linux-kernel - Make CONFIG_DEBUG_RODATA boot-time configurable

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Message-ID: <20100715210944.GA24961@redhat.com>
Date:	Thu, 15 Jul 2010 17:09:44 -0400
From:	Dave Jones <davej@...hat.com>
To:	Linux Kernel <linux-kernel@...r.kernel.org>
Cc:	x86@...nel.org
Subject: Make CONFIG_DEBUG_RODATA boot-time configurable

We had a request to disable DEBUG_RODATA in our kernel for debugging purposes.  
Turning it off completely seems a bit unfortunate for the minority case
of people wanting to do debugging, so I came up with this patch to make
it a boot-time 'disable_rodata' argument.

Signed-off-by: Dave Jones <davej@...hat.com>


diff --git a/init/main.c b/init/main.c
index a42fdf4..eb60fae 100644
--- a/init/main.c
+++ b/init/main.c
@@ -820,6 +820,15 @@ static void run_init_process(char *init_filename)
 	kernel_execve(init_filename, argv_init, envp_init);
 }
 
+static unsigned int disable_rodata;
+static int __init set_disable_rodata(char *str)
+{
+	disable_rodata = 1;
+	return 1;
+}
+__setup("disable_rodata", set_disable_rodata);
+
+
 /* This is a non __init function. Force it to be noinline otherwise gcc
  * makes it inline to init() and it becomes part of init.text section
  */
@@ -830,7 +839,8 @@ static noinline int init_post(void)
 	async_synchronize_full();
 	free_initmem();
 	unlock_kernel();
-	mark_rodata_ro();
+	if (disable_rodata == 0)
+		mark_rodata_ro();
 	system_state = SYSTEM_RUNNING;
 	numa_default_policy();
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4ddb58d..1320d80 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -651,6 +651,10 @@ and is between 256 and 4096 characters. It is defined in the file
 			MTRR settings.  This parameter disables that behavior,
 			possibly causing your machine to run very slowly.
 
+	disable_rodata [X86]
+			Don't mark .rodata section as read-only.
+			May be useful for debugging.
+
 	disable_timer_pin_1 [X86]
 			Disable PIN 1 of APIC timer
 			Can be useful to work around chipset bugs.
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