[PATCH v5] arm64: mm: fix linear mem mapping access performance degradation

From: Guanghui Feng <guanghuifeng@linux.alibaba.com>
To: baolin.wang@linux.alibaba.com, catalin.marinas@arm.com,
	will@kernel.org, akpm@linux-foundation.org, david@redhat.com,
	jianyong.wu@arm.com, james.morse@arm.com,
	quic_qiancai@quicinc.com, christophe.leroy@csgroup.eu,
	jonathan@marek.ca, mark.rutland@arm.com,
	thunder.leizhen@huawei.com, anshuman.khandual@arm.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, rppt@kernel.org,
	geert+renesas@glider.be, ardb@kernel.org, linux-mm@kvack.org,
	yaohongbo@linux.alibaba.com
Cc: alikernel-developer@linux.alibaba.com
Subject: [PATCH v5] arm64: mm: fix linear mem mapping access performance degradation
Date: Sun, 10 Jul 2022 21:44:17 +0800	[thread overview]
Message-ID: <1657460657-25698-1-git-send-email-guanghuifeng@linux.alibaba.com> (raw)
In-Reply-To: <f0dd1176-39f1-0a08-d0e2-627dd437aa5f@linux.alibaba.com>

The arm64 can build 2M/1G block/sectiion mapping. When using DMA/DMA32 zone
(enable crashkernel, disable rodata full, disable kfence), the mem_map will
use non block/section mapping(for crashkernel requires to shrink the region
in page granularity). But it will degrade performance when doing larging
continuous mem access in kernel(memcpy/memmove, etc).

There are many changes and discussions:
commit 031495635b46 ("arm64: Do not defer reserve_crashkernel() for
platforms with no DMA memory zones")
commit 0a30c53573b0 ("arm64: mm: Move reserve_crashkernel() into
mem_init()")
commit 2687275a5843 ("arm64: Force NO_BLOCK_MAPPINGS if crashkernel
reservation is required")

This patch changes mem_map to use block/section mapping with crashkernel.
Firstly, do block/section mapping(normally 2M or 1G) for all avail mem at
mem_map, reserve crashkernel memory. And then walking pagetable to split
block/section mapping to non block/section mapping(normally 4K) [[[only]]]
for crashkernel mem. So the linear mem mapping use block/section mapping
as more as possible. We will reduce the cpu dTLB miss conspicuously, and
accelerate mem access about 10-20% performance improvement.

I have tested it with pft(Page Fault Test) and fio, obtained great
performace improvement.

For fio test:
1.prepare ramdisk
  modprobe -r brd
  modprobe brd rd_nr=1 rd_size=67108864
  dmsetup remove_all
  wipefs -a --force /dev/ram0
  mkfs -t ext4 -E lazy_itable_init=0,lazy_journal_init=0 -q -F /dev/ram0
  mkdir -p /fs/ram0
  mount -t ext4 /dev/ram0 /fs/ram0

2.prepare fio paremeter in x.fio file:
[global]
bs=4k
ioengine=psync
iodepth=128
size=32G
direct=1
invalidate=1
group_reporting
thread=1
rw=read
directory=/fs/ram0
numjobs=1

[task_0]
cpus_allowed=16
stonewall=1

3.run testcase:
perf stat -e dTLB-load-misses fio x.fio

4.contrast
------------------------
			without patch		with patch
fio READ		aggrb=1493.2MB/s	aggrb=1775.3MB/s
dTLB-load-misses	1,818,320,693		438,729,774
time elapsed(s)		70.500326434		62.877316408
user(s)			15.926332000		15.684721000
sys(s)			54.211939000		47.046165000

5.conclusion
Using this patch will reduce dTLB misses and improve performace greatly.

Signed-off-by: Guanghui Feng <guanghuifeng@linux.alibaba.com>
---
 arch/arm64/include/asm/mmu.h         |   1 +
 arch/arm64/include/asm/mmu_context.h |  28 ++++
 arch/arm64/mm/init.c                 |   8 +-
 arch/arm64/mm/mmu.c                  | 305 +++++++++++++++++++++++++----------
 arch/arm64/mm/proc.S                 |  19 +++
 5 files changed, 267 insertions(+), 94 deletions(-)

diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index 48f8466..1a46b81 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -63,6 +63,7 @@ static inline bool arm64_kernel_unmapped_at_el0(void)
 extern void arm64_memblock_init(void);
 extern void paging_init(void);
 extern void bootmem_init(void);
+extern void map_crashkernel(void);
 extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
 extern void init_mem_pgprot(void);
 extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 6770667..10dffd4 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -139,6 +139,34 @@ static inline void cpu_install_ttbr0(phys_addr_t ttbr0, unsigned long t0sz)
 	isb();
 }
 
+static inline void __nocfi cpu_replace_ttbr1_with_phys(phys_addr_t ttbr1)
+{
+	typedef void (ttbr_replace_func)(phys_addr_t);
+	extern ttbr_replace_func idmap_cpu_replace_ttbr1_with_flush_tlb;
+	ttbr_replace_func *replace_phys;
+
+	/* phys_to_ttbr() zeros lower 2 bits of ttbr with 52-bit PA */
+	ttbr1 = phys_to_ttbr(ttbr1);
+
+	if (system_supports_cnp()) {
+		/*
+		 * cpu_replace_ttbr1() is used when there's a boot CPU
+		 * up (i.e. cpufeature framework is not up yet) and
+		 * latter only when we enable CNP via cpufeature's
+		 * enable() callback.
+		 * Also we rely on the cpu_hwcap bit being set before
+		 * calling the enable() function.
+		 */
+		ttbr1 |= TTBR_CNP_BIT;
+	}
+
+	replace_phys = (void *)__pa_symbol(function_nocfi(idmap_cpu_replace_ttbr1_with_flush_tlb));
+
+	cpu_install_idmap();
+	replace_phys(ttbr1);
+	cpu_uninstall_idmap();
+}
+
 /*
  * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD,
  * avoiding the possibility of conflicting TLB entries being allocated.
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 339ee84..241d27e 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -190,6 +190,7 @@ static void __init reserve_crashkernel(void)
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
 	insert_resource(&iomem_resource, &crashk_res);
+	map_crashkernel();
 }
 
 /*
@@ -388,10 +389,6 @@ void __init arm64_memblock_init(void)
 	}
 
 	early_init_fdt_scan_reserved_mem();
-
-	if (!IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32))
-		reserve_crashkernel();
-
 	high_memory = __va(memblock_end_of_DRAM() - 1) + 1;
 }
 
@@ -438,8 +435,7 @@ void __init bootmem_init(void)
 	 * request_standard_resources() depends on crashkernel's memory being
 	 * reserved, so do it here.
 	 */
-	if (IS_ENABLED(CONFIG_ZONE_DMA) || IS_ENABLED(CONFIG_ZONE_DMA32))
-		reserve_crashkernel();
+	reserve_crashkernel();
 
 	memblock_dump_all();
 }
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 626ec32..3e30c82 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -42,6 +42,7 @@
 #define NO_BLOCK_MAPPINGS	BIT(0)
 #define NO_CONT_MAPPINGS	BIT(1)
 #define NO_EXEC_MAPPINGS	BIT(2)	/* assumes FEAT_HPDS is not used */
+#define NO_SEC_REMAPPINGS	BIT(3)	/* rebuild with non block/sec mapping*/
 
 u64 idmap_t0sz = TCR_T0SZ(VA_BITS_MIN);
 u64 idmap_ptrs_per_pgd = PTRS_PER_PGD;
@@ -155,8 +156,22 @@ static bool pgattr_change_is_safe(u64 old, u64 new)
 	return ((old ^ new) & ~mask) == 0;
 }
 
+static void pte_clear_cont(pte_t *ptep)
+{
+	int i = 0;
+	pte_t pte = READ_ONCE(*ptep);
+	if (pte_none(pte) || !pte_cont(pte))
+		return;
+	ptep -= ((u64)ptep / sizeof(pte_t)) &
+		((1 << CONFIG_ARM64_CONT_PTE_SHIFT) - 1);
+	do {
+		pte = pte_mknoncont(READ_ONCE(*ptep));
+		set_pte(ptep, pte);
+	} while (++ptep, ++i < CONT_PTES);
+}
+
 static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
-		     phys_addr_t phys, pgprot_t prot)
+		     phys_addr_t phys, pgprot_t prot, int flags)
 {
 	pte_t *ptep;
 
@@ -164,6 +179,9 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
 	do {
 		pte_t old_pte = READ_ONCE(*ptep);
 
+		if (flags & NO_SEC_REMAPPINGS)
+			pte_clear_cont(ptep);
+
 		set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot));
 
 		/*
@@ -179,6 +197,22 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
 	pte_clear_fixmap();
 }
 
+static inline void allock_pte_page(pmd_t *pmdp,
+				   phys_addr_t (*pgtable_alloc)(int),
+				   int flags)
+{
+	pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN;
+	phys_addr_t pte_phys;
+	if (!pmd_none(READ_ONCE(*pmdp)))
+		return;
+
+	if (flags & NO_EXEC_MAPPINGS)
+		pmdval |= PMD_TABLE_PXN;
+	BUG_ON(!pgtable_alloc);
+	pte_phys = pgtable_alloc(PAGE_SHIFT);
+	__pmd_populate(pmdp, pte_phys, pmdval);
+}
+
 static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
 				unsigned long end, phys_addr_t phys,
 				pgprot_t prot,
@@ -189,17 +223,8 @@ static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
 	pmd_t pmd = READ_ONCE(*pmdp);
 
 	BUG_ON(pmd_sect(pmd));
-	if (pmd_none(pmd)) {
-		pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN;
-		phys_addr_t pte_phys;
-
-		if (flags & NO_EXEC_MAPPINGS)
-			pmdval |= PMD_TABLE_PXN;
-		BUG_ON(!pgtable_alloc);
-		pte_phys = pgtable_alloc(PAGE_SHIFT);
-		__pmd_populate(pmdp, pte_phys, pmdval);
-		pmd = READ_ONCE(*pmdp);
-	}
+	allock_pte_page(pmdp, pgtable_alloc, flags);
+	pmd = READ_ONCE(*pmdp);
 	BUG_ON(pmd_bad(pmd));
 
 	do {
@@ -208,16 +233,71 @@ static void alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
 		next = pte_cont_addr_end(addr, end);
 
 		/* use a contiguous mapping if the range is suitably aligned */
-		if ((((addr | next | phys) & ~CONT_PTE_MASK) == 0) &&
-		    (flags & NO_CONT_MAPPINGS) == 0)
+		if (!(flags & NO_SEC_REMAPPINGS) &&
+		   (((addr | next | phys) & ~CONT_PTE_MASK) == 0) &&
+		   (flags & NO_CONT_MAPPINGS) == 0)
 			__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
 
-		init_pte(pmdp, addr, next, phys, __prot);
+		init_pte(pmdp, addr, next, phys, __prot, flags);
 
 		phys += next - addr;
 	} while (addr = next, addr != end);
 }
 
+static void pmd_clear_cont(pmd_t *pmdp)
+{
+	int i = 0;
+	pmd_t pmd = READ_ONCE(*pmdp);
+	if (pmd_none(pmd) || !pmd_sect(pmd) || !pmd_cont(pmd))
+		return;
+	pmdp -= ((u64)pmdp / sizeof(pmd_t)) &
+		((1 << CONFIG_ARM64_CONT_PMD_SHIFT) - 1);
+	do {
+		pmd = READ_ONCE(*pmdp);
+		pmd = pte_pmd(pte_mknoncont(pmd_pte(pmd)));
+		set_pmd(pmdp, pmd);
+	} while (++pmdp, ++i < CONT_PMDS);
+}
+
+static void init_pmd_remap(pud_t *pudp, unsigned long addr, unsigned long end,
+			   phys_addr_t phys, pgprot_t prot,
+			   phys_addr_t (*pgtable_alloc)(int), int flags)
+{
+	unsigned long next;
+	pmd_t *pmdp;
+	phys_addr_t map_offset;
+
+	pmdp = pmd_set_fixmap_offset(pudp, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+
+		if (!pmd_none(*pmdp) && pmd_sect(*pmdp)) {
+			pmd_clear_cont(pmdp);
+			pmd_clear(pmdp);
+			allock_pte_page(pmdp, pgtable_alloc, flags);
+
+			map_offset = addr - (addr & PMD_MASK);
+			if (map_offset)
+			    alloc_init_cont_pte(pmdp, addr & PMD_MASK, addr,
+						phys - map_offset, prot,
+						pgtable_alloc,
+						flags & (~NO_SEC_REMAPPINGS));
+
+			if (next < (addr & PMD_MASK) + PMD_SIZE)
+			    alloc_init_cont_pte(pmdp, next,
+					       (addr & PUD_MASK) + PUD_SIZE,
+					        next - addr + phys,
+						prot, pgtable_alloc,
+						flags & (~NO_SEC_REMAPPINGS));
+		}
+		alloc_init_cont_pte(pmdp, addr, next, phys, prot,
+				    pgtable_alloc, flags);
+		phys += next - addr;
+	} while (pmdp++, addr = next, addr != end);
+
+	pmd_clear_fixmap();
+}
+
 static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end,
 		     phys_addr_t phys, pgprot_t prot,
 		     phys_addr_t (*pgtable_alloc)(int), int flags)
@@ -255,6 +335,22 @@ static void init_pmd(pud_t *pudp, unsigned long addr, unsigned long end,
 	pmd_clear_fixmap();
 }
 
+static inline void alloc_pmd_page(pud_t *pudp, phys_addr_t (*pgtable_alloc)(int), int flags)
+{
+
+	pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN;
+	phys_addr_t pmd_phys;
+
+	if (!pud_none(READ_ONCE(*pudp)))
+		return;
+
+	if (flags & NO_EXEC_MAPPINGS)
+		pudval |= PUD_TABLE_PXN;
+	BUG_ON(!pgtable_alloc);
+	pmd_phys = pgtable_alloc(PMD_SHIFT);
+	__pud_populate(pudp, pmd_phys, pudval);
+}
+
 static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
 				unsigned long end, phys_addr_t phys,
 				pgprot_t prot,
@@ -267,17 +363,8 @@ static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
 	 * Check for initial section mappings in the pgd/pud.
 	 */
 	BUG_ON(pud_sect(pud));
-	if (pud_none(pud)) {
-		pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN;
-		phys_addr_t pmd_phys;
-
-		if (flags & NO_EXEC_MAPPINGS)
-			pudval |= PUD_TABLE_PXN;
-		BUG_ON(!pgtable_alloc);
-		pmd_phys = pgtable_alloc(PMD_SHIFT);
-		__pud_populate(pudp, pmd_phys, pudval);
-		pud = READ_ONCE(*pudp);
-	}
+	alloc_pmd_page(pudp, pgtable_alloc, flags);
+	pud = READ_ONCE(*pudp);
 	BUG_ON(pud_bad(pud));
 
 	do {
@@ -286,16 +373,80 @@ static void alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
 		next = pmd_cont_addr_end(addr, end);
 
 		/* use a contiguous mapping if the range is suitably aligned */
-		if ((((addr | next | phys) & ~CONT_PMD_MASK) == 0) &&
+		if (!(flags & NO_SEC_REMAPPINGS) &&
+		   (((addr | next | phys) & ~CONT_PMD_MASK) == 0) &&
 		    (flags & NO_CONT_MAPPINGS) == 0)
 			__prot = __pgprot(pgprot_val(prot) | PTE_CONT);
 
-		init_pmd(pudp, addr, next, phys, __prot, pgtable_alloc, flags);
+		if (flags & NO_SEC_REMAPPINGS)
+			init_pmd_remap(pudp, addr, next, phys, __prot,
+				       pgtable_alloc, flags);
+		else
+			init_pmd(pudp, addr, next, phys, __prot,
+				 pgtable_alloc, flags);
 
 		phys += next - addr;
 	} while (addr = next, addr != end);
 }
 
+static void init_pud_remap(pud_t *pudp, unsigned long addr, unsigned long next,
+			   phys_addr_t phys, pgprot_t prot,
+			   phys_addr_t (*pgtable_alloc)(int),
+			   int flags)
+{
+	phys_addr_t map_offset;
+
+	if (!pud_none(*pudp) && pud_sect(*pudp)) {
+		pud_clear(pudp);
+		alloc_pmd_page(pudp, pgtable_alloc, flags);
+
+		map_offset = addr - (addr & PUD_MASK);
+		if (map_offset)
+		    alloc_init_cont_pmd(pudp, addr & PUD_MASK,
+					addr, phys - map_offset,
+					prot, pgtable_alloc,
+					flags &	(~NO_SEC_REMAPPINGS));
+
+		if (next < (addr & PUD_MASK) + PUD_SIZE)
+		    alloc_init_cont_pmd(pudp, next,
+				       (addr & PUD_MASK) + PUD_SIZE,
+					next - addr + phys,
+					prot, pgtable_alloc,
+					flags & (~NO_SEC_REMAPPINGS));
+	}
+	alloc_init_cont_pmd(pudp, addr, next, phys, prot,
+			    pgtable_alloc, flags);
+}
+
+static void init_pud(pud_t *pudp, unsigned long addr, unsigned long next,
+		     phys_addr_t phys, pgprot_t prot,
+		     phys_addr_t (*pgtable_alloc)(int),
+		     int flags)
+{
+	pud_t old_pud = READ_ONCE(*pudp);
+	/*
+	 * For 4K granule only, attempt to put down a 1GB block
+	 */
+	if (pud_sect_supported() &&
+	   ((addr | next | phys) & ~PUD_MASK) == 0 &&
+	   (flags & NO_BLOCK_MAPPINGS) == 0) {
+		pud_set_huge(pudp, phys, prot);
+
+		/*
+		 * After the PUD entry has been populated once, we
+		 * only allow updates to the permission attributes.
+		 */
+		BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
+					      READ_ONCE(pud_val(*pudp))));
+	} else {
+		alloc_init_cont_pmd(pudp, addr, next, phys, prot,
+				    pgtable_alloc, flags);
+
+		BUG_ON(pud_val(old_pud) != 0 &&
+		       pud_val(old_pud) != READ_ONCE(pud_val(*pudp)));
+	}
+}
+
 static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
 			   phys_addr_t phys, pgprot_t prot,
 			   phys_addr_t (*pgtable_alloc)(int),
@@ -325,37 +476,22 @@ static void alloc_init_pud(pgd_t *pgdp, unsigned long addr, unsigned long end,
 	 */
 	if (system_state != SYSTEM_BOOTING)
 		mutex_lock(&fixmap_lock);
+
 	pudp = pud_set_fixmap_offset(p4dp, addr);
 	do {
-		pud_t old_pud = READ_ONCE(*pudp);
-
 		next = pud_addr_end(addr, end);
 
-		/*
-		 * For 4K granule only, attempt to put down a 1GB block
-		 */
-		if (pud_sect_supported() &&
-		   ((addr | next | phys) & ~PUD_MASK) == 0 &&
-		    (flags & NO_BLOCK_MAPPINGS) == 0) {
-			pud_set_huge(pudp, phys, prot);
-
-			/*
-			 * After the PUD entry has been populated once, we
-			 * only allow updates to the permission attributes.
-			 */
-			BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
-						      READ_ONCE(pud_val(*pudp))));
-		} else {
-			alloc_init_cont_pmd(pudp, addr, next, phys, prot,
-					    pgtable_alloc, flags);
-
-			BUG_ON(pud_val(old_pud) != 0 &&
-			       pud_val(old_pud) != READ_ONCE(pud_val(*pudp)));
-		}
+		if (flags & NO_SEC_REMAPPINGS)
+			init_pud_remap(pudp, addr, next, phys, prot,
+				       pgtable_alloc, flags);
+		else
+			init_pud(pudp, addr, next, phys, prot, pgtable_alloc,
+				 flags);
 		phys += next - addr;
 	} while (pudp++, addr = next, addr != end);
 
 	pud_clear_fixmap();
+
 	if (system_state != SYSTEM_BOOTING)
 		mutex_unlock(&fixmap_lock);
 }
@@ -483,20 +619,37 @@ void __init mark_linear_text_alias_ro(void)
 			    PAGE_KERNEL_RO);
 }
 
-static bool crash_mem_map __initdata;
-
-static int __init enable_crash_mem_map(char *arg)
+#ifdef CONFIG_KEXEC_CORE
+void __init map_crashkernel(void)
 {
-	/*
-	 * Proper parameter parsing is done by reserve_crashkernel(). We only
-	 * need to know if the linear map has to avoid block mappings so that
-	 * the crashkernel reservations can be unmapped later.
-	 */
-	crash_mem_map = true;
+	if (can_set_direct_map() || IS_ENABLED(CONFIG_KFENCE))
+	    return;
 
-	return 0;
+	if (!crashk_res.end)
+	    return;
+
+	cpu_replace_ttbr1_with_phys(__pa_symbol(init_pg_dir));
+	init_mm.pgd = init_pg_dir;
+
+	__create_pgd_mapping(swapper_pg_dir, crashk_res.start,
+			     __phys_to_virt(crashk_res.start),
+			     crashk_res.end + 1 - crashk_res.start, PAGE_KERNEL,
+			     early_pgtable_alloc,
+			     NO_EXEC_MAPPINGS | NO_SEC_REMAPPINGS);
+
+	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
+	init_mm.pgd = swapper_pg_dir;
+
+	memblock_phys_free(__pa_symbol(init_pg_dir),
+			   __pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir));
 }
-early_param("crashkernel", enable_crash_mem_map);
+#else
+void __init map_crashkernel(void)
+{
+	memblock_phys_free(__pa_symbol(init_pg_dir),
+			   __pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir));
+}
+#endif
 
 static void __init map_mem(pgd_t *pgdp)
 {
@@ -527,17 +680,6 @@ static void __init map_mem(pgd_t *pgdp)
 	 */
 	memblock_mark_nomap(kernel_start, kernel_end - kernel_start);
 
-#ifdef CONFIG_KEXEC_CORE
-	if (crash_mem_map) {
-		if (IS_ENABLED(CONFIG_ZONE_DMA) ||
-		    IS_ENABLED(CONFIG_ZONE_DMA32))
-			flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
-		else if (crashk_res.end)
-			memblock_mark_nomap(crashk_res.start,
-			    resource_size(&crashk_res));
-	}
-#endif
-
 	/* map all the memory banks */
 	for_each_mem_range(i, &start, &end) {
 		if (start >= end)
@@ -570,19 +712,6 @@ static void __init map_mem(pgd_t *pgdp)
 	 * in page granularity and put back unused memory to buddy system
 	 * through /sys/kernel/kexec_crash_size interface.
 	 */
-#ifdef CONFIG_KEXEC_CORE
-	if (crash_mem_map &&
-	    !IS_ENABLED(CONFIG_ZONE_DMA) && !IS_ENABLED(CONFIG_ZONE_DMA32)) {
-		if (crashk_res.end) {
-			__map_memblock(pgdp, crashk_res.start,
-				       crashk_res.end + 1,
-				       PAGE_KERNEL,
-				       NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
-			memblock_clear_nomap(crashk_res.start,
-					     resource_size(&crashk_res));
-		}
-	}
-#endif
 }
 
 void mark_rodata_ro(void)
@@ -774,8 +903,8 @@ void __init paging_init(void)
 	cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
 	init_mm.pgd = swapper_pg_dir;
 
-	memblock_phys_free(__pa_symbol(init_pg_dir),
-			   __pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir));
+	//memblock_phys_free(__pa_symbol(init_pg_dir),
+	//		   __pa_symbol(init_pg_end) - __pa_symbol(init_pg_dir));
 
 	memblock_allow_resize();
 }
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 50bbed9..161bae6 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -178,6 +178,25 @@ SYM_FUNC_END(cpu_do_resume)
 	isb
 .endm
 
+SYM_FUNC_START(idmap_cpu_replace_ttbr1_with_flush_tlb)
+	save_and_disable_daif flags=x2
+
+	__idmap_cpu_set_reserved_ttbr1 x1, x3
+
+	offset_ttbr1 x0, x3
+	msr	ttbr1_el1, x0
+	isb
+
+	restore_daif x2
+
+	dsb nshst
+	tlbi	vmalle1
+	dsb	nsh
+	isb
+
+	ret
+SYM_FUNC_END(idmap_cpu_replace_ttbr1_with_flush_tlb)
+
 /*
  * void idmap_cpu_replace_ttbr1(phys_addr_t ttbr1)
  *
-- 
1.8.3.1

