Messages in this thread | | | Subject | Re: [Fastboot] Re: [announce] kexec for linux 2.6.6 | From | (Eric W. Biederman) | Date | 13 May 2004 23:21:11 -0600 |
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"Randy.Dunlap" <rddunlap@osdl.org> writes:
> On 12 May 2004 10:57:27 -0600 Eric W. Biederman wrote: > > | 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. > > [1:] > | > 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. > > Andrew tells me that he is OK with reserving a syscall number for > kexec, which is easy & quick. I don't know when vdso will be available > (for non-x86[2]) or when the AT_SYSINFO data will work for userlevel > code[1. above]. > > So is there any reason not to reserve the syscall number for kexec > for now? (patch is below) > > -- > ~Randy > > > [2] kexec is currently only available for x86, but there is interest > in it for ia64 and ppc64 at least.
Also been work on x86-64 and ppc32. So if we are going to reserve syscall numbers it would also be nice to have those reserved as well.
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