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From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>,
	linux-kernel@vger.kernel.org, 0x7f454c46@gmail.com,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
	x86@kernel.org, linux-mm@kvack.org
Subject: Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions
Date: Fri, 10 Feb 2017 21:10:30 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.20.1702102057330.4042@nanos> (raw)
In-Reply-To: <20170209135525.qlwrmlo7njk3fsaq@pd.tnic>

On Thu, 9 Feb 2017, Borislav Petkov wrote:
> I can't say that I'm thrilled about the ifdeffery this is adding.
> 
> But I can't think of a cleaner approach at a quick glance, though -
> that's generic and arch-specific code intertwined muck. Sad face.

It's trivial enough to do ....

Thanks,

	tglx

---
 arch/x86/mm/mmap.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
 #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
 #define MAX_GAP (TASK_SIZE/6*5)
 
+#ifndef CONFIG_COMPAT
+# define mmap_rnd_compat_bits	mmap_rnd_bits
+#endif
+
 static int mmap_is_legacy(void)
 {
 	if (current->personality & ADDR_COMPAT_LAYOUT)
@@ -66,20 +70,14 @@ static int mmap_is_legacy(void)
 	return sysctl_legacy_va_layout;
 }
 
-unsigned long arch_mmap_rnd(void)
+static unsigned long arch_rnd(unsigned int rndbits)
 {
-	unsigned long rnd;
-
-	if (mmap_is_ia32())
-#ifdef CONFIG_COMPAT
-		rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
-#else
-		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
-#endif
-	else
-		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
+	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
+}
 
-	return rnd << PAGE_SHIFT;
+unsigned long arch_mmap_rnd(void)
+{
+	return arch_rnd(mmap_is_ia32() ? mmap_rnd_compat_bits : mmap_rnd_bits);
 }
 
 static unsigned long mmap_base(unsigned long rnd)

WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>,
	linux-kernel@vger.kernel.org, 0x7f454c46@gmail.com,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
	x86@kernel.org, linux-mm@kvack.org
Subject: Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions
Date: Fri, 10 Feb 2017 21:10:30 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.20.1702102057330.4042@nanos> (raw)
In-Reply-To: <20170209135525.qlwrmlo7njk3fsaq@pd.tnic>

On Thu, 9 Feb 2017, Borislav Petkov wrote:
> I can't say that I'm thrilled about the ifdeffery this is adding.
> 
> But I can't think of a cleaner approach at a quick glance, though -
> that's generic and arch-specific code intertwined muck. Sad face.

It's trivial enough to do ....

Thanks,

	tglx

---
 arch/x86/mm/mmap.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
 #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
 #define MAX_GAP (TASK_SIZE/6*5)
 
+#ifndef CONFIG_COMPAT
+# define mmap_rnd_compat_bits	mmap_rnd_bits
+#endif
+
 static int mmap_is_legacy(void)
 {
 	if (current->personality & ADDR_COMPAT_LAYOUT)
@@ -66,20 +70,14 @@ static int mmap_is_legacy(void)
 	return sysctl_legacy_va_layout;
 }
 
-unsigned long arch_mmap_rnd(void)
+static unsigned long arch_rnd(unsigned int rndbits)
 {
-	unsigned long rnd;
-
-	if (mmap_is_ia32())
-#ifdef CONFIG_COMPAT
-		rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
-#else
-		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
-#endif
-	else
-		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
+	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
+}
 
-	return rnd << PAGE_SHIFT;
+unsigned long arch_mmap_rnd(void)
+{
+	return arch_rnd(mmap_is_ia32() ? mmap_rnd_compat_bits : mmap_rnd_bits);
 }
 
 static unsigned long mmap_base(unsigned long rnd)

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  parent reply	other threads:[~2017-02-10 20:10 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-30 12:04 [PATCHv4 0/5] Fix compatible mmap() return pointer over 4Gb Dmitry Safonov
2017-01-30 12:04 ` Dmitry Safonov
2017-01-30 12:04 ` [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions Dmitry Safonov
2017-01-30 12:04   ` Dmitry Safonov
2017-02-09 13:55   ` Borislav Petkov
2017-02-09 23:06     ` Andy Lutomirski
2017-02-09 23:06       ` Andy Lutomirski
2017-02-10 20:10     ` Thomas Gleixner [this message]
2017-02-10 20:10       ` Thomas Gleixner
2017-02-10 20:25       ` Borislav Petkov
2017-02-10 20:25         ` Borislav Petkov
2017-02-10 21:28       ` Dmitry Safonov
2017-02-10 21:28         ` Dmitry Safonov
2017-02-11  8:23         ` Thomas Gleixner
2017-02-11  8:23           ` Thomas Gleixner
2017-02-13 11:12           ` Dmitry Safonov
2017-02-13 11:12             ` Dmitry Safonov
2017-02-13 11:22             ` Thomas Gleixner
2017-02-13 11:22               ` Thomas Gleixner
2017-01-30 12:04 ` [PATCHv4 2/5] x86/mm: introduce mmap{,_legacy}_base Dmitry Safonov
2017-01-30 12:04   ` Dmitry Safonov
2017-02-11 14:13   ` Thomas Gleixner
2017-02-11 14:13     ` Thomas Gleixner
2017-02-13 13:02     ` Dmitry Safonov
2017-02-13 13:02       ` Dmitry Safonov
2017-02-13 13:13       ` Thomas Gleixner
2017-02-13 13:13         ` Thomas Gleixner
2017-02-13 14:37     ` Dmitry Safonov
2017-02-13 14:37       ` Dmitry Safonov
2017-02-13 15:35       ` Thomas Gleixner
2017-02-13 15:35         ` Thomas Gleixner
2017-01-30 12:04 ` [PATCHv4 3/5] x86/mm: fix 32-bit mmap() for 64-bit ELF Dmitry Safonov
2017-01-30 12:04   ` Dmitry Safonov
2017-02-11 19:49   ` Thomas Gleixner
2017-02-11 19:49     ` Thomas Gleixner
2017-02-14 15:24     ` Dmitry Safonov
2017-02-14 15:24       ` Dmitry Safonov
2017-01-30 12:04 ` [PATCHv4 4/5] x86/mm: check in_compat_syscall() instead TIF_ADDR32 for mmap(MAP_32BIT) Dmitry Safonov
2017-01-30 12:04   ` Dmitry Safonov
2017-02-11 20:13   ` Thomas Gleixner
2017-02-11 20:13     ` Thomas Gleixner
2017-02-14 16:11     ` Dmitry Safonov
2017-02-14 16:11       ` Dmitry Safonov
2017-02-14 16:14       ` Dmitry Safonov
2017-02-14 16:14         ` Dmitry Safonov
2017-01-30 12:04 ` [PATCHv4 5/5] selftests/x86: add test to check compat mmap() return addr Dmitry Safonov
2017-01-30 12:04   ` Dmitry Safonov
2017-02-06 16:46 ` [PATCHv4 0/5] Fix compatible mmap() return pointer over 4Gb Dmitry Safonov
2017-02-06 16:46   ` Dmitry Safonov

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