lkml.org 
[lkml]   [2017]   [Jan]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCHv2 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions
Date
I need those arch_{native,compat}_rnd() to compute separately
random factor for mmap() in compat syscalls for 64-bit binaries
and vice-versa for native syscall in 32-bit compat binaries.
They will be used in the following patches.

Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
---
arch/x86/include/asm/elf.h | 5 +++++
arch/x86/mm/mmap.c | 25 ++++++++++++++++---------
2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index e7f155c3045e..ee1a87782b2c 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -349,6 +349,11 @@ static inline int mmap_is_ia32(void)
test_thread_flag(TIF_ADDR32));
}

+#ifdef CONFIG_COMPAT
+extern unsigned long arch_compat_rnd(void);
+#endif
+extern unsigned long arch_native_rnd(void);
+
/* Do not change the values. See get_align_mask() */
enum align_flags {
ALIGN_VA_32 = BIT(0),
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index d2dc0438d654..0b2007b08194 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -65,20 +65,27 @@ static int mmap_is_legacy(void)
return sysctl_legacy_va_layout;
}

-unsigned long arch_mmap_rnd(void)
+#ifdef CONFIG_COMPAT
+unsigned long arch_compat_rnd(void)
{
- unsigned long rnd;
+ return (get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1))
+ << PAGE_SHIFT;
+}
+#endif

- if (mmap_is_ia32())
+unsigned long arch_native_rnd(void)
+{
+ return (get_random_long() & ((1UL << mmap_rnd_bits) - 1)) << PAGE_SHIFT;
+}
+
+unsigned long arch_mmap_rnd(void)
+{
#ifdef CONFIG_COMPAT
- rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
-#else
- rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
+ if (mmap_is_ia32())
+ return arch_compat_rnd();
#endif
- else
- rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);

- return rnd << PAGE_SHIFT;
+ return arch_native_rnd();
}

static unsigned long mmap_base(unsigned long rnd)
--
2.11.0
\
 
 \ /
  Last update: 2017-01-16 13:40    [W:0.140 / U:21.916 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site