Messages in this thread | | | Date | Sat, 17 Sep 2011 14:12:34 +0200 | From | Maarten Lankhorst <> | Subject | Re: [PATCH v2 10/10] x86, efi: EFI boot stub support |
| |
Hey Matt,
On 09/17/2011 01:44 PM, Matt Fleming wrote: > On Thu, 2011-09-15 at 14:44 +0200, Maarten Lankhorst wrote: >> Thanks, that makes much more sense. The man page makes mention >> of extra arguments, but it kind of looked like the way to pass it was by >> using -u -@ - which didn't work of course. :) >> >> So for reference: >> efibootmgr -L 'EFI Native Linux Boot' -l '\vmlinuz.efi' -d /dev/sdb -u root=/dev/sdb2 console=ttyS0,115200n8 >> >> or as ASCII (reads much prettier in efibootmgr -v) >> efibootmgr -L 'EFI Native Linux Boot' -l '\vmlinuz.efi' -d /dev/sdb root=/dev/sdb2 console=ttyS0,115200n8 >> >> This is the fixed patch I'm using for booting native linux kernel, >> with passing args tested for UCS-2 and ASCII. It seems that >> options_size can be halved safely, otherwise too much data is >> copied from input. > Thanks for looking at this Maarten. I've been staring at this code for > far too long to notice buglets like this ;-) > >> I keep the first word, since otherwise the first argument is stripped off, >> and it's probably harmless for the kernel to read something like >> \vmlinuz.efi when you don't do a direct boot. >> >> 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..f77f9f5 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; > If no options were passed to the stub then we really don't want to do > the allocation at all. Speaking of 'options_size', have you tested the > values that get passed in from image->load_options? Running with the > OVMF firmware under qemu I get sizes that are always larger than the > NUL-byte in the argument string. For example, executing "bzImage foo" > results in image->load_options being 38! I tested on my own physical system, not qemu or anything.
Anyhow it seems the cmdline_size is meant for reading, and setting it is completely ignored, see below. Could we make it a static array so no allocation needs to be done? > Remember that ->options_size represents 16-bit characters and cmdline is > going to be ASCII. options_size will always be larger than the value we > need, so there's no need for the +1. At the moment we're actually > allocating too much memory and that needs to be fixed. Reading up a bit more, I think the sane approach would be to allocate COMMAND_LINE_SIZE and null terminate it. cmdline_size is meant to be read only it seems:
Documentation/x86/boot.txt: Field name: cmdline_size Type: read Offset/size: 0x238/4 Protocol: 2.06+
The maximum size of the command line without the terminating zero. This means that the command line can contain at most cmdline_size characters. With protocol version 2.05 and earlier, the maximum size was 255.
>> @@ -633,27 +633,29 @@ 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; >> >> - if (s2 && options_size) { >> - /* Skip first word, that's the kernel name */ >> - while (*s2 && *s2 != ' ' && *s2 != '\n') { >> - options_size--; >> - s2++; >> - } >> - >> - /* skip space */ >> - if (*s2 == ' ') { >> - options_size--; >> - s2++; >> - } >> - >> - while (options_size-- != 0) { >> + if (options_size < 2 || !s2) { >> + *s1 = '\0'; >> + } else if (s2_8[1] && s2_8[1] < 0x80 && s2_8[0] < 0x80) { >> + /* Passed as ASCII */ >> + s2 = NULL; >> + memcpy(s1, s2_8, options_size); >> + hdr->cmdline_size = options_size; >> + } else { >> + options_size /= 2; /* Passed as UCS-2 */ >> + while (options_size-- != 0 && *s2) { >> *s1++ = *s2++; >> hdr->cmdline_size++; >> } >> - >> *s1 = '\0'; >> + s1 = (u8 *)(unsigned long)hdr->cmd_line_ptr; >> } >> + if (hdr->cmdline_size && s1[hdr->cmdline_size - 1] == '\0') >> + hdr->cmdline_size--; >> + if (hdr->cmdline_size && s1[hdr->cmdline_size - 1] == '\n') >> + hdr->cmdline_size--; >> + s1[hdr->cmdline_size] = '\0'; >> >> hdr->ramdisk_image = 0; >> hdr->ramdisk_size = 0; > Hmm... I'm really not convinced that we need to support ASCII cmdline > arguments, sorry. efibootmgr has support for UCS-2, so that's what > should be used. > I know, but this is nicer for displaying, compare this efibootmgr -v output:
Boot0002* Linux ASCII Boot HD(...)File(\vmlinuz.efi)root=/dev/sdb2 console=ttyS0,115200n8. Boot0003* Linux UCS-2 Boot HD(...)File(\vmlinuz.efi)r.o.o.t.=./.d.e.v./.s.d.b.2. .c.o.n.s.o.l.e.=.t.t.y.S.0.,.1.1.5.2.0.0.n.8...
And it's more foolproof, since it's easy to pass strings as ASCII since it's the default, and it would show up readable in efibootmgr.
~Maarten
| |