Messages in this thread | | | From | Alex Ghiti <> | Subject | Re: [PATCH v6 14/14] riscv: Make mmap allocation top-down by default | Date | Tue, 8 Oct 2019 05:19:16 -0400 |
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On 10/7/19 5:11 AM, Alex Ghiti wrote: > On 10/4/19 10:12 PM, Atish Patra wrote: >> On Thu, 2019-08-08 at 02:17 -0400, Alexandre Ghiti wrote: >>> In order to avoid wasting user address space by using bottom-up mmap >>> allocation scheme, prefer top-down scheme when possible. >>> >>> Before: >>> root@qemuriscv64:~# cat /proc/self/maps >>> 00010000-00016000 r-xp 00000000 fe:00 6389 /bin/cat.coreutils >>> 00016000-00017000 r--p 00005000 fe:00 6389 /bin/cat.coreutils >>> 00017000-00018000 rw-p 00006000 fe:00 6389 /bin/cat.coreutils >>> 00018000-00039000 rw-p 00000000 00:00 0 [heap] >>> 1555556000-155556d000 r-xp 00000000 fe:00 7193 /lib/ld-2.28.so >>> 155556d000-155556e000 r--p 00016000 fe:00 7193 /lib/ld-2.28.so >>> 155556e000-155556f000 rw-p 00017000 fe:00 7193 /lib/ld-2.28.so >>> 155556f000-1555570000 rw-p 00000000 00:00 0 >>> 1555570000-1555572000 r-xp 00000000 00:00 0 [vdso] >>> 1555574000-1555576000 rw-p 00000000 00:00 0 >>> 1555576000-1555674000 r-xp 00000000 fe:00 7187 /lib/libc-2.28.so >>> 1555674000-1555678000 r--p 000fd000 fe:00 7187 /lib/libc-2.28.so >>> 1555678000-155567a000 rw-p 00101000 fe:00 7187 /lib/libc-2.28.so >>> 155567a000-15556a0000 rw-p 00000000 00:00 0 >>> 3fffb90000-3fffbb1000 rw-p 00000000 00:00 0 [stack] >>> >>> After: >>> root@qemuriscv64:~# cat /proc/self/maps >>> 00010000-00016000 r-xp 00000000 fe:00 6389 /bin/cat.coreutils >>> 00016000-00017000 r--p 00005000 fe:00 6389 /bin/cat.coreutils >>> 00017000-00018000 rw-p 00006000 fe:00 6389 /bin/cat.coreutils >>> 2de81000-2dea2000 rw-p 00000000 00:00 0 [heap] >>> 3ff7eb6000-3ff7ed8000 rw-p 00000000 00:00 0 >>> 3ff7ed8000-3ff7fd6000 r-xp 00000000 fe:00 7187 /lib/libc-2.28.so >>> 3ff7fd6000-3ff7fda000 r--p 000fd000 fe:00 7187 /lib/libc-2.28.so >>> 3ff7fda000-3ff7fdc000 rw-p 00101000 fe:00 7187 /lib/libc-2.28.so >>> 3ff7fdc000-3ff7fe2000 rw-p 00000000 00:00 0 >>> 3ff7fe4000-3ff7fe6000 r-xp 00000000 00:00 0 [vdso] >>> 3ff7fe6000-3ff7ffd000 r-xp 00000000 fe:00 7193 /lib/ld-2.28.so >>> 3ff7ffd000-3ff7ffe000 r--p 00016000 fe:00 7193 /lib/ld-2.28.so >>> 3ff7ffe000-3ff7fff000 rw-p 00017000 fe:00 7193 /lib/ld-2.28.so >>> 3ff7fff000-3ff8000000 rw-p 00000000 00:00 0 >>> 3fff888000-3fff8a9000 rw-p 00000000 00:00 0 [stack] >>> >>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> >>> Acked-by: Paul Walmsley <paul.walmsley@sifive.com> >>> Reviewed-by: Christoph Hellwig <hch@lst.de> >>> Reviewed-by: Kees Cook <keescook@chromium.org> >>> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> >>> --- >>> arch/riscv/Kconfig | 12 ++++++++++++ >>> 1 file changed, 12 insertions(+) >>> >>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig >>> index 59a4727ecd6c..87dc5370becb 100644 >>> --- a/arch/riscv/Kconfig >>> +++ b/arch/riscv/Kconfig >>> @@ -54,6 +54,18 @@ config RISCV >>> select EDAC_SUPPORT >>> select ARCH_HAS_GIGANTIC_PAGE >>> select ARCH_WANT_HUGE_PMD_SHARE if 64BIT >>> + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU >>> + select HAVE_ARCH_MMAP_RND_BITS >>> + >>> +config ARCH_MMAP_RND_BITS_MIN >>> + default 18 if 64BIT >>> + default 8 >>> + >>> +# max bits determined by the following formula: >>> +# VA_BITS - PAGE_SHIFT - 3 >>> +config ARCH_MMAP_RND_BITS_MAX >>> + default 24 if 64BIT # SV39 based >>> + default 17 >>> config MMU >>> def_bool y >> With this patch, I am not able to boot a Fedora Linux(a Gnome desktop >> image) on RISC-V hardware (Unleashed + Microsemi Expansion board). The >> booting gets stuck right after systemd starts. >> >> https://paste.fedoraproject.org/paste/TOrUMqqKH-pGFX7CnfajDg >> >> Reverting just this patch allow to boot Fedora successfully on specific >> RISC-V hardware. I have not root caused the issue but it looks like it >> might have messed userpsace mapping. > > It might have messed userspace mapping but not enough to make > userspace completely broken > as systemd does some things. I would try to boot in legacy layout: if > you can try to set sysctl legacy_va_layout > at boottime, it will map userspace as it was before (bottom-up). If > that does not work, the problem could > be the randomization that is activated by default now. > Anyway, it's weird since userspace should not depend on how the > mapping is. > > If you can identify the program that stalls, that would be fantastic :) > > As the code is common to mips and arm now and I did not hear from > them, I imagine the problem comes > from us. > > Alex
Atish, do you have any news regarding this problem ? If you have an image I can execute on qemu that reproduces the issue, I can take a look.
Alex
>> >
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