diff mbox series

[v19,3/8] set_memory: allow set_direct_map_*_noflush() for multiple pages

Message ID 20210513184734.29317-4-rppt@kernel.org
State New
Headers show
Series mm: introduce memfd_secret system call to create "secret" memory areas | expand

Commit Message

Mike Rapoport May 13, 2021, 6:47 p.m. UTC 
From: Mike Rapoport <rppt@linux.ibm.com>

The underlying implementations of set_direct_map_invalid_noflush() and
set_direct_map_default_noflush() allow updating multiple contiguous pages
at once.

Add numpages parameter to set_direct_map_*_noflush() to expose this
ability with these APIs.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Hagen Paul Pfeifer <hagen@jauu.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tycho Andersen <tycho@tycho.ws>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/cacheflush.h |  4 ++--
 arch/arm64/mm/pageattr.c            | 10 ++++++----
 arch/riscv/include/asm/set_memory.h |  4 ++--
 arch/riscv/mm/pageattr.c            |  8 ++++----
 arch/x86/include/asm/set_memory.h   |  4 ++--
 arch/x86/mm/pat/set_memory.c        |  8 ++++----
 include/linux/set_memory.h          |  4 ++--
 kernel/power/snapshot.c             |  4 ++--
 mm/vmalloc.c                        |  5 +++--
 9 files changed, 27 insertions(+), 24 deletions(-)

Comments

David Hildenbrand May 14, 2021, 8:43 a.m. UTC | #1 
On 13.05.21 20:47, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> The underlying implementations of set_direct_map_invalid_noflush() and
> set_direct_map_default_noflush() allow updating multiple contiguous pages
> at once.
> 
> Add numpages parameter to set_direct_map_*_noflush() to expose this
> ability with these APIs.
> 

[...]

Finally doing some in-depth review, sorry for not having a detailed look 
earlier.


>   
> -int set_direct_map_invalid_noflush(struct page *page)
> +int set_direct_map_invalid_noflush(struct page *page, int numpages)
>   {
>   	struct page_change_data data = {
>   		.set_mask = __pgprot(0),
>   		.clear_mask = __pgprot(PTE_VALID),
>   	};
> +	unsigned long size = PAGE_SIZE * numpages;
>   

Nit: I'd have made this const and added an early exit for !numpages. But 
whatever you prefer.

>   	if (!debug_pagealloc_enabled() && !rodata_full)
>   		return 0;
>   
>   	return apply_to_page_range(&init_mm,
>   				   (unsigned long)page_address(page),
> -				   PAGE_SIZE, change_page_range, &data);
> +				   size, change_page_range, &data);
>   }
>   
> -int set_direct_map_default_noflush(struct page *page)
> +int set_direct_map_default_noflush(struct page *page, int numpages)
>   {
>   	struct page_change_data data = {
>   		.set_mask = __pgprot(PTE_VALID | PTE_WRITE),
>   		.clear_mask = __pgprot(PTE_RDONLY),
>   	};
> +	unsigned long size = PAGE_SIZE * numpages;
>   

Nit: dito

>   	if (!debug_pagealloc_enabled() && !rodata_full)
>   		return 0;
>   
>   	return apply_to_page_range(&init_mm,
>   				   (unsigned long)page_address(page),
> -				   PAGE_SIZE, change_page_range, &data);
> +				   size, change_page_range, &data);
>   }
>   


[...]

>   extern int kernel_set_to_readonly;
> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index 156cd235659f..15a55d6e9cec 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -2192,14 +2192,14 @@ static int __set_pages_np(struct page *page, int numpages)
>   	return __change_page_attr_set_clr(&cpa, 0);
>   }
>   
> -int set_direct_map_invalid_noflush(struct page *page)
> +int set_direct_map_invalid_noflush(struct page *page, int numpages)
>   {
> -	return __set_pages_np(page, 1);
> +	return __set_pages_np(page, numpages);
>   }
>   
> -int set_direct_map_default_noflush(struct page *page)
> +int set_direct_map_default_noflush(struct page *page, int numpages)
>   {
> -	return __set_pages_p(page, 1);
> +	return __set_pages_p(page, numpages);
>   }
>   

So, what happens if we succeeded setting 
set_direct_map_invalid_noflush() for some pages but fail when having to 
split a large mapping?

Did I miss something or would the current code not undo what it 
partially did? Or do we simply not care?

I guess to handle this cleanly we would either have to catch all error 
cases first (esp. splitting large mappings) before actually performing 
the set to invalid, or have some recovery code in place if possible.


AFAIKs, your patch #5 right now only calls it with 1 page, do we need 
this change at all? Feels like a leftover from older versions to me 
where we could have had more than a single page.
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 52e5c1623224..ace2c3d7ae7e 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -133,8 +133,8 @@  static __always_inline void __flush_icache_all(void)
 
 int set_memory_valid(unsigned long addr, int numpages, int enable);
 
-int set_direct_map_invalid_noflush(struct page *page);
-int set_direct_map_default_noflush(struct page *page);
+int set_direct_map_invalid_noflush(struct page *page, int numpages);
+int set_direct_map_default_noflush(struct page *page, int numpages);
 bool kernel_page_present(struct page *page);
 
 #include <asm-generic/cacheflush.h>
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 92eccaf595c8..b53ef37bf95a 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -148,34 +148,36 @@  int set_memory_valid(unsigned long addr, int numpages, int enable)
 					__pgprot(PTE_VALID));
 }
 
-int set_direct_map_invalid_noflush(struct page *page)
+int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
 	struct page_change_data data = {
 		.set_mask = __pgprot(0),
 		.clear_mask = __pgprot(PTE_VALID),
 	};
+	unsigned long size = PAGE_SIZE * numpages;
 
 	if (!debug_pagealloc_enabled() && !rodata_full)
 		return 0;
 
 	return apply_to_page_range(&init_mm,
 				   (unsigned long)page_address(page),
-				   PAGE_SIZE, change_page_range, &data);
+				   size, change_page_range, &data);
 }
 
-int set_direct_map_default_noflush(struct page *page)
+int set_direct_map_default_noflush(struct page *page, int numpages)
 {
 	struct page_change_data data = {
 		.set_mask = __pgprot(PTE_VALID | PTE_WRITE),
 		.clear_mask = __pgprot(PTE_RDONLY),
 	};
+	unsigned long size = PAGE_SIZE * numpages;
 
 	if (!debug_pagealloc_enabled() && !rodata_full)
 		return 0;
 
 	return apply_to_page_range(&init_mm,
 				   (unsigned long)page_address(page),
-				   PAGE_SIZE, change_page_range, &data);
+				   size, change_page_range, &data);
 }
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index 086f757e8ba3..06aed922ec1f 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -32,8 +32,8 @@  void protect_kernel_linear_mapping_text_rodata(void);
 static inline void protect_kernel_linear_mapping_text_rodata(void) {}
 #endif
 
-int set_direct_map_invalid_noflush(struct page *page);
-int set_direct_map_default_noflush(struct page *page);
+int set_direct_map_invalid_noflush(struct page *page, int numpages);
+int set_direct_map_default_noflush(struct page *page, int numpages);
 bool kernel_page_present(struct page *page);
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index 5e49e4b4a4cc..9618181b70be 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -156,11 +156,11 @@  int set_memory_nx(unsigned long addr, int numpages)
 	return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
 }
 
-int set_direct_map_invalid_noflush(struct page *page)
+int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
 	int ret;
 	unsigned long start = (unsigned long)page_address(page);
-	unsigned long end = start + PAGE_SIZE;
+	unsigned long end = start + PAGE_SIZE * numpages;
 	struct pageattr_masks masks = {
 		.set_mask = __pgprot(0),
 		.clear_mask = __pgprot(_PAGE_PRESENT)
@@ -173,11 +173,11 @@  int set_direct_map_invalid_noflush(struct page *page)
 	return ret;
 }
 
-int set_direct_map_default_noflush(struct page *page)
+int set_direct_map_default_noflush(struct page *page, int numpages)
 {
 	int ret;
 	unsigned long start = (unsigned long)page_address(page);
-	unsigned long end = start + PAGE_SIZE;
+	unsigned long end = start + PAGE_SIZE * numpages;
 	struct pageattr_masks masks = {
 		.set_mask = PAGE_KERNEL,
 		.clear_mask = __pgprot(0)
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 43fa081a1adb..5f84aa4b6961 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -80,8 +80,8 @@  int set_pages_wb(struct page *page, int numpages);
 int set_pages_ro(struct page *page, int numpages);
 int set_pages_rw(struct page *page, int numpages);
 
-int set_direct_map_invalid_noflush(struct page *page);
-int set_direct_map_default_noflush(struct page *page);
+int set_direct_map_invalid_noflush(struct page *page, int numpages);
+int set_direct_map_default_noflush(struct page *page, int numpages);
 bool kernel_page_present(struct page *page);
 
 extern int kernel_set_to_readonly;
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 156cd235659f..15a55d6e9cec 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -2192,14 +2192,14 @@  static int __set_pages_np(struct page *page, int numpages)
 	return __change_page_attr_set_clr(&cpa, 0);
 }
 
-int set_direct_map_invalid_noflush(struct page *page)
+int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
-	return __set_pages_np(page, 1);
+	return __set_pages_np(page, numpages);
 }
 
-int set_direct_map_default_noflush(struct page *page)
+int set_direct_map_default_noflush(struct page *page, int numpages)
 {
-	return __set_pages_p(page, 1);
+	return __set_pages_p(page, numpages);
 }
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
index fe1aa4e54680..c650f82db813 100644
--- a/include/linux/set_memory.h
+++ b/include/linux/set_memory.h
@@ -15,11 +15,11 @@  static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
 #endif
 
 #ifndef CONFIG_ARCH_HAS_SET_DIRECT_MAP
-static inline int set_direct_map_invalid_noflush(struct page *page)
+static inline int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
 	return 0;
 }
-static inline int set_direct_map_default_noflush(struct page *page)
+static inline int set_direct_map_default_noflush(struct page *page, int numpages)
 {
 	return 0;
 }
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 1a221dcb3c01..27cb4e7086b7 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -86,7 +86,7 @@  static inline void hibernate_restore_unprotect_page(void *page_address) {}
 static inline void hibernate_map_page(struct page *page)
 {
 	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
-		int ret = set_direct_map_default_noflush(page);
+		int ret = set_direct_map_default_noflush(page, 1);
 
 		if (ret)
 			pr_warn_once("Failed to remap page\n");
@@ -99,7 +99,7 @@  static inline void hibernate_unmap_page(struct page *page)
 {
 	if (IS_ENABLED(CONFIG_ARCH_HAS_SET_DIRECT_MAP)) {
 		unsigned long addr = (unsigned long)page_address(page);
-		int ret  = set_direct_map_invalid_noflush(page);
+		int ret = set_direct_map_invalid_noflush(page, 1);
 
 		if (ret)
 			pr_warn_once("Failed to remap page\n");
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a13ac524f6ff..5d96fee17226 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2469,14 +2469,15 @@  struct vm_struct *remove_vm_area(const void *addr)
 }
 
 static inline void set_area_direct_map(const struct vm_struct *area,
-				       int (*set_direct_map)(struct page *page))
+				       int (*set_direct_map)(struct page *page,
+							     int numpages))
 {
 	int i;
 
 	/* HUGE_VMALLOC passes small pages to set_direct_map */
 	for (i = 0; i < area->nr_pages; i++)
 		if (page_address(area->pages[i]))
-			set_direct_map(area->pages[i]);
+			set_direct_map(area->pages[i], 1);
 }
 
 /* Handle removing and resetting vm mappings related to the vm_struct. */