[glibc/arm/morello/main] aarch64: morello: elf: Return bounded pointer in __tls_get_addr

[glibc/arm/morello/main] aarch64: morello: elf: Return bounded pointer in __tls_get_addr

[Szabolcs Nagy]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f0e8f3667c16f9ba09a67c1768656a44e73488d4

commit f0e8f3667c16f9ba09a67c1768656a44e73488d4
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Sep 7 14:17:46 2022 +0100

    aarch64: morello: elf: Return bounded pointer in __tls_get_addr
    
    There is no traditional TLS support in morello that would explicitly
    call __tls_get_addr, but the libc uses it internally and the returned
    pointer escapes to user code.  So bound the pointers according to
    the tls symbol size instead of doing so in each caller.
    
    (Affects dlsym and dynamic TLSDESC.)

Diff:
---
 elf/dl-sym.c                         |  4 ++++
 sysdeps/aarch64/morello/dl-tls.c     | 39 ++++++++++++++++++++++++++++++++++++
 sysdeps/aarch64/morello/dl-tls.h     | 26 ++++++++++++++++++++++++
 sysdeps/aarch64/morello/dl-tlsdesc.S |  9 ---------
 4 files changed, 69 insertions(+), 9 deletions(-)

diff --git a/elf/dl-sym.c b/elf/dl-sym.c
index b1cf42f36d..cd7df7e6c7 100644
--- a/elf/dl-sym.c
+++ b/elf/dl-sym.c
@@ -49,6 +49,10 @@ _dl_tls_symaddr (struct link_map *map, const ElfW(Sym) *ref)
     {
       .ti_module = map->l_tls_modid,
       .ti_offset = ref->st_value
+#  ifdef __CHERI_PURE_CAPABILITY__
+	,
+      .ti_size = ref->st_size
+#  endif
     };
 
   return __TLS_GET_ADDR (&tmp);
diff --git a/sysdeps/aarch64/morello/dl-tls.c b/sysdeps/aarch64/morello/dl-tls.c
new file mode 100644
index 0000000000..6fadfe2350
--- /dev/null
+++ b/sysdeps/aarch64/morello/dl-tls.c
@@ -0,0 +1,39 @@
+/* Thread-local storage handling in the ELF dynamic linker.  Morello version.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifdef SHARED
+/* Add a wrapper around the generic __tls_get_addr code to set the
+   bounds on the returned pointer.  */
+
+# define __tls_get_addr __tls_get_addr_unbounded
+# include <elf/dl-tls.c>
+# undef __tls_get_addr
+
+void *__tls_get_addr (tls_index *ti);
+rtld_hidden_proto (__tls_get_addr)
+rtld_hidden_def (__tls_get_addr)
+
+void *
+__tls_get_addr (tls_index *ti)
+{
+  void *p = __tls_get_addr_unbounded (ti);
+  return __builtin_cheri_bounds_set_exact (p, ti->ti_size);
+}
+#else
+# include <elf/dl-tls.c>
+#endif
diff --git a/sysdeps/aarch64/morello/dl-tls.h b/sysdeps/aarch64/morello/dl-tls.h
new file mode 100644
index 0000000000..f47f89ca64
--- /dev/null
+++ b/sysdeps/aarch64/morello/dl-tls.h
@@ -0,0 +1,26 @@
+/* Copyright (C) 2022 Free Software Foundation, Inc.
+
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+typedef struct
+{
+  unsigned long int ti_module;
+  unsigned long int ti_offset;
+  unsigned long int ti_size;
+} tls_index;
+
+extern void *__tls_get_addr (tls_index *ti);
diff --git a/sysdeps/aarch64/morello/dl-tlsdesc.S b/sysdeps/aarch64/morello/dl-tlsdesc.S
index 6fced53734..d11f5d5fa7 100644
--- a/sysdeps/aarch64/morello/dl-tlsdesc.S
+++ b/sysdeps/aarch64/morello/dl-tlsdesc.S
@@ -193,18 +193,9 @@ _dl_tlsdesc_dynamic:
 
 	SAVE_Q_REGISTERS
 
-	/* TODO: remove once __tls_get_addr is fixed.  */
-	str	c1, [csp, #32*8]
-
 	mov	c0, c1
 	bl	__tls_get_addr
 
-	/* TODO: __tls_get_addr should return bounded pointer,
-	   currently it does not so bound it here.  */
-	ldr	c1, [csp, #32*8]
-	ldr	x3, [c1, #TLSDESC_SIZE]
-	scbndse	c0, c0, x3
-
 	mrs	c2, ctpidr_el0 /* Restore c2.  */
 
 	RESTORE_Q_REGISTERS