sparc64: Add support for ADI (Application Data Integrity)

ADI is a new feature supported on SPARC M7 and newer processors to allow
hardware to catch rogue accesses to memory. ADI is supported for data
fetches only and not instruction fetches. An app can enable ADI on its
data pages, set version tags on them and use versioned addresses to
access the data pages. Upper bits of the address contain the version
tag. On M7 processors, upper four bits (bits 63-60) contain the version
tag. If a rogue app attempts to access ADI enabled data pages, its
access is blocked and processor generates an exception. Please see
Documentation/sparc/adi.txt for further details.

This patch extends mprotect to enable ADI (TSTATE.mcde), enable/disable
MCD (Memory Corruption Detection) on selected memory ranges, enable
TTE.mcd in PTEs, return ADI parameters to userspace and save/restore ADI
version tags on page swap out/in or migration. ADI is not enabled by
default for any task. A task must explicitly enable ADI on a memory
range and set version tag for ADI to be effective for the task.

Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Khalid Aziz <khalid@gonehiking.org>
Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/sparc/include/asm/mmu_64.h b/arch/sparc/include/asm/mmu_64.h
index ad4fb93508ba..7e2704c770e9 100644
--- a/arch/sparc/include/asm/mmu_64.h
+++ b/arch/sparc/include/asm/mmu_64.h
@@ -90,6 +90,20 @@ struct tsb_config {
 #define MM_NUM_TSBS	1
 #endif
 
+/* ADI tags are stored when a page is swapped out and the storage for
+ * tags is allocated dynamically. There is a tag storage descriptor
+ * associated with each set of tag storage pages. Tag storage descriptors
+ * are allocated dynamically. Since kernel will allocate a full page for
+ * each tag storage descriptor, we can store up to
+ * PAGE_SIZE/sizeof(tag storage descriptor) descriptors on that page.
+ */
+typedef struct {
+	unsigned long	start;		/* Start address for this tag storage */
+	unsigned long	end;		/* Last address for tag storage */
+	unsigned char	*tags;		/* Where the tags are */
+	unsigned long	tag_users;	/* number of references to descriptor */
+} tag_storage_desc_t;
+
 typedef struct {
 	spinlock_t		lock;
 	unsigned long		sparc64_ctx_val;
@@ -98,6 +112,9 @@ typedef struct {
 	struct tsb_config	tsb_block[MM_NUM_TSBS];
 	struct hv_tsb_descr	tsb_descr[MM_NUM_TSBS];
 	void			*vdso;
+	bool			adi;
+	tag_storage_desc_t	*tag_store;
+	spinlock_t		tag_lock;
 } mm_context_t;
 
 #endif /* !__ASSEMBLY__ */