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[uclibc-ng-devel,21/32,ARM,FDPIC] nptl: Use linker-defined symbol to find start of .tdata section.

Message ID 20180704155605.1892-22-christophe.lyon@st.com
State Accepted
Headers show
Series FDPIC ABI for ARM | expand

Commit Message

Christophe Lyon July 4, 2018, 3:55 p.m. UTC 
phdr->p_vaddr of TLS segment is not a valid value for FDPIC so we can
either translate phdr->p_vaddr using loadmap (not easy here) or use a
new linker script defined symbol, whih this patch does.

	* libpthread/nptl/sysdeps/generic/libc-tls.c (__tdata_start): Declare.
	(__libc_setup_tls): Support __FDPIC__.

Signed-off-by: Mickaël Guêné <mickael.guene@st.com>
Signed-off-by: Christophe Lyon <christophe.lyon@st.com>
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Patch

diff --git a/libpthread/nptl/sysdeps/generic/libc-tls.c b/libpthread/nptl/sysdeps/generic/libc-tls.c
index 58e77ff..725f3df 100644
--- a/libpthread/nptl/sysdeps/generic/libc-tls.c
+++ b/libpthread/nptl/sysdeps/generic/libc-tls.c
@@ -36,6 +36,11 @@ 
 extern ElfW(Phdr) *_dl_phdr;
 extern size_t _dl_phnum;
 
+#ifdef __FDPIC__
+/* phdr->p_vaddr is not valid in FDPIC mode. To find tdata start we
+   use the linker script defined symbol __tdata_start.  */
+extern int __tdata_start;
+#endif
 
 static dtv_t static_dtv[2 + TLS_SLOTINFO_SURPLUS];
 
@@ -130,7 +135,11 @@  __libc_setup_tls (size_t tcbsize, size_t tcbalign)
 	  /* Remember the values we need.  */
 	  memsz = phdr->p_memsz;
 	  filesz = phdr->p_filesz;
+#ifdef __FDPIC__
+	  initimage = (void *) &__tdata_start;
+#else
 	  initimage = (void *) phdr->p_vaddr;
+#endif
 	  align = phdr->p_align;
 	  if (phdr->p_align > max_align)
 	    max_align = phdr->p_align;