x86/mm/init32: Mark text and rodata RO in one go (2a25dc7c) · Commits · 戴 / test

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 <rong.a.chen@intel.com> Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Reviewed-by:

Dave Hansen <dave.hansen@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Bin Yang <bin.yang@intel.com> Cc: Mark Gross <mark.gross@intel.com> Link: https://lkml.kernel.org/r/20180917143545.731701535@linutronix.de

arch/x86/mm/init_32.c

+4 −19

Original line number	Diff line number	Diff line
		@@ -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();

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