diff options
| -rw-r--r-- | ChangeLog | 11 | ||||
| -rw-r--r-- | bits/indirect-return.h | 25 | ||||
| -rw-r--r-- | misc/sys/cdefs.h | 6 | ||||
| -rw-r--r-- | stdlib/Makefile | 2 | ||||
| -rw-r--r-- | stdlib/ucontext.h | 6 | ||||
| -rw-r--r-- | string/tst-xbzero-opt.c | 10 | ||||
| -rw-r--r-- | sysdeps/x86/bits/indirect-return.h | 37 |
7 files changed, 94 insertions, 3 deletions
diff --git a/ChangeLog b/ChangeLog index cb01527111..8707c9c686 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,14 @@ +2018-07-24 H.J. Lu <hongjiu.lu@intel.com> + + * bits/indirect-return.h: New file. + * misc/sys/cdefs.h (__glibc_has_attribute): New. + * sysdeps/x86/bits/indirect-return.h: Likewise. + * stdlib/Makefile (headers): Add bits/indirect-return.h. + * stdlib/ucontext.h: Include <bits/indirect-return.h>. + (swapcontext): Add __INDIRECT_RETURN. + * string/tst-xbzero-opt.c (ALWAYS_INLINE): New. + (prepare_test_buffer): Use it. + 2018-07-24 Andreas Schwab <schwab@suse.de> [BZ #23448] diff --git a/bits/indirect-return.h b/bits/indirect-return.h new file mode 100644 index 0000000000..47f6f15a6e --- /dev/null +++ b/bits/indirect-return.h @@ -0,0 +1,25 @@ +/* Definition of __INDIRECT_RETURN. Generic version. + Copyright (C) 2018 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 + <http://www.gnu.org/licenses/>. */ + +#ifndef _UCONTEXT_H +# error "Never include <bits/indirect-return.h> directly; use <ucontext.h> instead." +#endif + +/* __INDIRECT_RETURN is used on swapcontext to indicate if it requires + special compiler treatment. */ +#define __INDIRECT_RETURN diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h index e80a45ca68..3f6fe3cc85 100644 --- a/misc/sys/cdefs.h +++ b/misc/sys/cdefs.h @@ -406,6 +406,12 @@ # define __glibc_likely(cond) (cond) #endif +#ifdef __has_attribute +# define __glibc_has_attribute(attr) __has_attribute (attr) +#else +# define __glibc_has_attribute(attr) 0 +#endif + #if (!defined _Noreturn \ && (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) < 201112 \ && !__GNUC_PREREQ (4,7)) diff --git a/stdlib/Makefile b/stdlib/Makefile index 808a8ceab7..b5e55b0a55 100644 --- a/stdlib/Makefile +++ b/stdlib/Makefile @@ -26,7 +26,7 @@ headers := stdlib.h bits/stdlib.h bits/stdlib-ldbl.h bits/stdlib-float.h \ monetary.h bits/monetary-ldbl.h \ inttypes.h stdint.h bits/wordsize.h \ errno.h sys/errno.h bits/errno.h bits/types/error_t.h \ - ucontext.h sys/ucontext.h \ + ucontext.h sys/ucontext.h bits/indirect-return.h \ alloca.h fmtmsg.h \ bits/stdlib-bsearch.h sys/random.h bits/stdint-intn.h \ bits/stdint-uintn.h diff --git a/stdlib/ucontext.h b/stdlib/ucontext.h index eec7611631..ec630038f6 100644 --- a/stdlib/ucontext.h +++ b/stdlib/ucontext.h @@ -22,6 +22,9 @@ #include <features.h> +/* Get definition of __INDIRECT_RETURN. */ +#include <bits/indirect-return.h> + /* Get machine dependent definition of data structures. */ #include <sys/ucontext.h> @@ -36,7 +39,8 @@ extern int setcontext (const ucontext_t *__ucp) __THROWNL; /* Save current context in context variable pointed to by OUCP and set context from variable pointed to by UCP. */ extern int swapcontext (ucontext_t *__restrict __oucp, - const ucontext_t *__restrict __ucp) __THROWNL; + const ucontext_t *__restrict __ucp) + __THROWNL __INDIRECT_RETURN; /* Manipulate user context UCP to continue with calling functions FUNC and the ARGC-1 parameters following ARGC when the context is used diff --git a/string/tst-xbzero-opt.c b/string/tst-xbzero-opt.c index cf7041f37a..aab4a7f715 100644 --- a/string/tst-xbzero-opt.c +++ b/string/tst-xbzero-opt.c @@ -100,7 +100,15 @@ static ucontext_t uc_main, uc_co; /* Always check the test buffer immediately after filling it; this makes externally visible side effects depend on the buffer existing and having been filled in. */ -static inline __attribute__ ((always_inline)) void +#if defined __CET__ && !__glibc_has_attribute (__indirect_return__) +/* Note: swapcontext returns via indirect branch when SHSTK is enabled. + Without indirect_return attribute, swapcontext is marked with + returns_twice attribute, which prevents always_inline to work. */ +# define ALWAYS_INLINE +#else +# define ALWAYS_INLINE __attribute__ ((always_inline)) +#endif +static inline ALWAYS_INLINE void prepare_test_buffer (unsigned char *buf) { for (unsigned int i = 0; i < PATTERN_REPS; i++) diff --git a/sysdeps/x86/bits/indirect-return.h b/sysdeps/x86/bits/indirect-return.h new file mode 100644 index 0000000000..d1acaca3b9 --- /dev/null +++ b/sysdeps/x86/bits/indirect-return.h @@ -0,0 +1,37 @@ +/* Definition of __INDIRECT_RETURN. x86 version. + Copyright (C) 2018 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 + <http://www.gnu.org/licenses/>. */ + +#ifndef _UCONTEXT_H +# error "Never include <bits/indirect-return.h> directly; use <ucontext.h> instead." +#endif + +/* On x86, swapcontext returns via indirect branch when the shadow stack + is enabled. Define __INDIRECT_RETURN to indicate whether swapcontext + returns via indirect branch. */ +#if defined __CET__ && (__CET__ & 2) != 0 +# if __glibc_has_attribute (__indirect_return__) +# define __INDIRECT_RETURN __attribute__ ((__indirect_return__)) +# else +/* Newer compilers provide the indirect_return attribute, but without + it we can use returns_twice to affect the optimizer in the same + way and avoid unsafe optimizations. */ +# define __INDIRECT_RETURN __attribute__ ((__returns_twice__)) +# endif +#else +# define __INDIRECT_RETURN +#endif |