linux-kernel - Re: [PATCH] Modify UEFI anti-bricking code

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Date:	Tue, 04 Jun 2013 11:35:33 +0800
From:	joeyli <jlee@...e.com>
To:	Matthew Garrett <matthew.garrett@...ula.com>
Cc:	"rja@....com" <rja@....com>, "mingo@...nel.org" <mingo@...nel.org>,
	"torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
	"bp@...en8.de" <bp@...en8.de>, "jkosina@...e.cz" <jkosina@...e.cz>,
	"matt.fleming@...el.com" <matt.fleming@...el.com>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"hpa@...ux.intel.com" <hpa@...ux.intel.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"oneukum@...e.de" <oneukum@...e.de>
Subject: Re: [PATCH] Modify UEFI anti-bricking code

於 一，2013-06-03 於 16:31 +0000，Matthew Garrett 提到：
> On Tue, 2013-06-04 at 00:13 +0800, joeyli wrote:
> 
> > Oliver raised a question for if power fails between that succesful
> > attempt and the deletion?
> 
> It's a pretty tiny window, but sure. Making sure we delete it seems
> sensible. In that case we should make the GUID a #define rather than
> write it out twice.
> 

Base on your patch, the following diff moved DUMMY GUID to #define, and
add a static efi name string:


Thanks a lot!
Joey Lee


diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 63e167a..cc3cfe8 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -53,6 +53,11 @@
 
 #define EFI_DEBUG	1
 
+#define EFI_DUMMY_GUID \
+	EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e, 0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92, 0xa9)
+
+static efi_char16_t efi_dummy_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
+
 struct efi __read_mostly efi = {
 	.mps        = EFI_INVALID_TABLE_ADDR,
 	.acpi       = EFI_INVALID_TABLE_ADDR,
@@ -981,6 +986,9 @@ void __init efi_enter_virtual_mode(void)
 		runtime_code_page_mkexec();
 
 	kfree(new_memmap);
+
+	/* clean DUMMY object */
+	efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID, 0, 0, NULL);
 }
 
 /*
@@ -1051,21 +1059,17 @@ efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
 		 */
 		unsigned long dummy_size = remaining_size + 1024;
 		void *dummy = kmalloc(dummy_size, GFP_ATOMIC);
-		efi_char16_t efi_name[6] = { 'D', 'U', 'M', 'M', 'Y', 0 };
-		efi_guid_t guid = EFI_GUID(0x4424ac57, 0xbe4b, 0x47dd, 0x9e,
-					   0x97, 0xed, 0x50, 0xf0, 0x9f, 0x92,
-					   0xa9);
 
-		status = efi.set_variable(efi_name, &guid, attributes,
-					  dummy_size, dummy);
+		status = efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+					  attributes, dummy_size, dummy);
 
 		if (status == EFI_SUCCESS) {
 			/*
 			 * This should have failed, so if it didn't make sure
 			 * that we delete it...
 			 */
-			efi.set_variable(efi_name, &guid, attributes, 0,
-					 dummy);
+			efi.set_variable(efi_dummy_name, &EFI_DUMMY_GUID,
+					 attributes, 0, dummy);
 		}
 
 		/*

--
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