Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 286 insertions, 0 deletions

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+================================
+Application Data Integrity (ADI)
+================================
+
+SPARC M7 processor adds the Application Data Integrity (ADI) feature.
+ADI allows a task to set version tags on any subset of its address
+space. Once ADI is enabled and version tags are set for ranges of
+address space of a task, the processor will compare the tag in pointers
+to memory in these ranges to the version set by the application
+previously. Access to memory is granted only if the tag in given pointer
+matches the tag set by the application. In case of mismatch, processor
+raises an exception.
+
+Following steps must be taken by a task to enable ADI fully:
+
+1. Set the user mode PSTATE.mcde bit. This acts as master switch for
+   the task's entire address space to enable/disable ADI for the task.
+
+2. Set TTE.mcd bit on any TLB entries that correspond to the range of
+   addresses ADI is being enabled on. MMU checks the version tag only
+   on the pages that have TTE.mcd bit set.
+
+3. Set the version tag for virtual addresses using stxa instruction
+   and one of the MCD specific ASIs. Each stxa instruction sets the
+   given tag for one ADI block size number of bytes. This step must
+   be repeated for entire page to set tags for entire page.
+
+ADI block size for the platform is provided by the hypervisor to kernel
+in machine description tables. Hypervisor also provides the number of
+top bits in the virtual address that specify the version tag.  Once
+version tag has been set for a memory location, the tag is stored in the
+physical memory and the same tag must be present in the ADI version tag
+bits of the virtual address being presented to the MMU. For example on
+SPARC M7 processor, MMU uses bits 63-60 for version tags and ADI block
+size is same as cacheline size which is 64 bytes. A task that sets ADI
+version to, say 10, on a range of memory, must access that memory using
+virtual addresses that contain 0xa in bits 63-60.
+
+ADI is enabled on a set of pages using mprotect() with PROT_ADI flag.
+When ADI is enabled on a set of pages by a task for the first time,
+kernel sets the PSTATE.mcde bit fot the task. Version tags for memory
+addresses are set with an stxa instruction on the addresses using
+ASI_MCD_PRIMARY or ASI_MCD_ST_BLKINIT_PRIMARY. ADI block size is
+provided by the hypervisor to the kernel.  Kernel returns the value of
+ADI block size to userspace using auxiliary vector along with other ADI
+info. Following auxiliary vectors are provided by the kernel:
+
+	============	===========================================
+	AT_ADI_BLKSZ	ADI block size. This is the granularity and
+			alignment, in bytes, of ADI versioning.
+	AT_ADI_NBITS	Number of ADI version bits in the VA
+	============	===========================================
+
+
+IMPORTANT NOTES
+===============
+
+- Version tag values of 0x0 and 0xf are reserved. These values match any
+  tag in virtual address and never generate a mismatch exception.
+
+- Version tags are set on virtual addresses from userspace even though
+  tags are stored in physical memory. Tags are set on a physical page
+  after it has been allocated to a task and a pte has been created for
+  it.
+
+- When a task frees a memory page it had set version tags on, the page
+  goes back to free page pool. When this page is re-allocated to a task,
+  kernel clears the page using block initialization ASI which clears the
+  version tags as well for the page. If a page allocated to a task is
+  freed and allocated back to the same task, old version tags set by the
+  task on that page will no longer be present.
+
+- ADI tag mismatches are not detected for non-faulting loads.
+
+- Kernel does not set any tags for user pages and it is entirely a
+  task's responsibility to set any version tags. Kernel does ensure the
+  version tags are preserved if a page is swapped out to the disk and
+  swapped back in. It also preserves that version tags if a page is
+  migrated.
+
+- ADI works for any size pages. A userspace task need not be aware of
+  page size when using ADI. It can simply select a virtual address
+  range, enable ADI on the range using mprotect() and set version tags
+  for the entire range. mprotect() ensures range is aligned to page size
+  and is a multiple of page size.
+
+- ADI tags can only be set on writable memory. For example, ADI tags can
+  not be set on read-only mappings.
+
+
+
+ADI related traps
+=================
+
+With ADI enabled, following new traps may occur:
+
+Disrupting memory corruption
+----------------------------
+
+	When a store accesses a memory localtion that has TTE.mcd=1,
+	the task is running with ADI enabled (PSTATE.mcde=1), and the ADI
+	tag in the address used (bits 63:60) does not match the tag set on
+	the corresponding cacheline, a memory corruption trap occurs. By
+	default, it is a disrupting trap and is sent to the hypervisor
+	first. Hypervisor creates a sun4v error report and sends a
+	resumable error (TT=0x7e) trap to the kernel. The kernel sends
+	a SIGSEGV to the task that resulted in this trap with the following
+	info::
+
+		siginfo.si_signo = SIGSEGV;
+		siginfo.errno = 0;
+		siginfo.si_code = SEGV_ADIDERR;
+		siginfo.si_addr = addr; /* PC where first mismatch occurred */
+		siginfo.si_trapno = 0;
+
+
+Precise memory corruption
+-------------------------
+
+	When a store accesses a memory location that has TTE.mcd=1,
+	the task is running with ADI enabled (PSTATE.mcde=1), and the ADI
+	tag in the address used (bits 63:60) does not match the tag set on
+	the corresponding cacheline, a memory corruption trap occurs. If
+	MCD precise exception is enabled (MCDPERR=1), a precise
+	exception is sent to the kernel with TT=0x1a. The kernel sends
+	a SIGSEGV to the task that resulted in this trap with the following
+	info::
+
+		siginfo.si_signo = SIGSEGV;
+		siginfo.errno = 0;
+		siginfo.si_code = SEGV_ADIPERR;
+		siginfo.si_addr = addr;	/* address that caused trap */
+		siginfo.si_trapno = 0;
+
+	NOTE:
+		ADI tag mismatch on a load always results in precise trap.
+
+
+MCD disabled
+------------
+
+	When a task has not enabled ADI and attempts to set ADI version
+	on a memory address, processor sends an MCD disabled trap. This
+	trap is handled by hypervisor first and the hypervisor vectors this
+	trap through to the kernel as Data Access Exception trap with
+	fault type set to 0xa (invalid ASI). When this occurs, the kernel
+	sends the task SIGSEGV signal with following info::
+
+		siginfo.si_signo = SIGSEGV;
+		siginfo.errno = 0;
+		siginfo.si_code = SEGV_ACCADI;
+		siginfo.si_addr = addr;	/* address that caused trap */
+		siginfo.si_trapno = 0;
+
+
+Sample program to use ADI
+-------------------------
+
+Following sample program is meant to illustrate how to use the ADI
+functionality::
+
+  #include <unistd.h>
+  #include <stdio.h>
+  #include <stdlib.h>
+  #include <elf.h>
+  #include <sys/ipc.h>
+  #include <sys/shm.h>
+  #include <sys/mman.h>
+  #include <asm/asi.h>
+
+  #ifndef AT_ADI_BLKSZ
+  #define AT_ADI_BLKSZ	48
+  #endif
+  #ifndef AT_ADI_NBITS
+  #define AT_ADI_NBITS	49
+  #endif
+
+  #ifndef PROT_ADI
+  #define PROT_ADI	0x10
+  #endif
+
+  #define BUFFER_SIZE     32*1024*1024UL
+
+  main(int argc, char* argv[], char* envp[])
+  {
+          unsigned long i, mcde, adi_blksz, adi_nbits;
+          char *shmaddr, *tmp_addr, *end, *veraddr, *clraddr;
+          int shmid, version;
+	Elf64_auxv_t *auxv;
+
+	adi_blksz = 0;
+
+	while(*envp++ != NULL);
+	for (auxv = (Elf64_auxv_t *)envp; auxv->a_type != AT_NULL; auxv++) {
+		switch (auxv->a_type) {
+		case AT_ADI_BLKSZ:
+			adi_blksz = auxv->a_un.a_val;
+			break;
+		case AT_ADI_NBITS:
+			adi_nbits = auxv->a_un.a_val;
+			break;
+		}
+	}
+	if (adi_blksz == 0) {
+		fprintf(stderr, "Oops! ADI is not supported\n");
+		exit(1);
+	}
+
+	printf("ADI capabilities:\n");
+	printf("\tBlock size = %ld\n", adi_blksz);
+	printf("\tNumber of bits = %ld\n", adi_nbits);
+
+          if ((shmid = shmget(2, BUFFER_SIZE,
+                                  IPC_CREAT | SHM_R | SHM_W)) < 0) {
+                  perror("shmget failed");
+                  exit(1);
+          }
+
+          shmaddr = shmat(shmid, NULL, 0);
+          if (shmaddr == (char *)-1) {
+                  perror("shm attach failed");
+                  shmctl(shmid, IPC_RMID, NULL);
+                  exit(1);
+          }
+
+	if (mprotect(shmaddr, BUFFER_SIZE, PROT_READ|PROT_WRITE|PROT_ADI)) {
+		perror("mprotect failed");
+		goto err_out;
+	}
+
+          /* Set the ADI version tag on the shm segment
+           */
+          version = 10;
+          tmp_addr = shmaddr;
+          end = shmaddr + BUFFER_SIZE;
+          while (tmp_addr < end) {
+                  asm volatile(
+                          "stxa %1, [%0]0x90\n\t"
+                          :
+                          : "r" (tmp_addr), "r" (version));
+                  tmp_addr += adi_blksz;
+          }
+	asm volatile("membar #Sync\n\t");
+
+          /* Create a versioned address from the normal address by placing
+	 * version tag in the upper adi_nbits bits
+           */
+          tmp_addr = (void *) ((unsigned long)shmaddr << adi_nbits);
+          tmp_addr = (void *) ((unsigned long)tmp_addr >> adi_nbits);
+          veraddr = (void *) (((unsigned long)version << (64-adi_nbits))
+                          | (unsigned long)tmp_addr);
+
+          printf("Starting the writes:\n");
+          for (i = 0; i < BUFFER_SIZE; i++) {
+                  veraddr[i] = (char)(i);
+                  if (!(i % (1024 * 1024)))
+                          printf(".");
+          }
+          printf("\n");
+
+          printf("Verifying data...");
+	fflush(stdout);
+          for (i = 0; i < BUFFER_SIZE; i++)
+                  if (veraddr[i] != (char)i)
+                          printf("\nIndex %lu mismatched\n", i);
+          printf("Done.\n");
+
+          /* Disable ADI and clean up
+           */
+	if (mprotect(shmaddr, BUFFER_SIZE, PROT_READ|PROT_WRITE)) {
+		perror("mprotect failed");
+		goto err_out;
+	}
+
+          if (shmdt((const void *)shmaddr) != 0)
+                  perror("Detach failure");
+          shmctl(shmid, IPC_RMID, NULL);
+
+          exit(0);
+
+  err_out:
+          if (shmdt((const void *)shmaddr) != 0)
+                  perror("Detach failure");
+          shmctl(shmid, IPC_RMID, NULL);
+          exit(1);
+  }