feature(CPU_FTR_SLB))
return;
for_each_possible_cpu(cpu) {
unsigned long newstab;
if (cpu == 0)
continue; /* stab for CPU 0 is statically allocated */
newstab = lmb_alloc_base(HW_PAGE_SIZE, HW_PAGE_SIZE,
1<<SID_SHIFT);
newstab = (unsigned long)__va(newstab);
memset((void *)newstab, 0, HW_PAGE_SIZE);
paca[cpu].stab_addr = newstab;
paca[cpu].stab_real = virt_to_abs(newstab);
printk(KERN_INFO "Segment table for CPU %d at 0x%lx "
"virtual, 0x%lx absolute\n",
cpu, paca[cpu].stab_addr, paca[cpu].stab_real);
}
}
/*
* Build an entry for the base kernel segment and put it into
* the segment table or SLB. All other segment table or SLB
* entries are faulted in.
*/
void stab_initialize(unsigned long stab)
{
unsigned long vsid = get_kernel_vsid(PAGE_OFFSET, MMU_SEGSIZE_256M);
unsigned long stabreal;
asm volatile("isync; slbia; isync":::"memory");
make_ste(stab, GET_ESID(PAGE_OFFSET), vsid);
/* Order update */
asm volatile("sync":::"memory");
/* Set ASR */
stabreal = get_paca()->stab_real | 0x1ul;
#ifdef CONFIG_PPC_ISERIES
if (firmware_has_feature(FW_FEATURE_ISERIES)) {
HvCall1(HvCallBaseSetASR, stabreal);
return;
}
#endif /* CONFIG_PPC_ISERIES */
mtspr(SPRN_ASR, stabreal);
}