tools/testing/selftests/x86/mpx-dig.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Written by Dave Hansen <dave.hansen@intel.com>
  */

 #include <stdlib.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <sys/mman.h>
 #include <string.h>
 #include <fcntl.h>
 #include "mpx-debug.h"
 #include "mpx-mm.h"
 #include "mpx-hw.h"

 unsigned long bounds_dir_global;

 #define mpx_dig_abort()	__mpx_dig_abort(__FILE__, __func__, __LINE__)
 static void inline __mpx_dig_abort(const char *file, const char *func, int line)
 {
 	fprintf(stderr, "MPX dig abort @ %s::%d in %s()\n", file, line, func);
 	printf("MPX dig abort @ %s::%d in %s()\n", file, line, func);
 	abort();
 }

 /*
  * run like this (BDIR finds the probably bounds directory):
  *
  *	BDIR="$(cat /proc/$pid/smaps | grep -B1 2097152 \
  *		| head -1 | awk -F- '{print $1}')";
  *	./mpx-dig $pid 0x$BDIR
  *
  * NOTE:
  *	assumes that the only 2097152-kb VMA is the bounds dir
  */

 long nr_incore(void *ptr, unsigned long size_bytes)
 {
 	int i;
 	long ret = 0;
 	long vec_len = size_bytes / PAGE_SIZE;
 	unsigned char *vec = malloc(vec_len);
 	int incore_ret;

 	if (!vec)
 		mpx_dig_abort();

 	incore_ret = mincore(ptr, size_bytes, vec);
 	if (incore_ret) {
 		printf("mincore ret: %d\n", incore_ret);
 		perror("mincore");
 		mpx_dig_abort();
 	}
 	for (i = 0; i < vec_len; i++)
 		ret += vec[i];
 	free(vec);
 	return ret;
 }

 int open_proc(int pid, char *file)
 {
 	static char buf[100];
 	int fd;

 	snprintf(&buf[0], sizeof(buf), "/proc/%d/%s", pid, file);
 	fd = open(&buf[0], O_RDONLY);
 	if (fd < 0)
 		perror(buf);

 	return fd;
 }

 struct vaddr_range {
 	unsigned long start;
 	unsigned long end;
 };
 struct vaddr_range *ranges;
 int nr_ranges_allocated;
 int nr_ranges_populated;
 int last_range = -1;

 int __pid_load_vaddrs(int pid)
 {
 	int ret = 0;
 	int proc_maps_fd = open_proc(pid, "maps");
 	char linebuf[10000];
 	unsigned long start;
 	unsigned long end;
 	char rest[1000];
 	FILE *f = fdopen(proc_maps_fd, "r");

 	if (!f)
 		mpx_dig_abort();
 	nr_ranges_populated = 0;
 	while (!feof(f)) {
 		char *readret = fgets(linebuf, sizeof(linebuf), f);
 		int parsed;

 		if (readret == NULL) {
 			if (feof(f))
 				break;
 			mpx_dig_abort();
 		}

 		parsed = sscanf(linebuf, "%lx-%lx%s", &start, &end, rest);
 		if (parsed != 3)
 			mpx_dig_abort();

 		dprintf4("result[%d]: %lx-%lx<->%s\n", parsed, start, end, rest);
 		if (nr_ranges_populated >= nr_ranges_allocated) {
 			ret = -E2BIG;
 			break;
 		}
 		ranges[nr_ranges_populated].start = start;
 		ranges[nr_ranges_populated].end = end;
 		nr_ranges_populated++;
 	}
 	last_range = -1;
 	fclose(f);
 	close(proc_maps_fd);
 	return ret;
 }

 int pid_load_vaddrs(int pid)
 {
 	int ret;

 	dprintf2("%s(%d)\n", __func__, pid);
 	if (!ranges) {
 		nr_ranges_allocated = 4;
 		ranges = malloc(nr_ranges_allocated * sizeof(ranges[0]));
 		dprintf2("%s(%d) allocated %d ranges @ %p\n", __func__, pid,
 			 nr_ranges_allocated, ranges);
 		assert(ranges != NULL);
 	}
 	do {
 		ret = __pid_load_vaddrs(pid);
 		if (!ret)
 			break;
 		if (ret == -E2BIG) {
 			dprintf2("%s(%d) need to realloc\n", __func__, pid);
 			nr_ranges_allocated *= 2;
 			ranges = realloc(ranges,
 					nr_ranges_allocated * sizeof(ranges[0]));
 			dprintf2("%s(%d) allocated %d ranges @ %p\n", __func__,
 					pid, nr_ranges_allocated, ranges);
 			assert(ranges != NULL);
 			dprintf1("reallocating to hold %d ranges\n", nr_ranges_allocated);
 		}
 	} while (1);

 	dprintf2("%s(%d) done\n", __func__, pid);

 	return ret;
 }

 static inline int vaddr_in_range(unsigned long vaddr, struct vaddr_range *r)
 {
 	if (vaddr < r->start)
 		return 0;
 	if (vaddr >= r->end)
 		return 0;
 	return 1;
 }

 static inline int vaddr_mapped_by_range(unsigned long vaddr)
 {
 	int i;

 	if (last_range > 0 && vaddr_in_range(vaddr, &ranges[last_range]))
 		return 1;

 	for (i = 0; i < nr_ranges_populated; i++) {
 		struct vaddr_range *r = &ranges[i];

 		if (vaddr_in_range(vaddr, r))
 			continue;
 		last_range = i;
 		return 1;
 	}
 	return 0;
 }

 const int bt_entry_size_bytes = sizeof(unsigned long) * 4;

 void *read_bounds_table_into_buf(unsigned long table_vaddr)
 {
 #ifdef MPX_DIG_STANDALONE
 	static char bt_buf[MPX_BOUNDS_TABLE_SIZE_BYTES];
 	off_t seek_ret = lseek(fd, table_vaddr, SEEK_SET);
 	if (seek_ret != table_vaddr)
 		mpx_dig_abort();

 	int read_ret = read(fd, &bt_buf, sizeof(bt_buf));
 	if (read_ret != sizeof(bt_buf))
 		mpx_dig_abort();
 	return &bt_buf;
 #else
 	return (void *)table_vaddr;
 #endif
 }

 int dump_table(unsigned long table_vaddr, unsigned long base_controlled_vaddr,
 		unsigned long bde_vaddr)
 {
 	unsigned long offset_inside_bt;
 	int nr_entries = 0;
 	int do_abort = 0;
 	char *bt_buf;

 	dprintf3("%s() base_controlled_vaddr: 0x%012lx bde_vaddr: 0x%012lx\n",
 			__func__, base_controlled_vaddr, bde_vaddr);

 	bt_buf = read_bounds_table_into_buf(table_vaddr);

 	dprintf4("%s() read done\n", __func__);

 	for (offset_inside_bt = 0;
 	     offset_inside_bt < MPX_BOUNDS_TABLE_SIZE_BYTES;
 	     offset_inside_bt += bt_entry_size_bytes) {
 		unsigned long bt_entry_index;
 		unsigned long bt_entry_controls;
 		unsigned long this_bt_entry_for_vaddr;
 		unsigned long *bt_entry_buf;
 		int i;

 		dprintf4("%s() offset_inside_bt: 0x%lx of 0x%llx\n", __func__,
 			offset_inside_bt, MPX_BOUNDS_TABLE_SIZE_BYTES);
 		bt_entry_buf = (void *)&bt_buf[offset_inside_bt];
 		if (!bt_buf) {
 			printf("null bt_buf\n");
 			mpx_dig_abort();
 		}
 		if (!bt_entry_buf) {
 			printf("null bt_entry_buf\n");
 			mpx_dig_abort();
 		}
 		dprintf4("%s() reading *bt_entry_buf @ %p\n", __func__,
 				bt_entry_buf);
 		if (!bt_entry_buf[0] &&
 		    !bt_entry_buf[1] &&
 		    !bt_entry_buf[2] &&
 		    !bt_entry_buf[3])
 			continue;

 		nr_entries++;

 		bt_entry_index = offset_inside_bt/bt_entry_size_bytes;
 		bt_entry_controls = sizeof(void *);
 		this_bt_entry_for_vaddr =
 			base_controlled_vaddr + bt_entry_index*bt_entry_controls;
 		/*
 		 * We sign extend vaddr bits 48->63 which effectively
 		 * creates a hole in the virtual address space.
 		 * This calculation corrects for the hole.
 		 */
 		if (this_bt_entry_for_vaddr > 0x00007fffffffffffUL)
 			this_bt_entry_for_vaddr |= 0xffff800000000000;

 		if (!vaddr_mapped_by_range(this_bt_entry_for_vaddr)) {
 			printf("bt_entry_buf: %p\n", bt_entry_buf);
 			printf("there is a bte for %lx but no mapping\n",
 					this_bt_entry_for_vaddr);
 			printf("	  bde   vaddr: %016lx\n", bde_vaddr);
 			printf("base_controlled_vaddr: %016lx\n", base_controlled_vaddr);
 			printf("	  table_vaddr: %016lx\n", table_vaddr);
 			printf("	  entry vaddr: %016lx @ offset %lx\n",
 				table_vaddr + offset_inside_bt, offset_inside_bt);
 			do_abort = 1;
 			mpx_dig_abort();
 		}
 		if (DEBUG_LEVEL < 4)
 			continue;

 		printf("table entry[%lx]: ", offset_inside_bt);
 		for (i = 0; i < bt_entry_size_bytes; i += sizeof(unsigned long))
 			printf("0x%016lx ", bt_entry_buf[i]);
 		printf("\n");
 	}
 	if (do_abort)
 		mpx_dig_abort();
 	dprintf4("%s() done\n",  __func__);
 	return nr_entries;
 }

 int search_bd_buf(char *buf, int len_bytes, unsigned long bd_offset_bytes,
 		int *nr_populated_bdes)
 {
 	unsigned long i;
 	int total_entries = 0;

 	dprintf3("%s(%p, %x, %lx, ...) buf end: %p\n", __func__, buf,
 			len_bytes, bd_offset_bytes, buf + len_bytes);

 	for (i = 0; i < len_bytes; i += sizeof(unsigned long)) {
 		unsigned long bd_index = (bd_offset_bytes + i) / sizeof(unsigned long);
 		unsigned long *bounds_dir_entry_ptr = (unsigned long *)&buf[i];
 		unsigned long bounds_dir_entry;
 		unsigned long bd_for_vaddr;
 		unsigned long bt_start;
 		unsigned long bt_tail;
 		int nr_entries;

 		dprintf4("%s() loop i: %ld bounds_dir_entry_ptr: %p\n", __func__, i,
 				bounds_dir_entry_ptr);

 		bounds_dir_entry = *bounds_dir_entry_ptr;
 		if (!bounds_dir_entry) {
 			dprintf4("no bounds dir at index 0x%lx / 0x%lx "
 				 "start at offset:%lx %lx\n", bd_index, bd_index,
 					bd_offset_bytes, i);
 			continue;
 		}
 		dprintf3("found bounds_dir_entry: 0x%lx @ "
 			 "index 0x%lx buf ptr: %p\n", bounds_dir_entry, i,
 					&buf[i]);
 		/* mask off the enable bit: */
 		bounds_dir_entry &= ~0x1;
 		(*nr_populated_bdes)++;
 		dprintf4("nr_populated_bdes: %p\n", nr_populated_bdes);
 		dprintf4("*nr_populated_bdes: %d\n", *nr_populated_bdes);

 		bt_start = bounds_dir_entry;
 		bt_tail = bounds_dir_entry + MPX_BOUNDS_TABLE_SIZE_BYTES - 1;
 		if (!vaddr_mapped_by_range(bt_start)) {
 			printf("bounds directory 0x%lx points to nowhere\n",
 					bounds_dir_entry);
 			mpx_dig_abort();
 		}
 		if (!vaddr_mapped_by_range(bt_tail)) {
 			printf("bounds directory end 0x%lx points to nowhere\n",
 					bt_tail);
 			mpx_dig_abort();
 		}
 		/*
 		 * Each bounds directory entry controls 1MB of virtual address
 		 * space.  This variable is the virtual address in the process
 		 * of the beginning of the area controlled by this bounds_dir.
 		 */
 		bd_for_vaddr = bd_index * (1UL<<20);

 		nr_entries = dump_table(bounds_dir_entry, bd_for_vaddr,
 				bounds_dir_global+bd_offset_bytes+i);
 		total_entries += nr_entries;
 		dprintf5("dir entry[%4ld @ %p]: 0x%lx %6d entries "
 			 "total this buf: %7d bd_for_vaddrs: 0x%lx -> 0x%lx\n",
 				bd_index, buf+i,
 				bounds_dir_entry, nr_entries, total_entries,
 				bd_for_vaddr, bd_for_vaddr + (1UL<<20));
 	}
 	dprintf3("%s(%p, %x, %lx, ...) done\n", __func__, buf, len_bytes,
 			bd_offset_bytes);
 	return total_entries;
 }

 int proc_pid_mem_fd = -1;

 void *fill_bounds_dir_buf_other(long byte_offset_inside_bounds_dir,
 			   long buffer_size_bytes, void *buffer)
 {
 	unsigned long seekto = bounds_dir_global + byte_offset_inside_bounds_dir;
 	int read_ret;
 	off_t seek_ret = lseek(proc_pid_mem_fd, seekto, SEEK_SET);

 	if (seek_ret != seekto)
 		mpx_dig_abort();

 	read_ret = read(proc_pid_mem_fd, buffer, buffer_size_bytes);
 	/* there shouldn't practically be short reads of /proc/$pid/mem */
 	if (read_ret != buffer_size_bytes)
 		mpx_dig_abort();

 	return buffer;
 }
 void *fill_bounds_dir_buf_self(long byte_offset_inside_bounds_dir,
 			   long buffer_size_bytes, void *buffer)

 {
 	unsigned char vec[buffer_size_bytes / PAGE_SIZE];
 	char *dig_bounds_dir_ptr =
 		(void *)(bounds_dir_global + byte_offset_inside_bounds_dir);
 	/*
 	 * use mincore() to quickly find the areas of the bounds directory
 	 * that have memory and thus will be worth scanning.
 	 */
 	int incore_ret;

 	int incore = 0;
 	int i;

 	dprintf4("%s() dig_bounds_dir_ptr: %p\n", __func__, dig_bounds_dir_ptr);

 	incore_ret = mincore(dig_bounds_dir_ptr, buffer_size_bytes, &vec[0]);
 	if (incore_ret) {
 		printf("mincore ret: %d\n", incore_ret);
 		perror("mincore");
 		mpx_dig_abort();
 	}
 	for (i = 0; i < sizeof(vec); i++)
 		incore += vec[i];
 	dprintf4("%s() total incore: %d\n", __func__, incore);
 	if (!incore)
 		return NULL;
 	dprintf3("%s() total incore: %d\n", __func__, incore);
 	return dig_bounds_dir_ptr;
 }

 int inspect_pid(int pid)
 {
 	static int dig_nr;
 	long offset_inside_bounds_dir;
 	char bounds_dir_buf[sizeof(unsigned long) * (1UL << 15)];
 	char *dig_bounds_dir_ptr;
 	int total_entries = 0;
 	int nr_populated_bdes = 0;
 	int inspect_self;

 	if (getpid() == pid) {
 		dprintf4("inspecting self\n");
 		inspect_self = 1;
 	} else {
 		dprintf4("inspecting pid %d\n", pid);
 		mpx_dig_abort();
 	}

 	for (offset_inside_bounds_dir = 0;
 	     offset_inside_bounds_dir < MPX_BOUNDS_TABLE_SIZE_BYTES;
 	     offset_inside_bounds_dir += sizeof(bounds_dir_buf)) {
 		static int bufs_skipped;
 		int this_entries;

 		if (inspect_self) {
 			dig_bounds_dir_ptr =
 				fill_bounds_dir_buf_self(offset_inside_bounds_dir,
 							 sizeof(bounds_dir_buf),
 							 &bounds_dir_buf[0]);
 		} else {
 			dig_bounds_dir_ptr =
 				fill_bounds_dir_buf_other(offset_inside_bounds_dir,
 							  sizeof(bounds_dir_buf),
 							  &bounds_dir_buf[0]);
 		}
 		if (!dig_bounds_dir_ptr) {
 			bufs_skipped++;
 			continue;
 		}
 		this_entries = search_bd_buf(dig_bounds_dir_ptr,
 					sizeof(bounds_dir_buf),
 					offset_inside_bounds_dir,
 					&nr_populated_bdes);
 		total_entries += this_entries;
 	}
 	printf("mpx dig (%3d) complete, SUCCESS (%8d / %4d)\n", ++dig_nr,
 			total_entries, nr_populated_bdes);
 	return total_entries + nr_populated_bdes;
 }

 #ifdef MPX_DIG_REMOTE
 int main(int argc, char **argv)
 {
 	int err;
 	char *c;
 	unsigned long bounds_dir_entry;
 	int pid;

 	printf("mpx-dig starting...\n");
 	err = sscanf(argv[1], "%d", &pid);
 	printf("parsing: '%s', err: %d\n", argv[1], err);
 	if (err != 1)
 		mpx_dig_abort();

 	err = sscanf(argv[2], "%lx", &bounds_dir_global);
 	printf("parsing: '%s': %d\n", argv[2], err);
 	if (err != 1)
 		mpx_dig_abort();

 	proc_pid_mem_fd = open_proc(pid, "mem");
 	if (proc_pid_mem_fd < 0)
 		mpx_dig_abort();

 	inspect_pid(pid);
 	return 0;
 }
 #endif

 long inspect_me(struct mpx_bounds_dir *bounds_dir)
 {
 	int pid = getpid();

 	pid_load_vaddrs(pid);
 	bounds_dir_global = (unsigned long)bounds_dir;
 	dprintf4("enter %s() bounds dir: %p\n", __func__, bounds_dir);
 	return inspect_pid(pid);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Written by Dave Hansen <dave.hansen@intel.com>
	*/

	#include <stdlib.h>
	#include <sys/types.h>
	#include <unistd.h>
	#include <stdio.h>
	#include <errno.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <unistd.h>
	#include <sys/mman.h>
	#include <string.h>
	#include <fcntl.h>
	#include "mpx-debug.h"
	#include "mpx-mm.h"
	#include "mpx-hw.h"

	unsigned long bounds_dir_global;

	#define mpx_dig_abort() __mpx_dig_abort(__FILE__, __func__, __LINE__)
	static void inline __mpx_dig_abort(const char file, const char func, int line)
	{
	fprintf(stderr, "MPX dig abort @ %s::%d in %s()\n", file, line, func);
	printf("MPX dig abort @ %s::%d in %s()\n", file, line, func);
	abort();
	}

	/*
	* run like this (BDIR finds the probably bounds directory):
	*
	* BDIR="$(cat /proc/$pid/smaps \| grep -B1 2097152 \
	* \| head -1 \| awk -F- '{print $1}')";
	* ./mpx-dig $pid 0x$BDIR
	*
	* NOTE:
	* assumes that the only 2097152-kb VMA is the bounds dir
	*/

	long nr_incore(void *ptr, unsigned long size_bytes)
	{
	int i;
	long ret = 0;
	long vec_len = size_bytes / PAGE_SIZE;
	unsigned char *vec = malloc(vec_len);
	int incore_ret;

	if (!vec)
	mpx_dig_abort();

	incore_ret = mincore(ptr, size_bytes, vec);
	if (incore_ret) {
	printf("mincore ret: %d\n", incore_ret);
	perror("mincore");
	mpx_dig_abort();
	}
	for (i = 0; i < vec_len; i++)
	ret += vec[i];
	free(vec);
	return ret;
	}

	int open_proc(int pid, char *file)
	{
	static char buf[100];
	int fd;

	snprintf(&buf[0], sizeof(buf), "/proc/%d/%s", pid, file);
	fd = open(&buf[0], O_RDONLY);
	if (fd < 0)
	perror(buf);

	return fd;
	}

	struct vaddr_range {
	unsigned long start;
	unsigned long end;
	};
	struct vaddr_range *ranges;
	int nr_ranges_allocated;
	int nr_ranges_populated;
	int last_range = -1;

	int __pid_load_vaddrs(int pid)
	{
	int ret = 0;
	int proc_maps_fd = open_proc(pid, "maps");
	char linebuf[10000];
	unsigned long start;
	unsigned long end;
	char rest[1000];
	FILE *f = fdopen(proc_maps_fd, "r");

	if (!f)
	mpx_dig_abort();
	nr_ranges_populated = 0;
	while (!feof(f)) {
	char *readret = fgets(linebuf, sizeof(linebuf), f);
	int parsed;

	if (readret == NULL) {
	if (feof(f))
	break;
	mpx_dig_abort();
	}

	parsed = sscanf(linebuf, "%lx-%lx%s", &start, &end, rest);
	if (parsed != 3)
	mpx_dig_abort();

	dprintf4("result[%d]: %lx-%lx<->%s\n", parsed, start, end, rest);
	if (nr_ranges_populated >= nr_ranges_allocated) {
	ret = -E2BIG;
	break;
	}
	ranges[nr_ranges_populated].start = start;
	ranges[nr_ranges_populated].end = end;
	nr_ranges_populated++;
	}
	last_range = -1;
	fclose(f);
	close(proc_maps_fd);
	return ret;
	}

	int pid_load_vaddrs(int pid)
	{
	int ret;

	dprintf2("%s(%d)\n", __func__, pid);
	if (!ranges) {
	nr_ranges_allocated = 4;
	ranges = malloc(nr_ranges_allocated * sizeof(ranges[0]));
	dprintf2("%s(%d) allocated %d ranges @ %p\n", __func__, pid,
	nr_ranges_allocated, ranges);
	assert(ranges != NULL);
	}
	do {
	ret = __pid_load_vaddrs(pid);
	if (!ret)
	break;
	if (ret == -E2BIG) {
	dprintf2("%s(%d) need to realloc\n", __func__, pid);
	nr_ranges_allocated *= 2;
	ranges = realloc(ranges,
	nr_ranges_allocated * sizeof(ranges[0]));
	dprintf2("%s(%d) allocated %d ranges @ %p\n", __func__,
	pid, nr_ranges_allocated, ranges);
	assert(ranges != NULL);
	dprintf1("reallocating to hold %d ranges\n", nr_ranges_allocated);
	}
	} while (1);

	dprintf2("%s(%d) done\n", __func__, pid);

	return ret;
	}

	static inline int vaddr_in_range(unsigned long vaddr, struct vaddr_range *r)
	{
	if (vaddr < r->start)
	return 0;
	if (vaddr >= r->end)
	return 0;
	return 1;
	}

	static inline int vaddr_mapped_by_range(unsigned long vaddr)
	{
	int i;

	if (last_range > 0 && vaddr_in_range(vaddr, &ranges[last_range]))
	return 1;

	for (i = 0; i < nr_ranges_populated; i++) {
	struct vaddr_range *r = &ranges[i];

	if (vaddr_in_range(vaddr, r))
	continue;
	last_range = i;
	return 1;
	}
	return 0;
	}

	const int bt_entry_size_bytes = sizeof(unsigned long) * 4;

	void *read_bounds_table_into_buf(unsigned long table_vaddr)
	{
	#ifdef MPX_DIG_STANDALONE
	static char bt_buf[MPX_BOUNDS_TABLE_SIZE_BYTES];
	off_t seek_ret = lseek(fd, table_vaddr, SEEK_SET);
	if (seek_ret != table_vaddr)
	mpx_dig_abort();

	int read_ret = read(fd, &bt_buf, sizeof(bt_buf));
	if (read_ret != sizeof(bt_buf))
	mpx_dig_abort();
	return &bt_buf;
	#else
	return (void *)table_vaddr;
	#endif
	}

	int dump_table(unsigned long table_vaddr, unsigned long base_controlled_vaddr,
	unsigned long bde_vaddr)
	{
	unsigned long offset_inside_bt;
	int nr_entries = 0;
	int do_abort = 0;
	char *bt_buf;

	dprintf3("%s() base_controlled_vaddr: 0x%012lx bde_vaddr: 0x%012lx\n",
	__func__, base_controlled_vaddr, bde_vaddr);

	bt_buf = read_bounds_table_into_buf(table_vaddr);

	dprintf4("%s() read done\n", __func__);

	for (offset_inside_bt = 0;
	offset_inside_bt < MPX_BOUNDS_TABLE_SIZE_BYTES;
	offset_inside_bt += bt_entry_size_bytes) {
	unsigned long bt_entry_index;
	unsigned long bt_entry_controls;
	unsigned long this_bt_entry_for_vaddr;
	unsigned long *bt_entry_buf;
	int i;

	dprintf4("%s() offset_inside_bt: 0x%lx of 0x%llx\n", __func__,
	offset_inside_bt, MPX_BOUNDS_TABLE_SIZE_BYTES);
	bt_entry_buf = (void *)&bt_buf[offset_inside_bt];
	if (!bt_buf) {
	printf("null bt_buf\n");
	mpx_dig_abort();
	}
	if (!bt_entry_buf) {
	printf("null bt_entry_buf\n");
	mpx_dig_abort();
	}
	dprintf4("%s() reading *bt_entry_buf @ %p\n", __func__,
	bt_entry_buf);
	if (!bt_entry_buf[0] &&
	!bt_entry_buf[1] &&
	!bt_entry_buf[2] &&
	!bt_entry_buf[3])
	continue;

	nr_entries++;

	bt_entry_index = offset_inside_bt/bt_entry_size_bytes;
	bt_entry_controls = sizeof(void *);
	this_bt_entry_for_vaddr =
	base_controlled_vaddr + bt_entry_index*bt_entry_controls;
	/*
	* We sign extend vaddr bits 48->63 which effectively
	* creates a hole in the virtual address space.
	* This calculation corrects for the hole.
	*/
	if (this_bt_entry_for_vaddr > 0x00007fffffffffffUL)
	this_bt_entry_for_vaddr \|= 0xffff800000000000;

	if (!vaddr_mapped_by_range(this_bt_entry_for_vaddr)) {
	printf("bt_entry_buf: %p\n", bt_entry_buf);
	printf("there is a bte for %lx but no mapping\n",
	this_bt_entry_for_vaddr);
	printf(" bde vaddr: %016lx\n", bde_vaddr);
	printf("base_controlled_vaddr: %016lx\n", base_controlled_vaddr);
	printf(" table_vaddr: %016lx\n", table_vaddr);
	printf(" entry vaddr: %016lx @ offset %lx\n",
	table_vaddr + offset_inside_bt, offset_inside_bt);
	do_abort = 1;
	mpx_dig_abort();
	}
	if (DEBUG_LEVEL < 4)
	continue;

	printf("table entry[%lx]: ", offset_inside_bt);
	for (i = 0; i < bt_entry_size_bytes; i += sizeof(unsigned long))
	printf("0x%016lx ", bt_entry_buf[i]);
	printf("\n");
	}
	if (do_abort)
	mpx_dig_abort();
	dprintf4("%s() done\n", __func__);
	return nr_entries;
	}

	int search_bd_buf(char *buf, int len_bytes, unsigned long bd_offset_bytes,
	int *nr_populated_bdes)
	{
	unsigned long i;
	int total_entries = 0;

	dprintf3("%s(%p, %x, %lx, ...) buf end: %p\n", __func__, buf,
	len_bytes, bd_offset_bytes, buf + len_bytes);

	for (i = 0; i < len_bytes; i += sizeof(unsigned long)) {
	unsigned long bd_index = (bd_offset_bytes + i) / sizeof(unsigned long);
	unsigned long bounds_dir_entry_ptr = (unsigned long )&buf[i];
	unsigned long bounds_dir_entry;
	unsigned long bd_for_vaddr;
	unsigned long bt_start;
	unsigned long bt_tail;
	int nr_entries;

	dprintf4("%s() loop i: %ld bounds_dir_entry_ptr: %p\n", __func__, i,
	bounds_dir_entry_ptr);

	bounds_dir_entry = *bounds_dir_entry_ptr;
	if (!bounds_dir_entry) {
	dprintf4("no bounds dir at index 0x%lx / 0x%lx "
	"start at offset:%lx %lx\n", bd_index, bd_index,
	bd_offset_bytes, i);
	continue;
	}
	dprintf3("found bounds_dir_entry: 0x%lx @ "
	"index 0x%lx buf ptr: %p\n", bounds_dir_entry, i,
	&buf[i]);
	/* mask off the enable bit: */
	bounds_dir_entry &= ~0x1;
	(*nr_populated_bdes)++;
	dprintf4("nr_populated_bdes: %p\n", nr_populated_bdes);
	dprintf4("nr_populated_bdes: %d\n", nr_populated_bdes);

	bt_start = bounds_dir_entry;
	bt_tail = bounds_dir_entry + MPX_BOUNDS_TABLE_SIZE_BYTES - 1;
	if (!vaddr_mapped_by_range(bt_start)) {
	printf("bounds directory 0x%lx points to nowhere\n",
	bounds_dir_entry);
	mpx_dig_abort();
	}
	if (!vaddr_mapped_by_range(bt_tail)) {
	printf("bounds directory end 0x%lx points to nowhere\n",
	bt_tail);
	mpx_dig_abort();
	}
	/*
	* Each bounds directory entry controls 1MB of virtual address
	* space. This variable is the virtual address in the process
	* of the beginning of the area controlled by this bounds_dir.
	*/
	bd_for_vaddr = bd_index * (1UL<<20);

	nr_entries = dump_table(bounds_dir_entry, bd_for_vaddr,
	bounds_dir_global+bd_offset_bytes+i);
	total_entries += nr_entries;
	dprintf5("dir entry[%4ld @ %p]: 0x%lx %6d entries "
	"total this buf: %7d bd_for_vaddrs: 0x%lx -> 0x%lx\n",
	bd_index, buf+i,
	bounds_dir_entry, nr_entries, total_entries,
	bd_for_vaddr, bd_for_vaddr + (1UL<<20));
	}
	dprintf3("%s(%p, %x, %lx, ...) done\n", __func__, buf, len_bytes,
	bd_offset_bytes);
	return total_entries;
	}

	int proc_pid_mem_fd = -1;

	void *fill_bounds_dir_buf_other(long byte_offset_inside_bounds_dir,
	long buffer_size_bytes, void *buffer)
	{
	unsigned long seekto = bounds_dir_global + byte_offset_inside_bounds_dir;
	int read_ret;
	off_t seek_ret = lseek(proc_pid_mem_fd, seekto, SEEK_SET);

	if (seek_ret != seekto)
	mpx_dig_abort();

	read_ret = read(proc_pid_mem_fd, buffer, buffer_size_bytes);
	/* there shouldn't practically be short reads of /proc/$pid/mem */
	if (read_ret != buffer_size_bytes)
	mpx_dig_abort();

	return buffer;
	}
	void *fill_bounds_dir_buf_self(long byte_offset_inside_bounds_dir,
	long buffer_size_bytes, void *buffer)

	{
	unsigned char vec[buffer_size_bytes / PAGE_SIZE];
	char *dig_bounds_dir_ptr =
	(void *)(bounds_dir_global + byte_offset_inside_bounds_dir);
	/*
	* use mincore() to quickly find the areas of the bounds directory
	* that have memory and thus will be worth scanning.
	*/
	int incore_ret;

	int incore = 0;
	int i;

	dprintf4("%s() dig_bounds_dir_ptr: %p\n", __func__, dig_bounds_dir_ptr);

	incore_ret = mincore(dig_bounds_dir_ptr, buffer_size_bytes, &vec[0]);
	if (incore_ret) {
	printf("mincore ret: %d\n", incore_ret);
	perror("mincore");
	mpx_dig_abort();
	}
	for (i = 0; i < sizeof(vec); i++)
	incore += vec[i];
	dprintf4("%s() total incore: %d\n", __func__, incore);
	if (!incore)
	return NULL;
	dprintf3("%s() total incore: %d\n", __func__, incore);
	return dig_bounds_dir_ptr;
	}

	int inspect_pid(int pid)
	{
	static int dig_nr;
	long offset_inside_bounds_dir;
	char bounds_dir_buf[sizeof(unsigned long) * (1UL << 15)];
	char *dig_bounds_dir_ptr;
	int total_entries = 0;
	int nr_populated_bdes = 0;
	int inspect_self;

	if (getpid() == pid) {
	dprintf4("inspecting self\n");
	inspect_self = 1;
	} else {
	dprintf4("inspecting pid %d\n", pid);
	mpx_dig_abort();
	}

	for (offset_inside_bounds_dir = 0;
	offset_inside_bounds_dir < MPX_BOUNDS_TABLE_SIZE_BYTES;
	offset_inside_bounds_dir += sizeof(bounds_dir_buf)) {
	static int bufs_skipped;
	int this_entries;

	if (inspect_self) {
	dig_bounds_dir_ptr =
	fill_bounds_dir_buf_self(offset_inside_bounds_dir,
	sizeof(bounds_dir_buf),
	&bounds_dir_buf[0]);
	} else {
	dig_bounds_dir_ptr =
	fill_bounds_dir_buf_other(offset_inside_bounds_dir,
	sizeof(bounds_dir_buf),
	&bounds_dir_buf[0]);
	}
	if (!dig_bounds_dir_ptr) {
	bufs_skipped++;
	continue;
	}
	this_entries = search_bd_buf(dig_bounds_dir_ptr,
	sizeof(bounds_dir_buf),
	offset_inside_bounds_dir,
	&nr_populated_bdes);
	total_entries += this_entries;
	}
	printf("mpx dig (%3d) complete, SUCCESS (%8d / %4d)\n", ++dig_nr,
	total_entries, nr_populated_bdes);
	return total_entries + nr_populated_bdes;
	}

	#ifdef MPX_DIG_REMOTE
	int main(int argc, char **argv)
	{
	int err;
	char *c;
	unsigned long bounds_dir_entry;
	int pid;

	printf("mpx-dig starting...\n");
	err = sscanf(argv[1], "%d", &pid);
	printf("parsing: '%s', err: %d\n", argv[1], err);
	if (err != 1)
	mpx_dig_abort();

	err = sscanf(argv[2], "%lx", &bounds_dir_global);
	printf("parsing: '%s': %d\n", argv[2], err);
	if (err != 1)
	mpx_dig_abort();

	proc_pid_mem_fd = open_proc(pid, "mem");
	if (proc_pid_mem_fd < 0)
	mpx_dig_abort();

	inspect_pid(pid);
	return 0;
	}
	#endif

	long inspect_me(struct mpx_bounds_dir *bounds_dir)
	{
	int pid = getpid();

	pid_load_vaddrs(pid);
	bounds_dir_global = (unsigned long)bounds_dir;
	dprintf4("enter %s() bounds dir: %p\n", __func__, bounds_dir);
	return inspect_pid(pid);
	}