x86/pti: Fix boot warning from Global-bit setting (58e65b51) · Commits · 戴 / test

commit 231df823c4f04176f607afc4576c989895cff40e The pageattr.c code attempts to process "faults" when it goes looking for PTEs to change and finds non-present entries. It allows these faults in the linear map which is "expected to have holes", but WARN()s about them elsewhere, like when called on the kernel image. However, change_page_attr_clear() is now called on the kernel image in the process of trying to clear the Global bit. This trips the warning in __cpa_process_fault() if a non-present PTE is encountered in the kernel image. The "holes" in the kernel image result from free_init_pages()'s use of set_memory_np(). These holes are totally fine, and result from normal operation, just as they would be in the kernel linear map. Just silence the warning when holes in the kernel image are encountered. Fixes: (x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image) Reported-by:

Mariusz Ceier <mceier@gmail.com> Reported-by:

Aaro Koskinen <aaro.koskinen@nokia.com> Signed-off-by:

Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by:

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

Aaro Koskinen <aaro.koskinen@nokia.com> Acked-by:

Ingo Molnar <mingo@kernel.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Nadav Amit <namit@vmware.com> Cc: Kees Cook <keescook@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Link: https://lkml.kernel.org/r/20180420222021.1C7D2B3F@viggo.jf.intel.com

arch/x86/mm/pageattr.c

+30 −10

Original line number	Diff line number	Diff line
		@@ -93,6 +93,18 @@ void arch_report_meminfo(struct seq_file *m)
		static inline void split_page_count(int level) { }
		#endif

		static inline int
		within(unsigned long addr, unsigned long start, unsigned long end)
		{
		return addr >= start && addr < end;
		}

		static inline int
		within_inclusive(unsigned long addr, unsigned long start, unsigned long end)
		{
		return addr >= start && addr <= end;
		}

		#ifdef CONFIG_X86_64

		static inline unsigned long highmap_start_pfn(void)
		@@ -106,20 +118,25 @@ static inline unsigned long highmap_end_pfn(void)
		return __pa_symbol(roundup(_brk_end, PMD_SIZE) - 1) >> PAGE_SHIFT;
		}

		#endif

		static inline int
		within(unsigned long addr, unsigned long start, unsigned long end)
		static bool __cpa_pfn_in_highmap(unsigned long pfn)
		{
		return addr >= start && addr < end;
		/*
		* Kernel text has an alias mapping at a high address, known
		* here as "highmap".
		*/
		return within_inclusive(pfn, highmap_start_pfn(), highmap_end_pfn());
		}

		static inline int
		within_inclusive(unsigned long addr, unsigned long start, unsigned long end)
		#else

		static bool __cpa_pfn_in_highmap(unsigned long pfn)
		{
		return addr >= start && addr <= end;
		/* There is no highmap on 32-bit */
		return false;
		}

		#endif

		/*
		* Flushing functions
		*/
		@@ -1183,6 +1200,10 @@ static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr,
		cpa->numpages = 1;
		cpa->pfn = __pa(vaddr) >> PAGE_SHIFT;
		return 0;

		} else if (__cpa_pfn_in_highmap(cpa->pfn)) {
		/* Faults in the highmap are OK, so do not warn: */
		return -EFAULT;
		} else {
		WARN(1, KERN_WARNING "CPA: called for zero pte. "
		"vaddr = %lx cpa->vaddr = %lx\n", vaddr,
		@@ -1335,8 +1356,7 @@ static int cpa_process_alias(struct cpa_data *cpa)
		* to touch the high mapped kernel as well:
		*/
		if (!within(vaddr, (unsigned long)_text, _brk_end) &&
		within_inclusive(cpa->pfn, highmap_start_pfn(),
		highmap_end_pfn())) {
		__cpa_pfn_in_highmap(cpa->pfn)) {
		unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) +
		__START_KERNEL_map - phys_base;
		alias_cpa = *cpa;

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