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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 /stdlib
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 'stdlib')
-rw-r--r--stdlib/Makefile2
-rw-r--r--stdlib/ucontext.h6
2 files changed, 6 insertions, 2 deletions
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