===================================================================
@@ -43,4 +43,9 @@
} \
while (0)
+#ifdef TARGET_LIBC_PROVIDES_TLS_SSP
+/* Aarch64 glibc provides __stack_chk_guard in [tp - 0x8]. */
+#define TARGET_THREAD_SSP_OFFSET (-1 * GET_MODE_SIZE (ptr_mode))
+#endif
+
#endif /* GCC_AARCH64_LINUX_H */
===================================================================
@@ -99,6 +99,10 @@
UNSPEC_TLSDESC
UNSPEC_USHL_2S
UNSPEC_VSTRUCTDUMMY
+ UNSPEC_SP_SET
+ UNSPEC_SP_TEST
+ UNSPEC_SP_TLS_SET
+ UNSPEC_SP_TLS_TEST
])
(define_c_enum "unspecv" [
@@ -3625,6 +3629,80 @@
DONE;
})
+
+;; Named patterns for stack smashing protection.
+(define_expand "stack_protect_set"
+ [(match_operand 0 "memory_operand")
+ (match_operand 1 "memory_operand")]
+ ""
+{
+ enum machine_mode mode = GET_MODE (operands[0]);
+
+#ifdef TARGET_THREAD_SSP_OFFSET
+ rtx tlsreg = gen_reg_rtx (Pmode);
+ emit_insn (gen_aarch64_load_tp_hard (tlsreg));
+ rtx addr = gen_rtx_PLUS (Pmode, tlsreg, GEN_INT (TARGET_THREAD_SSP_OFFSET));
+ operands[1] = gen_rtx_MEM (Pmode, addr);
+#endif
+
+ emit_insn ((mode == DImode
+ ? gen_stack_protect_set_di
+ : gen_stack_protect_set_si) (operands[0], operands[1]));
+ DONE;
+})
+
+(define_insn "stack_protect_set_<mode>"
+ [(set (match_operand:PTR 0 "memory_operand" "=m")
+ (unspec:PTR [(match_operand:PTR 1 "memory_operand" "m")]
+ UNSPEC_SP_SET))
+ (set (match_scratch:PTR 2 "=&r") (const_int 0))]
+ ""
+ "ldr\\t%x2, %1\;str\\t%x2, %0\;mov\t%x2,0"
+ [(set_attr "length" "12")])
+
+(define_expand "stack_protect_test"
+ [(match_operand 0 "memory_operand")
+ (match_operand 1 "memory_operand")
+ (match_operand 2)]
+ ""
+{
+
+#ifdef TARGET_THREAD_SSP_OFFSET
+ rtx tlsreg = gen_reg_rtx (Pmode);
+ emit_insn (gen_aarch64_load_tp_hard (tlsreg));
+ rtx addr = gen_rtx_PLUS (Pmode, tlsreg, GEN_INT (TARGET_THREAD_SSP_OFFSET));
+ operands[1] = gen_rtx_MEM (Pmode, addr);
+#endif
+
+ rtx result = gen_reg_rtx (Pmode);
+
+ enum machine_mode mode = GET_MODE (operands[0]);
+
+ emit_insn ((mode == DImode
+ ? gen_stack_protect_test_di
+ : gen_stack_protect_test_si) (result,
+ operands[0],
+ operands[1]));
+
+ if (mode == DImode)
+ emit_jump_insn (gen_cbranchdi4 (gen_rtx_EQ (VOIDmode, result, const0_rtx),
+ result, const0_rtx, operands[2]));
+ else
+ emit_jump_insn (gen_cbranchsi4 (gen_rtx_EQ (VOIDmode, result, const0_rtx),
+ result, const0_rtx, operands[2]));
+ DONE;
+})
+
+(define_insn "stack_protect_test_<mode>"
+ [(set (match_operand:PTR 0 "register_operand")
+ (unspec:PTR [(match_operand:PTR 1 "memory_operand" "m")
+ (match_operand:PTR 2 "memory_operand" "m")]
+ UNSPEC_SP_TEST))
+ (clobber (match_scratch:PTR 3 "=&r"))]
+ ""
+ "ldr\t%x3, %x1\;ldr\t%x0, %x2\;eor\t%x0, %x3, %x0"
+ [(set_attr "length" "12")])
+
;; AdvSIMD Stuff
(include "aarch64-simd.md")
===================================================================
@@ -27127,6 +27127,35 @@
fi
+# Test for tls based stack protector support in target C library.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking TLS stack guard support in target C library" >&5
+$as_echo_n "checking TLS stack guard support in target C library... " >&6; }
+if test "${gcc_cv_libc_provides_tls_ssp+set}" = set; then :
+ $as_echo_n "(cached) " >&6
+else
+ gcc_cv_libc_provides_tls_ssp=no
+ case "$target" in
+ aarch64-*-linux* | aarch64-*-kfreebsd*-gnu | aarch64-*-knetbsd*-gnu)
+ # glibc 2.19 and later provides TLS access to stack guard canary
+ # currently set for Aarch64.
+
+if test $glibc_version_major -gt 2 \
+ || ( test $glibc_version_major -eq 2 && test $glibc_version_minor -ge 19 ); then :
+ gcc_cv_libc_provides_tls_ssp=yes
+fi
+ ;;
+ *) gcc_cv_libc_provides_tls_ssp=no ;;
+ esac
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_libc_provides_tls_ssp" >&5
+$as_echo "$gcc_cv_libc_provides_tls_ssp" >&6; }
+
+if test x$gcc_cv_libc_provides_tls_ssp = xyes; then
+
+$as_echo "#define TARGET_LIBC_PROVIDES_TLS_SSP 1" >>confdefs.h
+
+fi
+
# Test for <sys/sdt.h> on the target.
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking sys/sdt.h in the target C library" >&5
===================================================================
@@ -1,6 +1,6 @@
/* Test that stack protection is done on chosen functions. */
-/* { dg-do compile { target i?86-*-* x86_64-*-* rs6000-*-* s390x-*-* } } */
+/* { dg-do compile { target i?86-*-* x86_64-*-* rs6000-*-* s390x-*-* aarch64-*-* } } */
/* { dg-options "-O2 -fstack-protector-strong" } */
#include<string.h>
===================================================================
@@ -1,6 +1,6 @@
/* Test that stack protection is done on chosen functions. */
-/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-do compile { target i?86-*-* x86_64-*-* aarch64*-*-* } } */
/* { dg-options "-O2 -fstack-protector-strong" } */
class A
===================================================================
@@ -1828,6 +1828,12 @@
#endif
+/* Define if your target C library provides TLS stack protector support. */
+#ifndef USED_FOR_TARGET
+#undef TARGET_LIBC_PROVIDES_TLS_SSP
+#endif
+
+
/* Define to 1 if you can safely include both <sys/time.h> and <time.h>. */
#ifndef USED_FOR_TARGET
#undef TIME_WITH_SYS_TIME
===================================================================
@@ -4896,6 +4896,24 @@
[Define if your target C library provides stack protector support])
fi
+# Test for tls based stack protector support in target C library.
+AC_CACHE_CHECK(TLS stack guard support in target C library,
+ gcc_cv_libc_provides_tls_ssp,
+ [gcc_cv_libc_provides_tls_ssp=no
+ case "$target" in
+ aarch64-*-linux* | aarch64-*-kfreebsd*-gnu | aarch64-*-knetbsd*-gnu)
+ # glibc 2.19 and later provides TLS access to stack guard canary
+ # currently set for Aarch64.
+ GCC_GLIBC_VERSION_GTE_IFELSE([2], [19], [gcc_cv_libc_provides_tls_ssp=yes])
+ ;;
+ *) gcc_cv_libc_provides_tls_ssp=no ;;
+ esac])
+
+if test x$gcc_cv_libc_provides_tls_ssp = xyes; then
+ AC_DEFINE(TARGET_LIBC_PROVIDES_TLS_SSP, 1,
+ [Define if your target C library provides TLS stack protector support.])
+fi
+
# Test for <sys/sdt.h> on the target.
GCC_TARGET_TEMPLATE([HAVE_SYS_SDT_H])
AC_MSG_CHECKING(sys/sdt.h in the target C library)
Hi Joseph/Jakub, Attached is Version 2 patch that adds machine descriptions for stack protection in Aarch64. I have removed the incorrect test case changes from the previous patch. To make GCC compatible with glibc, I have added a test for aarch64 in "GCC/configure". This tests for the glibc version >= 2.19, generate TLS based stack guard access, otherwise will fall back to global variable __stack_chk_guard based access. Also I will be submitting a glibc patch to export __stack_chk_guard and initialize it with proper value, to make sure that it coexists with TLS based stack guard access for aarch64. I have posted code snippet here. http://gcc.gnu.org/ml/gcc-patches/2013-11/msg02968.html ChangeLog: 2013-11-26 Venkataramanan Kumar <venkataramanan.kumar@linaro.org> * configure.ac (gcc_cv_libc_provides_tls_ssp): Add test to check TLS support in target C library for Aarch64. * configure: Regenerate. * config.in: Regenerate. * config/aarch64/aarch64.md (stack_protect_set, stack_protect_test) (stack_protect_set_<mode>, stack_protect_test_<mode>): Add initial machine description for Stack Smashing Protector. * config/aarch64/aarch64-linux.h (TARGET_THREAD_SSP_OFFSET): Define. 2013-11-26 Venkataramanan Kumar <venkataramanan.kumar@linaro.org> * g++.dg/fstack-protector-strong.C: Add aarch64 target. * gcc.dg/fstack-protector-strong.c: Likewise. Let me know your feed back and please advice on improving it further. regards, Venkat. On 23 November 2013 09:32, Venkataramanan Kumar <venkataramanan.kumar@linaro.org> wrote: > Hi Joseph, > > Thank you for the detail explanation. > >> You need to ensure that, when new glibc is built, whatever compiler it's >> built with, it continues to export the __stack_chk_guard symbol at version >> GLIBC_2.17. Furthermore, if any released GCC version would generate >> references to __stack_chk_guard when compiling code for AArch64 with stack >> protection, you need to ensure __stack_chk_guard is a normal symbol not a >> compat symbol so that people can continue to link against new glibc when >> using old GCC. If it's only a limited range of development versions of >> GCC that could have generated code using __stack_chk_guard because >> released versions didn't support stack protection on AArch64 at all, a >> compat symbol would probably be OK (but you should still ensure that the >> variable gets initialized with the correct value for any applications >> built with those development versions of GCC). > > As you said when THREAD_SET_STACK_GUARD is set glibc does not export > __stack_chk_guard. So I am planning to change the export logic by > adding a new macro EXPORT_GLOBAL_STACK_GUARD > and set it for Aarch64 port in glibc. > > ----snip---- > --- a/csu/libc-start.c > +++ b/csu/libc-start.c > -# ifndef THREAD_SET_STACK_GUARD > + > +#if !defined(THREAD_SET_STACK_GUARD) || defined(EXPORT_GLOBAL_STACK_GUARD) > /* Only exported for architectures that don't store the stack guard canary > in thread local area. */ > uintptr_t __stack_chk_guard attribute_relro; > -# endif > +#endif > + > ----snip---- > > I will find a better way to version that symbol as well. I will sent a > RFC patch to glibc mailing list. > > On the GCC side, trunk GCC configure script checks and sets > TARGET_LIBC_PROVIDES_SSP support when glibc is >=2.4 > > -----snip---- > # Test for stack protector support in target C library. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking __stack_chk_fail in > target C library" >&5 > $as_echo_n "checking __stack_chk_fail in target C library... " >&6; } > if test "${gcc_cv_libc_provides_ssp+set}" = set; then : > $as_echo_n "(cached) " >&6 > else > gcc_cv_libc_provides_ssp=no > case "$target" in > *-*-linux* | *-*-kfreebsd*-gnu | *-*-knetbsd*-gnu) > # glibc 2.4 and later provides __stack_chk_fail and > # either __stack_chk_guard, or TLS access to stack guard canary. > > if test $glibc_version_major -gt 2 \ > || ( test $glibc_version_major -eq 2 && test $glibc_version_minor > -ge 4 ); then : > gcc_cv_libc_provides_ssp=yes > > > if test x$gcc_cv_libc_provides_ssp = xyes; then > > $as_echo "#define TARGET_LIBC_PROVIDES_SSP 1" >>confdefs.h > fi > ----snip----- > > To make GCC for AArch64 generate TLS based stack access for glibc >= > 2.19 I need to introduce a new macro > TARGET_LIBC_PROVIDES_TLS_SSP and check and set it for glibc >= 2.19 in > GCC configure . > > Any better approach to this since it is specific to Aarch64? > > regards, > Venkat. > > On 20 November 2013 22:38, Joseph S. Myers <joseph@codesourcery.com> wrote: >> On Wed, 20 Nov 2013, Venkataramanan Kumar wrote: >> >>> > I would like to see a clear description of what happens with all eight >>> > combinations of (glibc version does or doesn't support this, GCC building >>> > glibc does or doesn't support this, GCC building user program does or >>> > doesn't support this). Which of the (GCC building glibc, glibc) >>> > combinations will successfully build glibc? Will all such glibcs be >>> > binary-compatible? Will both old and new GCC work for building user >>> > programs with both old and new glibc? >>> >>> Can you please clarify why we need to consider "the gcc compiler that >>> builds the glibc" in the combinations you want me to describe. I am >>> not able to understand that. >> >> Let's imagine this support goes in GCC 4.9 and the glibc support goes in >> glibc 2.19, whereas GCC 4.8 and glibc 2.18 are versions without this >> support. >> >> * Building glibc 2.18 with GCC 4.8 already works (I presume). >> >> * Suppose you use GCC 4.9 to build glibc 2.18. Does this work? If it >> works, it must produce a glibc binary that's ABI compatible with one built >> with GCC 4.8, meaning same symbols exported at same symbol versions. >> >> * Suppose you build glibc 2.19 with GCC 4.8. Does this work? If it does, >> then it must be ABI compatible with 2.18 (meaning the symbols exported at >> GLIBC_2.18 or earlier versions must be exactly the same as exported at >> those versions in 2.18). >> >> * Suppose you build glibc 2.19 with GCC 4.9. This needs to work and must >> again produce a binary compatible with the previous ones. >> >> Note: there is no current glibc support for architectures that gained >> TLS-based stack guards after 2.4 (meaning they need both a TLS-based >> scheme and backwards compatibility for binaries using __stack_chk_guard), >> and your glibc patch doesn't seem to add any. It looks to me like your >> glibc patch would have removed the __stack_chk_guard symbol and so failed >> ABI tests (this symbol being defined only if THREAD_SET_STACK_GUARD isn't >> defined) - you didn't make clear if your patch was tested with the glibc >> testsuite including passing the ABI tests. The normal presumption is that >> it's not acceptable to remove exported symbols from glibc as some >> application might be using them. >> >> You need to ensure that, when new glibc is built, whatever compiler it's >> built with, it continues to export the __stack_chk_guard symbol at version >> GLIBC_2.17. Furthermore, if any released GCC version would generate >> references to __stack_chk_guard when compiling code for AArch64 with stack >> protection, you need to ensure __stack_chk_guard is a normal symbol not a >> compat symbol so that people can continue to link against new glibc when >> using old GCC. If it's only a limited range of development versions of >> GCC that could have generated code using __stack_chk_guard because >> released versions didn't support stack protection on AArch64 at all, a >> compat symbol would probably be OK (but you should still ensure that the >> variable gets initialized with the correct value for any applications >> built with those development versions of GCC). >> >> -- >> Joseph S. Myers >> joseph@codesourcery.com