Le 16/01/2023 à 21:08, Geoff Levand a écrit : > Hi, > > On 1/15/23 16:06, Michael Ellerman wrote: >> Geoff Levand <ge...@infradead.org> writes: >>> On 1/9/23 09:41, Christophe Leroy wrote: >>>> >>>> >>>> Le 03/01/2023 à 18:51, Geoff Levand a écrit : >>>>> Commit fdacae8a84024474afff234bdd1dbe19ad597a10 (powerpc: Activate >>>>> CONFIG_STRICT_KERNEL_RWX by default) causes ps3_hpte_updateboltedpp() >>>>> to be called. Change the panic statment in ps3_hpte_updateboltedpp() >>>>> to a pr_info statement so that bootup can continue. >>>> >>>> But if I understand correctly, it means that CONFIG_STRICT_KERNEL_RWX >>>> won't work then. >>>> >>>> So, shouldn't we keep the panic and forbid CONFIG_STRICT_KERNEL_RWX on PS3 >>>> ? >>> >>> mmu_hash_ops.updateboltedpp returns void, so I can't return an error code to >>> indicate the feature is not supported. >> >> We could change that in the medium term. >> >>> I could do something like this in arch/powerpc/Kconfig: >>> >>> - select ARCH_HAS_STRICT_KERNEL_RWX if (PPC_BOOK3S || PPC_8xx >>> || 40x) && !HIBERNATION >>> + select ARCH_HAS_STRICT_KERNEL_RWX if (PPC_BOOK3S || PPC_8xx >>> || 40x) && !PPC_PS3 && !HIBERNATION >>> >>> But then the ppc64_defconfig would be built without STRICT_KERNEL_RWX. >> >> Yeah that would be a pity. >> >> We could do the above and disable PS3 in ppc64_defconfig, allowing >> ppc64_defconfig to still have STRICT_KERNEL_RWX. > > I really want to keep PS3 included in ppc64_defconfig. Not that I expect > anyone to boot a ppc64_defconfig kernel on PS3, but that is one of the > 'standard' configs that is built by some automated builders, and generally by > anyone doing changes to the powerpc arch, and I want to keep getting those > build tests for PS3. > >> I assume actual PS3 users would use a ps3_defconfig anyway right? > > Yeah, a derivative of it. They are most likely are using 'Jailbreak' firmware > that allows them to run Linux in the gameos partition. > >> Relatedly are there any actual PS3 users left? ;) > > It seems there are more users now than a few years ago. I think they buy PS5s > to play the latest games, and use their old console to mess around with Linux. > I generally get a private inquiry every 3 or 4 weeks. Usually asking how to > update their kernel, or how to install a modern distro. > >>> What other 'clean' way is there? >> >> If we want to have a multi-platform kernel image that can boot on PS3 >> and other platforms, and have strict kernel RWX, then we need some >> runtime logic to deal with that. >> >> I'd rather not do that though, because it adds complexity to deal with a >> pretty obscure corner case, and I suspect no one really boots a >> ppc64_defconfig on actual PS3 hardware these days. >> >> So my preference is we disable PS3 in ppc64_defconfig, and make PS3 >> incompatible with STRICT_KERNEL_RWX. > > As mentioned, I'd really like to keep PS3 included in ppc64_defconfig. My > original patch that basically just ignores the call to > mmu_hash_ops.updateboltedpp allows that, and I haven't experienced any > problems > with it yet.
When you say you have not experienced any problems with it, do you mean that STRICT_RWX works for you ? When you select CONFIG_DEBUG_RODATA_TEST it tells you that it works ? Otherwise it looks incorrect to enable something that doesn't work. > > My preference would be to keep PS3 in ppc64_defconfig, and either apply my > original patch, or I keep that patch in my ps3-linux repo on kernel.org. Then, > if we end up adding runtime support for RWX I then fixup PS3 to use that. > In that case I see two solutions: 1/ Implement updateboltedpp for PS3. 2/ Implement arch_parse_debug_rodata() to always set rodata_enabled = false on PS3, and update free_initmem() to only call mark_initmem_nx() when strict_kernel_rwx_enabled() returns true. Christophe
