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author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2020-06-04 09:33:35 +0100 |
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committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2020-07-13 13:49:20 +0100 |
commit | b097c7a27fb0796b2653a1d003cbf6b7a69d8961 (patch) | |
tree | 5562101be365c2497804621e3d1121e860420733 /libgcc/unwind-dw2.c | |
parent | 2bc95be3bb8c8138e2e87c1c11c84bfede989d61 (diff) | |
download | gcc-b097c7a27fb0796b2653a1d003cbf6b7a69d8961.zip gcc-b097c7a27fb0796b2653a1d003cbf6b7a69d8961.tar.gz gcc-b097c7a27fb0796b2653a1d003cbf6b7a69d8961.tar.bz2 |
libgcc: fix the handling of return address mangling [PR94891]
Mangling, currently only used on AArch64 for return address signing,
is an internal representation that should not be exposed via
__builtin_return_address return value,
__builtin_eh_return handler argument,
_Unwind_DebugHook handler argument.
Note that a mangled address might not even fit into a void *, e.g.
with AArch64 ilp32 ABI the return address is stored as 64bit, so
the mangled return address cannot be accessed via _Unwind_GetPtr.
This patch changes the unwinder hooks as follows:
MD_POST_EXTRACT_ROOT_ADDR is removed: root address comes from
__builtin_return_address which is not mangled.
MD_POST_EXTRACT_FRAME_ADDR is renamed to MD_DEMANGLE_RETURN_ADDR,
it now operates on _Unwind_Word instead of void *, so the hook
should work when return address signing is enabled on AArch64 ilp32.
(But for that __builtin_aarch64_autia1716 should be fixed to operate
on 64bit input instead of a void *.)
MD_POST_FROB_EH_HANDLER_ADDR is removed: it is the responsibility of
__builtin_eh_return to do the mangling if necessary.
2020-07-13 Szabolcs Nagy <szabolcs.nagy@arm.com>
libgcc/ChangeLog:
PR target/94891
* config/aarch64/aarch64-unwind.h (MD_POST_EXTRACT_ROOT_ADDR): Remove.
(MD_POST_FROB_EH_HANDLER_ADDR): Remove.
(MD_POST_EXTRACT_FRAME_ADDR): Rename to ...
(MD_DEMANGLE_RETURN_ADDR): This.
(aarch64_post_extract_frame_addr): Rename to ...
(aarch64_demangle_return_addr): This.
(aarch64_post_frob_eh_handler_addr): Remove.
* unwind-dw2.c (uw_update_context): Demangle return address.
(uw_frob_return_addr): Remove.
Diffstat (limited to 'libgcc/unwind-dw2.c')
-rw-r--r-- | libgcc/unwind-dw2.c | 34 |
1 files changed, 8 insertions, 26 deletions
diff --git a/libgcc/unwind-dw2.c b/libgcc/unwind-dw2.c index 62d4a3d..fe89656 100644 --- a/libgcc/unwind-dw2.c +++ b/libgcc/unwind-dw2.c @@ -1538,11 +1538,14 @@ uw_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs) { /* 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); + void *ret_addr; +#ifdef MD_DEMANGLE_RETURN_ADDR + _Unwind_Word ra = _Unwind_GetGR (context, fs->retaddr_column); + ret_addr = MD_DEMANGLE_RETURN_ADDR (context, fs, ra); +#else + ret_addr = _Unwind_GetPtr (context, fs->retaddr_column); #endif + context->ra = __builtin_extract_return_addr (ret_addr); } } @@ -1577,9 +1580,6 @@ 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; @@ -1616,9 +1616,6 @@ 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 *) @@ -1641,21 +1638,6 @@ _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 - __attribute__ ((__unused__)), - 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. FRAMES is a number of frames to be unwind. @@ -1667,7 +1649,7 @@ uw_frob_return_addr (struct _Unwind_Context *current do \ { \ long offset = uw_install_context_1 ((CURRENT), (TARGET)); \ - void *handler = uw_frob_return_addr ((CURRENT), (TARGET)); \ + void *handler = __builtin_frob_return_addr ((TARGET)->ra); \ _Unwind_DebugHook ((TARGET)->cfa, handler); \ _Unwind_Frames_Extra (FRAMES); \ __builtin_eh_return (offset, handler); \ |