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/* Verify that TLS blocks and the rseq area do not overlap.
Copyright (C) 2025 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <array_length.h>
#include <elf.h>
#include <link.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <support/check.h>
#include <support/xdlfcn.h>
#include <sys/auxv.h>
#include <sys/param.h>
#include <sys/rseq.h>
#include <thread_pointer.h>
#include <unistd.h>
/* Used to keep track of address ranges. The ranges are sorted and
then checked for overlap. */
struct address_range
{
const char *prefix;
const char *label;
uintptr_t start;
size_t length;
};
struct address_range ranges[20];
size_t range_count;
static void
add_range (const char *prefix, const char *label,
const void *start, size_t length)
{
TEST_VERIFY (start != NULL);
TEST_VERIFY (length > 0);
TEST_VERIFY_EXIT (range_count < array_length (ranges));
ranges[range_count].prefix = prefix;
ranges[range_count].label = label;
ranges[range_count].start = (uintptr_t) start;
ranges[range_count].length = length;
++range_count;
}
static int
range_compare (const void *a1, const void *b1)
{
const struct address_range *a = a1;
const struct address_range *b = b1;
if (a->start < b->start)
return -1;
if (a->start > b->start)
return 1;
return 0;
}
static void
check_for_overlap (void)
{
qsort (ranges, range_count, sizeof (ranges[0]), range_compare);
uintptr_t previous_end = ranges[0].start + ranges[0].length - 1;
for (size_t i = 1; i < range_count; ++i)
{
uintptr_t this_end = ranges[i].start + ranges[i].length - 1;
if (ranges[i].start <= previous_end)
{
puts ("error: overlap between address ranges");
printf (" %s%s: [0x%lx, 0x%lx)\n",
ranges[i - 1].prefix, ranges[i - 1].label,
(unsigned long int) ranges[i - 1].start,
(unsigned long int) previous_end);
printf (" %s%s: [0x%lx, 0x%lx)\n",
ranges[i].prefix, ranges[i].label,
(unsigned long int) ranges[i].start,
(unsigned long int) this_end);
}
previous_end = this_end;
}
}
static void
add_rseq (void)
{
/* The initial size of 32 bytes is always allocated. The value
reported by __rseq_size does not include the alignment, which can
be larger than 32 if requested by the kernel through the
auxiliary vector. */
size_t size = 32;
if (__rseq_size > 0)
size = roundup (__rseq_size, MAX (getauxval (AT_RSEQ_ALIGN), 32));
printf ("info: adding rseq area of %zu bytes\n", size);
add_range ("", "rseq area",
(char *) __thread_pointer () + __rseq_offset, size);
}
/* These functions add the TLS data for all loaded modules to the
recorded address ranges. */
static int
dlip_callback (struct dl_phdr_info *info, size_t size, void *ignored)
{
/* If the dynamic linker does not provide TLS address information,
there is nothing to register. */
if (info->dlpi_tls_data == NULL)
return 0;
for (int i = 0; i < info->dlpi_phnum; ++i)
{
if (info->dlpi_phdr[i].p_type == PT_TLS)
{
printf ("info: adding TLS range for \"%s\" (%zu bytes)\n",
info->dlpi_name, (size_t) info->dlpi_phdr[i].p_memsz);
add_range ("TLS for ",
info->dlpi_name[0] != '\0' ? info->dlpi_name : "main",
info->dlpi_tls_data, info->dlpi_phdr[i].p_memsz);
break;
}
}
return 0;
}
/* Returns true if any TLS ranges were found. */
static void
add_tls_ranges (void)
{
dl_iterate_phdr (dlip_callback, NULL);
}
volatile __thread int thread_var __attribute__ ((aligned (MAIN_TLS_ALIGN)));
static int
do_test (void)
{
void *original_brk = sbrk (0);
void *initial_allocation = malloc (16);
/* Ensure that the variable is not optimized away. */
thread_var = 0;
printf ("info: rseq area size: %u\n", __rseq_size);
puts ("info: checking address ranges with initially loaded modules");
add_range ("", "program break", original_brk, 1);
add_range ("", "malloc allocation", initial_allocation, 16);
add_rseq ();
add_tls_ranges ();
printf ("info: %zu ranges found\n", range_count);
check_for_overlap ();
range_count = 0;
puts ("info: checking address ranges after dlopen");
void *handle = xdlopen ("tst-rseq-tls-range-mod.so", RTLD_NOW);
int *mod_thread_var = xdlsym (handle, "mod_thread_var");
add_range ("", "program break", original_brk, 1);
add_range ("", "malloc allocation", initial_allocation, 16);
add_rseq ();
add_tls_ranges ();
{
bool found_objects = false;
for (size_t i = 0; i < range_count; ++i)
if (strchr (ranges[i].label, '/') != NULL)
found_objects = true;
if (!found_objects)
/* __tls_get_addr does not fully work with static dlopen.
Add some fall-back test data. */
add_range ("", "mod_thread_var",
mod_thread_var, sizeof (*mod_thread_var));
}
printf ("info: %zu ranges found\n", range_count);
check_for_overlap ();
xdlclose (handle);
free (initial_allocation);
return 0;
}
#include <support/test-driver.c>
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