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Message-Id: <1454615017-24672-3-git-send-email-labbott@fedoraproject.org>
Date: Thu, 4 Feb 2016 11:43:36 -0800
From: Laura Abbott <labbott@...oraproject.org>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
Mark Rutland <mark.rutland@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Laura Abbott <labbott@...oraproject.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCHv2 2/3] arm64: Add support for ARCH_SUPPORTS_DEBUG_PAGEALLOC
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.
Signed-off-by: Laura Abbott <labbott@...oraproject.org>
---
arch/arm64/Kconfig | 3 +++
arch/arm64/mm/mmu.c | 25 +++++++++++++++++++++----
arch/arm64/mm/pageattr.c | 46 ++++++++++++++++++++++++++++++++++++----------
3 files changed, 60 insertions(+), 14 deletions(-)
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..be81a59 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -180,8 +180,14 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
pmd = pmd_set_fixmap_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
- /* try section mapping first */
- if (((addr | next | phys) & ~SECTION_MASK) == 0) {
+ /*
+ * try a section mapping first
+ *
+ * See comment in use_1G_block for why we need the check
+ * for !pgtable_alloc with !debug_pagealloc
+ */
+ if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
+ (!debug_pagealloc_enabled() || !pgtable_alloc)) {
pmd_t old_pmd =*pmd;
set_pmd(pmd, __pmd(phys |
pgprot_val(mk_sect_prot(prot))));
@@ -208,8 +214,19 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
}
static inline bool use_1G_block(unsigned long addr, unsigned long next,
- unsigned long phys)
+ unsigned long phys, phys_addr_t (*pgtable_alloc)(void))
{
+ /*
+ * If debug_page_alloc is enabled we don't want to be using sections
+ * since everything needs to be mapped with pages. The catch is
+ * that we only want to force pages if we can allocate the next
+ * layer of page tables. If there is no pgtable_alloc function,
+ * it's too early to allocate another layer and we should use
+ * section mappings.
+ */
+ if (pgtable_alloc && debug_pagealloc_enabled())
+ return false;
+
if (PAGE_SHIFT != 12)
return false;
@@ -241,7 +258,7 @@ 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, 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..57877af 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
--
2.5.0
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