Messages in this thread | | | Subject | Re: [Fastboot] Re: [announce] kexec for linux 2.6.6 | From | (Eric W. Biederman) | Date | 12 May 2004 10:57:27 -0600 |
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Ulrich Drepper <drepper@redhat.com> writes:
> Eric W. Biederman wrote: > > > As a first draft we should be able to use the standard ELF mechanisms > > for this. It is not like PIC shared libraries were new. Or is > > there some specific problem you are thinking of with respect to > > randomization? > > The official kernel does not have vdso randomization. Ingo has a patch > for the Red Hat kernel which is used in the FC2 kernel. The patch > effectively only changes the location at which the vdso is mapped. It > does not change the vdso content. So the __kernel_vsyscall symbol in > the vdso's symbol table is not changed. > > AT_SYSINFO is the right way to go forward but it is not directly > accessible to userlevel code. And it is no pointer which will make > architectures with function descriptors unhappy.
It sounds like the vdso just needs to be treated as a prelinked vdso. You can find everything you need with AT_SYSINFO_EHDR.
In the case of function descriptors they should be in a data segment that can get copied to another page, and corrected. Leaving the code segment at it's randomized location.
Eric
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