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From: Andrei Vagin <avagin@gmail.com>
To: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Andrei Vagin <avagin@gmail.com>,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Dmitry Safonov <dima@arista.com>
Subject: [PATCH 1/5] arm64/vdso: use the fault callback to map vvar pages
Date: Tue,  4 Feb 2020 09:59:09 -0800	[thread overview]
Message-ID: <20200204175913.74901-2-avagin@gmail.com> (raw)
In-Reply-To: <20200204175913.74901-1-avagin@gmail.com>

This is required to support time namespaces where a time namespace data
page is different for each namespace.

Signed-off-by: Andrei Vagin <avagin@gmail.com>
---
 arch/arm64/kernel/vdso.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 354b11e27c07..c4b4758eaf0b 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -114,28 +114,32 @@ static int __vdso_init(enum arch_vdso_type arch_index)
 			PAGE_SHIFT;
 
 	/* Allocate the vDSO pagelist, plus a page for the data. */
-	vdso_pagelist = kcalloc(vdso_lookup[arch_index].vdso_pages + 1,
+	vdso_pagelist = kcalloc(vdso_lookup[arch_index].vdso_pages,
 				sizeof(struct page *),
 				GFP_KERNEL);
 	if (vdso_pagelist == NULL)
 		return -ENOMEM;
 
-	/* Grab the vDSO data page. */
-	vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
-
-
 	/* Grab the vDSO code pages. */
 	pfn = sym_to_pfn(vdso_lookup[arch_index].vdso_code_start);
 
 	for (i = 0; i < vdso_lookup[arch_index].vdso_pages; i++)
-		vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
+		vdso_pagelist[i] = pfn_to_page(pfn + i);
 
-	vdso_lookup[arch_index].dm->pages = &vdso_pagelist[0];
-	vdso_lookup[arch_index].cm->pages = &vdso_pagelist[1];
+	vdso_lookup[arch_index].cm->pages = vdso_pagelist;
 
 	return 0;
 }
 
+static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
+		      struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+	if (vmf->pgoff == 0)
+		return vmf_insert_pfn(vma, vmf->address,
+				sym_to_pfn(vdso_data));
+	return VM_FAULT_SIGBUS;
+}
+
 static int __setup_additional_pages(enum arch_vdso_type arch_index,
 				    struct mm_struct *mm,
 				    struct linux_binprm *bprm,
@@ -155,7 +159,7 @@ static int __setup_additional_pages(enum arch_vdso_type arch_index,
 	}
 
 	ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
-				       VM_READ|VM_MAYREAD,
+				       VM_READ|VM_MAYREAD|VM_PFNMAP,
 				       vdso_lookup[arch_index].dm);
 	if (IS_ERR(ret))
 		goto up_fail;
@@ -206,6 +210,8 @@ static int aarch32_vdso_mremap(const struct vm_special_mapping *sm,
 #define C_SIGPAGE	1
 #define C_PAGES		(C_SIGPAGE + 1)
 #endif /* CONFIG_COMPAT_VDSO */
+static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
+		      struct vm_area_struct *vma, struct vm_fault *vmf);
 static struct page *aarch32_vdso_pages[C_PAGES] __ro_after_init;
 static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
 	{
@@ -215,6 +221,7 @@ static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
 #ifdef CONFIG_COMPAT_VDSO
 	{
 		.name = "[vvar]",
+		.fault = vvar_fault,
 	},
 	{
 		.name = "[vdso]",
@@ -396,6 +403,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = {
 	{
 		.name	= "[vvar]",
+		.fault = vvar_fault,
 	},
 	{
 		.name	= "[vdso]",
-- 
2.24.1


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  reply	other threads:[~2020-02-04 17:59 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-04 17:59 [PATCH 0/5] arm64: add the time namespace support Andrei Vagin
2020-02-04 17:59 ` Andrei Vagin [this message]
2020-02-20 12:36   ` [PATCH 1/5] arm64/vdso: use the fault callback to map vvar pages Vincenzo Frascino
2020-02-04 17:59 ` [PATCH 2/5] arm64/vdso: Zap vvar pages when switching to a time namespace Andrei Vagin
2020-02-04 17:59 ` [PATCH 3/5] arm64/vdso: Add time napespace page Andrei Vagin
2020-02-20 12:03   ` Vincenzo Frascino
2020-02-04 17:59 ` [PATCH 4/5] arm64/vdso: Handle faults on timens page Andrei Vagin
2020-02-20 12:07   ` Vincenzo Frascino
2020-02-04 17:59 ` [PATCH 5/5] arm64/vdso: Restrict splitting VVAR VMA Andrei Vagin
2020-02-20 12:22   ` Vincenzo Frascino
2020-02-23 23:30     ` Andrei Vagin
2020-02-24 10:08       ` Vincenzo Frascino
2020-02-17 15:34 ` [PATCH 0/5] arm64: add the time namespace support Andrei Vagin
2020-02-17 18:25   ` Vincenzo Frascino
2020-02-20 12:40 ` Vincenzo Frascino
2020-02-23  8:08   ` Andrei Vagin

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