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ARM: Add pointer encryption support.
Add support for pointer encryption in glibc internal structures in C and assembler code. Pointer encryption is a glibc security feature described here: https://sourceware.org/glibc/wiki/PointerEncryption The ARM implementation uses global variables instead of thread pointer relative accesses to get the value of the pointer encryption guard because accessing the thread pointer can be very expensive on older ARM cores. ports/ChangeLog.arm: 2013-10-03 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/setjmp.S (__sigsetjmp): Mangle fp, sp and lr before storing register values. * sysdeps/arm/sysdep.h (LDST_GLOBAL): New macro. * sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE): New macro. (PTR_DEMANGLE): Likewise. (PTR_MANGLE2): Likewise. (PTR_DEMANGLE2): Likewise.
This commit is contained in:
Will Newton
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@ -1,3 +1,18 @@
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2013-10-03 Will Newton <will.newton@linaro.org>
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* sysdeps/arm/__longjmp.S (__longjmp): Demangle fp, sp
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and lr when restoring register values.
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* sysdeps/arm/include/bits/setjmp.h (JMP_BUF_REGLIST): Remove
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sp and lr from list and replace fp with a4.
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* sysdeps/arm/jmpbuf-unwind.h (_jmpbuf_sp): New function.
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(_JMPBUF_UNWINDS_ADJ): Call _jmpbuf_sp.
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* sysdeps/arm/setjmp.S (__sigsetjmp): Mangle fp, sp and lr
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before storing register values.
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* sysdeps/arm/sysdep.h (LDST_GLOBAL): New macro.
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* sysdeps/unix/sysv/linux/arm/sysdep.h (PTR_MANGLE): New macro.
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(PTR_DEMANGLE): Likewise. (PTR_MANGLE2): Likewise.
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(PTR_DEMANGLE2): Likewise.
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2013-09-24 Will Newton <will.newton@linaro.org>
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* ports/sysdeps/arm/nptl/tls.h (TLS_INIT_TP_EXPENSIVE): Remove
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@ -34,10 +34,24 @@ ENTRY (__longjmp)
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sfi_breg ip, \
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ldr r4, [\B, #32] /* jmpbuf's sp */
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cfi_undefined (r4)
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#ifdef PTR_DEMANGLE
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PTR_DEMANGLE (r4, r4, a3, a4)
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#endif
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CHECK_SP (r4)
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#endif
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sfi_sp sfi_breg ip, \
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ldmia \B!, JMP_BUF_REGLIST
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#ifdef PTR_DEMANGLE
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PTR_DEMANGLE (fp, a4, a3, a2)
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ldr a4, [ip], #4
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PTR_DEMANGLE2 (sp, a4, a3)
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ldr a4, [ip], #4
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PTR_DEMANGLE2 (lr, a4, a3)
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#else
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mov fp, a4
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ldr sp, [ip], #4
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ldr lr, [ip], #4
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#endif
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cfi_restore (v1)
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cfi_restore (v2)
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cfi_restore (v3)
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@ -26,8 +26,9 @@
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#ifndef _ISOMAC
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/* Register list for a ldm/stm instruction to load/store
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the general registers from a __jmp_buf. */
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# define JMP_BUF_REGLIST {v1-v6, sl, fp, sp, lr}
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the general registers from a __jmp_buf. The a4 register
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contains fp at this point. */
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# define JMP_BUF_REGLIST {a4, v1-v6, sl}
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/* Index of __jmp_buf where the sp register resides. */
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# define __JMP_BUF_SP 8
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@ -17,6 +17,7 @@
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#include <setjmp.h>
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#include <stdint.h>
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#include <sysdep.h>
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#include <unwind.h>
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/* Test if longjmp to JMPBUF would unwind the frame
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@ -27,8 +28,18 @@
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#define _JMPBUF_CFA_UNWINDS_ADJ(_jmpbuf, _context, _adj) \
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_JMPBUF_UNWINDS_ADJ (_jmpbuf, (void *) _Unwind_GetCFA (_context), _adj)
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static inline uintptr_t __attribute__ ((unused))
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_jmpbuf_sp (__jmp_buf regs)
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{
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uintptr_t sp = regs[__JMP_BUF_SP];
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#ifdef PTR_DEMANGLE
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PTR_DEMANGLE (sp);
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#endif
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return sp;
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}
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#define _JMPBUF_UNWINDS_ADJ(_jmpbuf, _address, _adj) \
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((uintptr_t) (_address) - (_adj) < (uintptr_t) (_jmpbuf)[__JMP_BUF_SP] - (_adj))
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((uintptr_t) (_address) - (_adj) < _jmpbuf_sp (_jmpbuf) - (_adj))
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/* We use the normal longjmp for unwinding. */
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#define __libc_unwind_longjmp(buf, val) __libc_longjmp (buf, val)
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@ -24,11 +24,25 @@
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#include <arm-features.h>
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ENTRY (__sigsetjmp)
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#ifdef PTR_MANGLE
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PTR_MANGLE (a4, fp, a3, ip)
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#else
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mov a4, fp
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#endif
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mov ip, r0
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/* Save registers */
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sfi_breg ip, \
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stmia \B!, JMP_BUF_REGLIST
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#ifdef PTR_MANGLE
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PTR_MANGLE2 (a4, sp, a3)
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str a4, [ip], #4
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PTR_MANGLE2 (a4, lr, a3)
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str a4, [ip], #4
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#else
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str sp, [ip], #4
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str lr, [ip], #4
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#endif
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#if !defined ARM_ASSUME_NO_IWMMXT || defined __SOFTFP__
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# define NEED_HWCAP 1
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@ -171,6 +171,18 @@
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99: OP R, [pc, T]
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# endif
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/* Load or store to/from a global EXPR into/from R, using T. */
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# define LDST_GLOBAL(OP, R, T, EXPR) \
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ldr T, 99f; \
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ldr R, 100f; \
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98: add T, T, pc; \
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ldr T, [T, R]; \
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.subsection 2; \
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99: .word _GLOBAL_OFFSET_TABLE_ - 98b - PC_OFS; \
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100: .word EXPR##(GOT); \
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.previous; \
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OP R, [T]
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/* Cope with negative memory offsets, which thumb can't encode.
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Use NEGOFF_ADJ_BASE to (conditionally) alter the base register,
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and then NEGOFF_OFF1 to use 0 for thumb and the offset for arm,
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@ -435,8 +435,44 @@ __local_syscall_error: \
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#endif /* __ASSEMBLER__ */
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/* Pointer mangling is not yet supported for ARM. */
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#define PTR_MANGLE(var) (void) (var)
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#define PTR_DEMANGLE(var) (void) (var)
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/* Pointer mangling support. */
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#if (defined NOT_IN_libc && defined IS_IN_rtld) || \
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(!defined SHARED && (!defined NOT_IN_libc || defined IS_IN_libpthread))
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# ifdef __ASSEMBLER__
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# define PTR_MANGLE(dst, src, guard, tmp) \
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LDST_PCREL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard_local)); \
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PTR_MANGLE2(dst, src, guard)
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/* Use PTR_MANGLE2 for efficiency if guard is already loaded. */
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# define PTR_MANGLE2(dst, src, guard) \
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eor dst, src, guard
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# define PTR_DEMANGLE(dst, src, guard, tmp) \
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PTR_MANGLE (dst, src, guard, tmp)
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# define PTR_DEMANGLE2(dst, src, guard) \
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PTR_MANGLE2 (dst, src, guard)
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# else
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extern uintptr_t __pointer_chk_guard_local attribute_relro attribute_hidden;
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# define PTR_MANGLE(var) \
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(var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
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# define PTR_DEMANGLE(var) PTR_MANGLE (var)
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# endif
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#else
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# ifdef __ASSEMBLER__
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# define PTR_MANGLE(dst, src, guard, tmp) \
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LDST_GLOBAL(ldr, guard, tmp, C_SYMBOL_NAME(__pointer_chk_guard)); \
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PTR_MANGLE2(dst, src, guard)
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/* Use PTR_MANGLE2 for efficiency if guard is already loaded. */
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# define PTR_MANGLE2(dst, src, guard) \
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eor dst, src, guard
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# define PTR_DEMANGLE(dst, src, guard, tmp) \
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PTR_MANGLE (dst, src, guard, tmp)
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# define PTR_DEMANGLE2(dst, src, guard) \
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PTR_MANGLE2 (dst, src, guard)
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# else
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extern uintptr_t __pointer_chk_guard attribute_relro;
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# define PTR_MANGLE(var) \
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(var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
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# define PTR_DEMANGLE(var) PTR_MANGLE (var)
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# endif
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#endif
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#endif /* linux/arm/sysdep.h */
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