From 3d732ccfb3687cb9e878cb09d75df41c6e11a368 Mon Sep 17 00:00:00 2001
From: Anshuman Khandual <anshuman.khandual@arm.com>
Date: Fri, 29 Oct 2021 14:31:48 +0800
Subject: [PATCH] mm/ioremap: probe platform for p4d huge map support

mainline inclusion
from mainline-v5.3-rc1
commit 0f472d04f59ff89d15b2a1c4eafde7317ddd67a2
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4EUVI
CVE: NA

Drop the support for powerpc platform.
---------------------------

Finish up what commit c2febafc6773 ("mm: convert generic code to 5-level
paging") started while levelling up P4D huge mapping support at par with
PUD and PMD.  A new arch call back arch_ioremap_p4d_supported() is added
which just maintains status quo (P4D huge map not supported) on x86,
arm64 and powerpc.

When HAVE_ARCH_HUGE_VMAP is enabled its just a simple check from the
arch about the support, hence runtime effects are minimal.

Link: http://lkml.kernel.org/r/1561699231-20991-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rui Xiang <rui.xiang@huawei.com>
Reviewed-by: Ding Tianhong <dingtianhong@huawei.com>
Reviewed-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 arch/arm64/mm/mmu.c   | 5 +++++
 arch/x86/mm/ioremap.c | 5 +++++
 include/linux/io.h    | 1 +
 lib/ioremap.c         | 2 ++
 4 files changed, 13 insertions(+)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 99a86326a301..437ee4ab41a1 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -921,6 +921,11 @@ void *__init fixmap_remap_fdt(phys_addr_t dt_phys)
 	return dt_virt;
 }
 
+int __init arch_ioremap_p4d_supported(void)
+{
+	return 0;
+}
+
 int __init arch_ioremap_pud_supported(void)
 {
 	/*
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index adc77904fc3e..6ce8a2b593e0 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -431,6 +431,11 @@ void iounmap(volatile void __iomem *addr)
 }
 EXPORT_SYMBOL(iounmap);
 
+int __init arch_ioremap_p4d_supported(void)
+{
+	return 0;
+}
+
 int __init arch_ioremap_pud_supported(void)
 {
 #ifdef CONFIG_X86_64
diff --git a/include/linux/io.h b/include/linux/io.h
index 32e30e8fb9db..58514cebfce6 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -45,6 +45,7 @@ static inline int ioremap_page_range(unsigned long addr, unsigned long end,
 
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
 void __init ioremap_huge_init(void);
+int arch_ioremap_p4d_supported(void);
 int arch_ioremap_pud_supported(void);
 int arch_ioremap_pmd_supported(void);
 #else
diff --git a/lib/ioremap.c b/lib/ioremap.c
index 063213685563..c3dc213b6980 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -30,6 +30,8 @@ early_param("nohugeiomap", set_nohugeiomap);
 void __init ioremap_huge_init(void)
 {
 	if (!ioremap_huge_disabled) {
+		if (arch_ioremap_p4d_supported())
+			ioremap_p4d_capable = 1;
 		if (arch_ioremap_pud_supported())
 			ioremap_pud_capable = 1;
 		if (arch_ioremap_pmd_supported())
-- 
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