From: Masayoshi Mizuma <msys.mizuma@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Baoquan He <bhe@redhat.com>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>,
Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v4 1/3] x86/mm: Add a kernel parameter to change the padding used for the physical memory mapping
Date: Thu, 27 Sep 2018 16:31:44 -0400 [thread overview]
Message-ID: <20180927203146.12201-2-msys.mizuma@gmail.com> (raw)
In-Reply-To: <20180927203146.12201-1-msys.mizuma@gmail.com>
From: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
If the physical memory layout has huge space for memory hotplug,
the padding used for the physical memory mapping section is not enough.
For example 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 by CONFIG_RANDOMIZE_MEMORY_PHYSICAL_PADDING,
however, the needed padding size depends on the physical memory layout
defined by SRAT. 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>
---
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 61db77b..00cf4ca 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)
--
2.18.0
next prev parent reply other threads:[~2018-09-27 20:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-27 20:31 [PATCH v4 0/3] Add a kernel parameter to change the padding size for KASLR Masayoshi Mizuma
2018-09-27 20:31 ` Masayoshi Mizuma [this message]
2018-09-27 20:31 ` [PATCH v4 2/3] ACPI / NUMA: Add warning message if the padding size for KASLR is not enough Masayoshi Mizuma
2018-09-27 21:14 ` Borislav Petkov
2018-09-28 2:21 ` Masayoshi Mizuma
2018-09-28 2:48 ` Baoquan He
2018-09-28 14:26 ` Masayoshi Mizuma
2018-09-27 20:31 ` [PATCH v4 3/3] docs: kernel-parameters.txt: document rand_mem_physical_padding parameter Masayoshi Mizuma
2018-09-27 21:17 ` Borislav Petkov
2018-09-28 2:26 ` Masayoshi Mizuma
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