114 lines
4.3 KiB
Diff
114 lines
4.3 KiB
Diff
A recent change only initializes the regs.how[] during Dwarf unwinding
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which resulted in an uninitialized offset used in return address signing
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and random failures during unwinding. The fix is to encode the return
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address signing state in REG_UNSAVED and REG_UNDEFINED.
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2023-01-10 Wilco Dijkstra <Wilco.Dijkstra@arm.com>
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PR target/107678
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* unwind-dw2.c (RA_SIGNED_BIT): Remove.
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* unwind-dw2-execute_cfa.h: Use REG_UNSAVED/UNDEFINED
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to encode return address signing state.
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* config/aarch64/aarch64-unwind.h (aarch64_demangle_return_addr)
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Check current return address signing state.
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(aarch64_frob_update_contex): Remove.
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--- libgcc/config/aarch64/aarch64-unwind.h
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+++ libgcc/config/aarch64/aarch64-unwind.h
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@@ -29,8 +29,6 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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#define MD_DEMANGLE_RETURN_ADDR(context, fs, addr) \
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aarch64_demangle_return_addr (context, fs, addr)
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-#define MD_FROB_UPDATE_CONTEXT(context, fs) \
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- aarch64_frob_update_context (context, fs)
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static inline int
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aarch64_cie_signed_with_b_key (struct _Unwind_Context *context)
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@@ -55,42 +53,27 @@ aarch64_cie_signed_with_b_key (struct _Unwind_Context *context)
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static inline void *
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aarch64_demangle_return_addr (struct _Unwind_Context *context,
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- _Unwind_FrameState *fs ATTRIBUTE_UNUSED,
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+ _Unwind_FrameState *fs,
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_Unwind_Word addr_word)
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{
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void *addr = (void *)addr_word;
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- if (context->flags & RA_SIGNED_BIT)
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+ const int reg = DWARF_REGNUM_AARCH64_RA_STATE;
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+
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+ if (fs->regs.how[reg] == REG_UNSAVED)
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+ return addr;
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+
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+ /* Return-address signing state is toggled by DW_CFA_GNU_window_save (where
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+ REG_UNDEFINED means enabled), or set by a DW_CFA_expression. */
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+ if (fs->regs.how[reg] == REG_UNDEFINED
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+ || (_Unwind_GetGR (context, reg) & 0x1) != 0)
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{
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_Unwind_Word salt = (_Unwind_Word) context->cfa;
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if (aarch64_cie_signed_with_b_key (context) != 0)
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return __builtin_aarch64_autib1716 (addr, salt);
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return __builtin_aarch64_autia1716 (addr, salt);
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}
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- else
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- return addr;
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-}
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-
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-/* Do AArch64 private initialization on CONTEXT based on frame info FS. Mark
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- CONTEXT as return address signed if bit 0 of DWARF_REGNUM_AARCH64_RA_STATE is
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- set. */
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-
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-static inline void
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-aarch64_frob_update_context (struct _Unwind_Context *context,
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- _Unwind_FrameState *fs)
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-{
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- const int reg = DWARF_REGNUM_AARCH64_RA_STATE;
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- int ra_signed;
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- if (fs->regs.how[reg] == REG_UNSAVED)
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- ra_signed = fs->regs.reg[reg].loc.offset & 0x1;
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- else
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- ra_signed = _Unwind_GetGR (context, reg) & 0x1;
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- if (ra_signed)
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- /* The flag is used for re-authenticating EH handler's address. */
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- context->flags |= RA_SIGNED_BIT;
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- else
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- context->flags &= ~RA_SIGNED_BIT;
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- return;
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+ return addr;
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}
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#endif /* defined AARCH64_UNWIND_H && defined __ILP32__ */
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--- libgcc/unwind-dw2.c
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+++ libgcc/unwind-dw2.c
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@@ -137,9 +137,6 @@ struct _Unwind_Context
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#define SIGNAL_FRAME_BIT ((~(_Unwind_Word) 0 >> 1) + 1)
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/* Context which has version/args_size/by_value fields. */
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#define EXTENDED_CONTEXT_BIT ((~(_Unwind_Word) 0 >> 2) + 1)
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- /* Bit reserved on AArch64, return address has been signed with A or B
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- key. */
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-#define RA_SIGNED_BIT ((~(_Unwind_Word) 0 >> 3) + 1)
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_Unwind_Word flags;
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/* 0 for now, can be increased when further fields are added to
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struct _Unwind_Context. */
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--- libgcc/unwind-dw2-execute_cfa.h 2023-01-02 17:53:56.003021412 +0100
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+++ libgcc/unwind-dw2-execute_cfa.h 2023-01-12 19:52:05.456327742 +0100
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@@ -278,10 +278,15 @@
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case DW_CFA_GNU_window_save:
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#if defined (__aarch64__) && !defined (__ILP32__)
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/* This CFA is multiplexed with Sparc. On AArch64 it's used to toggle
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- return address signing status. */
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+ return address signing status. The REG_UNDEFINED/UNSAVED states
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+ mean RA signing is enabled/disabled. */
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reg = DWARF_REGNUM_AARCH64_RA_STATE;
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- gcc_assert (fs->regs.how[reg] == REG_UNSAVED);
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- fs->regs.reg[reg].loc.offset ^= 1;
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+ gcc_assert (fs->regs.how[reg] == REG_UNSAVED
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+ || fs->regs.how[reg] == REG_UNDEFINED);
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+ if (fs->regs.how[reg] == REG_UNSAVED)
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+ fs->regs.how[reg] = REG_UNDEFINED;
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+ else
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+ fs->regs.how[reg] = REG_UNSAVED;
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#else
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/* ??? Hardcoded for SPARC register window configuration. */
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if (__LIBGCC_DWARF_FRAME_REGISTERS__ >= 32)
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