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From: tip-bot for Masayoshi Mizuma <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, tglx@linutronix.de, peterz@infradead.org,
	m.mizuma@jp.fujitsu.com, bhe@redhat.com,
	linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
	msys.mizuma@gmail.com, hpa@zytor.com, bp@alien8.de
Subject: [tip:x86/boot] x86/mm: Add a kernel parameter to change the padding used for the physical memory mapping
Date: Tue, 2 Oct 2018 03:18:08 -0700	[thread overview]
Message-ID: <tip-e79ac9354cf95d75ff6afd341f9c5aa5cbcd638b@git.kernel.org> (raw)
In-Reply-To: <20181001140843.26137-2-msys.mizuma@gmail.com>

Commit-ID:  e79ac9354cf95d75ff6afd341f9c5aa5cbcd638b
Gitweb:     https://git.kernel.org/tip/e79ac9354cf95d75ff6afd341f9c5aa5cbcd638b
Author:     Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
AuthorDate: Mon, 1 Oct 2018 10:08:41 -0400
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 2 Oct 2018 11:47:20 +0200

x86/mm: Add a kernel parameter to change the padding used for the physical memory mapping

If each node of physical memory layout has huge space for hotplug,
the padding used for the physical memory mapping section is not enough.
For exapmle of the layout:

  SRAT: Node 6 PXM 4 [mem 0x100000000000-0x13ffffffffff] hotplug
  SRAT: Node 7 PXM 5 [mem 0x140000000000-0x17ffffffffff] hotplug
  SRAT: Node 2 PXM 6 [mem 0x180000000000-0x1bffffffffff] hotplug
  SRAT: Node 3 PXM 7 [mem 0x1c0000000000-0x1fffffffffff] hotplug

We can increase the padding via CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING,
however, the needed padding size depends on the system environment.
The kernel option is better than changing the config.

Signed-off-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181001140843.26137-2-msys.mizuma@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/kaslr.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index 61db77b0eda9..00cf4cae38f5 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -40,6 +40,7 @@
  */
 static const unsigned long vaddr_end = CPU_ENTRY_AREA_BASE;
 
+int __initdata rand_mem_physical_padding = CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
 /*
  * Memory regions randomized by KASLR (except modules that use a separate logic
  * earlier during boot). The list is ordered based on virtual addresses. This
@@ -69,6 +70,20 @@ static inline bool kaslr_memory_enabled(void)
 	return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN);
 }
 
+static int __init rand_mem_physical_padding_setup(char *str)
+{
+	int max_padding = (1 << (MAX_PHYSMEM_BITS - TB_SHIFT)) - 1;
+
+	get_option(&str, &rand_mem_physical_padding);
+	if (rand_mem_physical_padding < 0)
+		rand_mem_physical_padding = 0;
+	else if (rand_mem_physical_padding > max_padding)
+		rand_mem_physical_padding = max_padding;
+
+	return 0;
+}
+early_param("rand_mem_physical_padding", rand_mem_physical_padding_setup);
+
 /* Initialize base and padding for each memory region randomized with KASLR */
 void __init kernel_randomize_memory(void)
 {
@@ -102,7 +117,7 @@ void __init kernel_randomize_memory(void)
 	 */
 	BUG_ON(kaslr_regions[0].base != &page_offset_base);
 	memory_tb = DIV_ROUND_UP(max_pfn << PAGE_SHIFT, 1UL << TB_SHIFT) +
-		CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING;
+		rand_mem_physical_padding;
 
 	/* Adapt phyiscal memory region size based on available memory */
 	if (memory_tb < kaslr_regions[0].size_tb)

  reply	other threads:[~2018-10-02 10:18 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-01 14:08 [PATCH v5 0/3] Add a kernel parameter to change the padding size for KASLR Masayoshi Mizuma
2018-10-01 14:08 ` [PATCH v5 1/3] x86/mm: Add a kernel parameter to change the padding used for the physical memory mapping Masayoshi Mizuma
2018-10-02 10:18   ` tip-bot for Masayoshi Mizuma [this message]
2018-10-01 14:08 ` [PATCH v5 2/3] ACPI / NUMA: Add warning message if the padding size for KASLR is not enough Masayoshi Mizuma
2018-10-02 10:18   ` [tip:x86/boot] ACPI/NUMA: " tip-bot for Masayoshi Mizuma
2018-10-02 15:05     ` Borislav Petkov
2018-10-02 21:19       ` Masayoshi Mizuma
2018-10-03 10:58     ` Masayoshi Mizuma
2018-10-03 12:34     ` Peter Zijlstra
2018-10-03 12:48       ` Borislav Petkov
2018-10-03 13:02         ` Masayoshi Mizuma
2018-10-03 14:21       ` [tip:x86/boot] x86/kaslr, ACPI/NUMA: Fix KASLR build error tip-bot for Peter Zijlstra (Intel)
2018-10-08 11:03         ` Naresh Kamboju
2018-10-08 13:01           ` Borislav Petkov
2018-10-08 13:48             ` Arnd Bergmann
2018-10-08 14:10               ` Borislav Petkov
2018-10-09 10:39       ` tip-bot for Peter Zijlstra (Intel)
2018-10-01 14:08 ` [PATCH v5 3/3] docs: kernel-parameters.txt: document rand_mem_physical_padding Masayoshi Mizuma
2018-10-02 10:19   ` [tip:x86/boot] Documentation/kernel-parameters.txt: Document rand_mem_physical_padding= tip-bot for Masayoshi Mizuma

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