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powerpc: rework 4xx PTE access and TLB miss

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This is some preliminary work to improve TLB management on SW loaded
TLB powerpc platforms. This introduce support for non-atomic PTE
operations in pgtable-ppc32.h and removes write back to the PTE from
the TLB miss handlers. In addition, the DSI interrupt code no longer
tries to fixup write permission, this is left to generic code, and
_PAGE_HWWRITE is gone.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
This commit is contained in:
Benjamin Herrenschmidt 2008-07-08 15:54:40 +10:00 committed by Josh Boyer
parent beae4c03c0
commit 1bc54c0311
5 changed files with 179 additions and 206 deletions
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280
arch/powerpc/kernel/head_44x.S
View file

@ -293,117 +293,7 @@ interrupt_base:
MCHECK_EXCEPTION(0x0210, MachineCheckA, machine_check_exception)
/* Data Storage Interrupt */
START_EXCEPTION(DataStorage)
mtspr SPRN_SPRG0, r10 /* Save some working registers */
mtspr SPRN_SPRG1, r11
mtspr SPRN_SPRG4W, r12
mtspr SPRN_SPRG5W, r13
mfcr r11
mtspr SPRN_SPRG7W, r11
/*
* Check if it was a store fault, if not then bail
* because a user tried to access a kernel or
* read-protected page. Otherwise, get the
* offending address and handle it.
*/
mfspr r10, SPRN_ESR
andis. r10, r10, ESR_ST@h
beq 2f
mfspr r10, SPRN_DEAR /* Get faulting address */
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
lis r11, PAGE_OFFSET@h
cmplw r10, r11
blt+ 3f
lis r11, swapper_pg_dir@h
ori r11, r11, swapper_pg_dir@l
mfspr r12,SPRN_MMUCR
rlwinm r12,r12,0,0,23 /* Clear TID */
b 4f
/* Get the PGD for the current thread */
3:
mfspr r11,SPRN_SPRG3
lwz r11,PGDIR(r11)
/* Load PID into MMUCR TID */
mfspr r12,SPRN_MMUCR /* Get MMUCR */
mfspr r13,SPRN_PID /* Get PID */
rlwimi r12,r13,0,24,31 /* Set TID */
4:
mtspr SPRN_MMUCR,r12
rlwinm r12, r10, 13, 19, 29 /* Compute pgdir/pmd offset */
lwzx r11, r12, r11 /* Get pgd/pmd entry */
rlwinm. r12, r11, 0, 0, 20 /* Extract pt base address */
beq 2f /* Bail if no table */
rlwimi r12, r10, 23, 20, 28 /* Compute pte address */
lwz r11, 4(r12) /* Get pte entry */
andi. r13, r11, _PAGE_RW /* Is it writeable? */
beq 2f /* Bail if not */
/* Update 'changed'.
*/
ori r11, r11, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
stw r11, 4(r12) /* Update Linux page table */
li r13, PPC44x_TLB_SR@l /* Set SR */
rlwimi r13, r11, 29, 29, 29 /* SX = _PAGE_HWEXEC */
rlwimi r13, r11, 0, 30, 30 /* SW = _PAGE_RW */
rlwimi r13, r11, 29, 28, 28 /* UR = _PAGE_USER */
rlwimi r12, r11, 31, 26, 26 /* (_PAGE_USER>>1)->r12 */
rlwimi r12, r11, 29, 30, 30 /* (_PAGE_USER>>3)->r12 */
and r12, r12, r11 /* HWEXEC/RW & USER */
rlwimi r13, r12, 0, 26, 26 /* UX = HWEXEC & USER */
rlwimi r13, r12, 3, 27, 27 /* UW = RW & USER */
rlwimi r11,r13,0,26,31 /* Insert static perms */
/*
* Clear U0-U3 and WL1 IL1I IL1D IL2I IL2D bits which are added
* on newer 440 cores like the 440x6 used on AMCC 460EX/460GT (see
* include/asm-powerpc/pgtable-ppc32.h for details).
*/
rlwinm r11,r11,0,20,10
/* find the TLB index that caused the fault. It has to be here. */
tlbsx r10, 0, r10
tlbwe r11, r10, PPC44x_TLB_ATTRIB /* Write ATTRIB */
/* Done...restore registers and get out of here.
*/
mfspr r11, SPRN_SPRG7R
mtcr r11
mfspr r13, SPRN_SPRG5R
mfspr r12, SPRN_SPRG4R
mfspr r11, SPRN_SPRG1
mfspr r10, SPRN_SPRG0
rfi /* Force context change */
2:
/*
* The bailout. Restore registers to pre-exception conditions
* and call the heavyweights to help us out.
*/
mfspr r11, SPRN_SPRG7R
mtcr r11
mfspr r13, SPRN_SPRG5R
mfspr r12, SPRN_SPRG4R
mfspr r11, SPRN_SPRG1
mfspr r10, SPRN_SPRG0
b data_access
DATA_STORAGE_EXCEPTION
/* Instruction Storage Interrupt */
INSTRUCTION_STORAGE_EXCEPTION
@ -423,7 +313,6 @@ interrupt_base:
#else
EXCEPTION(0x2010, FloatingPointUnavailable, unknown_exception, EXC_XFER_EE)
#endif
/* System Call Interrupt */
START_EXCEPTION(SystemCall)
NORMAL_EXCEPTION_PROLOG
@ -484,18 +373,57 @@ interrupt_base:
4:
mtspr SPRN_MMUCR,r12
/* Mask of required permission bits. Note that while we
* do copy ESR:ST to _PAGE_RW position as trying to write
* to an RO page is pretty common, we don't do it with
* _PAGE_DIRTY. We could do it, but it's a fairly rare
* event so I'd rather take the overhead when it happens
* rather than adding an instruction here. We should measure
* whether the whole thing is worth it in the first place
* as we could avoid loading SPRN_ESR completely in the first
* place...
*
* TODO: Is it worth doing that mfspr & rlwimi in the first
* place or can we save a couple of instructions here ?
*/
mfspr r12,SPRN_ESR
li r13,_PAGE_PRESENT|_PAGE_ACCESSED
rlwimi r13,r12,10,30,30
/* Load the PTE */
rlwinm r12, r10, 13, 19, 29 /* Compute pgdir/pmd offset */
lwzx r11, r12, r11 /* Get pgd/pmd entry */
rlwinm. r12, r11, 0, 0, 20 /* Extract pt base address */
beq 2f /* Bail if no table */
rlwimi r12, r10, 23, 20, 28 /* Compute pte address */
lwz r11, 4(r12) /* Get pte entry */
andi. r13, r11, _PAGE_PRESENT /* Is the page present? */
beq 2f /* Bail if not present */
lwz r11, 0(r12) /* Get high word of pte entry */
lwz r12, 4(r12) /* Get low word of pte entry */
ori r11, r11, _PAGE_ACCESSED
stw r11, 4(r12)
lis r10,tlb_44x_index@ha
andc. r13,r13,r12 /* Check permission */
/* Load the next available TLB index */
lwz r13,tlb_44x_index@l(r10)
bne 2f /* Bail if permission mismach */
/* Increment, rollover, and store TLB index */
addi r13,r13,1
/* Compare with watermark (instruction gets patched) */
.globl tlb_44x_patch_hwater_D
tlb_44x_patch_hwater_D:
cmpwi 0,r13,1 /* reserve entries */
ble 5f
li r13,0
5:
/* Store the next available TLB index */
stw r13,tlb_44x_index@l(r10)
/* Re-load the faulting address */
mfspr r10,SPRN_DEAR
/* Jump to common tlb load */
b finish_tlb_load
@ -510,7 +438,7 @@ interrupt_base:
mfspr r12, SPRN_SPRG4R
mfspr r11, SPRN_SPRG1
mfspr r10, SPRN_SPRG0
b data_access
b DataStorage
/* Instruction TLB Error Interrupt */
/*
@ -554,18 +482,42 @@ interrupt_base:
4:
mtspr SPRN_MMUCR,r12
/* Make up the required permissions */
li r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_HWEXEC
rlwinm r12, r10, 13, 19, 29 /* Compute pgdir/pmd offset */
lwzx r11, r12, r11 /* Get pgd/pmd entry */
rlwinm. r12, r11, 0, 0, 20 /* Extract pt base address */
beq 2f /* Bail if no table */
rlwimi r12, r10, 23, 20, 28 /* Compute pte address */
lwz r11, 4(r12) /* Get pte entry */
andi. r13, r11, _PAGE_PRESENT /* Is the page present? */
beq 2f /* Bail if not present */
lwz r11, 0(r12) /* Get high word of pte entry */
lwz r12, 4(r12) /* Get low word of pte entry */
ori r11, r11, _PAGE_ACCESSED
stw r11, 4(r12)
lis r10,tlb_44x_index@ha
andc. r13,r13,r12 /* Check permission */
/* Load the next available TLB index */
lwz r13,tlb_44x_index@l(r10)
bne 2f /* Bail if permission mismach */
/* Increment, rollover, and store TLB index */
addi r13,r13,1
/* Compare with watermark (instruction gets patched) */
.globl tlb_44x_patch_hwater_I
tlb_44x_patch_hwater_I:
cmpwi 0,r13,1 /* reserve entries */
ble 5f
li r13,0
5:
/* Store the next available TLB index */
stw r13,tlb_44x_index@l(r10)
/* Re-load the faulting address */
mfspr r10,SPRN_SRR0
/* Jump to common TLB load point */
b finish_tlb_load
@ -588,85 +540,39 @@ interrupt_base:
/*
* Local functions
*/
/*
* Data TLB exceptions will bail out to this point
* if they can't resolve the lightweight TLB fault.
*/
data_access:
NORMAL_EXCEPTION_PROLOG
mfspr r5,SPRN_ESR /* Grab the ESR, save it, pass arg3 */
stw r5,_ESR(r11)
mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */
EXC_XFER_EE_LITE(0x0300, handle_page_fault)
/*
* Both the instruction and data TLB miss get to this
* point to load the TLB.
* r10 - EA of fault
* r11 - available to use
* r12 - Pointer to the 64-bit PTE
* r13 - available to use
* r11 - PTE high word value
* r12 - PTE low word value
* r13 - TLB index
* MMUCR - loaded with proper value when we get here
* Upon exit, we reload everything and RFI.
*/
finish_tlb_load:
/*
* We set execute, because we don't have the granularity to
* properly set this at the page level (Linux problem).
* If shared is set, we cause a zero PID->TID load.
* Many of these bits are software only. Bits we don't set
* here we (properly should) assume have the appropriate value.
*/
/* Load the next available TLB index */
lis r13, tlb_44x_index@ha
lwz r13, tlb_44x_index@l(r13)
/* Load the TLB high watermark */
lis r11, tlb_44x_hwater@ha
lwz r11, tlb_44x_hwater@l(r11)
/* Increment, rollover, and store TLB index */
addi r13, r13, 1
cmpw 0, r13, r11 /* reserve entries */
ble 7f
li r13, 0
7:
/* Store the next available TLB index */
lis r11, tlb_44x_index@ha
stw r13, tlb_44x_index@l(r11)
lwz r11, 0(r12) /* Get MS word of PTE */
lwz r12, 4(r12) /* Get LS word of PTE */
rlwimi r11, r12, 0, 0 , 19 /* Insert RPN */
tlbwe r11, r13, PPC44x_TLB_XLAT /* Write XLAT */
/* Combine RPN & ERPN an write WS 0 */
rlwimi r11,r12,0,0,19
tlbwe r11,r13,PPC44x_TLB_XLAT
/*
* Create PAGEID. This is the faulting address,
* Create WS1. This is the faulting address (EPN),
* page size, and valid flag.
*/
li r11, PPC44x_TLB_VALID | PPC44x_TLB_4K
rlwimi r10, r11, 0, 20, 31 /* Insert valid and page size */
tlbwe r10, r13, PPC44x_TLB_PAGEID /* Write PAGEID */
li r11,PPC44x_TLB_VALID | PPC44x_TLB_4K
rlwimi r10,r11,0,20,31 /* Insert valid and page size*/
tlbwe r10,r13,PPC44x_TLB_PAGEID /* Write PAGEID */
li r10, PPC44x_TLB_SR@l /* Set SR */
rlwimi r10, r12, 0, 30, 30 /* Set SW = _PAGE_RW */
rlwimi r10, r12, 29, 29, 29 /* SX = _PAGE_HWEXEC */
rlwimi r10, r12, 29, 28, 28 /* UR = _PAGE_USER */
rlwimi r11, r12, 31, 26, 26 /* (_PAGE_USER>>1)->r12 */
and r11, r12, r11 /* HWEXEC & USER */
rlwimi r10, r11, 0, 26, 26 /* UX = HWEXEC & USER */
rlwimi r12, r10, 0, 26, 31 /* Insert static perms */
/*
* Clear U0-U3 and WL1 IL1I IL1D IL2I IL2D bits which are added
* on newer 440 cores like the 440x6 used on AMCC 460EX/460GT (see
* include/asm-powerpc/pgtable-ppc32.h for details).
*/
rlwinm r12, r12, 0, 20, 10
tlbwe r12, r13, PPC44x_TLB_ATTRIB /* Write ATTRIB */
/* And WS 2 */
li r10,0xf85 /* Mask to apply from PTE */
rlwimi r10,r12,29,30,30 /* DIRTY -> SW position */
and r11,r12,r10 /* Mask PTE bits to keep */
andi. r10,r12,_PAGE_USER /* User page ? */
beq 1f /* nope, leave U bits empty */
rlwimi r11,r11,3,26,28 /* yes, copy S bits to U */
1: tlbwe r11,r13,PPC44x_TLB_ATTRIB /* Write ATTRIB */
/* Done...restore registers and get out of here.
*/

8
arch/powerpc/kernel/head_booke.h
View file

@ -340,6 +340,14 @@
addi r3,r1,STACK_FRAME_OVERHEAD; \
EXC_XFER_TEMPLATE(DebugException, 0x2002, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), NOCOPY, crit_transfer_to_handler, ret_from_crit_exc)
#define DATA_STORAGE_EXCEPTION \
START_EXCEPTION(DataStorage) \
NORMAL_EXCEPTION_PROLOG; \
mfspr r5,SPRN_ESR; /* Grab the ESR and save it */ \
stw r5,_ESR(r11); \
mfspr r4,SPRN_DEAR; /* Grab the DEAR */ \
EXC_XFER_EE_LITE(0x0300, handle_page_fault)
#define INSTRUCTION_STORAGE_EXCEPTION \
START_EXCEPTION(InstructionStorage) \
NORMAL_EXCEPTION_PROLOG; \

29
arch/powerpc/mm/44x_mmu.c
View file

@ -27,6 +27,7 @@
#include <asm/mmu.h>
#include <asm/system.h>
#include <asm/page.h>
#include <asm/cacheflush.h>
#include "mmu_decl.h"
@ -37,11 +38,35 @@ unsigned int tlb_44x_index; /* = 0 */
unsigned int tlb_44x_hwater = PPC44x_TLB_SIZE - 1 - PPC44x_EARLY_TLBS;
int icache_44x_need_flush;
static void __init ppc44x_update_tlb_hwater(void)
{
extern unsigned int tlb_44x_patch_hwater_D[];
extern unsigned int tlb_44x_patch_hwater_I[];
/* The TLB miss handlers hard codes the watermark in a cmpli
* instruction to improve performances rather than loading it
* from the global variable. Thus, we patch the instructions
* in the 2 TLB miss handlers when updating the value
*/
tlb_44x_patch_hwater_D[0] = (tlb_44x_patch_hwater_D[0] & 0xffff0000) |
tlb_44x_hwater;
flush_icache_range((unsigned long)&tlb_44x_patch_hwater_D[0],
(unsigned long)&tlb_44x_patch_hwater_D[1]);
tlb_44x_patch_hwater_I[0] = (tlb_44x_patch_hwater_I[0] & 0xffff0000) |
tlb_44x_hwater;
flush_icache_range((unsigned long)&tlb_44x_patch_hwater_I[0],
(unsigned long)&tlb_44x_patch_hwater_I[1]);
}
/*
* "Pins" a 256MB TLB entry in AS0 for kernel lowmem
*/
static void __init ppc44x_pin_tlb(unsigned int virt, unsigned int phys)
{
unsigned int entry = tlb_44x_hwater--;
ppc44x_update_tlb_hwater();
__asm__ __volatile__(
"tlbwe %2,%3,%4\n"
"tlbwe %1,%3,%5\n"
@ -50,7 +75,7 @@ static void __init ppc44x_pin_tlb(unsigned int virt, unsigned int phys)
: "r" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G),
"r" (phys),
"r" (virt | PPC44x_TLB_VALID | PPC44x_TLB_256M),
"r" (tlb_44x_hwater--), /* slot for this TLB entry */
"r" (entry),
"i" (PPC44x_TLB_PAGEID),
"i" (PPC44x_TLB_XLAT),
"i" (PPC44x_TLB_ATTRIB));
@ -58,6 +83,8 @@ static void __init ppc44x_pin_tlb(unsigned int virt, unsigned int phys)
void __init MMU_init_hw(void)
{
ppc44x_update_tlb_hwater();
flush_instruction_cache();
}

3
arch/powerpc/mm/fault.c
View file

@ -306,7 +306,8 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address,
flush_dcache_icache_page(page);
set_bit(PG_arch_1, &page->flags);
}
pte_update(ptep, 0, _PAGE_HWEXEC);
pte_update(ptep, 0, _PAGE_HWEXEC |
_PAGE_ACCESSED);
_tlbie(address, mm->context.id);
pte_unmap_unlock(ptep, ptl);
up_read(&mm->mmap_sem);

45
include/asm-powerpc/pgtable-ppc32.h
View file

@ -182,6 +182,9 @@ extern int icache_44x_need_flush;
#define _PMD_SIZE_16M 0x0e0
#define PMD_PAGE_SIZE(pmdval) (1024 << (((pmdval) & _PMD_SIZE) >> 4))
/* Until my rework is finished, 40x still needs atomic PTE updates */
#define PTE_ATOMIC_UPDATES 1
#elif defined(CONFIG_44x)
/*
* Definitions for PPC440
@ -255,13 +258,13 @@ extern int icache_44x_need_flush;
#define _PAGE_PRESENT 0x00000001 /* S: PTE valid */
#define _PAGE_RW 0x00000002 /* S: Write permission */
#define _PAGE_FILE 0x00000004 /* S: nonlinear file mapping */
#define _PAGE_HWEXEC 0x00000004 /* H: Execute permission */
#define _PAGE_ACCESSED 0x00000008 /* S: Page referenced */
#define _PAGE_HWWRITE 0x00000010 /* H: Dirty & RW */
#define _PAGE_HWEXEC 0x00000020 /* H: Execute permission */
#define _PAGE_DIRTY 0x00000010 /* S: Page dirty */
#define _PAGE_USER 0x00000040 /* S: User page */
#define _PAGE_ENDIAN 0x00000080 /* H: E bit */
#define _PAGE_GUARDED 0x00000100 /* H: G bit */
#define _PAGE_DIRTY 0x00000200 /* S: Page dirty */
#define _PAGE_COHERENT 0x00000200 /* H: M bit */
#define _PAGE_NO_CACHE 0x00000400 /* H: I bit */
#define _PAGE_WRITETHRU 0x00000800 /* H: W bit */
@ -273,6 +276,7 @@ extern int icache_44x_need_flush;
/* ERPN in a PTE never gets cleared, ignore it */
#define _PTE_NONE_MASK 0xffffffff00000000ULL
#elif defined(CONFIG_FSL_BOOKE)
/*
MMU Assist Register 3:
@ -315,6 +319,9 @@ extern int icache_44x_need_flush;
#define _PMD_PRESENT_MASK (PAGE_MASK)
#define _PMD_BAD (~PAGE_MASK)
/* Until my rework is finished, FSL BookE still needs atomic PTE updates */
#define PTE_ATOMIC_UPDATES 1
#elif defined(CONFIG_8xx)
/* Definitions for 8xx embedded chips. */
#define _PAGE_PRESENT 0x0001 /* Page is valid */
@ -345,6 +352,9 @@ extern int icache_44x_need_flush;
#define _PTE_NONE_MASK _PAGE_ACCESSED
/* Until my rework is finished, 8xx still needs atomic PTE updates */
#define PTE_ATOMIC_UPDATES 1
#else /* CONFIG_6xx */
/* Definitions for 60x, 740/750, etc. */
#define _PAGE_PRESENT 0x001 /* software: pte contains a translation */
@ -365,6 +375,10 @@ extern int icache_44x_need_flush;
#define _PMD_PRESENT 0
#define _PMD_PRESENT_MASK (PAGE_MASK)
#define _PMD_BAD (~PAGE_MASK)
/* Hash table based platforms need atomic updates of the linux PTE */
#define PTE_ATOMIC_UPDATES 1
#endif
/*
@ -557,9 +571,11 @@ extern void add_hash_page(unsigned context, unsigned long va,
* low PTE word since we expect ALL flag bits to be there
*/
#ifndef CONFIG_PTE_64BIT
static inline unsigned long pte_update(pte_t *p, unsigned long clr,
static inline unsigned long pte_update(pte_t *p,
unsigned long clr,
unsigned long set)
{
#ifdef PTE_ATOMIC_UPDATES
unsigned long old, tmp;
__asm__ __volatile__("\
@ -572,16 +588,26 @@ static inline unsigned long pte_update(pte_t *p, unsigned long clr,
: "=&r" (old), "=&r" (tmp), "=m" (*p)
: "r" (p), "r" (clr), "r" (set), "m" (*p)
: "cc" );
#else /* PTE_ATOMIC_UPDATES */
unsigned long old = pte_val(*p);
*p = __pte((old & ~clr) | set);
#endif /* !PTE_ATOMIC_UPDATES */
#ifdef CONFIG_44x
if ((old & _PAGE_USER) && (old & _PAGE_HWEXEC))
icache_44x_need_flush = 1;
#endif
return old;
}
#else
static inline unsigned long long pte_update(pte_t *p, unsigned long clr,
#else /* CONFIG_PTE_64BIT */
/* TODO: Change that to only modify the low word and move set_pte_at()
* out of line
*/
static inline unsigned long long pte_update(pte_t *p,
unsigned long clr,
unsigned long set)
{
#ifdef PTE_ATOMIC_UPDATES
unsigned long long old;
unsigned long tmp;
@ -596,13 +622,18 @@ static inline unsigned long long pte_update(pte_t *p, unsigned long clr,
: "=&r" (old), "=&r" (tmp), "=m" (*p)
: "r" (p), "r" ((unsigned long)(p) + 4), "r" (clr), "r" (set), "m" (*p)
: "cc" );
#else /* PTE_ATOMIC_UPDATES */
unsigned long long old = pte_val(*p);
*p = __pte((old & ~clr) | set);
#endif /* !PTE_ATOMIC_UPDATES */
#ifdef CONFIG_44x
if ((old & _PAGE_USER) && (old & _PAGE_HWEXEC))
icache_44x_need_flush = 1;
#endif
return old;
}
#endif
#endif /* CONFIG_PTE_64BIT */
/*
* set_pte stores a linux PTE into the linux page table.