Thanks for the review.
On 19/01/17 14:18, Richard Earnshaw (lists) wrote:
diff --git a/libgcc/unwind-dw2.c b/libgcc/unwind-dw2.c
index
8085a42ace15d53f4cb0c6681717012d906a6d47..cf640135275deb76b820f8209fa51eacfd64c4a2
100644
--- a/libgcc/unwind-dw2.c
+++ b/libgcc/unwind-dw2.c
@@ -136,6 +136,8 @@ struct _Unwind_Context
#define SIGNAL_FRAME_BIT ((~(_Unwind_Word) 0 >> 1) + 1)
/* Context which has version/args_size/by_value fields. */
#define EXTENDED_CONTEXT_BIT ((~(_Unwind_Word) 0 >> 2) + 1)
+ /* Bit reserved on AArch64, return address has been signed with A key. */
+#define RA_A_SIGNED_BIT ((~(_Unwind_Word) 0 >> 3) + 1)
Why is this here? It appears to only be used within the
AArch64-specific header file.
I was putting it here so that when we allocate the next general purpose bit, we
know clearly that bit 3 is allocated to AArch64 already, and the new general bit
needs to go to the next one. This can avoid bit collision.
...
+/* Frob exception handler's address kept in TARGET before installing into
+ CURRENT context. */
+
+static void *
+uw_frob_return_addr (struct _Unwind_Context *current,
+ struct _Unwind_Context *target)
+{
+ void *ret_addr = __builtin_frob_return_addr (target->ra);
+#ifdef MD_POST_FROB_EH_HANDLER_ADDR
+ ret_addr = MD_POST_FROB_EH_HANDLER_ADDR (current, target, ret_addr);
+#endif
+ return ret_addr;
+}
+
I think this function should be marked inline. The optimizers would
probably inline it anyway, but it seems wrong for us to rely on that.
Thanks, fixed.
Does the updated patch looks OK to you know?
libgcc/
2017-01-19 Jiong Wang <jiong.w...@arm.com>
* config/aarch64/aarch64-unwind.h: New file.
(DWARF_REGNUM_AARCH64_RA_STATE): Define.
(MD_POST_EXTRACT_ROOT_ADDR): Define.
(MD_POST_EXTRACT_FRAME_ADDR): Define.
(MD_POST_FROB_EH_HANDLER_ADDR): Define.
(MD_FROB_UPDATE_CONTEXT): Define.
(aarch64_post_extract_frame_addr): New function.
(aarch64_post_frob_eh_handler_addr): New function.
(aarch64_frob_update_context): New function.
* config/aarch64/linux-unwind.h: Include aarch64-unwind.h
* config.host (aarch64*-*-elf, aarch64*-*-rtems*, aarch64*-*-freebsd*):
Initialize md_unwind_header to include aarch64-unwind.h.
* unwind-dw2.c (struct _Unwind_Context): Define "RA_A_SIGNED_BIT".
(execute_cfa_program): Multiplex DW_CFA_GNU_window_save for __aarch64__.
(uw_update_context): Honor MD_POST_EXTRACT_FRAME_ADDR.
(uw_init_context_1): Honor MD_POST_EXTRACT_ROOT_ADDR.
(uw_frob_return_addr): New function.
(_Unwind_DebugHook): Use uw_frob_return_addr.
diff --git a/libgcc/config.host b/libgcc/config.host
index 6f2e458e74e776a6b7a310919558bcca76389232..540bfa9635802adabb36a2d1b7cf3416462c59f3 100644
--- a/libgcc/config.host
+++ b/libgcc/config.host
@@ -331,11 +331,13 @@ aarch64*-*-elf | aarch64*-*-rtems*)
extra_parts="$extra_parts crtfastmath.o"
tmake_file="${tmake_file} ${cpu_type}/t-aarch64"
tmake_file="${tmake_file} ${cpu_type}/t-softfp t-softfp t-crtfm"
+ md_unwind_header=aarch64/aarch64-unwind.h
;;
aarch64*-*-freebsd*)
extra_parts="$extra_parts crtfastmath.o"
tmake_file="${tmake_file} ${cpu_type}/t-aarch64"
tmake_file="${tmake_file} ${cpu_type}/t-softfp t-softfp t-crtfm"
+ md_unwind_header=aarch64/aarch64-unwind.h
;;
aarch64*-*-linux*)
extra_parts="$extra_parts crtfastmath.o"
diff --git a/libgcc/config/aarch64/aarch64-unwind.h b/libgcc/config/aarch64/aarch64-unwind.h
new file mode 100644
index 0000000000000000000000000000000000000000..a43d965b358f3e830b85fc42c7bceacf7d41a671
--- /dev/null
+++ b/libgcc/config/aarch64/aarch64-unwind.h
@@ -0,0 +1,87 @@
+/* Copyright (C) 2017 Free Software Foundation, Inc.
+ Contributed by ARM Ltd.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC 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 General Public License
+for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+<http://www.gnu.org/licenses/>. */
+
+#ifndef AARCH64_UNWIND_H
+#define AARCH64_UNWIND_H
+
+#define DWARF_REGNUM_AARCH64_RA_STATE 34
+
+#define MD_POST_EXTRACT_ROOT_ADDR(addr) __builtin_aarch64_xpaclri (addr)
+#define MD_POST_EXTRACT_FRAME_ADDR(context, fs, addr) \
+ aarch64_post_extract_frame_addr (context, fs, addr)
+#define MD_POST_FROB_EH_HANDLER_ADDR(current, target, addr) \
+ aarch64_post_frob_eh_handler_addr (current, target, addr)
+#define MD_FROB_UPDATE_CONTEXT(context, fs) \
+ aarch64_frob_update_context (context, fs)
+
+/* Do AArch64 private extraction on ADDR based on context info CONTEXT and
+ unwind frame info FS. If ADDR is signed, we do address authentication on it
+ using CFA of current frame. */
+
+static inline void *
+aarch64_post_extract_frame_addr (struct _Unwind_Context *context,
+ _Unwind_FrameState *fs, void *addr)
+{
+ if (fs->regs.reg[DWARF_REGNUM_AARCH64_RA_STATE].loc.offset & 0x1)
+ {
+ _Unwind_Word salt = (_Unwind_Word) context->cfa;
+ return __builtin_aarch64_autia1716 (addr, salt);
+ }
+ else
+ return addr;
+}
+
+/* Do AArch64 private frob on exception handler's address HANDLER_ADDR before
+ installing it into current context CURRENT. TARGET is currently not used.
+ We need to sign exception handler's address if CURRENT itself is signed. */
+
+static inline void *
+aarch64_post_frob_eh_handler_addr (struct _Unwind_Context *current,
+ struct _Unwind_Context *target
+ ATTRIBUTE_UNUSED,
+ void *handler_addr)
+{
+ if (current->flags & RA_A_SIGNED_BIT)
+ return __builtin_aarch64_pacia1716 (handler_addr,
+ (_Unwind_Word) current->cfa);
+ else
+ return handler_addr;
+}
+
+/* Do AArch64 private initialization on CONTEXT based on frame info FS. Mark
+ CONTEXT as return address signed if bit 0 of DWARF_REGNUM_AARCH64_RA_STATE is
+ set. */
+
+static inline void
+aarch64_frob_update_context (struct _Unwind_Context *context,
+ _Unwind_FrameState *fs)
+{
+ if (fs->regs.reg[DWARF_REGNUM_AARCH64_RA_STATE].loc.offset & 0x1)
+ /* The flag is used for re-authenticating EH handler's address. */
+ context->flags |= RA_A_SIGNED_BIT;
+
+ return;
+}
+
+#endif /* defined AARCH64_UNWIND_H */
diff --git a/libgcc/config/aarch64/linux-unwind.h b/libgcc/config/aarch64/linux-unwind.h
index 1256f010007ac964de8bb895379a7d893a446bd9..75774b30c080ad2361fb37c7208bcf3d3b57d77a 100644
--- a/libgcc/config/aarch64/linux-unwind.h
+++ b/libgcc/config/aarch64/linux-unwind.h
@@ -24,6 +24,7 @@
#include <signal.h>
#include <sys/ucontext.h>
+#include "aarch64-unwind.h"
/* Since insns are always stored LE, on a BE system the opcodes will
diff --git a/libgcc/unwind-dw2.c b/libgcc/unwind-dw2.c
index 8085a42ace15d53f4cb0c6681717012d906a6d47..f2e5ce832190ff3ee69f31e3b6d44b68395f68df 100644
--- a/libgcc/unwind-dw2.c
+++ b/libgcc/unwind-dw2.c
@@ -136,6 +136,8 @@ struct _Unwind_Context
#define SIGNAL_FRAME_BIT ((~(_Unwind_Word) 0 >> 1) + 1)
/* Context which has version/args_size/by_value fields. */
#define EXTENDED_CONTEXT_BIT ((~(_Unwind_Word) 0 >> 2) + 1)
+ /* Bit reserved on AArch64, return address has been signed with A key. */
+#define RA_A_SIGNED_BIT ((~(_Unwind_Word) 0 >> 3) + 1)
_Unwind_Word flags;
/* 0 for now, can be increased when further fields are added to
struct _Unwind_Context. */
@@ -1185,6 +1187,11 @@ execute_cfa_program (const unsigned char *insn_ptr,
break;
case DW_CFA_GNU_window_save:
+#ifdef __aarch64__
+ /* This CFA is multiplexed with Sparc. On AArch64 it's used to toggle
+ return address signing status. */
+ fs->regs.reg[DWARF_REGNUM_AARCH64_RA_STATE].loc.offset ^= 1;
+#else
/* ??? Hardcoded for SPARC register window configuration. */
if (__LIBGCC_DWARF_FRAME_REGISTERS__ >= 32)
for (reg = 16; reg < 32; ++reg)
@@ -1192,6 +1199,7 @@ execute_cfa_program (const unsigned char *insn_ptr,
fs->regs.reg[reg].how = REG_SAVED_OFFSET;
fs->regs.reg[reg].loc.offset = (reg - 16) * sizeof (void *);
}
+#endif
break;
case DW_CFA_GNU_args_size:
@@ -1513,10 +1521,15 @@ uw_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
stack frame. */
context->ra = 0;
else
- /* Compute the return address now, since the return address column
- can change from frame to frame. */
- context->ra = __builtin_extract_return_addr
- (_Unwind_GetPtr (context, fs->retaddr_column));
+ {
+ /* Compute the return address now, since the return address column
+ can change from frame to frame. */
+ context->ra = __builtin_extract_return_addr
+ (_Unwind_GetPtr (context, fs->retaddr_column));
+#ifdef MD_POST_EXTRACT_FRAME_ADDR
+ context->ra = MD_POST_EXTRACT_FRAME_ADDR (context, fs, context->ra);
+#endif
+ }
}
static void
@@ -1550,6 +1563,9 @@ uw_init_context_1 (struct _Unwind_Context *context,
void *outer_cfa, void *outer_ra)
{
void *ra = __builtin_extract_return_addr (__builtin_return_address (0));
+#ifdef MD_POST_EXTRACT_ROOT_ADDR
+ ra = MD_POST_EXTRACT_ROOT_ADDR (ra);
+#endif
_Unwind_FrameState fs;
_Unwind_SpTmp sp_slot;
_Unwind_Reason_Code code;
@@ -1586,6 +1602,9 @@ uw_init_context_1 (struct _Unwind_Context *context,
initialization context, then we can't see it in the given
call frame data. So have the initialization context tell us. */
context->ra = __builtin_extract_return_addr (outer_ra);
+#ifdef MD_POST_EXTRACT_ROOT_ADDR
+ context->ra = MD_POST_EXTRACT_ROOT_ADDR (context->ra);
+#endif
}
static void _Unwind_DebugHook (void *, void *)
@@ -1608,6 +1627,20 @@ _Unwind_DebugHook (void *cfa __attribute__ ((__unused__)),
#endif
}
+/* Frob exception handler's address kept in TARGET before installing into
+ CURRENT context. */
+
+static inline void *
+uw_frob_return_addr (struct _Unwind_Context *current,
+ struct _Unwind_Context *target)
+{
+ void *ret_addr = __builtin_frob_return_addr (target->ra);
+#ifdef MD_POST_FROB_EH_HANDLER_ADDR
+ ret_addr = MD_POST_FROB_EH_HANDLER_ADDR (current, target, ret_addr);
+#endif
+ return ret_addr;
+}
+
/* Install TARGET into CURRENT so that we can return to it. This is a
macro because __builtin_eh_return must be invoked in the context of
our caller. */
@@ -1616,7 +1649,7 @@ _Unwind_DebugHook (void *cfa __attribute__ ((__unused__)),
do \
{ \
long offset = uw_install_context_1 ((CURRENT), (TARGET)); \
- void *handler = __builtin_frob_return_addr ((TARGET)->ra); \
+ void *handler = uw_frob_return_addr ((CURRENT), (TARGET)); \
_Unwind_DebugHook ((TARGET)->cfa, handler); \
__builtin_eh_return (offset, handler); \
} \
