diff mbox

[PATCHv4,2/3] arm64: Add support for ARCH_SUPPORTS_DEBUG_PAGEALLOC

Message ID 1454718288-31374-3-git-send-email-labbott@fedoraproject.org (mailing list archive)
State New, archived
Headers show

Commit Message

Laura Abbott Feb. 6, 2016, 12:24 a.m. UTC 
ARCH_SUPPORTS_DEBUG_PAGEALLOC provides a hook to map and unmap
pages for debugging purposes. This requires memory be mapped
with PAGE_SIZE mappings since breaking down larger mappings
at runtime will lead to TLB conflicts. Check if debug_pagealloc
is enabled at runtime and if so, map everyting with PAGE_SIZE
pages. Implement the functions to actually map/unmap the
pages at runtime.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
---
 arch/arm64/Kconfig       |  3 +++
 arch/arm64/mm/mmu.c      | 19 +++++++++++++++++--
 arch/arm64/mm/pageattr.c | 46 ++++++++++++++++++++++++++++++++++++----------
 3 files changed, 56 insertions(+), 12 deletions(-)

Comments

Catalin Marinas Feb. 10, 2016, 10:38 a.m. UTC | #1 
On Fri, Feb 05, 2016 at 04:24:47PM -0800, Laura Abbott wrote:
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -149,6 +149,19 @@ static void split_pud(pud_t *old_pud, pmd_t *pmd)
>  	} while (pmd++, i++, i < PTRS_PER_PMD);
>  }
>  
> +bool block_mappings_allowed(phys_addr_t (*pgtable_alloc)(void))
> +{
> +
> +	/*
> +	 * If debug_page_alloc is enabled we must map the linear map
> +	 * using pages. However, other mappings created by
> +	 * create_mapping_noalloc must use sections in some cases. Allow
> +	 * sections to be used in those cases, where no pgtable_alloc
> +	 * function is provided.
> +	 */
> +	return !pgtable_alloc || !debug_pagealloc_enabled();
> +}

This breaks the build when CONFIG_DEBUG_PAGEALLOC is not enabled
(defconfig) since debug_pagealloc_enabled() is not defined. A fix went
in next/master as commit 0987684b855c
("mm-slab-clean-up-debug_pagealloc-processing-code-fix"). I need to
track it down and merge it via the arm64 tree, otherwise I'll add some
#ifdefs in this function.

BTW, shouldn't the block_mappings_allowed() function be static?
Ard Biesheuvel Feb. 10, 2016, 10:40 a.m. UTC | #2 
On 10 February 2016 at 11:38, Catalin Marinas <catalin.marinas@arm.com> wrote:
> On Fri, Feb 05, 2016 at 04:24:47PM -0800, Laura Abbott wrote:
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -149,6 +149,19 @@ static void split_pud(pud_t *old_pud, pmd_t *pmd)
>>       } while (pmd++, i++, i < PTRS_PER_PMD);
>>  }
>>
>> +bool block_mappings_allowed(phys_addr_t (*pgtable_alloc)(void))
>> +{
>> +
>> +     /*
>> +      * If debug_page_alloc is enabled we must map the linear map
>> +      * using pages. However, other mappings created by
>> +      * create_mapping_noalloc must use sections in some cases. Allow
>> +      * sections to be used in those cases, where no pgtable_alloc
>> +      * function is provided.
>> +      */
>> +     return !pgtable_alloc || !debug_pagealloc_enabled();
>> +}
>
> This breaks the build when CONFIG_DEBUG_PAGEALLOC is not enabled
> (defconfig) since debug_pagealloc_enabled() is not defined. A fix went
> in next/master as commit 0987684b855c
> ("mm-slab-clean-up-debug_pagealloc-processing-code-fix"). I need to
> track it down and merge it via the arm64 tree, otherwise I'll add some
> #ifdefs in this function.
>
> BTW, shouldn't the block_mappings_allowed() function be static?
>

Yes, it should.
Mark Rutland Feb. 10, 2016, 10:54 a.m. UTC | #3 
On Wed, Feb 10, 2016 at 10:38:14AM +0000, Catalin Marinas wrote:
> On Fri, Feb 05, 2016 at 04:24:47PM -0800, Laura Abbott wrote:
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -149,6 +149,19 @@ static void split_pud(pud_t *old_pud, pmd_t *pmd)
> >  	} while (pmd++, i++, i < PTRS_PER_PMD);
> >  }
> >  
> > +bool block_mappings_allowed(phys_addr_t (*pgtable_alloc)(void))
> > +{
> > +
> > +	/*
> > +	 * If debug_page_alloc is enabled we must map the linear map
> > +	 * using pages. However, other mappings created by
> > +	 * create_mapping_noalloc must use sections in some cases. Allow
> > +	 * sections to be used in those cases, where no pgtable_alloc
> > +	 * function is provided.
> > +	 */
> > +	return !pgtable_alloc || !debug_pagealloc_enabled();
> > +}
> 
> This breaks the build when CONFIG_DEBUG_PAGEALLOC is not enabled
> (defconfig) since debug_pagealloc_enabled() is not defined. A fix went
> in next/master as commit 0987684b855c
> ("mm-slab-clean-up-debug_pagealloc-processing-code-fix"). I need to
> track it down and merge it via the arm64 tree, otherwise I'll add some
> #ifdefs in this function.

In the cover for v2 [1],  it was mentioend that we needed a patch [2]
"mm: provide debug_pagealloc_enabled() without CONFIG_DEBUG_PAGEALLOC".
I assumed that was already queued via the mm tree.

> BTW, shouldn't the block_mappings_allowed() function be static?

That would make sense to me, yes.

Mark.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2016-January/403439.html  
[2] http://article.gmane.org/gmane.linux.kernel.mm/1452
Catalin Marinas Feb. 10, 2016, 11:02 a.m. UTC | #4 
On Wed, Feb 10, 2016 at 10:38:14AM +0000, Catalin Marinas wrote:
> On Fri, Feb 05, 2016 at 04:24:47PM -0800, Laura Abbott wrote:
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -149,6 +149,19 @@ static void split_pud(pud_t *old_pud, pmd_t *pmd)
> >  	} while (pmd++, i++, i < PTRS_PER_PMD);
> >  }
> >  
> > +bool block_mappings_allowed(phys_addr_t (*pgtable_alloc)(void))
> > +{
> > +
> > +	/*
> > +	 * If debug_page_alloc is enabled we must map the linear map
> > +	 * using pages. However, other mappings created by
> > +	 * create_mapping_noalloc must use sections in some cases. Allow
> > +	 * sections to be used in those cases, where no pgtable_alloc
> > +	 * function is provided.
> > +	 */
> > +	return !pgtable_alloc || !debug_pagealloc_enabled();
> > +}
> 
> This breaks the build when CONFIG_DEBUG_PAGEALLOC is not enabled
> (defconfig) since debug_pagealloc_enabled() is not defined. A fix went
> in next/master as commit 0987684b855c
> ("mm-slab-clean-up-debug_pagealloc-processing-code-fix"). I need to
> track it down and merge it via the arm64 tree, otherwise I'll add some
> #ifdefs in this function.

It seems that there are other patches in the mm tree requiring this
change. I'll fix it locally (#ifdefs) and revert the change after -rc1.
diff mbox

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 8cc6228..0f33218 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -537,6 +537,9 @@  config HOTPLUG_CPU
 source kernel/Kconfig.preempt
 source kernel/Kconfig.hz
 
+config ARCH_SUPPORTS_DEBUG_PAGEALLOC
+	def_bool y
+
 config ARCH_HAS_HOLES_MEMORYMODEL
 	def_bool y if SPARSEMEM
 
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index ef0d66c..29dcc83 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -149,6 +149,19 @@  static void split_pud(pud_t *old_pud, pmd_t *pmd)
 	} while (pmd++, i++, i < PTRS_PER_PMD);
 }
 
+bool block_mappings_allowed(phys_addr_t (*pgtable_alloc)(void))
+{
+
+	/*
+	 * If debug_page_alloc is enabled we must map the linear map
+	 * using pages. However, other mappings created by
+	 * create_mapping_noalloc must use sections in some cases. Allow
+	 * sections to be used in those cases, where no pgtable_alloc
+	 * function is provided.
+	 */
+	return !pgtable_alloc || !debug_pagealloc_enabled();
+}
+
 static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 				  phys_addr_t phys, pgprot_t prot,
 				  phys_addr_t (*pgtable_alloc)(void))
@@ -181,7 +194,8 @@  static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 	do {
 		next = pmd_addr_end(addr, end);
 		/* try section mapping first */
-		if (((addr | next | phys) & ~SECTION_MASK) == 0) {
+		if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
+		      block_mappings_allowed(pgtable_alloc)) {
 			pmd_t old_pmd =*pmd;
 			set_pmd(pmd, __pmd(phys |
 					   pgprot_val(mk_sect_prot(prot))));
@@ -241,7 +255,8 @@  static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
 		/*
 		 * For 4K granule only, attempt to put down a 1GB block
 		 */
-		if (use_1G_block(addr, next, phys)) {
+		if (use_1G_block(addr, next, phys) &&
+		    block_mappings_allowed(pgtable_alloc)) {
 			pud_t old_pud = *pud;
 			set_pud(pud, __pud(phys |
 					   pgprot_val(mk_sect_prot(prot))));
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 1360a02..7ba87c4 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -37,14 +37,31 @@  static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
 	return 0;
 }
 
+/*
+ * This function assumes that the range is mapped with PAGE_SIZE pages.
+ */
+static int __change_memory_common(unsigned long start, unsigned long size,
+				pgprot_t set_mask, pgprot_t clear_mask)
+{
+	struct page_change_data data;
+	int ret;
+
+	data.set_mask = set_mask;
+	data.clear_mask = clear_mask;
+
+	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
+					&data);
+
+	flush_tlb_kernel_range(start, start + size);
+	return ret;
+}
+
 static int change_memory_common(unsigned long addr, int numpages,
 				pgprot_t set_mask, pgprot_t clear_mask)
 {
 	unsigned long start = addr;
 	unsigned long size = PAGE_SIZE*numpages;
 	unsigned long end = start + size;
-	int ret;
-	struct page_change_data data;
 	struct vm_struct *area;
 
 	if (!PAGE_ALIGNED(addr)) {
@@ -72,14 +89,7 @@  static int change_memory_common(unsigned long addr, int numpages,
 	    !(area->flags & VM_ALLOC))
 		return -EINVAL;
 
-	data.set_mask = set_mask;
-	data.clear_mask = clear_mask;
-
-	ret = apply_to_page_range(&init_mm, start, size, change_page_range,
-					&data);
-
-	flush_tlb_kernel_range(start, end);
-	return ret;
+	return __change_memory_common(start, size, set_mask, clear_mask);
 }
 
 int set_memory_ro(unsigned long addr, int numpages)
@@ -111,3 +121,19 @@  int set_memory_x(unsigned long addr, int numpages)
 					__pgprot(PTE_PXN));
 }
 EXPORT_SYMBOL_GPL(set_memory_x);
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+void __kernel_map_pages(struct page *page, int numpages, int enable)
+{
+	unsigned long addr = (unsigned long) page_address(page);
+
+	if (enable)
+		__change_memory_common(addr, PAGE_SIZE * numpages,
+					__pgprot(PTE_VALID),
+					__pgprot(0));
+	else
+		__change_memory_common(addr, PAGE_SIZE * numpages,
+					__pgprot(0),
+					__pgprot(PTE_VALID));
+}
+#endif