Re: sg_set_page not usable for .bss?

[Jan Engelhardt]

On Tuesday 2008-12-02 01:10, David Miller wrote:
>> On Monday 2008-12-01 23:02, John Haxby wrote:
>> >>>+	sg_init_table(sg, 2);
>> >>>+	sg_set_buf(&sg[0], data, n);
>> >>>+	strcpy(digest_password, sysrq_password);
>> >>>+	i = strlen(digest_password);
>> >>>+	sg_set_buf(&sg[1], digest_password, i);
>> >>
>> >> Could we directly use sysrq_password instead of copying it to
>> >> digest_password first?
>> >
>> > No :-)   Eventually I discovered the reason my code wasn't working
>> > boils down to the definition of sg_set_buf:
>> >
>> >   sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf))
>> >
>> > which doesn't work for sysrq_password.   I don't know why I'll
>> > double check.
>> 
>> Well, sysrq_password is in the .bss section, where as digest_password
>> is on the heap due to being kmalloc'ed. Maybe that makes a difference?
>> Someone more versed with the virtual memory layer might know.
>
>You can't use these interfaces on kernel image addresses.
>
Great :-)  So what is the best way to use the SHA1 crypto algo
with in-kernel addresses?


Jan
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