The patch titled
Subject: riscv: make mmap allocation top-down by default
has been added to the -mm tree. Its filename is
riscv-make-mmap-allocation-top-down-by-default.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/riscv-make-mmap-allocation-top-down-by-default.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/riscv-make-mmap-allocation-top-down-by-default.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Alexandre Ghiti <alex@xxxxxxxx>
Subject: riscv: make mmap allocation top-down by default
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]
Link: http://lkml.kernel.org/r/20190730055113.23635-15-alex@xxxxxxxx
Signed-off-by: Alexandre Ghiti <alex@xxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxx>
Cc: Paul Burton <paul.burton@xxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/riscv/Kconfig | 13 +++++++++++++
1 file changed, 13 insertions(+)
--- a/arch/riscv/Kconfig~riscv-make-mmap-allocation-top-down-by-default
+++ a/arch/riscv/Kconfig
@@ -54,6 +54,19 @@ 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 33 if RISCV_VM_SV48
+ default 24 if RISCV_VM_SV39
+ default 17 if RISCV_VM_SV32
config MMU
def_bool y
_
Patches currently in -mm which might be from alex@xxxxxxxx are
mm-fs-move-randomize_stack_top-from-fs-to-mm.patch
arm64-make-use-of-is_compat_task-instead-of-hardcoding-this-test.patch
arm64-consider-stack-randomization-for-mmap-base-only-when-necessary.patch
arm64-mm-move-generic-mmap-layout-functions-to-mm.patch
arm64-mm-make-randomization-selected-by-generic-topdown-mmap-layout.patch
arm-properly-account-for-stack-randomization-and-stack-guard-gap.patch
arm-use-stack_top-when-computing-mmap-base-address.patch
arm-use-generic-mmap-top-down-layout-and-brk-randomization.patch
mips-properly-account-for-stack-randomization-and-stack-guard-gap.patch
mips-use-stack_top-when-computing-mmap-base-address.patch
mips-adjust-brk-randomization-offset-to-fit-generic-version.patch
mips-replace-arch-specific-way-to-determine-32bit-task-with-generic-version.patch
mips-use-generic-mmap-top-down-layout-and-brk-randomization.patch
riscv-make-mmap-allocation-top-down-by-default.patch
