Commit b3c6858f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux 

Pull arm64 fixes from Will Deacon:
 "Here are some more arm64 fixes for 4.13. The main one is the PTE race
  with the hardware walker, but there are a couple of other things too.

   - Report correct timer frequency to userspace when trapping
     CNTFRQ_EL0

   - Fix race with hardware page table updates when updating access
     flags

   - Silence clang overflow warning in VA_START and PAGE_OFFSET
     calculations"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: avoid overflow in VA_START and PAGE_OFFSET
  arm64: Fix potential race with hardware DBM in ptep_set_access_flags()
  arm64: Use arch_timer_get_rate when trapping CNTFRQ_EL0
parents 0a23ea65 82cd5880

arch/arm64/include/asm/memory.h

+4 −2
Original line number Diff line number Diff line
@@ -64,8 +64,10 @@ 
 * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.

 */

#define VA_BITS			(CONFIG_ARM64_VA_BITS)

#define VA_START		(UL(0xffffffffffffffff) << VA_BITS)

#define PAGE_OFFSET		(UL(0xffffffffffffffff) << (VA_BITS - 1))

#define VA_START		(UL(0xffffffffffffffff) - \

	(UL(1) << VA_BITS) + 1)

#define PAGE_OFFSET		(UL(0xffffffffffffffff) - \

	(UL(1) << (VA_BITS - 1)) + 1)

#define KIMAGE_VADDR		(MODULES_END)

#define MODULES_END		(MODULES_VADDR + MODULES_VSIZE)

#define MODULES_VADDR		(VA_START + KASAN_SHADOW_SIZE)

arch/arm64/kernel/traps.c

+1 −1
Original line number Diff line number Diff line
@@ -523,7 +523,7 @@ static void cntfrq_read_handler(unsigned int esr, struct pt_regs *regs) 
{

	int rt = (esr & ESR_ELx_SYS64_ISS_RT_MASK) >> ESR_ELx_SYS64_ISS_RT_SHIFT;



	pt_regs_write_reg(regs, rt, read_sysreg(cntfrq_el0));

	pt_regs_write_reg(regs, rt, arch_timer_get_rate());

	regs->pc += 4;

}

arch/arm64/mm/fault.c

+8 −7
Original line number Diff line number Diff line
@@ -163,26 +163,27 @@ int ptep_set_access_flags(struct vm_area_struct *vma, 
	/* only preserve the access flags and write permission */

	pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY;



	/*

	 * PTE_RDONLY is cleared by default in the asm below, so set it in

	 * back if necessary (read-only or clean PTE).

	 */

	/* set PTE_RDONLY if actual read-only or clean PTE */

	if (!pte_write(entry) || !pte_sw_dirty(entry))

		pte_val(entry) |= PTE_RDONLY;



	/*

	 * Setting the flags must be done atomically to avoid racing with the

	 * hardware update of the access/dirty state.

	 * hardware update of the access/dirty state. The PTE_RDONLY bit must

	 * be set to the most permissive (lowest value) of *ptep and entry

	 * (calculated as: a & b == ~(~a | ~b)).

	 */

	pte_val(entry) ^= PTE_RDONLY;

	asm volatile("//	ptep_set_access_flags\n"

	"	prfm	pstl1strm, %2\n"

	"1:	ldxr	%0, %2\n"

	"	and	%0, %0, %3		// clear PTE_RDONLY\n"

	"	eor	%0, %0, %3		// negate PTE_RDONLY in *ptep\n"

	"	orr	%0, %0, %4		// set flags\n"

	"	eor	%0, %0, %3		// negate final PTE_RDONLY\n"

	"	stxr	%w1, %0, %2\n"

	"	cbnz	%w1, 1b\n"

	: "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep))

	: "L" (~PTE_RDONLY), "r" (pte_val(entry)));

	: "L" (PTE_RDONLY), "r" (pte_val(entry)));



	flush_tlb_fix_spurious_fault(vma, address);

	return 1;

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