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[PATCH] ARM: Add pointer guard support.
- From: Will Newton <will dot newton at linaro dot org>
- To: libc-ports at sourceware dot org
- Cc: patches at linaro dot org
- Date: Wed, 25 Sep 2013 10:06:37 +0100
- Subject: [PATCH] ARM: Add pointer guard support.
- Authentication-results: sourceware.org; auth=none
Add support for pointer mangling in glibc internal structures in C
and assembler code.
Tested on armv7 with hard and soft thread pointers.
ports/ChangeLog.arm:
2013-09-24 Will Newton <will.newton@linaro.org>
* sysdeps/arm/__longjmp.S (__longjmp): Demangle fp, sp
and lr when restoring register values.
* sysdeps/arm/include/bits/setjmp.h (JMP_BUF_REGLIST): Remove
sp and lr from list and replace fp with a4.
* sysdeps/arm/jmpbuf-unwind.h (_jmpbuf_sp): New function.
(_JMPBUF_UNWINDS_ADJ): Call _jmpbuf_sp.
* sysdeps/arm/nptl/tcb-offsets.sym: Add POINTER_GUARD.
* sysdeps/arm/nptl/tls.h (tcbhead_t): Remove private and add
pointer_guard. (THREAD_GET_POINTER_GUARD): New macro.
(THREAD_SET_POINTER_GUARD): New macro.
(THREAD_COPY_POINTER_GUARD): New macro.
* sysdeps/arm/setjmp.S (__sigsetjmp): Mangle fp, sp and lr
before storing register values.
* sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE): New macro.
(PTR_DEMANGLE): Likewise. (PTR_MANGLE2): Likewise.
(PTR_DEMANGLE2): Likewise.
---
ports/sysdeps/arm/__longjmp.S | 14 ++++++++++++++
ports/sysdeps/arm/include/bits/setjmp.h | 5 +++--
ports/sysdeps/arm/jmpbuf-unwind.h | 13 ++++++++++++-
ports/sysdeps/arm/nptl/tcb-offsets.sym | 2 ++
ports/sysdeps/arm/nptl/tls.h | 10 +++++++++-
ports/sysdeps/arm/setjmp.S | 14 ++++++++++++++
ports/sysdeps/unix/sysv/linux/arm/sysdep.h | 22 +++++++++++++++++++---
7 files changed, 73 insertions(+), 7 deletions(-)
diff --git a/ports/sysdeps/arm/__longjmp.S b/ports/sysdeps/arm/__longjmp.S
index a5edede..2b1f7f4 100644
--- a/ports/sysdeps/arm/__longjmp.S
+++ b/ports/sysdeps/arm/__longjmp.S
@@ -34,10 +34,24 @@ ENTRY (__longjmp)
sfi_breg ip, \
ldr r4, [\B, #32] /* jmpbuf's sp */
cfi_undefined (r4)
+#ifdef PTR_DEMANGLE
+ PTR_DEMANGLE (r4, r4, a3, a4)
+#endif
CHECK_SP (r4)
#endif
sfi_sp sfi_breg ip, \
ldmia \B!, JMP_BUF_REGLIST
+#ifdef PTR_DEMANGLE
+ PTR_DEMANGLE (fp, a4, a3, a2)
+ ldr a4, [ip], #4
+ PTR_DEMANGLE2 (sp, a4, a3)
+ ldr a4, [ip], #4
+ PTR_DEMANGLE2 (lr, a4, a3)
+#else
+ mov fp, a4
+ ldr sp, [ip], #4
+ ldr lr, [ip], #4
+#endif
cfi_restore (v1)
cfi_restore (v2)
cfi_restore (v3)
diff --git a/ports/sysdeps/arm/include/bits/setjmp.h b/ports/sysdeps/arm/include/bits/setjmp.h
index 1559d7b..64505dc 100644
--- a/ports/sysdeps/arm/include/bits/setjmp.h
+++ b/ports/sysdeps/arm/include/bits/setjmp.h
@@ -26,8 +26,9 @@
#ifndef _ISOMAC
/* Register list for a ldm/stm instruction to load/store
- the general registers from a __jmp_buf. */
-# define JMP_BUF_REGLIST {v1-v6, sl, fp, sp, lr}
+ the general registers from a __jmp_buf. The a4 register
+ contains fp at this point. */
+# define JMP_BUF_REGLIST {a4, v1-v6, sl}
/* Index of __jmp_buf where the sp register resides. */
# define __JMP_BUF_SP 8
diff --git a/ports/sysdeps/arm/jmpbuf-unwind.h b/ports/sysdeps/arm/jmpbuf-unwind.h
index 0863540..1b0d020 100644
--- a/ports/sysdeps/arm/jmpbuf-unwind.h
+++ b/ports/sysdeps/arm/jmpbuf-unwind.h
@@ -17,6 +17,7 @@
#include <setjmp.h>
#include <stdint.h>
+#include <sysdep.h>
#include <unwind.h>
/* Test if longjmp to JMPBUF would unwind the frame
@@ -27,8 +28,18 @@
#define _JMPBUF_CFA_UNWINDS_ADJ(_jmpbuf, _context, _adj) \
_JMPBUF_UNWINDS_ADJ (_jmpbuf, (void *) _Unwind_GetCFA (_context), _adj)
+static inline uintptr_t __attribute__ ((unused))
+_jmpbuf_sp (__jmp_buf regs)
+{
+ uintptr_t sp = regs[__JMP_BUF_SP];
+#ifdef PTR_DEMANGLE
+ PTR_DEMANGLE (sp);
+#endif
+ return sp;
+}
+
#define _JMPBUF_UNWINDS_ADJ(_jmpbuf, _address, _adj) \
- ((uintptr_t) (_address) - (_adj) < (uintptr_t) (_jmpbuf)[__JMP_BUF_SP] - (_adj))
+ ((uintptr_t) (_address) - (_adj) < _jmpbuf_sp (_jmpbuf) - (_adj))
/* We use the normal longjmp for unwinding. */
#define __libc_unwind_longjmp(buf, val) __libc_longjmp (buf, val)
diff --git a/ports/sysdeps/arm/nptl/tcb-offsets.sym b/ports/sysdeps/arm/nptl/tcb-offsets.sym
index 92cc441..06d792f 100644
--- a/ports/sysdeps/arm/nptl/tcb-offsets.sym
+++ b/ports/sysdeps/arm/nptl/tcb-offsets.sym
@@ -9,3 +9,5 @@
MULTIPLE_THREADS_OFFSET thread_offsetof (header.multiple_threads)
PID_OFFSET thread_offsetof (pid)
TID_OFFSET thread_offsetof (tid)
+
+POINTER_GUARD offsetof (tcbhead_t, pointer_guard)
diff --git a/ports/sysdeps/arm/nptl/tls.h b/ports/sysdeps/arm/nptl/tls.h
index da15027..e855507 100644
--- a/ports/sysdeps/arm/nptl/tls.h
+++ b/ports/sysdeps/arm/nptl/tls.h
@@ -56,7 +56,7 @@ typedef union dtv
typedef struct
{
dtv_t *dtv;
- void *private;
+ uintptr_t pointer_guard;
} tcbhead_t;
/* This is the size of the initial TCB. */
@@ -119,6 +119,14 @@ typedef struct
#define THREAD_SETMEM_NC(descr, member, idx, value) \
descr->member[idx] = (value)
+/* Get/set the pointer guard field in TCB head. */
+#define THREAD_GET_POINTER_GUARD() \
+ (((tcbhead_t *) __builtin_thread_pointer ())->pointer_guard)
+#define THREAD_SET_POINTER_GUARD(value) \
+ (((tcbhead_t *) __builtin_thread_pointer ())->pointer_guard = (value))
+# define THREAD_COPY_POINTER_GUARD(descr) \
+ (((tcbhead_t *) (descr + 1))->pointer_guard = THREAD_GET_POINTER_GUARD ())
+
/* Get and set the global scope generation counter in struct pthread. */
#define THREAD_GSCOPE_FLAG_UNUSED 0
#define THREAD_GSCOPE_FLAG_USED 1
diff --git a/ports/sysdeps/arm/setjmp.S b/ports/sysdeps/arm/setjmp.S
index a6c161d..b38b919 100644
--- a/ports/sysdeps/arm/setjmp.S
+++ b/ports/sysdeps/arm/setjmp.S
@@ -24,11 +24,25 @@
#include <arm-features.h>
ENTRY (__sigsetjmp)
+#ifdef PTR_MANGLE
+ PTR_MANGLE (a4, fp, a3, ip)
+#else
+ mov a4, fp
+#endif
mov ip, r0
/* Save registers */
sfi_breg ip, \
stmia \B!, JMP_BUF_REGLIST
+#ifdef PTR_MANGLE
+ PTR_MANGLE2 (a4, sp, a3)
+ str a4, [ip], #4
+ PTR_MANGLE2 (a4, lr, a3)
+ str a4, [ip], #4
+#else
+ str sp, [ip], #4
+ str lr, [ip], #4
+#endif
#if !defined ARM_ASSUME_NO_IWMMXT || defined __SOFTFP__
# define NEED_HWCAP 1
diff --git a/ports/sysdeps/unix/sysv/linux/arm/sysdep.h b/ports/sysdeps/unix/sysv/linux/arm/sysdep.h
index b195d8e..5991641 100644
--- a/ports/sysdeps/unix/sysv/linux/arm/sysdep.h
+++ b/ports/sysdeps/unix/sysv/linux/arm/sysdep.h
@@ -435,8 +435,24 @@ __local_syscall_error: \
#endif /* __ASSEMBLER__ */
-/* Pointer mangling is not yet supported for ARM. */
-#define PTR_MANGLE(var) (void) (var)
-#define PTR_DEMANGLE(var) (void) (var)
+/* Pointer mangling support. */
+#if defined NOT_IN_libc && defined IS_IN_rtld
+/* We cannot use the thread descriptor because in ld.so we use setjmp
+ earlier than the descriptor is initialized. */
+#else
+# ifdef __ASSEMBLER__
+# define PTR_MANGLE(dst, src, guard, tmp) \
+ mov tmp, r0; GET_TLS (guard); ldr guard, [r0, POINTER_GUARD]; \
+ eor dst, src, guard; mov r0, tmp
+# define PTR_MANGLE2(dst, src, guard) eor dst, src, guard
+# define PTR_DEMANGLE(dst, src, guard, tmp) \
+ PTR_MANGLE (dst, src, guard, tmp)
+# define PTR_DEMANGLE2(dst, src, guard) PTR_MANGLE2 (dst, src, guard)
+# else
+# define PTR_MANGLE(var) \
+ (var) = (__typeof (var)) ((uintptr_t) (var) ^ THREAD_GET_POINTER_GUARD ())
+# define PTR_DEMANGLE(var) PTR_MANGLE (var)
+# endif
+#endif
#endif /* linux/arm/sysdep.h */
--
1.8.1.4