Merge "arm64: mm: allow enforcing of strict break-before-make for page tables" (63eeb69d) · Commits · e / devices / android_kernel_fairphone_FP4

arch/arm64/Kconfig.debug

+3 −0

Original line number	Original line	Diff line number	Diff line
	@@ -96,6 +96,9 @@ config ARM64_RELOC_TEST
	depends on m		depends on m
	tristate "Relocation testing module"		tristate "Relocation testing module"

			config ARM64_STRICT_BREAK_BEFORE_MAKE
			bool "Enforce strict break-before-make on page table updates "

	source "drivers/hwtracing/coresight/Kconfig"		source "drivers/hwtracing/coresight/Kconfig"

	endmenu		endmenu

+29 −0

Original line number	Original line	Diff line number	Diff line
	@@ -19,6 +19,7 @@
	#include <asm/bug.h>		#include <asm/bug.h>
	#include <asm/proc-fns.h>		#include <asm/proc-fns.h>

			#include <asm/bug.h>
	#include <asm/memory.h>		#include <asm/memory.h>
	#include <asm/pgtable-hwdef.h>		#include <asm/pgtable-hwdef.h>
	#include <asm/pgtable-prot.h>		#include <asm/pgtable-prot.h>
	@@ -218,6 +219,34 @@ static inline pmd_t pmd_mkcont(pmd_t pmd)

	static inline void set_pte(pte_t *ptep, pte_t pte)		static inline void set_pte(pte_t *ptep, pte_t pte)
	{		{
			#ifdef CONFIG_ARM64_STRICT_BREAK_BEFORE_MAKE
			pteval_t old = pte_val(*ptep);
			pteval_t new = pte_val(pte);

			/* Only problematic if valid -> valid */
			if (!(old & new & PTE_VALID))
			goto pte_ok;

			/* Changing attributes should go via an invalid entry */
			if (WARN_ON((old & PTE_ATTRINDX_MASK) != (new & PTE_ATTRINDX_MASK)))
			goto pte_bad;

			/* Change of OA is only an issue if one mapping is writable */
			if (!(old & new & PTE_RDONLY) &&
			WARN_ON(pte_pfn(*ptep) != pte_pfn(pte)))
			goto pte_bad;

			goto pte_ok;

			pte_bad:
			*ptep = __pte(0);
			dsb(ishst);
			asm("tlbi vmalle1is");
			dsb(ish);
			isb();
			pte_ok:
			#endif

	WRITE_ONCE(*ptep, pte);		WRITE_ONCE(*ptep, pte);

	/*		/*