From: Baoquan He <bhe@redhat.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: linux-kernel@vger.kernel.org, kirill.shutemov@linux.intel.com,
dave.hansen@linux.intel.com, luto@kernel.org,
peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, hpa@zytor.com, x86@kernel.org,
keescook@chromium.org, thgarnie@google.com
Subject: [PATCH v3 0/2] x86/mm/KASLR: Change the granularity of randomization to PUD size in 5-level
Date: Thu, 28 Feb 2019 17:29:13 +0800 [thread overview]
Message-ID: <20190228092913.GR14858@MiWiFi-R3L-srv> (raw)
In-Reply-To: <20190228091001.5wvkwe7cqkf2euzc@kshutemo-mobl1>
The current randomization granularity of 5-level is 512 GB. Improve
it to 1 GB. This can add more randomness to memory region KASLR in
5-level paging mode
Signed-off-by: Baoquan He <bhe@redhat.com>
---
v2->v3:
The v2 was based on another patchset. Rebase it on the latest linus's
tree.
arch/x86/mm/kaslr.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index 4e7f07b466c5..4ef9a27a1361 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -125,10 +125,7 @@ void __init kernel_randomize_memory(void)
*/
entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);
prandom_bytes_state(&rand_state, &rand, sizeof(rand));
- if (pgtable_l5_enabled())
- entropy = (rand % (entropy + 1)) & P4D_MASK;
- else
- entropy = (rand % (entropy + 1)) & PUD_MASK;
+ entropy = (rand % (entropy + 1)) & PUD_MASK;
vaddr += entropy;
*kaslr_regions[i].base = vaddr;
@@ -137,10 +134,7 @@ void __init kernel_randomize_memory(void)
* randomization alignment.
*/
vaddr += get_padding(&kaslr_regions[i]);
- if (pgtable_l5_enabled())
- vaddr = round_up(vaddr + 1, P4D_SIZE);
- else
- vaddr = round_up(vaddr + 1, PUD_SIZE);
+ vaddr = round_up(vaddr + 1, PUD_SIZE);
remain_entropy -= entropy;
}
}
@@ -197,8 +191,8 @@ static void __meminit init_trampoline_pud(void)
* that area. In case KASLR disabled, the 1st PGD entry of the
* direct mapping is copied directly. If KASLR is enabled, only
* copy the 1st PUD entry where physical address 0 resides since
- * the granularity of randomization is PUD size in 4-level, and
- * P4D size in 5-level.
+ * the granularity of randomization is PUD size in both 4-level and
+ * 5-level.
*
* This consumes one low memory page in 4-level case, and extra one
* in 5-level.
--
2.17.2
next prev parent reply other threads:[~2019-02-28 9:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 0:35 [PATCH v2 0/2] x86/mm/KASLR: Change the granularity of randomization to PUD size in 5-level Baoquan He
2019-02-28 0:35 ` [PATCH v2 1/2] x86/mm/KASLR: Only build one PUD entry of area for real mode trampoline Baoquan He
2019-02-28 0:35 ` [PATCH v2 2/2] x86/mm/KASLR: Change the granularity of randomization to PUD size in 5-level Baoquan He
2019-02-28 9:10 ` [PATCH v2 0/2] " Kirill A. Shutemov
2019-02-28 9:23 ` Baoquan He
2019-02-28 9:55 ` Kirill A. Shutemov
2019-02-28 10:04 ` Baoquan He
2019-02-28 10:30 ` Kirill A. Shutemov
2019-02-28 13:01 ` Baoquan He
2019-03-01 14:45 ` Baoquan He
2019-03-04 8:15 ` Kirill A. Shutemov
2019-03-04 8:52 ` Baoquan He
2019-02-28 9:29 ` Baoquan He [this message]
2019-03-08 2:56 [PATCH v3 " Baoquan He
2019-04-04 2:18 ` Baoquan He
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