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.biesheu...@linaro.org>
Reviewed-by: Mark Rutland <mark.rutl...@arm.com>
Tested-by: Mark Rutland <mark.rutl...@arm.com>
Signed-off-by: Laura Abbott <labb...@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(-)
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
--
2.5.0
