From d0aa2924776c1eab96a55870c317a2f51b578b0b Mon Sep 17 00:00:00 2001
From: Michael Fairman <mfairman@tegimeki.com>
Date: Sun, 1 Oct 2023 12:34:43 -0700
Subject: [PATCH] bugfix: correct computation of stack size on Mac Posix port

Computes the stack size after the end is aligned to a page
boundary.  The original code in (#674) did not account for
this and some combinations of stack addresses and sizes
would cause a segfault.

Tested on ARM64 MacOS and Linux, but not Intel (yet).
---
 portable/ThirdParty/GCC/Posix/port.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/portable/ThirdParty/GCC/Posix/port.c b/portable/ThirdParty/GCC/Posix/port.c
index 8ec8193971b..24dd89f4539 100644
--- a/portable/ThirdParty/GCC/Posix/port.c
+++ b/portable/ThirdParty/GCC/Posix/port.c
@@ -148,10 +148,14 @@ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
      */
     thread = ( Thread_t * ) ( pxTopOfStack + 1 ) - 1;
     pxTopOfStack = ( StackType_t * ) thread - 1;
+
+    #ifdef __APPLE__
+        pxEndOfStack = ( StackType_t *) mach_vm_round_page( pxEndOfStack );
+    #endif
+
     ulStackSize = ( size_t ) ( pxTopOfStack + 1 - pxEndOfStack ) * sizeof( *pxTopOfStack );
 
     #ifdef __APPLE__
-        pxEndOfStack = mach_vm_round_page( pxEndOfStack );
         ulStackSize = mach_vm_trunc_page( ulStackSize );
     #endif