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Subject[PATCH 15/43] kmsan: mm: maintain KMSAN metadata for page operations
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Insert KMSAN hooks that make the necessary bookkeeping changes:
- poison page shadow and origins in alloc_pages()/free_page();
- clear page shadow and origins in clear_page(), copy_user_highpage();
- copy page metadata in copy_highpage(), wp_page_copy();
- handle vmap()/vunmap()/iounmap();

Signed-off-by: Alexander Potapenko <glider@google.com>
---
Link: https://linux-review.googlesource.com/id/I6d4f53a0e7eab46fa29f0348f3095d9f2e326850
---
arch/x86/include/asm/page_64.h | 13 +++++++++++++
arch/x86/mm/ioremap.c | 3 +++
include/linux/highmem.h | 3 +++
mm/memory.c | 2 ++
mm/page_alloc.c | 14 ++++++++++++++
mm/vmalloc.c | 20 ++++++++++++++++++--
6 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h
index 4bde0dc66100c..c10547510f1f4 100644
--- a/arch/x86/include/asm/page_64.h
+++ b/arch/x86/include/asm/page_64.h
@@ -44,14 +44,27 @@ void clear_page_orig(void *page);
void clear_page_rep(void *page);
void clear_page_erms(void *page);

+/* This is an assembly header, avoid including too much of kmsan.h */
+#ifdef CONFIG_KMSAN
+void kmsan_unpoison_memory(const void *addr, size_t size);
+#endif
+__no_sanitize_memory
static inline void clear_page(void *page)
{
+#ifdef CONFIG_KMSAN
+ /* alternative_call_2() changes @page. */
+ void *page_copy = page;
+#endif
alternative_call_2(clear_page_orig,
clear_page_rep, X86_FEATURE_REP_GOOD,
clear_page_erms, X86_FEATURE_ERMS,
"=D" (page),
"0" (page)
: "cc", "memory", "rax", "rcx");
+#ifdef CONFIG_KMSAN
+ /* Clear KMSAN shadow for the pages that have it. */
+ kmsan_unpoison_memory(page_copy, PAGE_SIZE);
+#endif
}

void copy_page(void *to, void *from);
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 026031b3b7829..4d0349ecc7cd7 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -17,6 +17,7 @@
#include <linux/cc_platform.h>
#include <linux/efi.h>
#include <linux/pgtable.h>
+#include <linux/kmsan.h>

#include <asm/set_memory.h>
#include <asm/e820/api.h>
@@ -474,6 +475,8 @@ void iounmap(volatile void __iomem *addr)
return;
}

+ kmsan_iounmap_page_range((unsigned long)addr,
+ (unsigned long)addr + get_vm_area_size(p));
memtype_free(p->phys_addr, p->phys_addr + get_vm_area_size(p));

/* Finally remove it */
diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 39bb9b47fa9cd..3e1898a44d7e3 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -6,6 +6,7 @@
#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/cacheflush.h>
+#include <linux/kmsan.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
@@ -277,6 +278,7 @@ static inline void copy_user_highpage(struct page *to, struct page *from,
vfrom = kmap_local_page(from);
vto = kmap_local_page(to);
copy_user_page(vto, vfrom, vaddr, to);
+ kmsan_unpoison_memory(page_address(to), PAGE_SIZE);
kunmap_local(vto);
kunmap_local(vfrom);
}
@@ -292,6 +294,7 @@ static inline void copy_highpage(struct page *to, struct page *from)
vfrom = kmap_local_page(from);
vto = kmap_local_page(to);
copy_page(vto, vfrom);
+ kmsan_copy_page_meta(to, from);
kunmap_local(vto);
kunmap_local(vfrom);
}
diff --git a/mm/memory.c b/mm/memory.c
index 8f1de811a1dcb..ea9e48daadb15 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -51,6 +51,7 @@
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/memremap.h>
+#include <linux/kmsan.h>
#include <linux/ksm.h>
#include <linux/rmap.h>
#include <linux/export.h>
@@ -3003,6 +3004,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
put_page(old_page);
return 0;
}
+ kmsan_copy_page_meta(new_page, old_page);
}

if (mem_cgroup_charge(page_folio(new_page), mm, GFP_KERNEL))
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c5952749ad40b..fa8029b714a81 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -26,6 +26,7 @@
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/kasan.h>
+#include <linux/kmsan.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/pagevec.h>
@@ -1288,6 +1289,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
VM_BUG_ON_PAGE(PageTail(page), page);

trace_mm_page_free(page, order);
+ kmsan_free_page(page, order);

if (unlikely(PageHWPoison(page)) && !order) {
/*
@@ -1734,6 +1736,9 @@ void __init memblock_free_pages(struct page *page, unsigned long pfn,
{
if (early_page_uninitialised(pfn))
return;
+ if (!kmsan_memblock_free_pages(page, order))
+ /* KMSAN will take care of these pages. */
+ return;
__free_pages_core(page, order);
}

@@ -3663,6 +3668,14 @@ static struct page *rmqueue_pcplist(struct zone *preferred_zone,
/*
* Allocate a page from the given zone. Use pcplists for order-0 allocations.
*/
+
+/*
+ * Do not instrument rmqueue() with KMSAN. This function may call
+ * __msan_poison_alloca() through a call to set_pfnblock_flags_mask().
+ * If __msan_poison_alloca() attempts to allocate pages for the stack depot, it
+ * may call rmqueue() again, which will result in a deadlock.
+ */
+__no_sanitize_memory
static inline
struct page *rmqueue(struct zone *preferred_zone,
struct zone *zone, unsigned int order,
@@ -5389,6 +5402,7 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid,
}

trace_mm_page_alloc(page, order, alloc_gfp, ac.migratetype);
+ kmsan_alloc_page(page, order, alloc_gfp);

return page;
}
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d2a00ad4e1dd1..333de26b3c56e 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -319,6 +319,9 @@ int ioremap_page_range(unsigned long addr, unsigned long end,
err = vmap_range_noflush(addr, end, phys_addr, pgprot_nx(prot),
ioremap_max_page_shift);
flush_cache_vmap(addr, end);
+ if (!err)
+ kmsan_ioremap_page_range(addr, end, phys_addr, prot,
+ ioremap_max_page_shift);
return err;
}

@@ -418,7 +421,7 @@ static void vunmap_p4d_range(pgd_t *pgd, unsigned long addr, unsigned long end,
*
* This is an internal function only. Do not use outside mm/.
*/
-void vunmap_range_noflush(unsigned long start, unsigned long end)
+void __vunmap_range_noflush(unsigned long start, unsigned long end)
{
unsigned long next;
pgd_t *pgd;
@@ -440,6 +443,12 @@ void vunmap_range_noflush(unsigned long start, unsigned long end)
arch_sync_kernel_mappings(start, end);
}

+void vunmap_range_noflush(unsigned long start, unsigned long end)
+{
+ kmsan_vunmap_range_noflush(start, end);
+ __vunmap_range_noflush(start, end);
+}
+
/**
* vunmap_range - unmap kernel virtual addresses
* @addr: start of the VM area to unmap
@@ -574,7 +583,7 @@ static int vmap_small_pages_range_noflush(unsigned long addr, unsigned long end,
*
* This is an internal function only. Do not use outside mm/.
*/
-int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
+int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
pgprot_t prot, struct page **pages, unsigned int page_shift)
{
unsigned int i, nr = (end - addr) >> PAGE_SHIFT;
@@ -600,6 +609,13 @@ int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
return 0;
}

+int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
+ pgprot_t prot, struct page **pages, unsigned int page_shift)
+{
+ kmsan_vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
+ return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
+}
+
/**
* vmap_pages_range - map pages to a kernel virtual address
* @addr: start of the VM area to map
--
2.34.1.173.g76aa8bc2d0-goog
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