diff mbox series

[Ada] arm-qnx-7.1: unwind goes wrong after regs restore

Message ID 20220601084515.GA1247637@adacore.com
State New
Headers show
Series [Ada] arm-qnx-7.1: unwind goes wrong after regs restore | expand

Commit Message

Pierre-Marie de Rodat June 1, 2022, 8:45 a.m. UTC 
Bump the pc +3 total for Thumb mode, the same calculation that as is
done for arm-linux.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* init.c (__gnat_adjust_context_for_raise) [QNX][__thumb2__]: Bump
	the pc an extra byte.
diff mbox series

Patch

diff --git a/gcc/ada/init.c b/gcc/ada/init.c
--- a/gcc/ada/init.c
+++ b/gcc/ada/init.c
@@ -2579,7 +2579,17 @@  __gnat_adjust_context_for_raise (int signo ATTRIBUTE_UNUSED,
   uintptr_t *pc_addr;
   mcontext_t *mcontext = &((ucontext_t *) sc)->uc_mcontext;
   pc_addr = (uintptr_t *)&mcontext->cpu.gpr [ARM_REG_PC];
+
+  /* ARM Bump has to be an even number because of odd/even architecture.  */
   *pc_addr += 2;
+#ifdef __thumb2__
+  /* For thumb, the return address must have the low order bit set, otherwise
+     the unwinder will reset to "arm" mode upon return.  As long as the
+     compilation unit containing the landing pad is compiled with the same
+     mode (arm vs thumb) as the signaling compilation unit, this works.  */
+  if (mcontext->cpu.spsr & ARM_CPSR_T)
+    *pc_addr += 1;
+#endif
 }
 #endif /* ARMEL */