- Fix kernel panic on specific Qualcomm platform due to broken erratum

workaround
 - Revert contiguous bit support due to TLB conflict aborts in simulation
 - Don't treat all CPU ID register fields as 4-bit quantities
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Will Deacon:
 "The main fix here addresses a kernel panic triggered on Qualcomm
  QDF2400 due to incorrect register usage in an erratum workaround
  introduced during the merge window.

  Summary:

   - Fix kernel panic on specific Qualcomm platform due to broken
     erratum workaround

   - Revert contiguous bit support due to TLB conflict aborts in
     simulation

   - Don't treat all CPU ID register fields as 4-bit quantities"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64/cpufeature: check correct field width when updating sys_val
  Revert "arm64: mm: set the contiguous bit for kernel mappings where appropriate"
  arm64: Avoid clobbering mm in erratum workaround on QDF2400

arch/arm64/include/asm/cpufeature.h

@@ -184,16 +184,22 @@ static inline u64 arm64_ftr_reg_user_value(const struct arm64_ftr_reg *reg)
 }
 
 static inline int __attribute_const__
-cpuid_feature_extract_field(u64 features, int field, bool sign)
+cpuid_feature_extract_field_width(u64 features, int field, int width, bool sign)
 {
 	return (sign) ?
-		cpuid_feature_extract_signed_field(features, field) :
+		cpuid_feature_extract_signed_field_width(features, field, width) :
-		cpuid_feature_extract_unsigned_field(features, field);
+		cpuid_feature_extract_unsigned_field_width(features, field, width);
+}
+
+static inline int __attribute_const__
+cpuid_feature_extract_field(u64 features, int field, bool sign)
+{
+	return cpuid_feature_extract_field_width(features, field, 4, sign);
 }
 
 static inline s64 arm64_ftr_value(const struct arm64_ftr_bits *ftrp, u64 val)
 {
-	return (s64)cpuid_feature_extract_field(val, ftrp->shift, ftrp->sign);
+	return (s64)cpuid_feature_extract_field_width(val, ftrp->shift, ftrp->width, ftrp->sign);
 }
 
 static inline bool id_aa64mmfr0_mixed_endian_el0(u64 mmfr0)

arch/arm64/mm/mmu.c

@@ -109,10 +109,8 @@ static bool pgattr_change_is_safe(u64 old, u64 new)
 static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
 				  unsigned long end, unsigned long pfn,
 				  pgprot_t prot,
-				  phys_addr_t (*pgtable_alloc)(void),
+				  phys_addr_t (*pgtable_alloc)(void))
-				  bool page_mappings_only)
 {
-	pgprot_t __prot = prot;
 	pte_t *pte;
 
 	BUG_ON(pmd_sect(*pmd));
@@ -130,18 +128,7 @@ static void alloc_init_pte(pmd_t *pmd, unsigned long addr,
 	do {
 		pte_t old_pte = *pte;
 
-		/*
+		set_pte(pte, pfn_pte(pfn, prot));
-		 * Set the contiguous bit for the subsequent group of PTEs if
-		 * its size and alignment are appropriate.
-		 */
-		if (((addr | PFN_PHYS(pfn)) & ~CONT_PTE_MASK) == 0) {
-			if (end - addr >= CONT_PTE_SIZE && !page_mappings_only)
-				__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
-			else
-				__prot = prot;
-		}
-
-		set_pte(pte, pfn_pte(pfn, __prot));
 		pfn++;
 
 		/*
@@ -160,7 +147,6 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 				  phys_addr_t (*pgtable_alloc)(void),
 				  bool page_mappings_only)
 {
-	pgprot_t __prot = prot;
 	pmd_t *pmd;
 	unsigned long next;
 
@@ -187,18 +173,7 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 		/* try section mapping first */
 		if (((addr | next | phys) & ~SECTION_MASK) == 0 &&
 		      !page_mappings_only) {
-			/*
+			pmd_set_huge(pmd, phys, prot);
-			 * Set the contiguous bit for the subsequent group of
-			 * PMDs if its size and alignment are appropriate.
-			 */
-			if (((addr | phys) & ~CONT_PMD_MASK) == 0) {
-				if (end - addr >= CONT_PMD_SIZE)
-					__prot = __pgprot(pgprot_val(prot) |
-							  PTE_CONT);
-				else
-					__prot = prot;
-			}
-			pmd_set_huge(pmd, phys, __prot);
 
 			/*
 			 * After the PMD entry has been populated once, we
@@ -208,8 +183,7 @@ static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end,
 						      pmd_val(*pmd)));
 		} else {
 			alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys),
-				       prot, pgtable_alloc,
+				       prot, pgtable_alloc);
-				       page_mappings_only);
 
 			BUG_ON(pmd_val(old_pmd) != 0 &&
 			       pmd_val(old_pmd) != pmd_val(*pmd));

arch/arm64/mm/proc.S

@@ -138,7 +138,7 @@ ENDPROC(cpu_do_resume)
  *	- pgd_phys - physical address of new TTB
  */
 ENTRY(cpu_do_switch_mm)
-	pre_ttbr0_update_workaround x0, x1, x2
+	pre_ttbr0_update_workaround x0, x2, x3
 	mmid	x1, x1				// get mm->context.id
 	bfi	x0, x1, #48, #16		// set the ASID
 	msr	ttbr0_el1, x0			// set TTBR0