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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 /string
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 'string')
-rw-r--r--string/tst-xbzero-opt.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/string/tst-xbzero-opt.c b/string/tst-xbzero-opt.c
index cf7041f37a1..aab4a7f715b 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++)