[MINI-OS PATCH v2 10/12] Mini-OS: kexec: switch read-only area to be writable again

[Juergen Gross <jgross@xxxxxxxx>]

In order to allow writing the new kernel, make the readonly area
covering current kernel text writable again.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Jason Andryuk <jason.andryuk@xxxxxxx>
---
V2:
- modify printk() statement (Jason Andryuk)
---
 arch/x86/mm.c | 3 ++-
 kexec.c       | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm.c b/arch/x86/mm.c
index f4419d95..26ede6f4 100644
--- a/arch/x86/mm.c
+++ b/arch/x86/mm.c
@@ -529,7 +529,8 @@ void change_readonly(bool readonly)
 #endif
     }
 
-    printk("setting %p-%p readonly\n", &_text, &_erodata);
+    printk("setting %p-%p %s\n", &_text, &_erodata,
+           readonly ? "readonly" : "writable");
     walk_pt(start_address, ro.etext, change_readonly_func, &ro);
 
 #ifdef CONFIG_PARAVIRT
diff --git a/kexec.c b/kexec.c
index 3b11a69c..1ef7ce84 100644
--- a/kexec.c
+++ b/kexec.c
@@ -183,6 +183,8 @@ int kexec(void *kernel, unsigned long kernel_size, const 
char *cmdline)
         goto err;
     }
 
+    change_readonly(false);
+
     ret = kexec_move_used_pages(kexec_last_addr, (unsigned long)kernel,
                                 kernel_size);
     if ( ret )
@@ -192,6 +194,7 @@ int kexec(void *kernel, unsigned long kernel_size, const 
char *cmdline)
     ret = ENOSYS;
 
  err:
+    change_readonly(true);
     unreserve_memory_below();
     kexec_move_used_pages_undo();
     kexec_get_entry_undo();
-- 
2.43.0