From 007e4dce13673b01a38b19384f54fa50a79a66de Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Sun, 8 Oct 2023 21:17:43 +0200
Subject: [PATCH] ARM64: Restore fp before sp in C stack unwinders.

Thanks to Peter Cawley. #1096
---
 src/host/buildvm_peobj.c | 3 ++-
 src/vm_arm64.dasc        | 4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/host/buildvm_peobj.c b/src/host/buildvm_peobj.c
index 7ce3b05a..8f04c496 100644
--- a/src/host/buildvm_peobj.c
+++ b/src/host/buildvm_peobj.c
@@ -373,11 +373,12 @@ void emit_peobj(BuildCtx *ctx)
 
     /* Unwind codes for .text section with handler. */
     p = uwc;
+    CADD_FP(192);		/* +2 */
     CSAVE_REGS(19, 28, 176);	/* +5*2 */
     CSAVE_FREGS(8, 15, 96);	/* +4*2 */
     CSAVE_FPLR(192);		/* +1 */
     CALLOC_S(208);		/* +1 */
-    CEND_ALIGN;			/* +1 +3 -> 24 */
+    CEND_ALIGN;			/* +1 +1 -> 24 */
 
     u32 = ((24u >> 2) << 27) | (1u << 20) | (fcofs >> 2);
     owrite(ctx, &u32, 4);
diff --git a/src/vm_arm64.dasc b/src/vm_arm64.dasc
index 3044a8ac..26973686 100644
--- a/src/vm_arm64.dasc
+++ b/src/vm_arm64.dasc
@@ -430,6 +430,7 @@ static void build_subroutines(BuildCtx *ctx)
   |
   |->vm_unwind_c:			// Unwind C stack, return from vm_pcall.
   |  // (void *cframe, int errcode)
+  |  add fp, CARG1, # SAVE_FP_LR_
   |  mov sp, CARG1
   |  mov CRET1, CARG2
   |  ldr L, SAVE_L
@@ -441,7 +442,8 @@ static void build_subroutines(BuildCtx *ctx)
   |
   |->vm_unwind_ff:			// Unwind C stack, return from ff pcall.
   |  // (void *cframe)
-  |  and sp, CARG1, #CFRAME_RAWMASK
+  |  add fp, CARG1, # SAVE_FP_LR_
+  |  mov sp, CARG1
   |  ldr L, SAVE_L
   |    movz TISNUM, #(LJ_TISNUM>>1)&0xffff, lsl #48
   |    movz TISNUMhi, #(LJ_TISNUM>>1)&0xffff, lsl #16