[PATCH] Use 64k pages without needing cache-inhibited large pages
Paul Mackerras
paulus at samba.org
Tue Jun 13 13:39:49 EST 2006
Some POWER5+ machines can do 64k hardware pages for normal memory but
not for cache-inhibited pages. This patch lets us use 64k hardware
pages for most user processes on such machines (assuming the kernel
has been configured with CONFIG_PPC_64K_PAGES=y). User processes
start out using 64k pages and get switched to 4k pages if they use any
non-cacheable mappings.
With this, we use 64k pages for the vmalloc region and 4k pages for
the imalloc region. If anything creates a non-cacheable mapping in
the vmalloc region, the vmalloc region will get switched to 4k pages.
I don't know of any driver other than the DRM that would do this,
though, and these machines don't have AGP.
When a region gets switched from 64k pages to 4k pages, we do not have
to clear out all the 64k HPTEs from the hash table immediately. We
use the _PAGE_COMBO bit in the Linux PTE to indicate whether the page
was hashed in as a 64k page or a set of 4k pages. If hash_page is
trying to insert a 4k page for a Linux PTE and it sees that it has
already been inserted as a 64k page, it first invalidates the 64k HPTE
before inserting the 4k HPTE. The hash invalidation routines also use
the _PAGE_COMBO bit, to determine whether to look for a 64k HPTE or a
set of 4k HPTEs to remove. With those two changes, we can tolerate a
mix of 4k and 64k HPTEs in the hash table, and they will all get
removed when the address space is torn down.
Signed-off-by: Paul Mackerras <paulus at samba.org>
---
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index aa0486d..ff29405 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -122,6 +122,8 @@ #ifdef CONFIG_PPC64
DEFINE(PACASLBCACHE, offsetof(struct paca_struct, slb_cache));
DEFINE(PACASLBCACHEPTR, offsetof(struct paca_struct, slb_cache_ptr));
DEFINE(PACACONTEXTID, offsetof(struct paca_struct, context.id));
+ DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct, context.sllp));
+ DEFINE(PACAVMALLOCSLLP, offsetof(struct paca_struct, vmalloc_sllp));
#ifdef CONFIG_HUGETLB_PAGE
DEFINE(PACALOWHTLBAREAS, offsetof(struct paca_struct, context.low_htlb_areas));
DEFINE(PACAHIGHHTLBAREAS, offsetof(struct paca_struct, context.high_htlb_areas));
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 969f4ab..d77d24a 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -948,7 +948,10 @@ static struct ibm_pa_feature {
{CPU_FTR_CTRL, 0, 0, 3, 0},
{CPU_FTR_NOEXECUTE, 0, 0, 6, 0},
{CPU_FTR_NODSISRALIGN, 0, 1, 1, 1},
+#if 0
+ /* put this back once we know how to test if firmware does 64k IO */
{CPU_FTR_CI_LARGE_PAGE, 0, 1, 2, 0},
+#endif
};
static void __init check_cpu_pa_features(unsigned long node)
diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S
index 106fba3..52e9142 100644
--- a/arch/powerpc/mm/hash_low_64.S
+++ b/arch/powerpc/mm/hash_low_64.S
@@ -369,6 +369,7 @@ _GLOBAL(__hash_page_4K)
rlwinm r30,r4,32-9+7,31-7,31-7 /* _PAGE_RW -> _PAGE_DIRTY */
or r30,r30,r31
ori r30,r30,_PAGE_BUSY | _PAGE_ACCESSED | _PAGE_HASHPTE
+ oris r30,r30,_PAGE_COMBO at h
/* Write the linux PTE atomically (setting busy) */
stdcx. r30,0,r6
bne- 1b
@@ -428,6 +429,14 @@ END_FTR_SECTION(CPU_FTR_NOEXECUTE|CPU_FT
andi. r0,r31,_PAGE_HASHPTE
li r26,0 /* Default hidx */
beq htab_insert_pte
+
+ /*
+ * Check if the pte was already inserted into the hash table
+ * as a 64k HW page, and invalidate the 64k HPTE if so.
+ */
+ andis. r0,r31,_PAGE_COMBO at h
+ beq htab_inval_old_hpte
+
ld r6,STK_PARM(r6)(r1)
ori r26,r6,0x8000 /* Load the hidx mask */
ld r26,0(r26)
@@ -498,6 +507,19 @@ _GLOBAL(htab_call_hpte_remove)
/* Try all again */
b htab_insert_pte
+ /*
+ * Call out to C code to invalidate an 64k HW HPTE that is
+ * useless now that the segment has been switched to 4k pages.
+ */
+htab_inval_old_hpte:
+ mr r3,r29 /* virtual addr */
+ mr r4,r31 /* PTE.pte */
+ li r5,0 /* PTE.hidx */
+ li r6,MMU_PAGE_64K /* psize */
+ ld r7,STK_PARM(r8)(r1) /* local */
+ bl .flush_hash_page
+ b htab_insert_pte
+
htab_bail_ok:
li r3,0
b htab_bail
@@ -638,6 +660,12 @@ _GLOBAL(__hash_page_64K)
* is changing this PTE anyway and might hash it.
*/
bne- ht64_bail_ok
+BEGIN_FTR_SECTION
+ /* Check if PTE has the cache-inhibit bit set */
+ andi. r0,r31,_PAGE_NO_CACHE
+ /* If so, bail out and refault as a 4k page */
+ bne- ht64_bail_ok
+END_FTR_SECTION_IFCLR(CPU_FTR_CI_LARGE_PAGE)
/* Prepare new PTE value (turn access RW into DIRTY, then
* add BUSY,HASHPTE and ACCESSED)
*/
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index b43ed92..d03fd2b 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -92,10 +92,15 @@ unsigned long htab_size_bytes;
unsigned long htab_hash_mask;
int mmu_linear_psize = MMU_PAGE_4K;
int mmu_virtual_psize = MMU_PAGE_4K;
+int mmu_vmalloc_psize = MMU_PAGE_4K;
+int mmu_io_psize = MMU_PAGE_4K;
#ifdef CONFIG_HUGETLB_PAGE
int mmu_huge_psize = MMU_PAGE_16M;
unsigned int HPAGE_SHIFT;
#endif
+#ifdef CONFIG_PPC_64K_PAGES
+int mmu_ci_restrictions;
+#endif
/* There are definitions of page sizes arrays to be used when none
* is provided by the firmware.
@@ -308,20 +313,31 @@ static void __init htab_init_page_sizes(
else if (mmu_psize_defs[MMU_PAGE_1M].shift)
mmu_linear_psize = MMU_PAGE_1M;
+#ifdef CONFIG_PPC_64K_PAGES
/*
* Pick a size for the ordinary pages. Default is 4K, we support
- * 64K if cache inhibited large pages are supported by the
- * processor
+ * 64K for user mappings and vmalloc if supported by the processor.
+ * We only use 64k for ioremap if the processor
+ * (and firmware) support cache-inhibited large pages.
+ * If not, we use 4k and set mmu_ci_restrictions so that
+ * hash_page knows to switch processes that use cache-inhibited
+ * mappings to 4k pages.
*/
-#ifdef CONFIG_PPC_64K_PAGES
- if (mmu_psize_defs[MMU_PAGE_64K].shift &&
- cpu_has_feature(CPU_FTR_CI_LARGE_PAGE))
+ if (mmu_psize_defs[MMU_PAGE_64K].shift) {
mmu_virtual_psize = MMU_PAGE_64K;
+ mmu_vmalloc_psize = MMU_PAGE_64K;
+ if (cpu_has_feature(CPU_FTR_CI_LARGE_PAGE))
+ mmu_io_psize = MMU_PAGE_64K;
+ else
+ mmu_ci_restrictions = 1;
+ }
#endif
- printk(KERN_DEBUG "Page orders: linear mapping = %d, others = %d\n",
+ printk(KERN_DEBUG "Page orders: linear mapping = %d, "
+ "virtual = %d, io = %d\n",
mmu_psize_defs[mmu_linear_psize].shift,
- mmu_psize_defs[mmu_virtual_psize].shift);
+ mmu_psize_defs[mmu_virtual_psize].shift,
+ mmu_psize_defs[mmu_io_psize].shift);
#ifdef CONFIG_HUGETLB_PAGE
/* Init large page size. Currently, we pick 16M or 1M depending
@@ -556,6 +572,7 @@ int hash_page(unsigned long ea, unsigned
pte_t *ptep;
cpumask_t tmp;
int rc, user_region = 0, local = 0;
+ int psize;
DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n",
ea, access, trap);
@@ -575,10 +592,15 @@ int hash_page(unsigned long ea, unsigned
return 1;
}
vsid = get_vsid(mm->context.id, ea);
+ psize = mm->context.user_psize;
break;
case VMALLOC_REGION_ID:
mm = &init_mm;
vsid = get_kernel_vsid(ea);
+ if (ea < VMALLOC_END)
+ psize = mmu_vmalloc_psize;
+ else
+ psize = mmu_io_psize;
break;
default:
/* Not a valid range
@@ -629,7 +651,40 @@ #endif
#ifndef CONFIG_PPC_64K_PAGES
rc = __hash_page_4K(ea, access, vsid, ptep, trap, local);
#else
- if (mmu_virtual_psize == MMU_PAGE_64K)
+ if (mmu_ci_restrictions) {
+ /* If this PTE is non-cacheable, switch to 4k */
+ if (psize == MMU_PAGE_64K &&
+ (pte_val(*ptep) & _PAGE_NO_CACHE)) {
+ if (user_region) {
+ psize = MMU_PAGE_4K;
+ mm->context.user_psize = MMU_PAGE_4K;
+ mm->context.sllp = SLB_VSID_USER |
+ mmu_psize_defs[MMU_PAGE_4K].sllp;
+ } else if (ea < VMALLOC_END) {
+ /*
+ * some driver did a non-cacheable mapping
+ * in vmalloc space, so switch vmalloc
+ * to 4k pages
+ */
+ printk(KERN_ALERT "Reducing vmalloc segment "
+ "to 4kB pages because of "
+ "non-cacheable mapping\n");
+ psize = mmu_vmalloc_psize = MMU_PAGE_4K;
+ }
+ }
+ if (user_region) {
+ if (psize != get_paca()->context.user_psize) {
+ get_paca()->context = mm->context;
+ slb_flush_and_rebolt();
+ }
+ } else if (get_paca()->vmalloc_sllp !=
+ mmu_psize_defs[mmu_vmalloc_psize].sllp) {
+ get_paca()->vmalloc_sllp =
+ mmu_psize_defs[mmu_vmalloc_psize].sllp;
+ slb_flush_and_rebolt();
+ }
+ }
+ if (psize == MMU_PAGE_64K)
rc = __hash_page_64K(ea, access, vsid, ptep, trap, local);
else
rc = __hash_page_4K(ea, access, vsid, ptep, trap, local);
@@ -681,7 +736,18 @@ void hash_preload(struct mm_struct *mm,
#ifndef CONFIG_PPC_64K_PAGES
__hash_page_4K(ea, access, vsid, ptep, trap, local);
#else
- if (mmu_virtual_psize == MMU_PAGE_64K)
+ if (mmu_ci_restrictions) {
+ /* If this PTE is non-cacheable, switch to 4k */
+ if (mm->context.user_psize == MMU_PAGE_64K &&
+ (pte_val(*ptep) & _PAGE_NO_CACHE)) {
+ mm->context.user_psize = MMU_PAGE_4K;
+ mm->context.sllp = SLB_VSID_USER |
+ mmu_psize_defs[MMU_PAGE_4K].sllp;
+ get_paca()->context = mm->context;
+ slb_flush_and_rebolt();
+ }
+ }
+ if (mm->context.user_psize == MMU_PAGE_64K)
__hash_page_64K(ea, access, vsid, ptep, trap, local);
else
__hash_page_4K(ea, access, vsid, ptep, trap, local);
diff --git a/arch/powerpc/mm/mmu_context_64.c b/arch/powerpc/mm/mmu_context_64.c
index 714a84d..65d18dc 100644
--- a/arch/powerpc/mm/mmu_context_64.c
+++ b/arch/powerpc/mm/mmu_context_64.c
@@ -49,6 +49,9 @@ again:
}
mm->context.id = index;
+ mm->context.user_psize = mmu_virtual_psize;
+ mm->context.sllp = SLB_VSID_USER |
+ mmu_psize_defs[mmu_virtual_psize].sllp;
return 0;
}
diff --git a/arch/powerpc/mm/slb.c b/arch/powerpc/mm/slb.c
index 2cc6173..6a8bf6c 100644
--- a/arch/powerpc/mm/slb.c
+++ b/arch/powerpc/mm/slb.c
@@ -60,19 +60,19 @@ static inline void create_slbe(unsigned
: "memory" );
}
-static void slb_flush_and_rebolt(void)
+void slb_flush_and_rebolt(void)
{
/* If you change this make sure you change SLB_NUM_BOLTED
* appropriately too. */
- unsigned long linear_llp, virtual_llp, lflags, vflags;
+ unsigned long linear_llp, vmalloc_llp, lflags, vflags;
unsigned long ksp_esid_data;
WARN_ON(!irqs_disabled());
linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
- virtual_llp = mmu_psize_defs[mmu_virtual_psize].sllp;
+ vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
lflags = SLB_VSID_KERNEL | linear_llp;
- vflags = SLB_VSID_KERNEL | virtual_llp;
+ vflags = SLB_VSID_KERNEL | vmalloc_llp;
ksp_esid_data = mk_esid_data(get_paca()->kstack, 2);
if ((ksp_esid_data & ESID_MASK) == PAGE_OFFSET)
@@ -164,11 +164,10 @@ static inline void patch_slb_encoding(un
void slb_initialize(void)
{
- unsigned long linear_llp, virtual_llp;
+ unsigned long linear_llp, vmalloc_llp, io_llp;
static int slb_encoding_inited;
extern unsigned int *slb_miss_kernel_load_linear;
- extern unsigned int *slb_miss_kernel_load_virtual;
- extern unsigned int *slb_miss_user_load_normal;
+ extern unsigned int *slb_miss_kernel_load_io;
#ifdef CONFIG_HUGETLB_PAGE
extern unsigned int *slb_miss_user_load_huge;
unsigned long huge_llp;
@@ -178,18 +177,19 @@ #endif
/* Prepare our SLB miss handler based on our page size */
linear_llp = mmu_psize_defs[mmu_linear_psize].sllp;
- virtual_llp = mmu_psize_defs[mmu_virtual_psize].sllp;
+ io_llp = mmu_psize_defs[mmu_io_psize].sllp;
+ vmalloc_llp = mmu_psize_defs[mmu_vmalloc_psize].sllp;
+ get_paca()->vmalloc_sllp = SLB_VSID_KERNEL | vmalloc_llp;
+
if (!slb_encoding_inited) {
slb_encoding_inited = 1;
patch_slb_encoding(slb_miss_kernel_load_linear,
SLB_VSID_KERNEL | linear_llp);
- patch_slb_encoding(slb_miss_kernel_load_virtual,
- SLB_VSID_KERNEL | virtual_llp);
- patch_slb_encoding(slb_miss_user_load_normal,
- SLB_VSID_USER | virtual_llp);
+ patch_slb_encoding(slb_miss_kernel_load_io,
+ SLB_VSID_KERNEL | io_llp);
DBG("SLB: linear LLP = %04x\n", linear_llp);
- DBG("SLB: virtual LLP = %04x\n", virtual_llp);
+ DBG("SLB: io LLP = %04x\n", io_llp);
#ifdef CONFIG_HUGETLB_PAGE
patch_slb_encoding(slb_miss_user_load_huge,
SLB_VSID_USER | huge_llp);
@@ -204,7 +204,7 @@ #ifndef CONFIG_PPC_ISERIES
unsigned long lflags, vflags;
lflags = SLB_VSID_KERNEL | linear_llp;
- vflags = SLB_VSID_KERNEL | virtual_llp;
+ vflags = SLB_VSID_KERNEL | vmalloc_llp;
/* Invalidate the entire SLB (even slot 0) & all the ERATS */
asm volatile("isync":::"memory");
@@ -212,7 +212,6 @@ #ifndef CONFIG_PPC_ISERIES
asm volatile("isync; slbia; isync":::"memory");
create_slbe(PAGE_OFFSET, lflags, 0);
- /* VMALLOC space has 4K pages always for now */
create_slbe(VMALLOC_START, vflags, 1);
/* We don't bolt the stack for the time being - we're in boot,
diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index abfaabf..8548dcf 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -59,10 +59,19 @@ _GLOBAL(slb_miss_kernel_load_linear)
li r11,0
b slb_finish_load
-1: /* vmalloc/ioremap mapping encoding bits, the "li" instruction below
+1: /* vmalloc/ioremap mapping encoding bits, the "li" instructions below
* will be patched by the kernel at boot
*/
-_GLOBAL(slb_miss_kernel_load_virtual)
+BEGIN_FTR_SECTION
+ /* check whether this is in vmalloc or ioremap space */
+ clrldi r11,r10,48
+ cmpldi r11,(VMALLOC_SIZE >> 28) - 1
+ bgt 5f
+ lhz r11,PACAVMALLOCSLLP(r13)
+ b slb_finish_load
+5:
+END_FTR_SECTION_IFCLR(CPU_FTR_CI_LARGE_PAGE)
+_GLOBAL(slb_miss_kernel_load_io)
li r11,0
b slb_finish_load
@@ -96,9 +105,7 @@ _GLOBAL(slb_miss_user_load_huge)
1:
#endif /* CONFIG_HUGETLB_PAGE */
-_GLOBAL(slb_miss_user_load_normal)
- li r11,0
-
+ lhz r11,PACACONTEXTSLLP(r13)
2:
ld r9,PACACONTEXTID(r13)
rldimi r10,r9,USER_ESID_BITS,0
diff --git a/arch/powerpc/mm/stab.c b/arch/powerpc/mm/stab.c
diff --git a/arch/powerpc/mm/tlb_64.c b/arch/powerpc/mm/tlb_64.c
index f734b11..4bcfd45 100644
--- a/arch/powerpc/mm/tlb_64.c
+++ b/arch/powerpc/mm/tlb_64.c
@@ -131,7 +131,7 @@ void hpte_update(struct mm_struct *mm, u
{
struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
unsigned long vsid;
- unsigned int psize = mmu_virtual_psize;
+ unsigned int psize;
int i;
i = batch->index;
@@ -148,7 +148,8 @@ #ifdef CONFIG_HUGETLB_PAGE
#else
BUG();
#endif
- }
+ } else
+ psize = (pte & _PAGE_COMBO)? MMU_PAGE_4K: MMU_PAGE_64K;
/*
* This can happen when we are in the middle of a TLB batch and
diff --git a/include/asm-powerpc/mmu.h b/include/asm-powerpc/mmu.h
index 8853974..3a5ebe2 100644
--- a/include/asm-powerpc/mmu.h
+++ b/include/asm-powerpc/mmu.h
@@ -165,6 +165,16 @@ #ifndef __ASSEMBLY__
extern struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];
extern int mmu_linear_psize;
extern int mmu_virtual_psize;
+extern int mmu_vmalloc_psize;
+extern int mmu_io_psize;
+
+/*
+ * If the processor supports 64k normal pages but not 64k cache
+ * inhibited pages, we have to be prepared to switch processes
+ * to use 4k pages when they create cache-inhibited mappings.
+ * If this is the case, mmu_ci_restrictions will be set to 1.
+ */
+extern int mmu_ci_restrictions;
#ifdef CONFIG_HUGETLB_PAGE
/*
@@ -256,6 +266,7 @@ extern long iSeries_hpte_insert(unsigned
extern void stabs_alloc(void);
extern void slb_initialize(void);
+extern void slb_flush_and_rebolt(void);
extern void stab_initialize(unsigned long stab);
#endif /* __ASSEMBLY__ */
@@ -359,6 +370,8 @@ typedef unsigned long mm_context_id_t;
typedef struct {
mm_context_id_t id;
+ u16 user_psize; /* page size index */
+ u16 sllp; /* SLB entry page size encoding */
#ifdef CONFIG_HUGETLB_PAGE
u16 low_htlb_areas, high_htlb_areas;
#endif
diff --git a/include/asm-powerpc/mmu_context.h b/include/asm-powerpc/mmu_context.h
diff --git a/include/asm-powerpc/paca.h b/include/asm-powerpc/paca.h
index c17fd54..1740635 100644
--- a/include/asm-powerpc/paca.h
+++ b/include/asm-powerpc/paca.h
@@ -81,6 +81,7 @@ #endif /* CONFIG_PPC_ISERIES */
* on the linear mapping */
mm_context_t context;
+ u16 vmalloc_sllp;
u16 slb_cache[SLB_CACHE_ENTRIES];
u16 slb_cache_ptr;
diff --git a/include/asm-powerpc/pgtable.h b/include/asm-powerpc/pgtable.h
index e9f1f46..260a0fa 100644
--- a/include/asm-powerpc/pgtable.h
+++ b/include/asm-powerpc/pgtable.h
@@ -47,8 +47,8 @@ #endif
/*
* Define the address range of the vmalloc VM area.
*/
-#define VMALLOC_START (0xD000000000000000ul)
-#define VMALLOC_SIZE (0x80000000000UL)
+#define VMALLOC_START ASM_CONST(0xD000000000000000)
+#define VMALLOC_SIZE ASM_CONST(0x80000000000)
#define VMALLOC_END (VMALLOC_START + VMALLOC_SIZE)
/*
@@ -413,12 +413,6 @@ static inline void set_pte_at(struct mm_
flush_tlb_pending();
}
pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
-
-#ifdef CONFIG_PPC_64K_PAGES
- if (mmu_virtual_psize != MMU_PAGE_64K)
- pte = __pte(pte_val(pte) | _PAGE_COMBO);
-#endif /* CONFIG_PPC_64K_PAGES */
-
*ptep = pte;
}
More information about the Linuxppc-dev
mailing list