From: Alexandre Ghiti <alex@ghiti.fr>
To: Christoph Hellwig <hch@infradead.org>,
Russell King <linux@armlinux.org.uk>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Ralf Baechle <ralf@linux-mips.org>,
Paul Burton <paul.burton@mips.com>,
James Hogan <jhogan@kernel.org>,
Palmer Dabbelt <palmer@sifive.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Luis Chamberlain <mcgrof@kernel.org>,
Kees Cook <keescook@chromium.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org
Cc: Alexandre Ghiti <alex@ghiti.fr>
Subject: [PATCH 4/4] riscv: Make mmap allocation top-down by default
Date: Fri, 22 Mar 2019 03:42:25 -0400 [thread overview]
Message-ID: <20190322074225.22282-5-alex@ghiti.fr> (raw)
In-Reply-To: <20190322074225.22282-1-alex@ghiti.fr>
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>
---
arch/riscv/Kconfig | 12 ++++++++++++
arch/riscv/include/asm/processor.h | 1 +
2 files changed, 13 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index eb56c82d8aa1..7661335d1667 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -50,6 +50,18 @@ config RISCV
select ARCH_HAS_PTE_SPECIAL
select HAVE_EBPF_JIT if 64BIT
+config HAVE_ARCH_MMAP_RND_BITS
+ def_bool y
+
+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
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index ce70bceb8872..e68a1b1e144a 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -23,6 +23,7 @@
* space during mmap's.
*/
#define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE / 3)
+#define ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
#define STACK_TOP TASK_SIZE
#define STACK_TOP_MAX STACK_TOP
--
2.20.1
next prev parent reply other threads:[~2019-03-22 7:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-22 7:42 [PATCH 0/4] Provide generic top-down mmap layout functions Alexandre Ghiti
2019-03-22 7:42 ` [PATCH 1/4] arm64, mm: Move generic mmap layout functions to mm Alexandre Ghiti
2019-03-22 13:21 ` Christoph Hellwig
2019-03-23 8:18 ` Alex Ghiti
2019-03-22 7:42 ` [PATCH 2/4] arm: Use generic mmap top-down layout Alexandre Ghiti
2019-03-22 7:42 ` [PATCH 3/4] mips: " Alexandre Ghiti
2019-03-22 7:42 ` Alexandre Ghiti [this message]
2019-03-22 13:22 ` [PATCH 4/4] riscv: Make mmap allocation top-down by default Christoph Hellwig
2019-03-23 8:05 ` Alex Ghiti
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