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 5/5] arm64/vdso: Restrict splitting VVAR VMA
Date: Tue, 4 Feb 2020 09:59:13 -0800 [thread overview]
Message-ID: <20200204175913.74901-6-avagin@gmail.com> (raw)
In-Reply-To: <20200204175913.74901-1-avagin@gmail.com>
Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the
amount of corner-cases to consider while working further on VDSO time
namespace support.
As the offset from timens to VVAR page is computed compile-time, the pages
in VVAR should stay together and not being partically mremap()'ed.
Signed-off-by: Andrei Vagin <avagin@gmail.com>
---
arch/arm64/kernel/vdso.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 2e553468b183..e6ebdc184c1e 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -229,6 +229,17 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
return vmf_insert_pfn(vma, vmf->address, pfn);
}
+static int vvar_mremap(const struct vm_special_mapping *sm,
+ struct vm_area_struct *new_vma)
+{
+ unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+
+ if (new_size != VVAR_NR_PAGES * PAGE_SIZE)
+ return -EINVAL;
+
+ return 0;
+}
+
static int __setup_additional_pages(enum arch_vdso_type arch_index,
struct mm_struct *mm,
struct linux_binprm *bprm,
@@ -311,6 +322,7 @@ static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = {
{
.name = "[vvar]",
.fault = vvar_fault,
+ .mremap = vvar_mremap,
},
{
.name = "[vdso]",
@@ -493,6 +505,7 @@ static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = {
{
.name = "[vvar]",
.fault = vvar_fault,
+ .mremap = vvar_mremap,
},
{
.name = "[vdso]",
--
2.24.1
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next prev parent reply other threads:[~2020-02-04 18:00 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 ` [PATCH 1/5] arm64/vdso: use the fault callback to map vvar pages Andrei Vagin
2020-02-20 12:36 ` 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 ` Andrei Vagin [this message]
2020-02-20 12:22 ` [PATCH 5/5] arm64/vdso: Restrict splitting VVAR VMA 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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