From: Ben Pfaff <blp@cs.stanford.edu>
Date: Mon, 25 Sep 2006 21:43:09 +0000 (+0000)
Subject: Move assignment to _end_kernel_text inside .rodata.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6f7be4d89547dd7f9801f518e52572046a113daf;p=pintos-anon

Move assignment to _end_kernel_text inside .rodata.

Without this change, any orphan, read-only sections (such as .eh_frame
from libgcc) will be placed by GNU ld between .rodata and
_end_kernel_text.  The result is that _end_kernel_text gets pushed
into the middle of a page that now contains some read-only and some
read/write data.  After paging_init() marks that page read-only, the
first write to it (in intr_init() in my case) causes Pintos to go
ka-boom!

With this change, orphan read-only sections just don't get marked
read-only in the page tables.  Big deal.
---

diff --git a/src/threads/kernel.lds.S b/src/threads/kernel.lds.S
index 437ced3..6154d08 100644
--- a/src/threads/kernel.lds.S
+++ b/src/threads/kernel.lds.S
@@ -12,8 +12,9 @@ SECTIONS
 
   /* Kernel starts with code, followed by read-only data and writable data. */
   .text : { *(.start) *(.text) } = 0x90
-  .rodata : { *(.rodata) *(.rodata.*) . = ALIGN(0x1000); }
-  _end_kernel_text = .;
+  .rodata : { *(.rodata) *(.rodata.*) 
+	      . = ALIGN(0x1000); 
+	      _end_kernel_text = .; }
   .data : { *(.data) }
 
   /* BSS (zero-initialized data) is after everything else. */