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arm: Update _dl_tlsdesc_dynamic to preserve caller-saved registers (BZ 31372)

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ARM _dl_tlsdesc_dynamic slow path has two issues:

  * The ip/r12 is defined by AAPCS as a scratch register, and gcc is
    used to save the stack pointer before on some function calls.  So it
    should also be saved/restored as well.  It fixes the tst-gnu2-tls2.

  * None of the possible VFP registers are saved/restored.  ARM has the
    additional complexity to have different VFP bank sizes (depending of
    VFP support by the chip).

The tst-gnu2-tls2 test is extended to check for VFP registers, although
only for hardfp builds.  Different than setcontext, _dl_tlsdesc_dynamic
does not have  HWCAP_ARM_IWMMXT (I don't have a way to properly test
it and it is almost a decade since newer hardware was released).

With this patch there is no need to mark tst-gnu2-tls2 as XFAIL.

Checked on arm-linux-gnueabihf.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This commit is contained in:
Adhemerval Zanella 2024-03-12 13:21:19 -03:00
parent 968b0ca944
commit 64c7e34428
10 changed files with 250 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
config.h.in
View File

@ -141,6 +141,9 @@
/* LOONGARCH floating-point ABI for ld.so. */
#undef LOONGARCH_ABI_FRLEN
/* Define whether ARM used hard-float and support VFPvX-D32. */
#undef HAVE_ARM_PCS_VFP_D32
/* Linux specific: minimum supported kernel version. */
#undef __LINUX_KERNEL_VERSION

4
elf/Makefile
View File

@ -3059,10 +3059,6 @@ $(objpfx)tst-gnu2-tls2.out: \
$(objpfx)tst-gnu2-tls2mod2.so
ifeq (yes,$(have-mtls-dialect-gnu2))
# This test fails if dl_tlsdesc_dynamic doesn't preserve all caller-saved
# registers. See https://sourceware.org/bugzilla/show_bug.cgi?id=31372
test-xfail-tst-gnu2-tls2 = yes
CFLAGS-tst-tlsgap-mod0.c += -mtls-dialect=gnu2
CFLAGS-tst-tlsgap-mod1.c += -mtls-dialect=gnu2
CFLAGS-tst-tlsgap-mod2.c += -mtls-dialect=gnu2

4
elf/tst-gnu2-tls2.h
View File

@ -27,6 +27,10 @@ extern struct tls *apply_tls (struct tls *);
/* An architecture can define them to verify that clobber caller-saved
registers aren't changed by the implicit TLSDESC call. */
#ifndef INIT_TLSDESC_CALL
# define INIT_TLSDESC_CALL()
#endif
#ifndef BEFORE_TLSDESC_CALL
# define BEFORE_TLSDESC_CALL()
#endif

3
elf/tst-gnu2-tls2mod0.c
View File

@ -16,13 +16,14 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include "tst-gnu2-tls2.h"
#include <tst-gnu2-tls2.h>
__thread struct tls tls_var0 __attribute__ ((visibility ("hidden")));
struct tls *
apply_tls (struct tls *p)
{
INIT_TLSDESC_CALL ();
BEFORE_TLSDESC_CALL ();
tls_var0 = *p;
struct tls *ret = &tls_var0;

3
elf/tst-gnu2-tls2mod1.c
View File

@ -16,13 +16,14 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include "tst-gnu2-tls2.h"
#include <tst-gnu2-tls2.h>
__thread struct tls tls_var1[100] __attribute__ ((visibility ("hidden")));
struct tls *
apply_tls (struct tls *p)
{
INIT_TLSDESC_CALL ();
BEFORE_TLSDESC_CALL ();
tls_var1[1] = *p;
struct tls *ret = &tls_var1[1];

3
elf/tst-gnu2-tls2mod2.c
View File

@ -16,13 +16,14 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include "tst-gnu2-tls2.h"
#include <tst-gnu2-tls2.h>
__thread struct tls tls_var2 __attribute__ ((visibility ("hidden")));
struct tls *
apply_tls (struct tls *p)
{
INIT_TLSDESC_CALL ();
BEFORE_TLSDESC_CALL ();
tls_var2 = *p;
struct tls *ret = &tls_var2;

32
sysdeps/arm/configure vendored
View File

@ -187,6 +187,38 @@ else
default-abi = soft"
fi
{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether VFP supports 32 registers" >&5
printf %s "checking whether VFP supports 32 registers... " >&6; }
if test ${libc_cv_arm_pcs_vfp_d32+y}
then :
printf %s "(cached) " >&6
else $as_nop
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
void foo (void)
{
asm volatile ("vldr d16,=17" : : : "d16");
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"
then :
libc_cv_arm_pcs_vfp_d32=yes
else $as_nop
libc_cv_arm_pcs_vfp_d32=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
fi
{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_arm_pcs_vfp_d32" >&5
printf "%s\n" "$libc_cv_arm_pcs_vfp_d32" >&6; }
if test "$libc_cv_arm_pcs_vfp_d32" = yes ;
then
printf "%s\n" "#define HAVE_ARM_PCS_VFP_D32 1" >>confdefs.h
fi
{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether PC-relative relocs in movw/movt work properly" >&5
printf %s "checking whether PC-relative relocs in movw/movt work properly... " >&6; }
if test ${libc_cv_arm_pcrel_movw+y}

15
sysdeps/arm/configure.ac
View File

@ -21,6 +21,21 @@ else
LIBC_CONFIG_VAR([default-abi], [soft])
fi
AC_CACHE_CHECK([whether VFP supports 32 registers],
libc_cv_arm_pcs_vfp_d32, [
AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
void foo (void)
{
asm volatile ("vldr d16,=17" : : : "d16");
}
]])],
[libc_cv_arm_pcs_vfp_d32=yes],
[libc_cv_arm_pcs_vfp_d32=no])])
if test "$libc_cv_arm_pcs_vfp_d32" = yes ;
then
AC_DEFINE(HAVE_ARM_PCS_VFP_D32)
fi
AC_CACHE_CHECK([whether PC-relative relocs in movw/movt work properly],
libc_cv_arm_pcrel_movw, [
cat > conftest.s <<\EOF

70
sysdeps/arm/dl-tlsdesc.S
View File

@ -19,6 +19,7 @@
#include <sysdep.h>
#include <arm-features.h>
#include <tls.h>
#include <rtld-global-offsets.h>
#include "tlsdesc.h"
.text
@ -83,14 +84,20 @@ _dl_tlsdesc_dynamic(struct tlsdesc *tdp)
.align 2
_dl_tlsdesc_dynamic:
/* Our calling convention is to clobber r0, r1 and the processor
flags. All others that are modified must be saved */
eabi_save ({r2,r3,r4,lr})
push {r2,r3,r4,lr}
cfi_adjust_cfa_offset (16)
flags. All others that are modified must be saved. r5 is
used as the hwcap value to avoid reload after __tls_get_addr
call. If required we will save the vector register on the slow
path. */
eabi_save ({r2,r3,r4,r5,ip,lr})
push {r2,r3,r4,r5,ip,lr}
cfi_adjust_cfa_offset (24)
cfi_rel_offset (r2,0)
cfi_rel_offset (r3,4)
cfi_rel_offset (r4,8)
cfi_rel_offset (lr,12)
cfi_rel_offset (r5,12)
cfi_rel_offset (ip,16)
cfi_rel_offset (lr,20)
ldr r1, [r0] /* td */
GET_TLS (lr)
mov r4, r0 /* r4 = tp */
@ -113,22 +120,69 @@ _dl_tlsdesc_dynamic:
rsbne r0, r4, r3
bne 2f
1: mov r0, r1
/* Load the hwcap to check for vector support. */
ldr r2, 3f
ldr r1, .Lrtld_global_ro
0: add r2, pc, r2
ldr r2, [r2, r1]
ldr r5, [r2, #RTLD_GLOBAL_RO_DL_HWCAP_OFFSET]
#ifdef __SOFTFP__
tst r5, #HWCAP_ARM_VFP
beq .Lno_vfp
#endif
/* Store the VFP registers. Don't use VFP instructions directly
because this code is used in non-VFP multilibs. */
#define VFP_STACK_REQ (32*8 + 8)
sub sp, sp, VFP_STACK_REQ
cfi_adjust_cfa_offset (VFP_STACK_REQ)
mov r3, sp
.inst 0xeca30b20 /* vstmia r3!, {d0-d15} */
tst r5, #HWCAP_ARM_VFPD32
beq 4f
.inst 0xece30b20 /* vstmia r3!, {d16-d31} */
/* Store the floating-point status register. */
4: .inst 0xeef12a10 /* vmrs r2, fpscr */
str r2, [r3]
.Lno_vfp:
bl __tls_get_addr
rsb r0, r4, r0
#ifdef __SOFTFP__
tst r5, #HWCAP_ARM_VFP
beq 2f
#endif
mov r3, sp
.inst 0xecb30b20 /* vldmia r3!, {d0-d15} */
tst r5, #HWCAP_ARM_VFPD32
beq 5f
.inst 0xecf30b20 /* vldmia r3!, {d16-d31} */
ldr r4, [r3]
5: .inst 0xeee14a10 /* vmsr fpscr, r4 */
add sp, sp, VFP_STACK_REQ
cfi_adjust_cfa_offset (-VFP_STACK_REQ)
2:
#if ((defined (__ARM_ARCH_4T__) && defined (__THUMB_INTERWORK__)) \
|| defined (ARM_ALWAYS_BX))
pop {r2,r3,r4, lr}
cfi_adjust_cfa_offset (-16)
pop {r2,r3,r4,r5,ip, lr}
cfi_adjust_cfa_offset (-20)
cfi_restore (lr)
cfi_restore (ip)
cfi_restore (r5)
cfi_restore (r4)
cfi_restore (r3)
cfi_restore (r2)
bx lr
#else
pop {r2,r3,r4, pc}
pop {r2,r3,r4,r5,ip, pc}
#endif
eabi_fnend
cfi_endproc
.size _dl_tlsdesc_dynamic, .-_dl_tlsdesc_dynamic
3: .long _GLOBAL_OFFSET_TABLE_ - 0b - PC_OFS
.Lrtld_global_ro:
.long C_SYMBOL_NAME(_rtld_global_ro)(GOT)
#endif /* SHARED */

128
sysdeps/arm/tst-gnu2-tls2.h Normal file
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@ -0,0 +1,128 @@
/* Test TLSDESC relocation. ARM version.
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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 <config.h>
#include <sys/auxv.h>
#include <string.h>
#include <stdlib.h>
#include <endian.h>
#ifndef __SOFTFP__
# ifdef HAVE_ARM_PCS_VFP_D32
# define SAVE_VFP_D32 \
asm volatile ("vldr d16,=17" : : : "d16"); \
asm volatile ("vldr d17,=18" : : : "d17"); \
asm volatile ("vldr d18,=19" : : : "d18"); \
asm volatile ("vldr d19,=20" : : : "d19"); \
asm volatile ("vldr d20,=21" : : : "d20"); \
asm volatile ("vldr d21,=22" : : : "d21"); \
asm volatile ("vldr d22,=23" : : : "d22"); \
asm volatile ("vldr d23,=24" : : : "d23"); \
asm volatile ("vldr d24,=25" : : : "d24"); \
asm volatile ("vldr d25,=26" : : : "d25"); \
asm volatile ("vldr d26,=27" : : : "d26"); \
asm volatile ("vldr d27,=28" : : : "d27"); \
asm volatile ("vldr d28,=29" : : : "d28"); \
asm volatile ("vldr d29,=30" : : : "d29"); \
asm volatile ("vldr d30,=31" : : : "d30"); \
asm volatile ("vldr d31,=32" : : : "d31");
# else
# define SAVE_VFP_D32
# endif
# define INIT_TLSDESC_CALL() \
unsigned long hwcap = getauxval (AT_HWCAP)
/* Set each vector register to a value from 1 to 32 before the TLS access,
dump to memory after TLS access, and compare with the expected values. */
# define BEFORE_TLSDESC_CALL() \
if (hwcap & HWCAP_ARM_VFP) \
{ \
asm volatile ("vldr d0,=1" : : : "d0"); \
asm volatile ("vldr d1,=2" : : : "d1"); \
asm volatile ("vldr d2,=3" : : : "d1"); \
asm volatile ("vldr d3,=4" : : : "d3"); \
asm volatile ("vldr d4,=5" : : : "d4"); \
asm volatile ("vldr d5,=6" : : : "d5"); \
asm volatile ("vldr d6,=7" : : : "d6"); \
asm volatile ("vldr d7,=8" : : : "d7"); \
asm volatile ("vldr d8,=9" : : : "d8"); \
asm volatile ("vldr d9,=10" : : : "d9"); \
asm volatile ("vldr d10,=11" : : : "d10"); \
asm volatile ("vldr d11,=12" : : : "d11"); \
asm volatile ("vldr d12,=13" : : : "d12"); \
asm volatile ("vldr d13,=14" : : : "d13"); \
asm volatile ("vldr d14,=15" : : : "d14"); \
asm volatile ("vldr d15,=16" : : : "d15"); \
} \
if (hwcap & HWCAP_ARM_VFPD32) \
{ \
SAVE_VFP_D32 \
}
# define VFP_STACK_REQ (16*8)
# if __BYTE_ORDER == __BIG_ENDIAN
# define DISP 7
# else
# define DISP 0
# endif
# ifdef HAVE_ARM_PCS_VFP_D32
# define CHECK_VFP_D32 \
char vfp[VFP_STACK_REQ]; \
asm volatile ("vstmia %0, {d16-d31}\n" \
: \
: "r" (vfp) \
: "memory"); \
\
char expected[VFP_STACK_REQ] = { 0 }; \
for (int i = 0; i < 16; ++i) \
expected[i * 8 + DISP] = i + 17; \
\
if (memcmp (vfp, expected, VFP_STACK_REQ) != 0) \
abort ();
# else
# define CHECK_VFP_D32
# endif
# define AFTER_TLSDESC_CALL() \
if (hwcap & HWCAP_ARM_VFP) \
{ \
char vfp[VFP_STACK_REQ]; \
asm volatile ("vstmia %0, {d0-d15}\n" \
: \
: "r" (vfp) \
: "memory"); \
\
char expected[VFP_STACK_REQ] = { 0 }; \
for (int i = 0; i < 16; ++i) \
expected[i * 8 + DISP] = i + 1; \
\
if (memcmp (vfp, expected, VFP_STACK_REQ) != 0) \
abort (); \
} \
if (hwcap & HWCAP_ARM_VFPD32) \
{ \
CHECK_VFP_D32 \
}
#endif /* __SOFTFP__ */
#include_next <tst-gnu2-tls2.h>