On Thu Sep 26, 2024 at 4:47 AM EEST, Jarkko Sakkinen wrote: > On Thu Sep 26, 2024 at 3:38 AM EEST, Kai Huang wrote: > > > > > > On 26/09/2024 12:33 pm, Jarkko Sakkinen wrote: > > > On Thu Sep 26, 2024 at 3:07 AM EEST, Kai Huang wrote: > > >> > > >> > > >> On 23/09/2024 7:48 pm, Jarkko Sakkinen wrote: > > >>> On Sun Sep 22, 2024 at 7:57 PM EEST, Jarkko Sakkinen wrote: > > >>>>> On Sun Sep 22, 2024 at 7:27 PM EEST, Jarkko Sakkinen wrote: > > >>>>>> Hi > > >>>>>> > > >>>>>> I started to look into this old issue with mm subsystem and SGX, i.e. > > >>>>>> can we make SGX VMA's to merge together? > > >>>>>> > > >>>>>> This demonstrates the problem pretty well: > > >>>>>> > > >>>>>> https://lore.kernel.org/linux-sgx/884c7ea454cf2eb0ba2e95f7c25bd42018824f97.camel@xxxxxxxxxx/ > > >>>>>> > > >>>>>> It was result of brk() syscall being applied a few times. > > >>>> > > >>>> Briging some context here. This can be fixed in the run-time by book > > >>>> keeping the ranges and doing unmapping/mapping. I guess this goes > > >>>> beyond what mm should support? > > >>>> > > >>>> I thought to plain check this as it has been two years since my last > > >>>> query on topic (if we could improve either the driver or mm somehow). > > >>> > > >>> In the past I've substituted kernel's mm merge code with user space > > >>> replacement: > > >>> > > >>> https://github.com/enarx/mmledger/blob/main/src/lib.rs > > >>> > > >>> It's essentially a reimplementation of al stuff that goes into > > >>> mm/mmap.c's vma_merge(). I cannot recall anymore whether merges > > >>> which map over existing ranges were working correctly, i.e. was > > >>> the issue only concerning adjacent VMA's. > > >>> > > >>> What I'm looking here is that can we make some cosntraints that > > >>> if satisfied by the pfnmap code, it could leverage the code from > > >>> vma_merge(). Perhaps by making explicit call to vma_merge()? > > >>> I get that implicit use moves too much responsibility to the mm > > >>> subsystem. > > >>> > > >> > > >> Hi Jarkko, > > >> > > >> Just want to understand more on the background: > > >> > > >> Are you seeing any real problem due to needing a lot of mmap()s to the > > >> same enclave, or it is just a problem that doesn't look nice and you > > >> want to resolve? > > >> > > >> I mean, this problem doesn't seem to be SGX-specific but a common one > > >> for VMAs with VM_PFNMAP (any bit in VM_SPECIAL), e.g., from random > > >> device drivers with mmap() support. We will need a good justification > > >> if we want to make any core-mm change, if any, for this. > > > > > > It requires essentially replicating core mm in user space. > > > > > > > Is there any real problem if we don't do this at all (neither in core mm > > nor in userspace)? > > 7f8f00000000-7f8f00009000 r--s 00000000 00:05 84 /dev/sgx_enclave > 7f8f00009000-7f8f00034000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f00034000-7f8f000ff000 r-xs 00000000 00:05 84 /dev/sgx_enclave > 7f8f000ff000-7f8f00201000 ---p 00000000 00:00 0 > 7f8f00201000-7f8f003fc000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f003fc000-7f8f003fd000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f003fd000-7f8f00400000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f00400000-7f8f00643000 r--s 00000000 00:05 84 /dev/sgx_enclave > 7f8f00643000-7f8f0197b000 r-xs 00000000 00:05 84 /dev/sgx_enclave > 7f8f0197b000-7f8f01bab000 r--s 00000000 00:05 84 /dev/sgx_enclave > 7f8f01bab000-7f8f01fa7000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f01fa7000-7f8f08000000 ---p 00000000 00:00 0 > 7f8f08000000-7f8f08001000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08001000-7f8f08003000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08003000-7f8f08006000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08006000-7f8f0800b000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0800b000-7f8f08014000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08014000-7f8f08025000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08025000-7f8f08046000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08046000-7f8f0804a000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0804a000-7f8f0804b000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0804b000-7f8f0804c000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0804c000-7f8f0804d000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0804d000-7f8f0804e000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0804e000-7f8f0804f000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0804f000-7f8f08050000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08050000-7f8f08051000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08051000-7f8f08052000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08052000-7f8f08053000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08053000-7f8f08054000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08054000-7f8f08055000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08055000-7f8f08056000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08056000-7f8f08057000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08057000-7f8f08058000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08058000-7f8f08059000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08059000-7f8f0805a000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0805a000-7f8f0805b000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0805b000-7f8f0805c000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0805c000-7f8f0805d000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0805d000-7f8f0805e000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0805e000-7f8f0805f000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0805f000-7f8f08060000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08060000-7f8f08062000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08062000-7f8f08063000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08063000-7f8f08064000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08064000-7f8f08065000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08065000-7f8f08066000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08066000-7f8f08067000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08067000-7f8f08068000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08068000-7f8f08069000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08069000-7f8f0806a000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0806a000-7f8f0806b000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0806b000-7f8f0806c000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0806c000-7f8f0806d000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0806d000-7f8f0806e000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0806e000-7f8f0806f000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0806f000-7f8f08070000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08070000-7f8f08071000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08071000-7f8f08072000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08072000-7f8f08081000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08081000-7f8f08082000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08082000-7f8f08083000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08083000-7f8f08084000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08084000-7f8f08085000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08085000-7f8f08086000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08086000-7f8f08087000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08087000-7f8f08088000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08088000-7f8f08089000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08089000-7f8f0808a000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0808a000-7f8f0808b000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0808b000-7f8f0809a000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0809a000-7f8f0809c000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0809c000-7f8f0809d000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0809d000-7f8f0809e000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0809e000-7f8f080a0000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080a0000-7f8f080a3000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080a3000-7f8f080a9000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080a9000-7f8f080b5000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080b5000-7f8f080c0000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080c0000-7f8f080c6000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080c6000-7f8f080d1000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080d1000-7f8f080dd000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080dd000-7f8f080f4000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f080f4000-7f8f08121000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08121000-7f8f0814a000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f0814a000-7f8f08162000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08162000-7f8f08177000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08177000-7f8f081a0000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f081a0000-7f8f081c1000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f081c1000-7f8f081d6000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f081d6000-7f8f081ff000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f081ff000-7f8f08228000 rw-s 00000000 00:05 84 /dev/sgx_enclave > 7f8f08228000-7f8ffffff000 ---p 00000000 00:00 0 > 7f8ffffff000-7f9000000000 rw-s 00000000 00:05 84 /dev/sgx_enclave Just giving ridiculous answer to a ridiculous question. You clearly started commenting w/o reading the original thread. BR, Jarkko
