[PATCH v4 0/3] Fix issues with huge mapping in ioremap for ARM64

[PATCH v4 0/3] Fix issues with huge mapping in ioremap for ARM64

[Chintan Pandya]

This series of patches are follow up work (and depends on)
Toshi Kani <toshi.kani@hpe.com>'s patches "fix memory leak/
panic in ioremap huge pages".

This series of patches are tested on 4.9 kernel with Cortex-A75
based SoC.

Chintan Pandya (3):
  ioremap: Update pgtable free interfaces with addr
  arm64: Implement page table free interfaces
  Revert "arm64: Enforce BBM for huge IO/VMAP mappings"

>From V3->V4:
 - Add header for 'addr' in x86 implementation
 - Re-order pmd/pud clear and table free
 - Avoid redundant TLB invalidatation in one perticular case

>From V2->V3:
 - Use the exisiting page table free interface to do arm64
   specific things

>From V1->V2:
 - Rebased my patches on top of "[PATCH v2 1/2] mm/vmalloc:
   Add interfaces to free unmapped page table"
 - Honored BBM for ARM64

 arch/arm64/mm/mmu.c           | 51 +++++++++++++++++++++++++++++++++----------
 arch/x86/mm/pgtable.c         |  6 +++--
 include/asm-generic/pgtable.h |  8 +++----
 lib/ioremap.c                 |  4 ++--
 4 files changed, 49 insertions(+), 20 deletions(-)

-- 
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Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project

[PATCH v4 1/3] ioremap: Update pgtable free interfaces with addr

[Chintan Pandya]

This patch ("mm/vmalloc: Add interfaces to free unmapped
page table") adds following 2 interfaces to free the page
table in case we implement huge mapping.

pud_free_pmd_page() and pmd_free_pte_page()

Some architectures (like arm64) needs to do proper TLB
maintanance after updating pagetable entry even in map.
Why ? Read this,
https://patchwork.kernel.org/patch/10134581/

Pass 'addr' in these interfaces so that proper TLB ops
can be performed.

Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
---
 arch/arm64/mm/mmu.c           | 4 ++--
 arch/x86/mm/pgtable.c         | 6 ++++--
 include/asm-generic/pgtable.h | 8 ++++----
 lib/ioremap.c                 | 4 ++--
 4 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 2dbb2c9..da98828 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -973,12 +973,12 @@ int pmd_clear_huge(pmd_t *pmdp)
 	return 1;
 }
 
-int pud_free_pmd_page(pud_t *pud)
+int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 {
 	return pud_none(*pud);
 }
 
-int pmd_free_pte_page(pmd_t *pmd)
+int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 {
 	return pmd_none(*pmd);
 }
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 34cda7e..f640ba3 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -706,11 +706,12 @@ int pmd_clear_huge(pmd_t *pmd)
 /**
  * pud_free_pmd_page - Clear pud entry and free pmd page.
  * @pud: Pointer to a PUD.
+ * @addr: Virtual address associated with pud.
  *
  * Context: The pud range has been unmaped and TLB purged.
  * Return: 1 if clearing the entry succeeded. 0 otherwise.
  */
-int pud_free_pmd_page(pud_t *pud)
+int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 {
 	pmd_t *pmd;
 	int i;
@@ -733,11 +734,12 @@ int pud_free_pmd_page(pud_t *pud)
 /**
  * pmd_free_pte_page - Clear pmd entry and free pte page.
  * @pmd: Pointer to a PMD.
+ * @addr: Virtual address associated with pmd.
  *
  * Context: The pmd range has been unmaped and TLB purged.
  * Return: 1 if clearing the entry succeeded. 0 otherwise.
  */
-int pmd_free_pte_page(pmd_t *pmd)
+int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 {
 	pte_t *pte;
 
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index bfbb44a..e6310f4 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -983,8 +983,8 @@ static inline int p4d_clear_huge(p4d_t *p4d)
 int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot);
 int pud_clear_huge(pud_t *pud);
 int pmd_clear_huge(pmd_t *pmd);
-int pud_free_pmd_page(pud_t *pud);
-int pmd_free_pte_page(pmd_t *pmd);
+int pud_free_pmd_page(pud_t *pud, unsigned long addr);
+int pmd_free_pte_page(pmd_t *pmd, unsigned long addr);
 #else	/* !CONFIG_HAVE_ARCH_HUGE_VMAP */
 static inline int p4d_set_huge(p4d_t *p4d, phys_addr_t addr, pgprot_t prot)
 {
@@ -1010,11 +1010,11 @@ static inline int pmd_clear_huge(pmd_t *pmd)
 {
 	return 0;
 }
-static inline int pud_free_pmd_page(pud_t *pud)
+static inline int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 {
 	return 0;
 }
-static inline int pmd_free_pte_page(pmd_t *pmd)
+static inline int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 {
 	return 0;
 }
diff --git a/lib/ioremap.c b/lib/ioremap.c
index 54e5bba..517f585 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -92,7 +92,7 @@ static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
 		if (ioremap_pmd_enabled() &&
 		    ((next - addr) == PMD_SIZE) &&
 		    IS_ALIGNED(phys_addr + addr, PMD_SIZE) &&
-		    pmd_free_pte_page(pmd)) {
+		    pmd_free_pte_page(pmd, addr)) {
 			if (pmd_set_huge(pmd, phys_addr + addr, prot))
 				continue;
 		}
@@ -119,7 +119,7 @@ static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
 		if (ioremap_pud_enabled() &&
 		    ((next - addr) == PUD_SIZE) &&
 		    IS_ALIGNED(phys_addr + addr, PUD_SIZE) &&
-		    pud_free_pmd_page(pud)) {
+		    pud_free_pmd_page(pud, addr)) {
 			if (pud_set_huge(pud, phys_addr + addr, prot))
 				continue;
 		}
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation
Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project

Re: [PATCH v4 1/3] ioremap: Update pgtable free interfaces with addr

[Kani, Toshi]

On Tue, 2018-03-20 at 17:15 +0530, Chintan Pandya wrote:
> This patch ("mm/vmalloc: Add interfaces to free unmapped
> page table") adds following 2 interfaces to free the page
> table in case we implement huge mapping.
> 
> pud_free_pmd_page() and pmd_free_pte_page()
> 
> Some architectures (like arm64) needs to do proper TLB
> maintanance after updating pagetable entry even in map.
> Why ? Read this,
> https://patchwork.kernel.org/patch/10134581/
> 
> Pass 'addr' in these interfaces so that proper TLB ops
> can be performed.
> 
> Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>

Thanks for the update.  The change looks good.

Reviewed-by: Toshi Kani <toshi.kani@hpe.com>

-Toshi

[PATCH v4 2/3] arm64: Implement page table free interfaces

[Chintan Pandya]

Implement pud_free_pmd_page() and pmd_free_pte_page().

Implementation requires,
 1) Freeing of the un-used next level page tables
 2) Clearing off the current pud/pmd entry
 3) Invalidate TLB which could have previously
    valid but not stale entry

Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
---
 arch/arm64/mm/mmu.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index da98828..7be3106 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -45,6 +45,7 @@
 #include <asm/memblock.h>
 #include <asm/mmu_context.h>
 #include <asm/ptdump.h>
+#include <asm/tlbflush.h>
 
 #define NO_BLOCK_MAPPINGS	BIT(0)
 #define NO_CONT_MAPPINGS	BIT(1)
@@ -973,12 +974,47 @@ int pmd_clear_huge(pmd_t *pmdp)
 	return 1;
 }
 
+static int __pmd_free_pte_page(pmd_t *pmd, unsigned long addr, bool tlb_inv)
+{
+	pmd_t *table;
+
+	if (pmd_val(*pmd)) {
+		table = __va(pmd_val(*pmd));
+		pmd_clear(pmd);
+		/*
+		 * FIXME: __flush_tlb_pgtable(&init_mm, addr) is
+		 *        ideal candidate here, which exactly
+		 *        flushes intermediate pgtables. But,
+		 *        this is broken (evident from tests).
+		 *        So, use safe TLB op unless that is fixed.
+		 */
+		if (tlb_inv)
+			flush_tlb_kernel_range(addr, addr + PMD_SIZE);
+
+		free_page((unsigned long) table);
+	}
+	return 1;
+}
+
 int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 {
-	return pud_none(*pud);
+	pmd_t *table;
+	int i;
+
+	if (pud_val(*pud)) {
+		table = __va(pud_val(*pud));
+		for (i = 0; i < PTRS_PER_PMD; i++)
+			__pmd_free_pte_page(&table[i], addr + (i * PMD_SIZE),
+						false);
+
+		pud_clear(pud);
+		flush_tlb_kernel_range(addr, addr + PUD_SIZE);
+		free_page((unsigned long) table);
+	}
+	return 1;
 }
 
 int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
 {
-	return pmd_none(*pmd);
+	return __pmd_free_pte_page(pmd, addr, true);
 }
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation
Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project

Re: [PATCH v4 2/3] arm64: Implement page table free interfaces

[Mark Rutland]

On Tue, Mar 20, 2018 at 05:15:13PM +0530, Chintan Pandya wrote:
> +static int __pmd_free_pte_page(pmd_t *pmd, unsigned long addr, bool tlb_inv)
> +{
> +	pmd_t *table;
> +
> +	if (pmd_val(*pmd)) {
> +		table = __va(pmd_val(*pmd));
> +		pmd_clear(pmd);
> +		/*
> +		 * FIXME: __flush_tlb_pgtable(&init_mm, addr) is
> +		 *        ideal candidate here, which exactly
> +		 *        flushes intermediate pgtables. But,
> +		 *        this is broken (evident from tests).
> +		 *        So, use safe TLB op unless that is fixed.
> +		 */
> +		if (tlb_inv)
> +			flush_tlb_kernel_range(addr, addr + PMD_SIZE);

I don't think that __flush_tlb_pgtable() is broken. It's only valid to
call it for user page tables, since it doesn't affect all ASIDs.

We can add a simlar helper for kernel mappings, which affects all ASIDs,
e.g.

static inline void __flush_tlb_kernel_pgtable(unsigned long addr)
{
	addr >>= 12;
	__tlbi(vaae1is, addr);
	dsb(ish);
}

Thanks,
Mark.

Re: [PATCH v4 2/3] arm64: Implement page table free interfaces

[Chintan Pandya]

On 3/26/2018 3:25 PM, Mark Rutland wrote:
> On Tue, Mar 20, 2018 at 05:15:13PM +0530, Chintan Pandya wrote:
>> +static int __pmd_free_pte_page(pmd_t *pmd, unsigned long addr, bool tlb_inv)
>> +{
>> +	pmd_t *table;
>> +
>> +	if (pmd_val(*pmd)) {
>> +		table = __va(pmd_val(*pmd));
>> +		pmd_clear(pmd);
>> +		/*
>> +		 * FIXME: __flush_tlb_pgtable(&init_mm, addr) is
>> +		 *        ideal candidate here, which exactly
>> +		 *        flushes intermediate pgtables. But,
>> +		 *        this is broken (evident from tests).
>> +		 *        So, use safe TLB op unless that is fixed.
>> +		 */
>> +		if (tlb_inv)
>> +			flush_tlb_kernel_range(addr, addr + PMD_SIZE);
> 
> I don't think that __flush_tlb_pgtable() is broken. It's only valid to
> call it for user page tables, since it doesn't affect all ASIDs.
> 
> We can add a simlar helper for kernel mappings, which affects all ASIDs,
> e.g.
> 
Okay. I will test it and update v5.

> static inline void __flush_tlb_kernel_pgtable(unsigned long addr)
> {
> 	addr >>= 12;
> 	__tlbi(vaae1is, addr);
> 	dsb(ish);
> }
> 
> Thanks,
> Mark.
> 

Chintan
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center,
Inc. is a member of the Code Aurora Forum, a Linux Foundation
Collaborative Project

[PATCH v4 3/3] Revert "arm64: Enforce BBM for huge IO/VMAP mappings"

[Chintan Pandya]

This commit 15122ee2c515a ("arm64: Enforce BBM for huge
IO/VMAP mappings") is a temporary work-around until the
issues with CONFIG_HAVE_ARCH_HUGE_VMAP gets fixed.

Revert this change as we have fixes for the issue.

Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
---
 arch/arm64/mm/mmu.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 7be3106..1238717 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -935,10 +935,6 @@ int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
 	pgprot_t sect_prot = __pgprot(PUD_TYPE_SECT |
 					pgprot_val(mk_sect_prot(prot)));
 
-	/* ioremap_page_range doesn't honour BBM */
-	if (pud_present(READ_ONCE(*pudp)))
-		return 0;
-
 	BUG_ON(phys & ~PUD_MASK);
 	set_pud(pudp, pfn_pud(__phys_to_pfn(phys), sect_prot));
 	return 1;
@@ -949,10 +945,6 @@ int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
 	pgprot_t sect_prot = __pgprot(PMD_TYPE_SECT |
 					pgprot_val(mk_sect_prot(prot)));
 
-	/* ioremap_page_range doesn't honour BBM */
-	if (pmd_present(READ_ONCE(*pmdp)))
-		return 0;
-
 	BUG_ON(phys & ~PMD_MASK);
 	set_pmd(pmdp, pfn_pmd(__phys_to_pfn(phys), sect_prot));
 	return 1;
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation
Center, Inc., is a member of Code Aurora Forum, a Linux Foundation
Collaborative Project