[PATCH v1 1/6] powerpc/8xx: DEBUG_PAGEALLOC doesn't require an ITLB miss exception handler

[PATCH v1 1/6] powerpc/8xx: DEBUG_PAGEALLOC doesn't require an ITLB miss exception handler

[Christophe Leroy]

Since commit e611939fc8ec ("powerpc/mm: Ensure change_page_attr()
doesn't invalidate pinned TLBs"), pinned TLBs are not anymore
invalidated by __kernel_map_pages() when CONFIG_DEBUG_PAGEALLOC is
selected.

Remove the dependency on CONFIG_DEBUG_PAGEALLOC.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_8xx.S | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index ee0bfebc375f..66ee62f30d36 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -47,8 +47,7 @@
  * - Either we have modules
  * - Or we have not pinned the first 8M
  */
-#if defined(CONFIG_MODULES) || !defined(CONFIG_PIN_TLB_TEXT) || \
-    defined(CONFIG_DEBUG_PAGEALLOC)
+#if defined(CONFIG_MODULES) || !defined(CONFIG_PIN_TLB_TEXT)
 #define ITLB_MISS_KERNEL	1
 #endif
 
-- 
2.25.0

[PATCH v1 2/6] powerpc/8xx: Always pin kernel text TLB

[Christophe Leroy]

There is no big poing in not pinning kernel text anymore, as now
we can keep pinned TLB even with things like DEBUG_PAGEALLOC.

Remove CONFIG_PIN_TLB_TEXT, making it always right.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/Kconfig               |  3 +--
 arch/powerpc/kernel/head_8xx.S     | 20 +++-----------------
 arch/powerpc/mm/nohash/8xx.c       |  3 +--
 arch/powerpc/platforms/8xx/Kconfig |  7 -------
 4 files changed, 5 insertions(+), 28 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index e9f13fe08492..bf088b5b0a89 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -795,8 +795,7 @@ config DATA_SHIFT_BOOL
 	bool "Set custom data alignment"
 	depends on ADVANCED_OPTIONS
 	depends on STRICT_KERNEL_RWX || DEBUG_PAGEALLOC
-	depends on PPC_BOOK3S_32 || (PPC_8xx && !PIN_TLB_DATA && \
-				     (!PIN_TLB_TEXT || !STRICT_KERNEL_RWX))
+	depends on PPC_BOOK3S_32 || (PPC_8xx && !PIN_TLB_DATA && !STRICT_KERNEL_RWX)
 	help
 	  This option allows you to set the kernel data alignment. When
 	  RAM is mapped by blocks, the alignment needs to fit the size and
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 66ee62f30d36..775b4f4d011e 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -42,15 +42,6 @@
 #endif
 .endm
 
-/*
- * We need an ITLB miss handler for kernel addresses if:
- * - Either we have modules
- * - Or we have not pinned the first 8M
- */
-#if defined(CONFIG_MODULES) || !defined(CONFIG_PIN_TLB_TEXT)
-#define ITLB_MISS_KERNEL	1
-#endif
-
 /*
  * Value for the bits that have fixed value in RPN entries.
  * Also used for tagging DAR for DTLBerror.
@@ -209,12 +200,12 @@ InstructionTLBMiss:
 	mfspr	r10, SPRN_SRR0	/* Get effective address of fault */
 	INVALIDATE_ADJACENT_PAGES_CPU15(r10)
 	mtspr	SPRN_MD_EPN, r10
-#ifdef ITLB_MISS_KERNEL
+#ifdef CONFIG_MODULES
 	mfcr	r11
 	compare_to_kernel_boundary r10, r10
 #endif
 	mfspr	r10, SPRN_M_TWB	/* Get level 1 table */
-#ifdef ITLB_MISS_KERNEL
+#ifdef CONFIG_MODULES
 	blt+	3f
 	rlwinm	r10, r10, 0, 20, 31
 	oris	r10, r10, (swapper_pg_dir - PAGE_OFFSET)@ha
@@ -618,10 +609,6 @@ start_here:
 	lis	r0, (MD_TWAM | MD_RSV4I)@h
 	mtspr	SPRN_MD_CTR, r0
 #endif
-#ifndef CONFIG_PIN_TLB_TEXT
-	li	r0, 0
-	mtspr	SPRN_MI_CTR, r0
-#endif
 #if !defined(CONFIG_PIN_TLB_DATA) && !defined(CONFIG_PIN_TLB_IMMR)
 	lis	r0, MD_TWAM@h
 	mtspr	SPRN_MD_CTR, r0
@@ -739,7 +726,6 @@ _GLOBAL(mmu_pin_tlb)
 	mtspr	SPRN_MD_CTR, r6
 	tlbia
 
-#ifdef CONFIG_PIN_TLB_TEXT
 	LOAD_REG_IMMEDIATE(r5, 28 << 8)
 	LOAD_REG_IMMEDIATE(r6, PAGE_OFFSET)
 	LOAD_REG_IMMEDIATE(r7, MI_SVALID | MI_PS8MEG | _PMD_ACCESSED)
@@ -760,7 +746,7 @@ _GLOBAL(mmu_pin_tlb)
 	bdnzt	lt, 2b
 	lis	r0, MI_RSV4I@h
 	mtspr	SPRN_MI_CTR, r0
-#endif
+
 	LOAD_REG_IMMEDIATE(r5, 28 << 8 | MD_TWAM)
 #ifdef CONFIG_PIN_TLB_DATA
 	LOAD_REG_IMMEDIATE(r6, PAGE_OFFSET)
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index 231ca95f9ffb..19a3eec1d8c5 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -186,8 +186,7 @@ void mmu_mark_initmem_nx(void)
 	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
 	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
 
-	if (IS_ENABLED(CONFIG_PIN_TLB_TEXT))
-		mmu_pin_tlb(block_mapped_ram, false);
+	mmu_pin_tlb(block_mapped_ram, false);
 }
 
 #ifdef CONFIG_STRICT_KERNEL_RWX
diff --git a/arch/powerpc/platforms/8xx/Kconfig b/arch/powerpc/platforms/8xx/Kconfig
index cdda034733ff..1a8400bfbe82 100644
--- a/arch/powerpc/platforms/8xx/Kconfig
+++ b/arch/powerpc/platforms/8xx/Kconfig
@@ -202,13 +202,6 @@ config PIN_TLB_IMMR
 	  CONFIG_PIN_TLB_DATA is also selected, it will reduce
 	  CONFIG_PIN_TLB_DATA to 24 Mbytes.
 
-config PIN_TLB_TEXT
-	bool "Pinned TLB for TEXT"
-	depends on PIN_TLB
-	default y
-	help
-	  This pins kernel text with 8M pages.
-
 endmenu
 
 endmenu
-- 
2.25.0

Re: [PATCH v1 2/6] powerpc/8xx: Always pin kernel text TLB

[Michael Ellerman]

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> There is no big poing in not pinning kernel text anymore, as now
> we can keep pinned TLB even with things like DEBUG_PAGEALLOC.
>
> Remove CONFIG_PIN_TLB_TEXT, making it always right.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>  arch/powerpc/Kconfig               |  3 +--
>  arch/powerpc/kernel/head_8xx.S     | 20 +++-----------------
>  arch/powerpc/mm/nohash/8xx.c       |  3 +--
>  arch/powerpc/platforms/8xx/Kconfig |  7 -------
>  4 files changed, 5 insertions(+), 28 deletions(-)
>
...
> diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
> index 231ca95f9ffb..19a3eec1d8c5 100644
> --- a/arch/powerpc/mm/nohash/8xx.c
> +++ b/arch/powerpc/mm/nohash/8xx.c
> @@ -186,8 +186,7 @@ void mmu_mark_initmem_nx(void)
>  	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
>  	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
>  
> -	if (IS_ENABLED(CONFIG_PIN_TLB_TEXT))
> -		mmu_pin_tlb(block_mapped_ram, false);
> +	mmu_pin_tlb(block_mapped_ram, false);
>  }

This broke mpc885_ads_defconfig with:

  ld: arch/powerpc/mm/nohash/8xx.o: in function `mmu_mark_initmem_nx':
  /home/michael/linux/arch/powerpc/mm/nohash/8xx.c:189: undefined reference to `mmu_pin_tlb'
  make[1]: *** [/home/michael/linux/Makefile:1164: vmlinux] Error 1
  make: *** [Makefile:185: __sub-make] Error 2

Fixed by:

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 35707e86c5f3..52702f3db6df 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -702,7 +702,6 @@ FixupDAR:/* Entry point for dcbx workaround. */
 	mtspr	SPRN_DER, r8
 	blr
 
-#ifdef CONFIG_PIN_TLB
 _GLOBAL(mmu_pin_tlb)
 	lis	r9, (1f - PAGE_OFFSET)@h
 	ori	r9, r9, (1f - PAGE_OFFSET)@l
@@ -802,7 +801,6 @@ _GLOBAL(mmu_pin_tlb)
 	mtspr	SPRN_SRR1, r10
 	mtspr	SPRN_SRR0, r11
 	rfi
-#endif /* CONFIG_PIN_TLB */
 
 /*
  * We put a few things here that have to be page-aligned.


cheers

Re: [PATCH v1 2/6] powerpc/8xx: Always pin kernel text TLB

[Christophe Leroy]

Le 09/12/2020 à 11:43, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>> There is no big poing in not pinning kernel text anymore, as now
>> we can keep pinned TLB even with things like DEBUG_PAGEALLOC.
>>
>> Remove CONFIG_PIN_TLB_TEXT, making it always right.
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>>   arch/powerpc/Kconfig               |  3 +--
>>   arch/powerpc/kernel/head_8xx.S     | 20 +++-----------------
>>   arch/powerpc/mm/nohash/8xx.c       |  3 +--
>>   arch/powerpc/platforms/8xx/Kconfig |  7 -------
>>   4 files changed, 5 insertions(+), 28 deletions(-)
>>
> ...
>> diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
>> index 231ca95f9ffb..19a3eec1d8c5 100644
>> --- a/arch/powerpc/mm/nohash/8xx.c
>> +++ b/arch/powerpc/mm/nohash/8xx.c
>> @@ -186,8 +186,7 @@ void mmu_mark_initmem_nx(void)
>>   	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
>>   	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
>>   
>> -	if (IS_ENABLED(CONFIG_PIN_TLB_TEXT))
>> -		mmu_pin_tlb(block_mapped_ram, false);
>> +	mmu_pin_tlb(block_mapped_ram, false);
>>   }
> 
> This broke mpc885_ads_defconfig with:

:surprise:

How did I get it working ? Anyway, thanks for fixing it.

Christophe


> 
>    ld: arch/powerpc/mm/nohash/8xx.o: in function `mmu_mark_initmem_nx':
>    /home/michael/linux/arch/powerpc/mm/nohash/8xx.c:189: undefined reference to `mmu_pin_tlb'
>    make[1]: *** [/home/michael/linux/Makefile:1164: vmlinux] Error 1
>    make: *** [Makefile:185: __sub-make] Error 2
> 
> Fixed by:
> 
> diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
> index 35707e86c5f3..52702f3db6df 100644
> --- a/arch/powerpc/kernel/head_8xx.S
> +++ b/arch/powerpc/kernel/head_8xx.S
> @@ -702,7 +702,6 @@ FixupDAR:/* Entry point for dcbx workaround. */
>   	mtspr	SPRN_DER, r8
>   	blr
>   
> -#ifdef CONFIG_PIN_TLB
>   _GLOBAL(mmu_pin_tlb)
>   	lis	r9, (1f - PAGE_OFFSET)@h
>   	ori	r9, r9, (1f - PAGE_OFFSET)@l
> @@ -802,7 +801,6 @@ _GLOBAL(mmu_pin_tlb)
>   	mtspr	SPRN_SRR1, r10
>   	mtspr	SPRN_SRR0, r11
>   	rfi
> -#endif /* CONFIG_PIN_TLB */
>   
>   /*
>    * We put a few things here that have to be page-aligned.
> 
> 
> cheers
> 

Re: [PATCH v1 2/6] powerpc/8xx: Always pin kernel text TLB

[Michael Ellerman]

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> Le 09/12/2020 à 11:43, Michael Ellerman a écrit :
>> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>>> There is no big poing in not pinning kernel text anymore, as now
>>> we can keep pinned TLB even with things like DEBUG_PAGEALLOC.
>>>
>>> Remove CONFIG_PIN_TLB_TEXT, making it always right.
>>>
>>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>>> ---
>>>   arch/powerpc/Kconfig               |  3 +--
>>>   arch/powerpc/kernel/head_8xx.S     | 20 +++-----------------
>>>   arch/powerpc/mm/nohash/8xx.c       |  3 +--
>>>   arch/powerpc/platforms/8xx/Kconfig |  7 -------
>>>   4 files changed, 5 insertions(+), 28 deletions(-)
>>>
>> ...
>>> diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
>>> index 231ca95f9ffb..19a3eec1d8c5 100644
>>> --- a/arch/powerpc/mm/nohash/8xx.c
>>> +++ b/arch/powerpc/mm/nohash/8xx.c
>>> @@ -186,8 +186,7 @@ void mmu_mark_initmem_nx(void)
>>>   	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, false);
>>>   	mmu_mapin_ram_chunk(boundary, einittext8, PAGE_KERNEL, false);
>>>   
>>> -	if (IS_ENABLED(CONFIG_PIN_TLB_TEXT))
>>> -		mmu_pin_tlb(block_mapped_ram, false);
>>> +	mmu_pin_tlb(block_mapped_ram, false);
>>>   }
>> 
>> This broke mpc885_ads_defconfig with:
>
> :surprise:
>
> How did I get it working ? Anyway, thanks for fixing it.

No worries. I figured you must have tested with some other series(s)
applied and/or with different configs, it happens :)

cheers

[PATCH v1 3/6] powerpc/8xx: Simplify INVALIDATE_ADJACENT_PAGES_CPU15

[Christophe Leroy]

We now have r11 available as a scratch register so
INVALIDATE_ADJACENT_PAGES_CPU15() can be simplified.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_8xx.S | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 775b4f4d011e..558c8e615ef9 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -180,14 +180,13 @@ SystemCall:
  */
 
 #ifdef CONFIG_8xx_CPU15
-#define INVALIDATE_ADJACENT_PAGES_CPU15(addr)	\
-	addi	addr, addr, PAGE_SIZE;	\
-	tlbie	addr;			\
-	addi	addr, addr, -(PAGE_SIZE << 1);	\
-	tlbie	addr;			\
-	addi	addr, addr, PAGE_SIZE
+#define INVALIDATE_ADJACENT_PAGES_CPU15(addr, tmp)	\
+	addi	tmp, addr, PAGE_SIZE;	\
+	tlbie	tmp;			\
+	addi	tmp, addr, -PAGE_SIZE;	\
+	tlbie	tmp
 #else
-#define INVALIDATE_ADJACENT_PAGES_CPU15(addr)
+#define INVALIDATE_ADJACENT_PAGES_CPU15(addr, tmp)
 #endif
 
 InstructionTLBMiss:
@@ -198,7 +197,7 @@ InstructionTLBMiss:
 	 * kernel page tables.
 	 */
 	mfspr	r10, SPRN_SRR0	/* Get effective address of fault */
-	INVALIDATE_ADJACENT_PAGES_CPU15(r10)
+	INVALIDATE_ADJACENT_PAGES_CPU15(r10, r11)
 	mtspr	SPRN_MD_EPN, r10
 #ifdef CONFIG_MODULES
 	mfcr	r11
-- 
2.25.0

[PATCH v1 4/6] powerpc/8xx: Use SPRN_SPRG_SCRATCH2 in ITLB miss exception

[Christophe Leroy]

In order to re-enable MMU earlier, ensure ITLB miss exception
cannot clobber SPRN_SPRG_SCRATCH0 and SPRN_SPRG_SCRATCH1.
Do so by using SPRN_SPRG_SCRATCH2 and SPRN_M_TW instead, like
the DTLB miss exception.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_8xx.S | 12 ++++++------
 arch/powerpc/perf/8xx-pmu.c    |  4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 558c8e615ef9..45239b06b6ce 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -190,8 +190,8 @@ SystemCall:
 #endif
 
 InstructionTLBMiss:
-	mtspr	SPRN_SPRG_SCRATCH0, r10
-	mtspr	SPRN_SPRG_SCRATCH1, r11
+	mtspr	SPRN_SPRG_SCRATCH2, r10
+	mtspr	SPRN_M_TW, r11
 
 	/* If we are faulting a kernel address, we have to use the
 	 * kernel page tables.
@@ -230,8 +230,8 @@ InstructionTLBMiss:
 	mtspr	SPRN_MI_RPN, r10	/* Update TLB entry */
 
 	/* Restore registers */
-0:	mfspr	r10, SPRN_SPRG_SCRATCH0
-	mfspr	r11, SPRN_SPRG_SCRATCH1
+0:	mfspr	r10, SPRN_SPRG_SCRATCH2
+	mfspr	r11, SPRN_M_TW
 	rfi
 	patch_site	0b, patch__itlbmiss_exit_1
 
@@ -240,8 +240,8 @@ InstructionTLBMiss:
 0:	lwz	r10, (itlb_miss_counter - PAGE_OFFSET)@l(0)
 	addi	r10, r10, 1
 	stw	r10, (itlb_miss_counter - PAGE_OFFSET)@l(0)
-	mfspr	r10, SPRN_SPRG_SCRATCH0
-	mfspr	r11, SPRN_SPRG_SCRATCH1
+	mfspr	r10, SPRN_SPRG_SCRATCH2
+	mfspr	r11, SPRN_M_TW
 	rfi
 #endif
 
diff --git a/arch/powerpc/perf/8xx-pmu.c b/arch/powerpc/perf/8xx-pmu.c
index e53c3c161257..02db58c7427a 100644
--- a/arch/powerpc/perf/8xx-pmu.c
+++ b/arch/powerpc/perf/8xx-pmu.c
@@ -165,9 +165,9 @@ static void mpc8xx_pmu_del(struct perf_event *event, int flags)
 		break;
 	case PERF_8xx_ID_ITLB_LOAD_MISS:
 		if (atomic_dec_return(&itlb_miss_ref) == 0) {
-			/* mfspr r10, SPRN_SPRG_SCRATCH0 */
+			/* mfspr r10, SPRN_SPRG_SCRATCH2 */
 			struct ppc_inst insn = ppc_inst(PPC_INST_MFSPR | __PPC_RS(R10) |
-					    __PPC_SPR(SPRN_SPRG_SCRATCH0));
+					    __PPC_SPR(SPRN_SPRG_SCRATCH2));
 
 			patch_instruction_site(&patch__itlbmiss_exit_1, insn);
 		}
-- 
2.25.0

[PATCH v1 5/6] powerpc/8xx: Use SPRN_SPRG_SCRATCH2 in DTLB miss exception

[Christophe Leroy]

Use SPRN_SPRG_SCRATCH2 in DTLB miss exception instead of DAR
in order to be similar to ITLB miss exception.

This also simplifies mpc8xx_pmu_del()

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_8xx.S |  9 ++++-----
 arch/powerpc/perf/8xx-pmu.c    | 19 +++++++------------
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 45239b06b6ce..35707e86c5f3 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -247,7 +247,7 @@ InstructionTLBMiss:
 
 	. = 0x1200
 DataStoreTLBMiss:
-	mtspr	SPRN_DAR, r10
+	mtspr	SPRN_SPRG_SCRATCH2, r10
 	mtspr	SPRN_M_TW, r11
 	mfcr	r11
 
@@ -286,11 +286,11 @@ DataStoreTLBMiss:
 	li	r11, RPN_PATTERN
 	rlwimi	r10, r11, 0, 24, 27	/* Set 24-27 */
 	mtspr	SPRN_MD_RPN, r10	/* Update TLB entry */
+	mtspr	SPRN_DAR, r11		/* Tag DAR */
 
 	/* Restore registers */
 
-0:	mfspr	r10, SPRN_DAR
-	mtspr	SPRN_DAR, r11	/* Tag DAR */
+0:	mfspr	r10, SPRN_SPRG_SCRATCH2
 	mfspr	r11, SPRN_M_TW
 	rfi
 	patch_site	0b, patch__dtlbmiss_exit_1
@@ -300,8 +300,7 @@ DataStoreTLBMiss:
 0:	lwz	r10, (dtlb_miss_counter - PAGE_OFFSET)@l(0)
 	addi	r10, r10, 1
 	stw	r10, (dtlb_miss_counter - PAGE_OFFSET)@l(0)
-	mfspr	r10, SPRN_DAR
-	mtspr	SPRN_DAR, r11	/* Tag DAR */
+	mfspr	r10, SPRN_SPRG_SCRATCH2
 	mfspr	r11, SPRN_M_TW
 	rfi
 #endif
diff --git a/arch/powerpc/perf/8xx-pmu.c b/arch/powerpc/perf/8xx-pmu.c
index 02db58c7427a..93004ee586a1 100644
--- a/arch/powerpc/perf/8xx-pmu.c
+++ b/arch/powerpc/perf/8xx-pmu.c
@@ -153,6 +153,11 @@ static void mpc8xx_pmu_read(struct perf_event *event)
 
 static void mpc8xx_pmu_del(struct perf_event *event, int flags)
 {
+	struct ppc_inst insn;
+
+	/* mfspr r10, SPRN_SPRG_SCRATCH2 */
+	insn = ppc_inst(PPC_INST_MFSPR | __PPC_RS(R10) | __PPC_SPR(SPRN_SPRG_SCRATCH2));
+
 	mpc8xx_pmu_read(event);
 
 	/* If it was the last user, stop counting to avoid useles overhead */
@@ -164,22 +169,12 @@ static void mpc8xx_pmu_del(struct perf_event *event, int flags)
 			mtspr(SPRN_ICTRL, 7);
 		break;
 	case PERF_8xx_ID_ITLB_LOAD_MISS:
-		if (atomic_dec_return(&itlb_miss_ref) == 0) {
-			/* mfspr r10, SPRN_SPRG_SCRATCH2 */
-			struct ppc_inst insn = ppc_inst(PPC_INST_MFSPR | __PPC_RS(R10) |
-					    __PPC_SPR(SPRN_SPRG_SCRATCH2));
-
+		if (atomic_dec_return(&itlb_miss_ref) == 0)
 			patch_instruction_site(&patch__itlbmiss_exit_1, insn);
-		}
 		break;
 	case PERF_8xx_ID_DTLB_LOAD_MISS:
-		if (atomic_dec_return(&dtlb_miss_ref) == 0) {
-			/* mfspr r10, SPRN_DAR */
-			struct ppc_inst insn = ppc_inst(PPC_INST_MFSPR | __PPC_RS(R10) |
-					    __PPC_SPR(SPRN_DAR));
-
+		if (atomic_dec_return(&dtlb_miss_ref) == 0)
 			patch_instruction_site(&patch__dtlbmiss_exit_1, insn);
-		}
 		break;
 	}
 }
-- 
2.25.0

[PATCH v1 6/6] powerpc/ppc-opcode: Add PPC_RAW_MFSPR()

[Christophe Leroy]

Add PPC_RAW_MFSPR() to replace open coding done in 8xx-pmu.c

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/include/asm/ppc-opcode.h | 3 ++-
 arch/powerpc/perf/8xx-pmu.c           | 5 +----
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
index a6e3700c4566..da6f300e9788 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -230,7 +230,6 @@
 #define PPC_INST_POPCNTB_MASK		0xfc0007fe
 #define PPC_INST_RFEBB			0x4c000124
 #define PPC_INST_RFID			0x4c000024
-#define PPC_INST_MFSPR			0x7c0002a6
 #define PPC_INST_MFSPR_DSCR		0x7c1102a6
 #define PPC_INST_MFSPR_DSCR_MASK	0xfc1ffffe
 #define PPC_INST_MTSPR_DSCR		0x7c1103a6
@@ -507,6 +506,8 @@
 
 #define PPC_RAW_NEG(d, a)		(0x7c0000d0 | ___PPC_RT(d) | ___PPC_RA(a))
 
+#define PPC_RAW_MFSPR(d, spr)		(0x7c0002a6 | ___PPC_RT(d) | __PPC_SPR(spr))
+
 /* Deal with instructions that older assemblers aren't aware of */
 #define	PPC_BCCTR_FLUSH		stringify_in_c(.long PPC_INST_BCCTR_FLUSH)
 #define	PPC_CP_ABORT		stringify_in_c(.long PPC_RAW_CP_ABORT)
diff --git a/arch/powerpc/perf/8xx-pmu.c b/arch/powerpc/perf/8xx-pmu.c
index 93004ee586a1..f970d1510d3d 100644
--- a/arch/powerpc/perf/8xx-pmu.c
+++ b/arch/powerpc/perf/8xx-pmu.c
@@ -153,10 +153,7 @@ static void mpc8xx_pmu_read(struct perf_event *event)
 
 static void mpc8xx_pmu_del(struct perf_event *event, int flags)
 {
-	struct ppc_inst insn;
-
-	/* mfspr r10, SPRN_SPRG_SCRATCH2 */
-	insn = ppc_inst(PPC_INST_MFSPR | __PPC_RS(R10) | __PPC_SPR(SPRN_SPRG_SCRATCH2));
+	struct ppc_inst insn = ppc_inst(PPC_RAW_MFSPR(10, SPRN_SPRG_SCRATCH2));
 
 	mpc8xx_pmu_read(event);
 
-- 
2.25.0

Re: [PATCH v1 1/6] powerpc/8xx: DEBUG_PAGEALLOC doesn't require an ITLB miss exception handler

[Michael Ellerman]

On Tue, 24 Nov 2020 15:24:54 +0000 (UTC), Christophe Leroy wrote:
> Since commit e611939fc8ec ("powerpc/mm: Ensure change_page_attr()
> doesn't invalidate pinned TLBs"), pinned TLBs are not anymore
> invalidated by __kernel_map_pages() when CONFIG_DEBUG_PAGEALLOC is
> selected.
> 
> Remove the dependency on CONFIG_DEBUG_PAGEALLOC.

Applied to powerpc/next.

[1/6] powerpc/8xx: DEBUG_PAGEALLOC doesn't require an ITLB miss exception handler
      https://git.kernel.org/powerpc/c/613df979da6c032cbe6fa273fb8ca21af022157e
[2/6] powerpc/8xx: Always pin kernel text TLB
      https://git.kernel.org/powerpc/c/bccc58986a2f98e3af349c85c5f49aac7fb19ef2
[3/6] powerpc/8xx: Simplify INVALIDATE_ADJACENT_PAGES_CPU15
      https://git.kernel.org/powerpc/c/576e02bbf1062b9118d5bbb96a40ed3b6b359f22
[4/6] powerpc/8xx: Use SPRN_SPRG_SCRATCH2 in ITLB miss exception
      https://git.kernel.org/powerpc/c/a314ea5abf6dbaf35f14c9bd1d93105260fb9336
[5/6] powerpc/8xx: Use SPRN_SPRG_SCRATCH2 in DTLB miss exception
      https://git.kernel.org/powerpc/c/89eecd938cab80f0da18abbd2ed997a521f83f01
[6/6] powerpc/ppc-opcode: Add PPC_RAW_MFSPR()
      https://git.kernel.org/powerpc/c/70b588a068668dd7a92ed19cf0373ba92847957c

cheers