[libunwind] r342895 - [AArch64] Unwinding support for return address signing
Luke Cheeseman via cfe-commits
cfe-commits at lists.llvm.org
Mon Sep 24 08:55:36 PDT 2018
Author: lukecheeseman
Date: Mon Sep 24 08:55:35 2018
New Revision: 342895
URL: http://llvm.org/viewvc/llvm-project?rev=342895&view=rev
Log:
[AArch64] Unwinding support for return address signing
- When return address signing is enabled, the LR may be signed on function entry
- When an exception is thrown the return address is inspected used to unwind the call stack
- Before this happens, the return address must be correctly authenticated to avoid causing an abort by dereferencing the signed pointer
Differential Revision: https://reviews.llvm.org/D51432
Modified:
libunwind/trunk/include/libunwind.h
libunwind/trunk/src/DwarfInstructions.hpp
libunwind/trunk/src/DwarfParser.hpp
libunwind/trunk/src/Registers.hpp
libunwind/trunk/src/dwarf2.h
Modified: libunwind/trunk/include/libunwind.h
URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/include/libunwind.h?rev=342895&r1=342894&r2=342895&view=diff
==============================================================================
--- libunwind/trunk/include/libunwind.h (original)
+++ libunwind/trunk/include/libunwind.h Mon Sep 24 08:55:35 2018
@@ -57,6 +57,9 @@ enum {
UNW_EINVAL = -6547, /* unsupported operation or bad value */
UNW_EBADVERSION = -6548, /* unwind info has unsupported version */
UNW_ENOINFO = -6549 /* no unwind info found */
+#if defined(_LIBUNWIND_TARGET_AARCH64) && !defined(_LIBUNWIND_IS_NATIVE_ONLY)
+ , UNW_ECROSSRASIGNING = -6550 /* cross unwind with return address signing */
+#endif
};
struct unw_context_t {
@@ -547,6 +550,8 @@ enum {
UNW_ARM64_X31 = 31,
UNW_ARM64_SP = 31,
// reserved block
+ UNW_ARM64_RA_SIGN_STATE = 34,
+ // reserved block
UNW_ARM64_D0 = 64,
UNW_ARM64_D1 = 65,
UNW_ARM64_D2 = 66,
Modified: libunwind/trunk/src/DwarfInstructions.hpp
URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/DwarfInstructions.hpp?rev=342895&r1=342894&r2=342895&view=diff
==============================================================================
--- libunwind/trunk/src/DwarfInstructions.hpp (original)
+++ libunwind/trunk/src/DwarfInstructions.hpp Mon Sep 24 08:55:35 2018
@@ -198,6 +198,24 @@ int DwarfInstructions<A, R>::stepWithDwa
// restoring SP means setting it to CFA.
newRegisters.setSP(cfa);
+#if defined(_LIBUNWIND_TARGET_AARCH64)
+ // If the target is aarch64 then the return address may have been signed
+ // using the v8.3 pointer authentication extensions. The original
+ // return address needs to be authenticated before the return address is
+ // restored. autia1716 is used instead of autia as autia1716 assembles
+ // to a NOP on pre-v8.3a architectures.
+ if (prolog.savedRegisters[UNW_ARM64_RA_SIGN_STATE].value) {
+#if !defined(_LIBUNWIND_IS_NATIVE_ONLY)
+ return UNW_ECROSSRASIGNING;
+#else
+ register unsigned long long x17 __asm("x17") = returnAddress;
+ register unsigned long long x16 __asm("x16") = cfa;
+ asm("autia1716": "+r"(x17): "r"(x16));
+ returnAddress = x17;
+#endif
+ }
+#endif
+
// Return address is address after call site instruction, so setting IP to
// that does simualates a return.
newRegisters.setIP(returnAddress);
Modified: libunwind/trunk/src/DwarfParser.hpp
URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/DwarfParser.hpp?rev=342895&r1=342894&r2=342895&view=diff
==============================================================================
--- libunwind/trunk/src/DwarfParser.hpp (original)
+++ libunwind/trunk/src/DwarfParser.hpp Mon Sep 24 08:55:35 2018
@@ -666,6 +666,14 @@ bool CFI_Parser<A>::parseInstructions(A
_LIBUNWIND_TRACE_DWARF(
"DW_CFA_GNU_negative_offset_extended(%" PRId64 ")\n", offset);
break;
+
+#if defined(_LIBUNWIND_TARGET_AARCH64)
+ case DW_CFA_AARCH64_negate_ra_state:
+ results->savedRegisters[UNW_ARM64_RA_SIGN_STATE].value ^= 0x1;
+ _LIBUNWIND_TRACE_DWARF("DW_CFA_AARCH64_negate_ra_state\n");
+ break;
+#endif
+
default:
operand = opcode & 0x3F;
switch (opcode & 0xC0) {
Modified: libunwind/trunk/src/Registers.hpp
URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/Registers.hpp?rev=342895&r1=342894&r2=342895&view=diff
==============================================================================
--- libunwind/trunk/src/Registers.hpp (original)
+++ libunwind/trunk/src/Registers.hpp Mon Sep 24 08:55:35 2018
@@ -1786,7 +1786,7 @@ private:
uint64_t __lr; // Link register x30
uint64_t __sp; // Stack pointer x31
uint64_t __pc; // Program counter
- uint64_t padding; // 16-byte align
+ uint64_t __ra_sign_state; // RA sign state register
};
GPRs _registers;
@@ -1822,6 +1822,8 @@ inline bool Registers_arm64::validRegist
return false;
if (regNum > 95)
return false;
+ if (regNum == UNW_ARM64_RA_SIGN_STATE)
+ return true;
if ((regNum > 31) && (regNum < 64))
return false;
return true;
@@ -1832,8 +1834,11 @@ inline uint64_t Registers_arm64::getRegi
return _registers.__pc;
if (regNum == UNW_REG_SP)
return _registers.__sp;
+ if (regNum == UNW_ARM64_RA_SIGN_STATE)
+ return _registers.__ra_sign_state;
if ((regNum >= 0) && (regNum < 32))
return _registers.__x[regNum];
+
_LIBUNWIND_ABORT("unsupported arm64 register");
}
@@ -1842,6 +1847,8 @@ inline void Registers_arm64::setRegister
_registers.__pc = value;
else if (regNum == UNW_REG_SP)
_registers.__sp = value;
+ else if (regNum == UNW_ARM64_RA_SIGN_STATE)
+ _registers.__ra_sign_state = value;
else if ((regNum >= 0) && (regNum < 32))
_registers.__x[regNum] = value;
else
Modified: libunwind/trunk/src/dwarf2.h
URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/dwarf2.h?rev=342895&r1=342894&r2=342895&view=diff
==============================================================================
--- libunwind/trunk/src/dwarf2.h (original)
+++ libunwind/trunk/src/dwarf2.h Mon Sep 24 08:55:35 2018
@@ -49,7 +49,10 @@ enum {
// GNU extensions
DW_CFA_GNU_window_save = 0x2D,
DW_CFA_GNU_args_size = 0x2E,
- DW_CFA_GNU_negative_offset_extended = 0x2F
+ DW_CFA_GNU_negative_offset_extended = 0x2F,
+
+ // AARCH64 extensions
+ DW_CFA_AARCH64_negate_ra_state = 0x2D
};
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