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authorChristophe Lyon <christophe.lyon@st.com>2018-07-04 15:55:23 (GMT)
committerWaldemar Brodkorb <wbrodkorb@conet.de>2018-08-10 14:02:23 (GMT)
commit99dfb1e26f784429e23f2e67eef5bbbc6e646b83 (patch)
tree32a01b6e85cf0289648a7ad091dde8bc4a2e68a9
parentae80d12e5f55ad491d1f1e6fe094bc291d908903 (diff)
Allow to generate PIE 'static' binary
* libc/misc/internals/__uClibc_main.c (funcdesc_value): New. (fdpic_init_array_jump): New. (__uClibc_fini): Support __FDPIC__. (__uClibc_main): Likewise. Signed-off-by: Mickaël Guêné <mickael.guene@st.com> Signed-off-by: Christophe Lyon <christophe.lyon@st.com>
-rw-r--r--libc/misc/internals/__uClibc_main.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/libc/misc/internals/__uClibc_main.c b/libc/misc/internals/__uClibc_main.c
index d80565e..d8286f2 100644
--- a/libc/misc/internals/__uClibc_main.c
+++ b/libc/misc/internals/__uClibc_main.c
@@ -48,6 +48,39 @@
int _pe_secure = 0;
libc_hidden_data_def(_pe_secure)
+#if !defined(SHARED) && defined(__FDPIC__)
+struct funcdesc_value
+{
+ void *entry_point;
+ void *got_value;
+} __attribute__((__aligned__(8)));
+
+
+/* Prevent compiler optimization that removes GOT assignment.
+
+ Due to optimization passes (block split and move), in the rare case
+ where use r9 is the single instruction in a block we can have the
+ following behaviour:
+ - this block is marked as a forward block since use is not
+ considered as an active instruction after reload pass.
+
+ - In this case a jump in this block can be moved to the start of the
+ next one and so remove use in this flow of instructions which can
+ lead to a removal of r9 restoration after a call. */
+#define _dl_stabilize_funcdesc(val) \
+ ({ __asm__ ("" : "+m" (*(val))); (val); })
+
+static void fdpic_init_array_jump(void *addr)
+{
+ struct funcdesc_value *fm = (struct funcdesc_value *) fdpic_init_array_jump;
+ struct funcdesc_value fd = {addr, fm->got_value};
+
+ void (*pf)(void) = (void*) _dl_stabilize_funcdesc(&fd);
+
+ (*pf)();
+}
+#endif
+
#ifndef SHARED
void *__libc_stack_end = NULL;
@@ -307,7 +340,11 @@ void __uClibc_fini(void)
# elif !defined (__UCLIBC_FORMAT_SHARED_FLAT__)
size_t i = __fini_array_end - __fini_array_start;
while (i-- > 0)
+#if !defined(SHARED) && defined(__FDPIC__)
+ fdpic_init_array_jump(__fini_array_start[i]);
+#else
(*__fini_array_start [i]) ();
+#endif
# endif
if (__app_fini != NULL)
(__app_fini)();
@@ -436,7 +473,11 @@ void __uClibc_main(int (*main)(int, char **, char **), int argc,
const size_t size = __preinit_array_end - __preinit_array_start;
size_t i;
for (i = 0; i < size; i++)
+#if !defined(SHARED) && defined(__FDPIC__)
+ fdpic_init_array_jump(__preinit_array_start[i]);
+#else
(*__preinit_array_start [i]) ();
+#endif
}
# endif
/* Run all the application's ctors now. */
@@ -452,7 +493,11 @@ void __uClibc_main(int (*main)(int, char **, char **), int argc,
const size_t size = __init_array_end - __init_array_start;
size_t i;
for (i = 0; i < size; i++)
+#if !defined(SHARED) && defined(__FDPIC__)
+ fdpic_init_array_jump(__init_array_start[i]);
+#else
(*__init_array_start [i]) ();
+#endif
}
# endif
#endif