Merge branch 'sparc64-ADI'

Khalid Aziz says:

====================
Application Data Integrity feature introduced by SPARC M7

V12 changes:
This series is same as v10 and v11 and was simply rebased on 4.16-rc2
kernel and patch 11 was added to update signal delivery code to use the
new helper functions added by Eric Biederman. Can mm maintainers please
review patches 2, 7, 8 and 9 which are arch independent, and
include/linux/mm.h and mm/ksm.c changes in patch 10 and ack these if
everything looks good?

SPARC M7 processor adds additional metadata for memory address space
that can be used to secure access to regions of memory. This additional
metadata is implemented as a 4-bit tag attached to each cacheline size
block of memory. A task can set a tag on any number of such blocks.
Access to such block is granted only if the virtual address used to
access that block of memory has the tag encoded in the uppermost 4 bits
of VA. Since sparc processor does not implement all 64 bits of VA, top 4
bits are available for ADI tags. Any mismatch between tag encoded in VA
and tag set on the memory block results in a trap. Tags are verified in
the VA presented to the MMU and tags are associated with the physical
page VA maps on to. If a memory page is swapped out and page frame gets
reused for another task, the tags are lost and hence must be saved when
swapping or migrating the page.

A userspace task enables ADI through mprotect(). This patch series adds
a page protection bit PROT_ADI and a corresponding VMA flag
VM_SPARC_ADI. VM_SPARC_ADI is used to trigger setting TTE.mcd bit in the
sparc pte that enables ADI checking on the corresponding page. MMU
validates the tag embedded in VA for every page that has TTE.mcd bit set
in its pte. After enabling ADI on a memory range, the userspace task can
set ADI version tags using stxa instruction with ASI_MCD_PRIMARY or
ASI_MCD_ST_BLKINIT_PRIMARY ASI.

Once userspace task calls mprotect() with PROT_ADI, kernel takes
following overall steps:

1. Find the VMAs covering the address range passed in to mprotect and
set VM_SPARC_ADI flag. If address range covers a subset of a VMA, the
VMA will be split.

2. When a page is allocated for a VA and the VMA covering this VA has
VM_SPARC_ADI flag set, set the TTE.mcd bit so MMU will check the
vwersion tag.

3. Userspace can now set version tags on the memory it has enabled ADI
on. Userspace accesses ADI enabled memory using a virtual address that
has the version tag embedded in the high bits. MMU validates this
version tag against the actual tag set on the memory. If tag matches,
MMU performs the VA->PA translation and access is granted. If there is a
mismatch, hypervisor sends a data access exception or precise memory
corruption detected exception depending upon whether precise exceptions
are enabled or not (controlled by MCDPERR register). Kernel sends
SIGSEGV to the task with appropriate si_code.

4. If a page is being swapped out or migrated, kernel must save any ADI
tags set on the page. Kernel maintains a page worth of tag storage
descriptors. Each descriptors pointsto a tag storage space and the
address range it covers. If the page being swapped out or migrated has
ADI enabled on it, kernel finds a tag storage descriptor that covers the
address range for the page or allocates a new descriptor if none of the
existing descriptors cover the address range. Kernel saves tags from the
page into the tag storage space descriptor points to.

5. When the page is swapped back in or reinstantiated after migration,
kernel restores the version tags on the new physical page by retrieving
the original tag from tag storage pointed to by a tag storage descriptor
for the virtual address range for new page.

User task can disable ADI by calling mprotect() again on the memory
range with PROT_ADI bit unset. Kernel clears the VM_SPARC_ADI flag in
VMAs, merges adjacent VMAs if necessary, and clears TTE.mcd bit in the
corresponding ptes.

IOMMU does not support ADI checking. Any version tags embedded in the
top bits of VA meant for IOMMU, are cleared and replaced with sign
extension of the first non-version tag bit (bit 59 for SPARC M7) for
IOMMU addresses.

This patch series adds support for this feature in 11 patches:

Patch 1/11
  Tag mismatch on access by a task results in a trap from hypervisor as
  data access exception or a precide memory corruption detected
  exception. As part of handling these exceptions, kernel sends a
  SIGSEGV to user process with special si_code to indicate which fault
  occurred. This patch adds three new si_codes to differentiate between
  various mismatch errors.

Patch 2/11
  When a page is swapped or migrated, metadata associated with the page
  must be saved so it can be restored later. This patch adds a new
  function that saves/restores this metadata when updating pte upon a
  swap/migration.

Patch 3/11
  SPARC M7 processor adds new fields to control registers to support ADI
  feature. It also adds a new exception for precise traps on tag
  mismatch. This patch adds definitions for the new control register
  fields, new ASIs for ADI and an exception handler for the precise trap
  on tag mismatch.

Patch 4/11
  New hypervisor fault types were added by sparc M7 processor to support
  ADI feature. This patch adds code to handle these fault types for data
  access exception handler.

Patch 5/11
  When ADI is in use for a page and a tag mismatch occurs, processor
  raises "Memory corruption Detected" trap. This patch adds a handler
  for this trap.

Patch 6/11
  ADI usage is governed by ADI properties on a platform. These
  properties are provided to kernel by firmware. Thsi patch adds new
  auxiliary vectors that provide these values to userpsace.

Patch 7/11
  arch_validate_prot() is used to validate the new protection bits asked
  for by the userspace app. Validating protection bits may need the
  context of address space the bits are being applied to. One such
  example is PROT_ADI bit on sparc processor that enables ADI protection
  on an address range. ADI protection applies only to addresses covered
  by physical RAM and not other PFN mapped addresses or device
  addresses. This patch adds "address" to the parameters being passed to
  arch_validate_prot() to provide that context.

Patch 8/11
  When protection bits are changed on a page, kernel carries forward all
  protection bits except for read/write/exec. Additional code was added
  to allow kernel to clear PKEY bits on x86 but this requirement to
  clear other bits is not unique to x86. This patch extends the existing
  code to allow other architectures to clear any other protection bits
  as well on protection bit change.

Patch 9/11
  When a processor supports additional metadata on memory pages, that
  additional metadata needs to be copied to new memory pages when those
  pages are moved. This patch allows architecture specific code to
  replace the default copy_highpage() routine with arch specific
  version that copies the metadata as well besides the data on the page.

Patch 10/11
  This patch adds support for a user space task to enable ADI and enable
  tag checking for subsets of its address space. As part of enabling
  this feature, this patch adds to support manipulation of precise
  exception for memory corruption detection, adds code to save and
  restore tags on page swap and migration, and adds code to handle ADI
  tagged addresses for DMA.

Patch 11/11
  Update signal delivery code in arch/sparc/kernel/traps_64.c to use
  the new helper function force_sig_fault() added by commit
  f8ec66014ffd ("signal: Add send_sig_fault and force_sig_fault").

Changelog v12:

	  - Rebased to 4.16-rc2
	  - Added patch 11 to update signal delivery functions

Changelog v11:

	  - Rebased to 4.15

Changelog v10:

	  - Patch 1/10: Updated si_codes definitions for SEGV to match 4.14
	  - Patch 2/10: No changes
	  - Patch 3/10: Updated copyright
	  - Patch 4/10: No changes
	  - Patch 5/10: No changes
	  - Patch 6/10: Updated copyright
	  - Patch 7/10: No changes
	  - Patch 8/10: No changes
	  - Patch 9/10: No changes
	  - Patch 10/10: Added code to return from kernel path to set
	    PSTATE.mcde if kernel continues execution in another thread
	      (Suggested by Anthony)

Changelog v9:

	  - Patch 1/10: No changes
	  - Patch 2/10: No changes
	  - Patch 3/10: No changes
	  - Patch 4/10: No changes
	  - Patch 5/10: No changes
	  - Patch 6/10: No changes
	  - Patch 7/10: No changes
	  - Patch 8/10: No changes
	  - Patch 9/10: New patch
	  - Patch 10/10: Patch 9 from v8. Added code to copy ADI tags when
	    pages are migrated. Updated code to detect overflow and underflow
	      of addresses when allocating tag storage.

Changelog v8:

	  - Patch 1/9: No changes
	  - Patch 2/9: Fixed and erroneous "}"
	  - Patch 3/9: Minor print formatting change
	  - Patch 4/9: No changes
	  - Patch 5/9: No changes
	  - Patch 6/9: Added AT_ADI_UEONADI back
	  - Patch 7/9: Added addr parameter to powerpc arch_validate_prot()
	  - Patch 8/9: No changes
	  - Patch 9/9:
	    - Documentation updates
	      - Added an IPI on mprotect(...PROT_ADI...) call and
	      	  restore of TSTATE.MCDE on context switch
		  	  - Removed restriction on enabling ADI on read-only
			      memory
				- Changed kzalloc() for tag storage to use GFP_NOWAIT
				  - Added code to handle overflow and underflow when
				      allocating tag storage
				      		 - Replaced sun_m7_patch_1insn_range() with
						     sun4v_patch_1insn_range()
							- Added membar after restoring ADI tags in
							    copy_user_highpage()

Changelog v7:

	  - Patch 1/9: No changes
	  - Patch 2/9: Updated parameters to arch specific swap in/out
	    handlers
	    - Patch 3/9: No changes
	    - Patch 4/9: new patch split off from patch 4/4 in v6
	    - Patch 5/9: new patch split off from patch 4/4 in v6
	    - Patch 6/9: new patch split off from patch 4/4 in v6
	    - Patch 7/9: new patch
	    - Patch 8/9: new patch
	    - Patch 9/9:
	      - Enhanced arch_validate_prot() to enable ADI only on
	      	  writable addresses backed by physical RAM
		  	   - Added support for saving/restoring ADI tags for each
			       ADI block size address range on a page on swap in/out
			       	   - copy ADI tags on COW
				     - Updated values for auxiliary vectors to not conflict
				         with values on other architectures to avoid conflict
					        in glibc
						   - Disable same page merging on ADI enabled pages
						     - Enable ADI only on writable addresses backed by
						         physical RAM
							 	  - Split parts of patch off into separate patches

Changelog v6:
	  - Patch 1/4: No changes
	  - Patch 2/4: No changes
	  - Patch 3/4: Added missing nop in the delay slot in
	    sun4v_mcd_detect_precise
	    - Patch 4/4: Eliminated instructions to read and write PSTATE
	      as well as MCDPER and PMCDPER on every access to userspace
	        addresses by setting PSTATE and PMCDPER correctly upon entry
		  into kernel

Changelog v5:
	  - Patch 1/4: No changes
	  - Patch 2/4: Replaced set_swp_pte_at() with new architecture
	    functions arch_do_swap_page() and arch_unmap_one() that
	      suppoprt architecture specific actions to be taken on page
	        swap and migration
		- Patch 3/4: Fixed indentation issues in assembly code
		- Patch 4/4:
		  - Fixed indentation issues and instrcuctions in assembly
		      code
			- Removed CONFIG_SPARC64 from mdesc.c
			  - Changed to maintain state of MCDPER register in thread
			      info flags as opposed to in mm context. MCDPER is a
			      	     per-thread state and belongs in thread info flag as
				     		  opposed to mm context which is shared across threads.
						  	    Added comments to clarify this is a lazily maintained
							    	    state and must be updated on context switch and
								    	    copy_process()
									    		   - Updated code to use the new arch_do_swap_page() and
											       arch_unmap_one() functions

Testing:

- All functionality was tested with 8K normal pages as well as hugepages
  using malloc, mmap and shm.
- Multiple long duration stress tests were run using hugepages over 2+
  months. Normal pages were tested with shorter duration stress tests.
- Tested swapping with malloc and shm by reducing max memory and
  allocating three times the available system memory by active processes
  using ADI on allocated memory. Ran through multiple hours long runs of
  this test.
- Tested page migration with malloc and shm by migrating data pages of
  active ADI test process using migratepages, back and forth between two
  nodes every few seconds over an hour long run. Verified page migration
  through /proc/<pid>/numa_maps.
- Tested COW support using test that forks children that read from
  ADI enabled pages shared with parent and other children and write to
  them as well forcing COW.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 48 insertions, 0 deletions

diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 339920fdf9ed..44d6ac47e035 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -19,6 +19,7 @@
 #include <asm/types.h>
 #include <asm/spitfire.h>
 #include <asm/asi.h>
+#include <asm/adi.h>
 #include <asm/page.h>
 #include <asm/processor.h>
 
@@ -164,6 +165,8 @@ bool kern_addr_valid(unsigned long addr);
 #define _PAGE_E_4V	  _AC(0x0000000000000800,UL) /* side-Effect          */
 #define _PAGE_CP_4V	  _AC(0x0000000000000400,UL) /* Cacheable in P-Cache */
 #define _PAGE_CV_4V	  _AC(0x0000000000000200,UL) /* Cacheable in V-Cache */
+/* Bit 9 is used to enable MCD corruption detection instead on M7 */
+#define _PAGE_MCD_4V      _AC(0x0000000000000200,UL) /* Memory Corruption    */
 #define _PAGE_P_4V	  _AC(0x0000000000000100,UL) /* Privileged Page      */
 #define _PAGE_EXEC_4V	  _AC(0x0000000000000080,UL) /* Executable Page      */
 #define _PAGE_W_4V	  _AC(0x0000000000000040,UL) /* Writable             */
@@ -604,6 +607,18 @@ static inline pte_t pte_mkspecial(pte_t pte)
 	return pte;
 }
 
+static inline pte_t pte_mkmcd(pte_t pte)
+{
+	pte_val(pte) |= _PAGE_MCD_4V;
+	return pte;
+}
+
+static inline pte_t pte_mknotmcd(pte_t pte)
+{
+	pte_val(pte) &= ~_PAGE_MCD_4V;
+	return pte;
+}
+
 static inline unsigned long pte_young(pte_t pte)
 {
 	unsigned long mask;
@@ -1046,6 +1061,39 @@ int page_in_phys_avail(unsigned long paddr);
 int remap_pfn_range(struct vm_area_struct *, unsigned long, unsigned long,
 		    unsigned long, pgprot_t);
 
+void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
+		      unsigned long addr, pte_t pte);
+
+int adi_save_tags(struct mm_struct *mm, struct vm_area_struct *vma,
+		  unsigned long addr, pte_t oldpte);
+
+#define __HAVE_ARCH_DO_SWAP_PAGE
+static inline void arch_do_swap_page(struct mm_struct *mm,
+				     struct vm_area_struct *vma,
+				     unsigned long addr,
+				     pte_t pte, pte_t oldpte)
+{
+	/* If this is a new page being mapped in, there can be no
+	 * ADI tags stored away for this page. Skip looking for
+	 * stored tags
+	 */
+	if (pte_none(oldpte))
+		return;
+
+	if (adi_state.enabled && (pte_val(pte) & _PAGE_MCD_4V))
+		adi_restore_tags(mm, vma, addr, pte);
+}
+
+#define __HAVE_ARCH_UNMAP_ONE
+static inline int arch_unmap_one(struct mm_struct *mm,
+				 struct vm_area_struct *vma,
+				 unsigned long addr, pte_t oldpte)
+{
+	if (adi_state.enabled && (pte_val(oldpte) & _PAGE_MCD_4V))
+		return adi_save_tags(mm, vma, addr, oldpte);
+	return 0;
+}
+
 static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 				     unsigned long from, unsigned long pfn,
 				     unsigned long size, pgprot_t prot)