diff mbox series

[v3,11/11] riscv: Make mmap allocation top-down by default

Message ID 20190417052247.17809-12-alex@ghiti.fr (mailing list archive)
State New, archived
Headers show
Series Provide generic top-down mmap layout functions | expand

Commit Message

Alexandre Ghiti April 17, 2019, 5:22 a.m. UTC 
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
00018000-00039000 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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 arch/riscv/Kconfig | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Kees Cook April 18, 2019, 5:31 a.m. UTC | #1 
On Wed, Apr 17, 2019 at 12:34 AM Alexandre Ghiti <alex@ghiti.fr> 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
> 00018000-00039000 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>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  arch/riscv/Kconfig | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index eb56c82d8aa1..f5897e0dbc1c 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -49,6 +49,17 @@ config RISCV
>         select GENERIC_IRQ_MULTI_HANDLER
>         select ARCH_HAS_PTE_SPECIAL
>         select HAVE_EBPF_JIT 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
> +
> +# max bits determined by the following formula:
> +#  VA_BITS - PAGE_SHIFT - 3
> +config ARCH_MMAP_RND_BITS_MAX
> +       default 33 if 64BIT # SV48 based
> +       default 18
>
>  config MMU
>         def_bool y
> --
> 2.20.1
>
Alexandre Ghiti April 18, 2019, 6:09 a.m. UTC | #2 
On 4/18/19 1:31 AM, Kees Cook wrote:
> On Wed, Apr 17, 2019 at 12:34 AM Alexandre Ghiti <alex@ghiti.fr> 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
>> 00018000-00039000 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>
>> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Reviewed-by: Kees Cook <keescook@chromium.org>


Thank you very much for all your comments,

Alex


>
> -Kees
>
>> ---
>>   arch/riscv/Kconfig | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index eb56c82d8aa1..f5897e0dbc1c 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -49,6 +49,17 @@ config RISCV
>>          select GENERIC_IRQ_MULTI_HANDLER
>>          select ARCH_HAS_PTE_SPECIAL
>>          select HAVE_EBPF_JIT 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
>> +
>> +# max bits determined by the following formula:
>> +#  VA_BITS - PAGE_SHIFT - 3
>> +config ARCH_MMAP_RND_BITS_MAX
>> +       default 33 if 64BIT # SV48 based
>> +       default 18
>>
>>   config MMU
>>          def_bool y
>> --
>> 2.20.1
>>
>
Christoph Hellwig April 22, 2019, 7:56 p.m. UTC | #3 
Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>
diff mbox series

Patch

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index eb56c82d8aa1..f5897e0dbc1c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -49,6 +49,17 @@  config RISCV
 	select GENERIC_IRQ_MULTI_HANDLER
 	select ARCH_HAS_PTE_SPECIAL
 	select HAVE_EBPF_JIT 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
+
+# max bits determined by the following formula:
+#  VA_BITS - PAGE_SHIFT - 3
+config ARCH_MMAP_RND_BITS_MAX
+	default 33 if 64BIT # SV48 based
+	default 18
 
 config MMU
 	def_bool y