From: Masayoshi Mizuma <msys.mizuma@gmail.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Baoquan He <bhe@redhat.com>,
Borislav Petkov <bp@alien8.de>
Cc: Masayoshi Mizuma <msys.mizuma@gmail.com>, linux-kernel@vger.kernel.org
Subject: [PATCH v6 1/3] x86/mm: Add a kernel parameter to change the padding used for the physical memory mapping
Date: Tue, 2 Oct 2018 21:33:21 -0400 [thread overview]
Message-ID: <20181003013323.4162-2-msys.mizuma@gmail.com> (raw)
In-Reply-To: <20181003013323.4162-1-msys.mizuma@gmail.com>
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>
---
arch/x86/include/asm/setup.h | 9 +++++++++
arch/x86/mm/kaslr.c | 22 +++++++++++++++++++++-
2 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index ae13bc9..1765a15 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -80,6 +80,15 @@ static inline unsigned long kaslr_offset(void)
return (unsigned long)&_text - __START_KERNEL;
}
+#ifdef CONFIG_RANDOMIZE_MEMORY
+extern inline int __init get_rand_mem_physical_padding(void);
+#else
+static inline int __init get_rand_mem_physical_padding(void)
+{
+ return 0;
+}
+#endif
+
/*
* Do NOT EVER look at the BIOS memory size location.
* It does not work on many machines.
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index 61db77b..eb47f05 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;
+static int rand_mem_physical_padding __initdata = 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 +70,25 @@ static inline bool kaslr_memory_enabled(void)
return kaslr_enabled() && !IS_ENABLED(CONFIG_KASAN);
}
+inline int __init get_rand_mem_physical_padding(void)
+{
+ return rand_mem_physical_padding;
+}
+
+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 +122,7 @@ 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;
+ get_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:[~2018-10-03 1:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 1:33 [PATCH v6 0/3] Add a kernel parameter to change the padding size for KASLR Masayoshi Mizuma
2018-10-03 1:33 ` Masayoshi Mizuma [this message]
2018-10-03 1:33 ` [PATCH v6 2/3] ACPI/NUMA: Add warning message if the padding size for KASLR is not enough Masayoshi Mizuma
2018-10-03 1:33 ` [PATCH v6 3/3] Documentation/kernel-parameters.txt: Document rand_mem_physical_padding= Masayoshi Mizuma
2018-10-03 6:52 ` [PATCH v6 0/3] Add a kernel parameter to change the padding size for KASLR Ingo Molnar
2018-10-03 11:00 ` Masayoshi Mizuma
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