unwind: repair register restoration for OR1K

Currently, OR1K architecture put the program counter at offset 0x128 of the current `or1k_thread_state_t`. However, the PC is restored after updating the thread pointer in `r3`, which causes the PC to be fetched incorrectly. This patch swaps the order of restoration of `r9` and `r3`, such that the PC is restored to `r9` using the current thread state. Patch by Oi Chee Cheung! Reviewed By: whitequark, compnerd Differential Revision: https://reviews.llvm.org/D107042
intel · Aug 2, 2021 · d6d0b65 · d6d0b65
1 parent 9e02f58
commit d6d0b65
Showing 1 changed file with 3 additions and 2 deletions.
diff --git a/libunwind/src/UnwindRegistersRestore.S b/libunwind/src/UnwindRegistersRestore.S
@@ -800,11 +800,12 @@ DEFINE_LIBUNWIND_FUNCTION(_ZN9libunwind14Registers_or1k6jumptoEv)
   l.lwz    r30,120(r3)
   l.lwz    r31,124(r3)
 
+  # load new pc into ra
+  l.lwz    r9, 128(r3)
+
   # at last, restore r3
   l.lwz    r3,  12(r3)
 
-  # load new pc into ra
-  l.lwz    r9, 128(r3)
   # jump to pc
   l.jr     r9
    l.nop