From e27f41ba2b6101be1a511905bff5502ffd23828b Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Tue, 24 Jul 2018 07:55:35 -0700 Subject: Add MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add and include it in . __INDIRECT_RETURN defined in indicates if swapcontext requires special compiler treatment. The default __INDIRECT_RETURN is empty. On x86, when shadow stack is enabled, __INDIRECT_RETURN is defined with indirect_return attribute, which has been added to GCC 9, to indicate that swapcontext returns via indirect branch. Otherwise __INDIRECT_RETURN is defined with returns_twice attribute. When shadow stack is enabled, remove always_inline attribute from prepare_test_buffer in string/tst-xbzero-opt.c to avoid: tst-xbzero-opt.c: In function ‘prepare_test_buffer’: tst-xbzero-opt.c:105:1: error: function ‘prepare_test_buffer’ can never be inlined because it uses setjmp prepare_test_buffer (unsigned char *buf) when indirect_return attribute isn't available. Reviewed-by: Carlos O'Donell * 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 . (swapcontext): Add __INDIRECT_RETURN. * string/tst-xbzero-opt.c (ALWAYS_INLINE): New. (prepare_test_buffer): Use it. --- stdlib/ucontext.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'stdlib/ucontext.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 +/* Get definition of __INDIRECT_RETURN. */ +#include + /* Get machine dependent definition of data structures. */ #include @@ -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 -- cgit 1.4.1