Skip to content

Commit

Permalink
powerpc/8xx: Use L1 entry APG to handle _PAGE_ACCESSED for CONFIG_SWAP
Browse files Browse the repository at this point in the history 
When CONFIG_SWAP is set, the TLB miss handlers have to also take
into account _PAGE_ACCESSED flag. At the moment it is done by
anding _PAGE_ACCESSED into _PAGE_PRESENT using 3 instructions.

This patch uses APG for handling _PAGE_ACCESSED, allowing to
just copy _PAGE_ACCESSED bit into APG field, hence reducing the
action to a single instruction.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
  • Loading branch information
Christophe Leroy authored and Michael Ellerman committed Jan 16, 2018
1 parent de0f938 commit 4f94b2c
Show file tree
Hide file tree
Showing 3 changed files with 47 additions and 34 deletions.
34 changes: 28 additions & 6 deletions arch/powerpc/include/asm/mmu-8xx.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,12 +34,20 @@
* respectively NA for All or X for Supervisor and no access for User.
* Then we use the APG to say whether accesses are according to Page rules or
* "all Supervisor" rules (Access to all)
* Therefore, we define 2 APG groups. lsb is _PMD_USER
* 0 => No user => 01 (all accesses performed according to page definition)
* 1 => User => 00 (all accesses performed as supervisor iaw page definition)
* We also use the 2nd APG bit for _PAGE_ACCESSED when having SWAP:
* When that bit is not set access is done iaw "all user"
* which means no access iaw page rules.
* Therefore, we define 4 APG groups. lsb is _PMD_USER, 2nd is _PAGE_ACCESSED
* 0x => No access => 11 (all accesses performed as user iaw page definition)
* 10 => No user => 01 (all accesses performed according to page definition)
* 11 => User => 00 (all accesses performed as supervisor iaw page definition)
* We define all 16 groups so that all other bits of APG can take any value
*/
#ifdef CONFIG_SWAP
#define MI_APG_INIT 0xf4f4f4f4
#else
#define MI_APG_INIT 0x44444444
#endif

/* The effective page number register. When read, contains the information
* about the last instruction TLB miss. When MI_RPN is written, bits in
Expand Down Expand Up @@ -107,12 +115,20 @@
* Supervisor and no access for user and NA for ALL.
* Then we use the APG to say whether accesses are according to Page rules or
* "all Supervisor" rules (Access to all)
* Therefore, we define 2 APG groups. lsb is _PMD_USER
* 0 => No user => 01 (all accesses performed according to page definition)
* 1 => User => 00 (all accesses performed as supervisor iaw page definition)
* We also use the 2nd APG bit for _PAGE_ACCESSED when having SWAP:
* When that bit is not set access is done iaw "all user"
* which means no access iaw page rules.
* Therefore, we define 4 APG groups. lsb is _PMD_USER, 2nd is _PAGE_ACCESSED
* 0x => No access => 11 (all accesses performed as user iaw page definition)
* 10 => No user => 01 (all accesses performed according to page definition)
* 11 => User => 00 (all accesses performed as supervisor iaw page definition)
* We define all 16 groups so that all other bits of APG can take any value
*/
#ifdef CONFIG_SWAP
#define MD_APG_INIT 0xf4f4f4f4
#else
#define MD_APG_INIT 0x44444444
#endif

/* The effective page number register. When read, contains the information
* about the last instruction TLB miss. When MD_RPN is written, bits in
Expand Down Expand Up @@ -164,6 +180,12 @@
*/
#define SPRN_M_TW 799

/* APGs */
#define M_APG0 0x00000000
#define M_APG1 0x00000020
#define M_APG2 0x00000040
#define M_APG3 0x00000060

#ifndef __ASSEMBLY__
typedef struct {
unsigned int id;
Expand Down
45 changes: 18 additions & 27 deletions arch/powerpc/kernel/head_8xx.S
View file
Original file line number Diff line number Diff line change
Expand Up @@ -354,14 +354,13 @@ _ENTRY(ITLBMiss_cmp)
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mtcr r12
#endif
/* Load the MI_TWC with the attributes for this "segment." */
mtspr SPRN_MI_TWC, r11 /* Set segment attributes */

#ifdef CONFIG_SWAP
rlwinm r11, r10, 32-5, _PAGE_PRESENT
and r11, r11, r10
rlwimi r10, r11, 0, _PAGE_PRESENT
rlwinm r11, r10, 31, _PAGE_ACCESSED >> 1
#endif
/* Load the MI_TWC with the attributes for this "segment." */
mtspr SPRN_MI_TWC, r11 /* Set segment attributes */

li r11, RPN_PATTERN | 0x200
/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 20 and 23 must be clear.
Expand Down Expand Up @@ -472,22 +471,14 @@ _ENTRY(DTLBMiss_jmp)
* above.
*/
rlwimi r11, r10, 0, _PAGE_GUARDED
mtspr SPRN_MD_TWC, r11

/* Both _PAGE_ACCESSED and _PAGE_PRESENT has to be set.
* We also need to know if the insn is a load/store, so:
* Clear _PAGE_PRESENT and load that which will
* trap into DTLB Error with store bit set accordinly.
*/
/* PRESENT=0x1, ACCESSED=0x20
* r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5));
* r10 = (r10 & ~PRESENT) | r11;
*/
#ifdef CONFIG_SWAP
rlwinm r11, r10, 32-5, _PAGE_PRESENT
and r11, r11, r10
rlwimi r10, r11, 0, _PAGE_PRESENT
/* _PAGE_ACCESSED has to be set. We use second APG bit for that, 0
* on that bit will represent a Non Access group
*/
rlwinm r11, r10, 31, _PAGE_ACCESSED >> 1
#endif
mtspr SPRN_MD_TWC, r11

/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 24, 25, 26, and 27 must be
* set. All other Linux PTE bits control the behavior
Expand Down Expand Up @@ -647,8 +638,8 @@ InstructionBreakpoint:
*/
DTLBMissIMMR:
mtcr r12
/* Set 512k byte guarded page and mark it valid */
li r10, MD_PS512K | MD_GUARDED | MD_SVALID
/* Set 512k byte guarded page and mark it valid and accessed */
li r10, MD_PS512K | MD_GUARDED | MD_SVALID | M_APG2
mtspr SPRN_MD_TWC, r10
mfspr r10, SPRN_IMMR /* Get current IMMR */
rlwinm r10, r10, 0, 0xfff80000 /* Get 512 kbytes boundary */
Expand All @@ -666,8 +657,8 @@ _ENTRY(dtlb_miss_exit_2)

DTLBMissLinear:
mtcr r12
/* Set 8M byte page and mark it valid */
li r11, MD_PS8MEG | MD_SVALID
/* Set 8M byte page and mark it valid and accessed */
li r11, MD_PS8MEG | MD_SVALID | M_APG2
mtspr SPRN_MD_TWC, r11
rlwinm r10, r10, 0, 0x0f800000 /* 8xx supports max 256Mb RAM */
ori r10, r10, 0xf0 | MD_SPS16K | _PAGE_PRIVILEGED | _PAGE_DIRTY | \
Expand All @@ -685,8 +676,8 @@ _ENTRY(dtlb_miss_exit_3)
#ifndef CONFIG_PIN_TLB_TEXT
ITLBMissLinear:
mtcr r12
/* Set 8M byte page and mark it valid */
li r11, MI_PS8MEG | MI_SVALID
/* Set 8M byte page and mark it valid,accessed */
li r11, MI_PS8MEG | MI_SVALID | M_APG2
mtspr SPRN_MI_TWC, r11
rlwinm r10, r10, 0, 0x0f800000 /* 8xx supports max 256Mb RAM */
ori r10, r10, 0xf0 | MI_SPS16K | _PAGE_PRIVILEGED | _PAGE_DIRTY | \
Expand Down Expand Up @@ -969,7 +960,7 @@ initial_mmu:
ori r8, r8, MI_EVALID /* Mark it valid */
mtspr SPRN_MI_EPN, r8
li r8, MI_PS8MEG /* Set 8M byte page */
ori r8, r8, MI_SVALID /* Make it valid */
ori r8, r8, MI_SVALID | M_APG2 /* Make it valid, APG 2 */
mtspr SPRN_MI_TWC, r8
li r8, MI_BOOTINIT /* Create RPN for address 0 */
mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
Expand All @@ -996,7 +987,7 @@ initial_mmu:
ori r8, r8, MD_EVALID /* Mark it valid */
mtspr SPRN_MD_EPN, r8
li r8, MD_PS512K | MD_GUARDED /* Set 512k byte page */
ori r8, r8, MD_SVALID /* Make it valid */
ori r8, r8, MD_SVALID | M_APG2 /* Make it valid and accessed */
mtspr SPRN_MD_TWC, r8
mr r8, r9 /* Create paddr for TLB */
ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
Expand Down
2 changes: 1 addition & 1 deletion arch/powerpc/mm/8xx_mmu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,7 @@ void __init MMU_init_hw(void)
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_TWC, MD_PS8MEG | MD_SVALID | M_APG2);
mtspr(SPRN_MD_RPN, addr | flags | _PAGE_PRESENT);
addr += LARGE_PAGE_SIZE_8M;
mem -= LARGE_PAGE_SIZE_8M;
Expand Down

0 comments on commit 4f94b2c

Please sign in to comment.