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/*
* This file contains the routines for initializing the MMU
* on the 8xx series of chips.
* -- christophe
*
* Derived from arch/powerpc/mm/40x_mmu.c:
*
* 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 <linux/memblock.h>
#include <linux/mmu_context.h>
#include <asm/fixmap.h>
#include <asm/code-patching.h>
#include "mmu_decl.h"
#define IMMR_SIZE (FIX_IMMR_SIZE << PAGE_SHIFT)
extern int __map_without_ltlbs;
static unsigned long block_mapped_ram;
/*
* Return PA for this VA if it is in an area mapped with LTLBs.
* Otherwise, returns 0
*/
phys_addr_t v_block_mapped(unsigned long va)
{
unsigned long p = PHYS_IMMR_BASE;
if (__map_without_ltlbs)
return 0;
if (va >= VIRT_IMMR_BASE && va < VIRT_IMMR_BASE + IMMR_SIZE)
return p + va - VIRT_IMMR_BASE;
if (va >= PAGE_OFFSET && va < PAGE_OFFSET + block_mapped_ram)
return __pa(va);
return 0;
}
/*
* Return VA for a given PA mapped with LTLBs or 0 if not mapped
*/
unsigned long p_block_mapped(phys_addr_t pa)
{
unsigned long p = PHYS_IMMR_BASE;
if (__map_without_ltlbs)
return 0;
if (pa >= p && pa < p + IMMR_SIZE)
return VIRT_IMMR_BASE + pa - p;
if (pa < block_mapped_ram)
return (unsigned long)__va(pa);
return 0;
}
#define LARGE_PAGE_SIZE_8M (1<<23)
/*
* MMU_init_hw does the chip-specific initialization of the MMU hardware.
*/
void __init MMU_init_hw(void)
{
/* PIN up to the 3 first 8Mb after IMMR in DTLB table */
if (IS_ENABLED(CONFIG_PIN_TLB_DATA)) {
unsigned long ctr = mfspr(SPRN_MD_CTR) & 0xfe000000;
unsigned long flags = 0xf0 | MD_SPS16K | _PAGE_SH | _PAGE_DIRTY;
int i = IS_ENABLED(CONFIG_PIN_TLB_IMMR) ? 29 : 28;
unsigned long addr = 0;
unsigned long mem = total_lowmem;
for (; i < 32 && mem >= LARGE_PAGE_SIZE_8M; i++) {
mtspr(SPRN_MD_CTR, ctr | (i << 8));
mtspr(SPRN_MD_EPN, (unsigned long)__va(addr) | MD_EVALID);
mtspr(SPRN_MD_TWC, MD_PS8MEG | MD_SVALID);
mtspr(SPRN_MD_RPN, addr | flags | _PAGE_PRESENT);
addr += LARGE_PAGE_SIZE_8M;
mem -= LARGE_PAGE_SIZE_8M;
}
}
}
static void __init mmu_mapin_immr(void)
{
unsigned long p = PHYS_IMMR_BASE;
unsigned long v = VIRT_IMMR_BASE;
int offset;
for (offset = 0; offset < IMMR_SIZE; offset += PAGE_SIZE)
map_kernel_page(v + offset, p + offset, PAGE_KERNEL_NCG);
}
static void mmu_patch_cmp_limit(s32 *site, unsigned long mapped)
{
modify_instruction_site(site, 0xffff, (unsigned long)__va(mapped) >> 16);
}
static void mmu_patch_addis(s32 *site, long simm)
{
unsigned int instr = *(unsigned int *)patch_site_addr(site);
instr &= 0xffff0000;
instr |= ((unsigned long)simm) >> 16;
patch_instruction_site(site, instr);
}
unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
{
unsigned long mapped;
if (__map_without_ltlbs) {
mapped = 0;
mmu_mapin_immr();
if (!IS_ENABLED(CONFIG_PIN_TLB_IMMR))
patch_instruction_site(&patch__dtlbmiss_immr_jmp, PPC_INST_NOP);
if (!IS_ENABLED(CONFIG_PIN_TLB_TEXT))
mmu_patch_cmp_limit(&patch__itlbmiss_linmem_top, 0);
} else {
mapped = top & ~(LARGE_PAGE_SIZE_8M - 1);
if (!IS_ENABLED(CONFIG_PIN_TLB_TEXT))
mmu_patch_cmp_limit(&patch__itlbmiss_linmem_top,
_ALIGN(__pa(_einittext), 8 << 20));
}
mmu_patch_cmp_limit(&patch__dtlbmiss_linmem_top, mapped);
mmu_patch_cmp_limit(&patch__fixupdar_linmem_top, mapped);
/* If the size of RAM is not an exact power of two, we may not
* have covered RAM in its entirety with 8 MiB
* pages. Consequently, restrict the top end of RAM currently
* allocable so that calls to the MEMBLOCK to allocate PTEs for "tail"
* coverage with normal-sized pages (or other reasons) do not
* attempt to allocate outside the allowed range.
*/
if (mapped)
memblock_set_current_limit(mapped);
block_mapped_ram = mapped;
return mapped;
}
void mmu_mark_initmem_nx(void)
{
if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX) && CONFIG_ETEXT_SHIFT < 23)
mmu_patch_addis(&patch__itlbmiss_linmem_top8,
-((long)_etext & ~(LARGE_PAGE_SIZE_8M - 1)));
if (!IS_ENABLED(CONFIG_PIN_TLB_TEXT))
mmu_patch_cmp_limit(&patch__itlbmiss_linmem_top, __pa(_etext));
}
#ifdef CONFIG_STRICT_KERNEL_RWX
void mmu_mark_rodata_ro(void)
{
if (CONFIG_DATA_SHIFT < 23)
mmu_patch_addis(&patch__dtlbmiss_romem_top8,
-__pa(((unsigned long)_sinittext) &
~(LARGE_PAGE_SIZE_8M - 1)));
mmu_patch_addis(&patch__dtlbmiss_romem_top, -__pa(_sinittext));
}
#endif
void __init setup_initial_memory_limit(phys_addr_t first_memblock_base,
phys_addr_t first_memblock_size)
{
/* We don't currently support the first MEMBLOCK not mapping 0
* physical on those processors
*/
BUG_ON(first_memblock_base != 0);
/* 8xx can only access 32MB at the moment */
memblock_set_current_limit(min_t(u64, first_memblock_size, 0x02000000));
}
/*
* Set up to use a given MMU context.
* id is context number, pgd is PGD pointer.
*
* We place the physical address of the new task page directory loaded
* into the MMU base register, and set the ASID compare register with
* the new "context."
*/
void set_context(unsigned long id, pgd_t *pgd)
{
s16 offset = (s16)(__pa(swapper_pg_dir));
/* Context switch the PTE pointer for the Abatron BDI2000.
* The PGDIR is passed as second argument.
*/
if (IS_ENABLED(CONFIG_BDI_SWITCH))
abatron_pteptrs[1] = pgd;
/* Register M_TWB will contain base address of level 1 table minus the
* lower part of the kernel PGDIR base address, so that all accesses to
* level 1 table are done relative to lower part of kernel PGDIR base
* address.
*/
mtspr(SPRN_M_TWB, __pa(pgd) - offset);
/* Update context */
mtspr(SPRN_M_CASID, id - 1);
/* sync */
mb();
}
void flush_instruction_cache(void)
{
isync();
mtspr(SPRN_IC_CST, IDC_INVALL);
isync();
}
#ifdef CONFIG_PPC_KUEP
void __init setup_kuep(bool disabled)
{
if (disabled)
return;
pr_info("Activating Kernel Userspace Execution Prevention\n");
mtspr(SPRN_MI_AP, MI_APG_KUEP);
}
#endif
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