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848f0e46f0
Compiler generates the following instruction sequence for dynamic TLS access: leal tls_var@tlsgd(,%ebx,1), %eax call ___tls_get_addr@PLT CALL instruction is transparent to compiler which assumes all registers, except for EFLAGS, AX, CX, and DX, are unchanged after CALL. But ___tls_get_addr is a normal function which doesn't preserve any vector registers. 1. Rename the generic __tls_get_addr function to ___tls_get_addr_internal. 2. Change ___tls_get_addr to a wrapper function with implementations for FNSAVE, FXSAVE, XSAVE and XSAVEC to save and restore all vector registers. 3. dl-tlsdesc-dynamic.h has: _dl_tlsdesc_dynamic: /* Like all TLS resolvers, preserve call-clobbered registers. We need two scratch regs anyway. */ subl $32, %esp cfi_adjust_cfa_offset (32) It is wrong to use movl %ebx, -28(%esp) movl %esp, %ebx cfi_def_cfa_register(%ebx) ... mov %ebx, %esp cfi_def_cfa_register(%esp) movl -28(%esp), %ebx to preserve EBX on stack. Fix it with: movl %ebx, 28(%esp) movl %esp, %ebx cfi_def_cfa_register(%ebx) ... mov %ebx, %esp cfi_def_cfa_register(%esp) movl 28(%esp), %ebx 4. Update _dl_tlsdesc_dynamic to call ___tls_get_addr_internal directly. 5. Add have-test-mtls-traditional to compile tst-tls23-mod.c with traditional TLS variant to verify the fix. 6. Define DL_RUNTIME_RESOLVE_REALIGN_STACK in sysdeps/x86/sysdep.h. This fixes BZ #32996. Co-Authored-By: Adhemerval Zanella <adhemerval.zanella@linaro.org> Signed-off-by: H.J. Lu <hjl.tools@gmail.com> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
107 lines
2.4 KiB
C
107 lines
2.4 KiB
C
/* Test that __tls_get_addr preserves caller-saved registers.
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Copyright (C) 2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <dlfcn.h>
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#include <pthread.h>
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#include <support/xdlfcn.h>
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#include <support/xthread.h>
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#include <support/check.h>
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#include <support/test-driver.h>
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#include <tst-tls23.h>
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#ifndef IS_SUPPORTED
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# define IS_SUPPORTED() true
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#endif
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/* An architecture can define it to clobber caller-saved registers in
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malloc below to verify that __tls_get_addr won't change caller-saved
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registers. */
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#ifndef PREPARE_MALLOC
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# define PREPARE_MALLOC()
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#endif
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extern void * __libc_malloc (size_t);
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size_t malloc_counter = 0;
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void *
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malloc (size_t n)
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{
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PREPARE_MALLOC ();
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malloc_counter++;
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return __libc_malloc (n);
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}
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static void *mod;
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static const char *modname = "tst-tls23-mod.so";
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static void
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open_mod (void)
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{
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mod = xdlopen (modname, RTLD_LAZY);
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printf ("open %s\n", modname);
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}
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static void
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close_mod (void)
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{
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xdlclose (mod);
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mod = NULL;
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printf ("close %s\n", modname);
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}
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static void
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access_mod (const char *sym)
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{
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struct tls var = { -4, -4, -4, -4 };
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struct tls *(*f) (struct tls *) = xdlsym (mod, sym);
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/* Check that our malloc is called. */
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malloc_counter = 0;
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struct tls *p = f (&var);
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TEST_VERIFY (malloc_counter != 0);
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printf ("access %s: %s() = %p\n", modname, sym, p);
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TEST_VERIFY_EXIT (memcmp (p, &var, sizeof (var)) == 0);
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++(p->a);
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}
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static void *
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start (void *arg)
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{
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access_mod ("apply_tls");
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return arg;
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}
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static int
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do_test (void)
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{
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if (!IS_SUPPORTED ())
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return EXIT_UNSUPPORTED;
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open_mod ();
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pthread_t t = xpthread_create (NULL, start, NULL);
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xpthread_join (t);
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close_mod ();
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return 0;
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}
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#include <support/test-driver.c>
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