linux-kernel - [ 086/153] x86, efi: Make "noefi" really disable EFI runtime serivces

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Message-Id: <20130304033716.068432725@decadent.org.uk>
Date:	Mon, 04 Mar 2013 03:38:33 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, Matt Fleming <matt.fleming@...el.com>,
	Walt Nelson Jr <walt0924@...il.com>,
	Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: [ 086/153] x86, efi: Make "noefi" really disable EFI runtime serivces

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Fleming <matt.fleming@...el.com>

commit fb834c7acc5e140cf4f9e86da93a66de8c0514da upstream.

commit 1de63d60cd5b ("efi: Clear EFI_RUNTIME_SERVICES rather than
EFI_BOOT by "noefi" boot parameter") attempted to make "noefi" true to
its documentation and disable EFI runtime services to prevent the
bricking bug described in commit e0094244e41c ("samsung-laptop:
Disable on EFI hardware"). However, it's not possible to clear
EFI_RUNTIME_SERVICES from an early param function because
EFI_RUNTIME_SERVICES is set in efi_init() *after* parse_early_param().

This resulted in "noefi" effectively becoming a no-op and no longer
providing users with a way to disable EFI, which is bad for those
users that have buggy machines.

Reported-by: Walt Nelson Jr <walt0924@...il.com>
Cc: Satoru Takeuchi <takeuchi_satoru@...fujitsu.com>
Signed-off-by: Matt Fleming <matt.fleming@...el.com>
Link: http://lkml.kernel.org/r/1361392572-25657-1-git-send-email-matt@console-pimps.org
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
[bwh: Backported to 3.2: efi_runtime_init() is not a separate function,
 so put a whole set of statements in an if (!disable_runtime) block]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -83,9 +83,10 @@ int efi_enabled(int facility)
 }
 EXPORT_SYMBOL(efi_enabled);
 
+static bool disable_runtime = false;
 static int __init setup_noefi(char *arg)
 {
-	clear_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
+	disable_runtime = true;
 	return 0;
 }
 early_param("noefi", setup_noefi);
@@ -549,35 +550,37 @@ void __init efi_init(void)
 
 	set_bit(EFI_CONFIG_TABLES, &x86_efi_facility);
 
-	/*
-	 * Check out the runtime services table. We need to map
-	 * the runtime services table so that we can grab the physical
-	 * address of several of the EFI runtime functions, needed to
-	 * set the firmware into virtual mode.
-	 */
-	runtime = early_ioremap((unsigned long)efi.systab->runtime,
-				sizeof(efi_runtime_services_t));
-	if (runtime != NULL) {
-		/*
-		 * We will only need *early* access to the following
-		 * two EFI runtime services before set_virtual_address_map
-		 * is invoked.
-		 */
-		efi_phys.get_time = (efi_get_time_t *)runtime->get_time;
-		efi_phys.set_virtual_address_map =
-			(efi_set_virtual_address_map_t *)
-			runtime->set_virtual_address_map;
+	if (!disable_runtime) {
 		/*
-		 * Make efi_get_time can be called before entering
-		 * virtual mode.
+		 * Check out the runtime services table. We need to map
+		 * the runtime services table so that we can grab the physical
+		 * address of several of the EFI runtime functions, needed to
+		 * set the firmware into virtual mode.
 		 */
-		efi.get_time = phys_efi_get_time;
-
-		set_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
-	} else
-		printk(KERN_ERR "Could not map the EFI runtime service "
-		       "table!\n");
-	early_iounmap(runtime, sizeof(efi_runtime_services_t));
+		runtime = early_ioremap((unsigned long)efi.systab->runtime,
+					sizeof(efi_runtime_services_t));
+		if (runtime != NULL) {
+			/*
+			 * We will only need *early* access to the following
+			 * two EFI runtime services before set_virtual_address_map
+			 * is invoked.
+			 */
+			efi_phys.get_time = (efi_get_time_t *)runtime->get_time;
+			efi_phys.set_virtual_address_map =
+				(efi_set_virtual_address_map_t *)
+				runtime->set_virtual_address_map;
+			/*
+			 * Make efi_get_time can be called before entering
+			 * virtual mode.
+			 */
+			efi.get_time = phys_efi_get_time;
+			
+			set_bit(EFI_RUNTIME_SERVICES, &x86_efi_facility);
+		} else
+			printk(KERN_ERR "Could not map the EFI runtime service "
+			       "table!\n");
+		early_iounmap(runtime, sizeof(efi_runtime_services_t));
+	}
 
 	/* Map the EFI memory map */
 	memmap.map = early_ioremap((unsigned long)memmap.phys_map,


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