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authorH.J. Lu <hjl.tools@gmail.com>2018-07-24 07:55:35 -0700
committerH.J. Lu <hjl.tools@gmail.com>2018-07-24 07:55:47 -0700
commite27f41ba2b6101be1a511905bff5502ffd23828b (patch)
treef7bd74631da12cc22e2dc5f6556a9ea2b45de5f0 /misc/sys
parent21526a507df8f1b2e37492193a754534d8938c0b (diff)
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Add <bits/indirect-return.h>
Add <bits/indirect-return.h> and include it in <ucontext.h>. __INDIRECT_RETURN defined in <bits/indirect-return.h> 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 <carlos@redhat.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.
Diffstat (limited to 'misc/sys')
-rw-r--r--misc/sys/cdefs.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index e80a45c..3f6fe3c 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))