Re: [PATCH v2 10/10] x86, efi: EFI boot stub support

[Maarten Lankhorst <m.b.lankhorst@gmail.com>]

On 09/15/2011 10:04 AM, Maarten Lankhorst wrote:
> Hey Matt,
>
> On 09/15/2011 06:52 AM, Matt Domsch wrote:
>> On Wed, Sep 14, 2011 at 11:07:58AM -0500, Matt Fleming wrote:
>>> On Tue, 2011-09-13 at 16:33 +0200, Maarten Lankhorst wrote:
>>>> This version seems to boot for me.
>>> Yay! Thanks for testing.
>>>
>>>> Is it useful to add 32-bits support though?
>>>> It seems that only some older versions of OSX use it. I could see if I can
>>>> revive my mac mini, iirc it has 32-bits efi, or at least used to have.
>>> 32-bit UEFI platforms do exist, so I think it's worth supporting them.
>>>
>>>> Do I need to pass anything to add it to efibootmgr?
>>>>
>>>> I tried something like this:
>>>> echo "args" | efibootmgr -c -l '\vmlinuz.efi' -L 'Native EFI linux boot' -@ - -u -d /dev/sdb
>>>>
>>>> And it boots vmlinuz.efi, but the arguments I passed do not appear to
>>>> have any effect.
>>> No idea, I've never used efibootmgr. Let's add Matt Domsch to the
>>> discussion (now Cc'd).
>> Maarten, do you not see your 'args' in /proc/cmdline after booting the
>> entry?  From reading this thread, that's what you should see.
>>
>> Can you provide an 'efibootmgr -v' and hexdump -C
>> /sys/firmware/efi/vars/Boot*  to see the args are appended as expected
>> in the boot variable in nvram?
>>
>> Adding Jordan Hargrave, who is maintainer for efibootmgr now.
> Thanks, that helped. It looks like efibootmgr stores the arguments without converting it to UCS-2.
>
> Patch below is a rough check for ascii, in which case it passes it unmodified.
>
> After this 'args' is passed succesfully. :)
>
> Should probably be folded in 10/10.
>
> Signed-off-by: Maarten Lankhorst <m.b.lankhorst@gmail.com>
>
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index 6c34828..b24affb 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -619,12 +619,12 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
>  	unsigned long cmdline;
>  	u8 nr_entries;
>  	u16 *s2;
> -	u8 *s1;
> +	u8 *s1, *s2_8;
>  	int i;
>  
>  	hdr->type_of_loader = 0x21;
>  
> -	status = low_alloc(options_size, 1, &cmdline);
> +	status = low_alloc(options_size+1, 1, &cmdline);
>  	if (status != EFI_SUCCESS)
>  		goto fail;
>  
> @@ -633,6 +633,14 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
>  	/* Convert unicode cmdline to ascii */
>  	s1 = (u8 *)(unsigned long)hdr->cmd_line_ptr;
>  	s2 = (u16 *)options;
> +	s2_8 = (u8*)options;
> +	/* Assume the first byte is < 0x128 */
Woops, typo.
> +	if (options_size > 1 && s2_8[1] && s2_8[1] < 0x80 && s2_8[0] < 0x80) {
> +		s2 = NULL;
> +		memcpy(s1, s2_8, options_size);
> +		s1[options_size] = 0;
> +		hdr->cmdline_size = options_size;
> +	}
>  
>  	if (s2 && options_size) {
>  		/* Skip first word, that's the kernel name */
I noticed 10/10 doesn't include the size of null pointer is this expected?
And when options_size = 0, you do a null allocation and never null-terminate.
Also in s2 && options_size you initially check for newline, but when copying
arguments, you ignore it. With echo moo | efibootmgr -@ - you'd pass a newline,
which should probably be stripped. I think this would fix both cases:

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 6c34828..dbaaf54 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -619,12 +619,12 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
 	unsigned long cmdline;
 	u8 nr_entries;
 	u16 *s2;
-	u8 *s1;
+	u8 *s1, *s2_8;
 	int i;
 
 	hdr->type_of_loader = 0x21;
 
-	status = low_alloc(options_size, 1, &cmdline);
+	status = low_alloc(options_size+1, 1, &cmdline);
 	if (status != EFI_SUCCESS)
 		goto fail;
 
@@ -633,6 +633,14 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
 	/* Convert unicode cmdline to ascii */
 	s1 = (u8 *)(unsigned long)hdr->cmd_line_ptr;
 	s2 = (u16 *)options;
+	s2_8 = (u8*)options;
+	/* Assume the first byte is < 128 */
+	if (options_size > 1 && s2_8[1] s2_8[1] < 0x80 && s2_8[0] < 0x80) {
+		s2 = NULL;
+		memcpy(s1, s2_8, options_size);
+		s1[options_size] = '\0';
+		hdr->cmdline_size = options_size;
+	}
 
 	if (s2 && options_size) {
 		/* Skip first word, that's the kernel name */
@@ -655,6 +663,11 @@ static efi_status_t make_boot_params(struct boot_params *boot_params,
 		*s1 = '\0';
 	}
 
+	if (!hdr->cmdline_size)
+		*s1 = '\0';
+	else if (hdr->cmd_line_ptr[hdr->cmdline_size-1] == '\n')
+		hdr->cmd_line_ptr[--hdr->cmdline_size] = '\0';
+
 	hdr->ramdisk_image = 0;
 	hdr->ramdisk_size = 0;