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powerpc/booke: Use power-of-two mappings in 64-bit pmap_mapdev

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Summary:
This reduces the precious TLB1 entry consumption (64 possible in
existing 64-bit cores), by adjusting the size and alignment of a device
mapping to a power of 2, to encompass the full mapping and its
surroundings.

One caveat with this: If a mapping really is smaller than a power of 2,
it's possible to get a machine check or hang if the 'missing' physical
space is accessed.  In practice this should not be an issue for users,
as devices overwhelmingly have physical spaces on power-of-two sizes and
alignments, and any design that includes devices which don't follow this
can be addressed by undefining the POW2_MAPPINGS guard.

Reviewed by:	bdragon
Differential Revision: https://reviews.freebsd.org/D24248
This commit is contained in:
Justin Hibbits 2020-04-11 00:17:55 +00:00
parent d7c0543ff8
commit 69e8f478d5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=359793
1 changed files with 49 additions and 4 deletions
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53
sys/powerpc/booke/pmap.c
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@ -128,6 +128,10 @@ __FBSDID("$FreeBSD$");
#include "mmu_if.h"
#define SPARSE_MAPDEV
/* Use power-of-two mappings in mmu_booke_mapdev(), to save entries. */
#define POW2_MAPPINGS
#ifdef DEBUG
#define debugf(fmt, args...) printf(fmt, ##args)
#else
@ -2211,6 +2215,8 @@ tlb1_find_pa(vm_paddr_t pa, tlb_entry_t *e)
for (i = 0; i < TLB1_ENTRIES; i++) {
tlb1_read_entry(e, i);
if ((e->mas1 & MAS1_VALID) == 0)
continue;
if (e->phys == pa)
return (i);
}
return (-1);
@ -2224,7 +2230,7 @@ mmu_booke_mapdev_attr(mmu_t mmu, vm_paddr_t pa, vm_size_t size, vm_memattr_t ma)
#ifndef __powerpc64__
uintptr_t tmpva;
#endif
uintptr_t va;
uintptr_t va, retva;
vm_size_t sz;
int i;
int wimge;
@ -2245,7 +2251,7 @@ mmu_booke_mapdev_attr(mmu_t mmu, vm_paddr_t pa, vm_size_t size, vm_memattr_t ma)
if (tmppa >= e.phys && tmppa < e.phys + e.size) {
va = e.virt + (pa - e.phys);
tmppa = e.phys + e.size;
sz -= MIN(sz, e.size);
sz -= MIN(sz, e.size - (pa - e.phys));
while (sz > 0 && (i = tlb1_find_pa(tmppa, &e)) != -1) {
if (wimge != (e.mas2 & (MAS2_WIMGE_MASK & ~_TLB_ENTRY_SHARED)))
break;
@ -2264,6 +2270,25 @@ mmu_booke_mapdev_attr(mmu_t mmu, vm_paddr_t pa, vm_size_t size, vm_memattr_t ma)
KASSERT(pa < VM_MAPDEV_PA_MAX,
("Unsupported physical address! %lx", pa));
va = VM_MAPDEV_BASE + pa;
retva = va;
#ifdef POW2_MAPPINGS
/*
* Align the mapping to a power of 2 size, taking into account that we
* may need to increase the size multiple times to satisfy the size and
* alignment requirements.
*
* This works in the general case because it's very rare (near never?)
* to have different access properties (WIMG) within a single
* power-of-two region. If a design does call for that, POW2_MAPPINGS
* can be undefined, and exact mappings will be used instead.
*/
sz = size;
size = roundup2(size, 1 << ilog2(size));
while (rounddown2(va, size) + size < va + sz)
size <<= 1;
va = rounddown2(va, size);
pa = rounddown2(pa, size);
#endif
#else
/*
* The device mapping area is between VM_MAXUSER_ADDRESS and
@ -2288,14 +2313,15 @@ mmu_booke_mapdev_attr(mmu_t mmu, vm_paddr_t pa, vm_size_t size, vm_memattr_t ma)
sz = sz ? min(roundup(sz + 3, 4), flsl(size) - 1) : flsl(size) - 1;
va = roundup(tlb1_map_base, 1 << sz) | (((1 << sz) - 1) & pa);
} while (!atomic_cmpset_int(&tlb1_map_base, tmpva, va + size));
va = atomic_fetchadd_int(&tlb1_map_base, size);
#endif
va = atomic_fetchadd_int(&tlb1_map_base, size);
retva = va;
#endif
if (tlb1_mapin_region(va, pa, size, tlb_calc_wimg(pa, ma)) != size)
return (NULL);
return ((void *)va);
return ((void *)retva);
}
/*
@ -2583,6 +2609,24 @@ tlb1_find_free(void)
return (-1);
}
static void
tlb1_purge_va_range(vm_offset_t va, vm_size_t size)
{
tlb_entry_t e;
int i;
for (i = 0; i < TLB1_ENTRIES; i++) {
tlb1_read_entry(&e, i);
if ((e.mas1 & MAS1_VALID) == 0)
continue;
if ((e.mas2 & MAS2_EPN_MASK) >= va &&
(e.mas2 & MAS2_EPN_MASK) < va + size) {
mtspr(SPR_MAS1, e.mas1 & ~MAS1_VALID);
__asm __volatile("isync; tlbwe; isync; msync");
}
}
}
static void
tlb1_write_entry_int(void *arg)
{
@ -2591,6 +2635,7 @@ tlb1_write_entry_int(void *arg)
idx = args->idx;
if (idx == -1) {
tlb1_purge_va_range(args->e->virt, args->e->size);
idx = tlb1_find_free();
if (idx == -1)
panic("No free TLB1 entries!\n");