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0002-x86-mm-init32-Mark-text-and-rodata-RO-in-one-go.patch
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0002-x86-mm-init32-Mark-text-and-rodata-RO-in-one-go.patch
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From e0bd44ca27e84f9650bf7e2b2ef748c24455138e Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <[email protected]>
Date: Mon, 17 Sep 2018 16:29:07 +0200
Subject: [PATCH 02/12] x86/mm/init32: Mark text and rodata RO in one go
The sequence of marking text and rodata read-only in 32bit init is:
set_ro(text);
kernel_set_to_readonly = 1;
set_ro(rodata);
When kernel_set_to_readonly is 1 it enables the protection mechanism in CPA
for the read only regions. With the upcoming checks for existing mappings
this consequently triggers the warning about an existing mapping being
incorrect vs. static protections because rodata has not been converted yet.
There is no technical reason to split the two, so just combine the RO
protection to convert text and rodata in one go.
Convert the printks to pr_info while at it.
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Dave Hansen <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Bin Yang <[email protected]>
Cc: Mark Gross <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Cc: Zhang Ning <[email protected]>
Signed-off-by: Lili Li <[email protected]>
---
arch/x86/mm/init_32.c | 23 ++++-------------------
1 file changed, 4 insertions(+), 19 deletions(-)
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 979e0a02cbe1..142c7d9f89cc 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -923,34 +923,19 @@ static void mark_nxdata_nx(void)
void mark_rodata_ro(void)
{
unsigned long start = PFN_ALIGN(_text);
- unsigned long size = PFN_ALIGN(_etext) - start;
+ unsigned long size = (unsigned long)__end_rodata - start;
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
- printk(KERN_INFO "Write protecting the kernel text: %luk\n",
+ pr_info("Write protecting kernel text and read-only data: %luk\n",
size >> 10);
kernel_set_to_readonly = 1;
#ifdef CONFIG_CPA_DEBUG
- printk(KERN_INFO "Testing CPA: Reverting %lx-%lx\n",
- start, start+size);
- set_pages_rw(virt_to_page(start), size>>PAGE_SHIFT);
-
- printk(KERN_INFO "Testing CPA: write protecting again\n");
- set_pages_ro(virt_to_page(start), size>>PAGE_SHIFT);
-#endif
-
- start += size;
- size = (unsigned long)__end_rodata - start;
- set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
- printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
- size >> 10);
-
-#ifdef CONFIG_CPA_DEBUG
- printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, start + size);
+ pr_info("Testing CPA: Reverting %lx-%lx\n", start, start + size);
set_pages_rw(virt_to_page(start), size >> PAGE_SHIFT);
- printk(KERN_INFO "Testing CPA: write protecting again\n");
+ pr_info("Testing CPA: write protecting again\n");
set_pages_ro(virt_to_page(start), size >> PAGE_SHIFT);
#endif
mark_nxdata_nx();
--
2.19.1