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powerpc/book3e: Adjust the page sizes list based on MMU config
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Use the MMU config registers to scan for available direct and
indirect page sizes and print out the result. Will be needed
for future hugetlbfs implementation.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Benjamin Herrenschmidt committed Jul 14, 2010
1 parent 0324715 commit f2b26c9
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Showing 3 changed files with 109 additions and 32 deletions.
4 changes: 4 additions & 0 deletions arch/powerpc/include/asm/mmu-book3e.h
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Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,10 @@ struct mmu_psize_def
{
unsigned int shift; /* number of bits */
unsigned int enc; /* PTE encoding */
unsigned int ind; /* Corresponding indirect page size shift */
unsigned int flags;
#define MMU_PAGE_SIZE_DIRECT 0x1 /* Supported as a direct size */
#define MMU_PAGE_SIZE_INDIRECT 0x2 /* Supported as an indirect size */
};
extern struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];

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1 change: 1 addition & 0 deletions arch/powerpc/include/asm/reg_booke.h
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,7 @@
#define SPRN_TLB0PS 0x158 /* TLB 0 Page Size Register */
#define SPRN_MAS5_MAS6 0x15c /* MMU Assist Register 5 || 6 */
#define SPRN_MAS8_MAS1 0x15d /* MMU Assist Register 8 || 1 */
#define SPRN_EPTCFG 0x15e /* Embedded Page Table Config */
#define SPRN_MAS7_MAS3 0x174 /* MMU Assist Register 7 || 3 */
#define SPRN_MAS0_MAS1 0x175 /* MMU Assist Register 0 || 1 */
#define SPRN_IVOR0 0x190 /* Interrupt Vector Offset Register 0 */
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136 changes: 104 additions & 32 deletions arch/powerpc/mm/tlb_nohash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@
struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {
[MMU_PAGE_4K] = {
.shift = 12,
.ind = 20,
.enc = BOOK3E_PAGESZ_4K,
},
[MMU_PAGE_16K] = {
Expand All @@ -54,6 +55,7 @@ struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {
},
[MMU_PAGE_64K] = {
.shift = 16,
.ind = 28,
.enc = BOOK3E_PAGESZ_64K,
},
[MMU_PAGE_1M] = {
Expand All @@ -62,6 +64,7 @@ struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT] = {
},
[MMU_PAGE_16M] = {
.shift = 24,
.ind = 36,
.enc = BOOK3E_PAGESZ_16M,
},
[MMU_PAGE_256M] = {
Expand Down Expand Up @@ -344,16 +347,108 @@ void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address)
}
}

/*
* Early initialization of the MMU TLB code
*/
static void __early_init_mmu(int boot_cpu)
static void setup_page_sizes(void)
{
unsigned int tlb0cfg = mfspr(SPRN_TLB0CFG);
unsigned int tlb0ps = mfspr(SPRN_TLB0PS);
unsigned int eptcfg = mfspr(SPRN_EPTCFG);
int i, psize;

/* Look for supported direct sizes */
for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
struct mmu_psize_def *def = &mmu_psize_defs[psize];

if (tlb0ps & (1U << (def->shift - 10)))
def->flags |= MMU_PAGE_SIZE_DIRECT;
}

/* Indirect page sizes supported ? */
if ((tlb0cfg & TLBnCFG_IND) == 0)
goto no_indirect;

/* Now, we only deal with one IND page size for each
* direct size. Hopefully all implementations today are
* unambiguous, but we might want to be careful in the
* future.
*/
for (i = 0; i < 3; i++) {
unsigned int ps, sps;

sps = eptcfg & 0x1f;
eptcfg >>= 5;
ps = eptcfg & 0x1f;
eptcfg >>= 5;
if (!ps || !sps)
continue;
for (psize = 0; psize < MMU_PAGE_COUNT; psize++) {
struct mmu_psize_def *def = &mmu_psize_defs[psize];

if (ps == (def->shift - 10))
def->flags |= MMU_PAGE_SIZE_INDIRECT;
if (sps == (def->shift - 10))
def->ind = ps + 10;
}
}
no_indirect:

/* Cleanup array and print summary */
pr_info("MMU: Supported page sizes\n");
for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
struct mmu_psize_def *def = &mmu_psize_defs[psize];
const char *__page_type_names[] = {
"unsupported",
"direct",
"indirect",
"direct & indirect"
};
if (def->flags == 0) {
def->shift = 0;
continue;
}
pr_info(" %8ld KB as %s\n", 1ul << (def->shift - 10),
__page_type_names[def->flags & 0x3]);
}
}

static void setup_mmu_htw(void)
{
extern unsigned int interrupt_base_book3e;
extern unsigned int exc_data_tlb_miss_htw_book3e;
extern unsigned int exc_instruction_tlb_miss_htw_book3e;

unsigned int *ibase = &interrupt_base_book3e;

/* Check if HW tablewalk is present, and if yes, enable it by:
*
* - patching the TLB miss handlers to branch to the
* one dedicates to it
*
* - setting the global book3e_htw_enabled
*/
unsigned int tlb0cfg = mfspr(SPRN_TLB0CFG);

if ((tlb0cfg & TLBnCFG_IND) &&
(tlb0cfg & TLBnCFG_PT)) {
/* Our exceptions vectors start with a NOP and -then- a branch
* to deal with single stepping from userspace which stops on
* the second instruction. Thus we need to patch the second
* instruction of the exception, not the first one
*/
patch_branch(ibase + (0x1c0 / 4) + 1,
(unsigned long)&exc_data_tlb_miss_htw_book3e, 0);
patch_branch(ibase + (0x1e0 / 4) + 1,
(unsigned long)&exc_instruction_tlb_miss_htw_book3e, 0);
book3e_htw_enabled = 1;
}
pr_info("MMU: Book3E Page Tables %s\n",
book3e_htw_enabled ? "Enabled" : "Disabled");
}

/*
* Early initialization of the MMU TLB code
*/
static void __early_init_mmu(int boot_cpu)
{
unsigned int mas4;

/* XXX This will have to be decided at runtime, but right
Expand All @@ -370,40 +465,17 @@ static void __early_init_mmu(int boot_cpu)
*/
mmu_vmemmap_psize = MMU_PAGE_16M;

/* Check if HW tablewalk is present, and if yes, enable it by:
*
* - patching the TLB miss handlers to branch to the
* one dedicates to it
*
* - setting the global book3e_htw_enabled
*
* - Set MAS4:INDD and default page size
*/

/* XXX This code only checks for TLB 0 capabilities and doesn't
* check what page size combos are supported by the HW. It
* also doesn't handle the case where a separate array holds
* the IND entries from the array loaded by the PT.
*/
if (boot_cpu) {
unsigned int tlb0cfg = mfspr(SPRN_TLB0CFG);

/* Check if HW loader is supported */
if ((tlb0cfg & TLBnCFG_IND) &&
(tlb0cfg & TLBnCFG_PT)) {
/* Our exceptions vectors start with a NOP and -then- a branch
* to deal with single stepping from userspace which stops on
* the second instruction. Thus we need to patch the second
* instruction of the exception, not the first one
*/
patch_branch(ibase + (0x1c0 / 4) + 1,
(unsigned long)&exc_data_tlb_miss_htw_book3e, 0);
patch_branch(ibase + (0x1e0 / 4) + 1,
(unsigned long)&exc_instruction_tlb_miss_htw_book3e, 0);
book3e_htw_enabled = 1;
}
pr_info("MMU: Book3E Page Tables %s\n",
book3e_htw_enabled ? "Enabled" : "Disabled");
/* Look for supported page sizes */
setup_page_sizes();

/* Look for HW tablewalk support */
setup_mmu_htw();
}

/* Set MAS4 based on page table setting */
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