A recent change only initializes the regs.how[] during Dwarf unwinding
which resulted in an uninitialized offset used in return address signing
and random failures during unwinding. The fix is to use REG_SAVED_OFFSET
as the state where the return address signing bit is valid, and if the
state is REG_UNSAVED, initialize it to 0.
Passes bootstrap & regress, OK for commit?
libgcc/
PR target/107678
* unwind-dw2.c (execute_cfa_program): Initialize offset of
DWARF_REGNUM_AARCH64_RA_STATE if in REG_UNSAVED state.
* config/aarch64/aarch64-unwind.h (aarch64_frob_update_contex):
Check state is REG_SAVED_OFFSET before using offset for RA state.
---
diff --git a/libgcc/config/aarch64/aarch64-unwind.h
b/libgcc/config/aarch64/aarch64-unwind.h
index
26db9cbd9e5c526e0c410a4fc6be2bedb7d261cf..597133b3d708a50a366c8bfeff57475f5522b3f6
100644
--- a/libgcc/config/aarch64/aarch64-unwind.h
+++ b/libgcc/config/aarch64/aarch64-unwind.h
@@ -71,21 +71,15 @@ aarch64_demangle_return_addr (struct _Unwind_Context
*context,
}
/* 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. */
+ CONTEXT as having a signed return address if DWARF_REGNUM_AARCH64_RA_STATE
+ is initialized (REG_SAVED_OFFSET state) and the offset has bit 0 set. */
static inline void
aarch64_frob_update_context (struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
- const int reg = DWARF_REGNUM_AARCH64_RA_STATE;
- int ra_signed;
- if (fs->regs.how[reg] == REG_UNSAVED)
- ra_signed = fs->regs.reg[reg].loc.offset & 0x1;
- else
- ra_signed = _Unwind_GetGR (context, reg) & 0x1;
- if (ra_signed)
- /* The flag is used for re-authenticating EH handler's address. */
+ if (fs->regs.how[DWARF_REGNUM_AARCH64_RA_STATE] == REG_SAVED_OFFSET
+ && (fs->regs.reg[DWARF_REGNUM_AARCH64_RA_STATE].loc.offset & 1) != 0)
context->flags |= RA_SIGNED_BIT;
else
context->flags &= ~RA_SIGNED_BIT;
diff --git a/libgcc/unwind-dw2.c b/libgcc/unwind-dw2.c
index
eaceace20298b9b13344aff9d1fe9ee5f9c7bd73..87f2ae065b67982ce48f74e45523d9c754a7661c
100644
--- a/libgcc/unwind-dw2.c
+++ b/libgcc/unwind-dw2.c
@@ -1203,11 +1203,16 @@ execute_cfa_program (const unsigned char *insn_ptr,
case DW_CFA_GNU_window_save:
#if defined (__aarch64__) && !defined (__ILP32__)
- /* This CFA is multiplexed with Sparc. On AArch64 it's used to toggle
- return address signing status. */
- reg = DWARF_REGNUM_AARCH64_RA_STATE;
- gcc_assert (fs->regs.how[reg] == REG_UNSAVED);
- fs->regs.reg[reg].loc.offset ^= 1;
+ /* This CFA is multiplexed with Sparc. On AArch64 it's used to toggle
+ the return address signing status. It is initialized at the first
+ use and the state is stored in bit 0 of the offset. */
+ reg = DWARF_REGNUM_AARCH64_RA_STATE;
+ if (fs->regs.how[reg] == REG_UNSAVED)
+ {
+ fs->regs.how[reg] = REG_SAVED_OFFSET;
+ fs->regs.reg[reg].loc.offset = 0;
+ }
+ fs->regs.reg[reg].loc.offset ^= 1;
#else
/* ??? Hardcoded for SPARC register window configuration. */
if (__LIBGCC_DWARF_FRAME_REGISTERS__ >= 32)
