From: Boqun Feng <boqun.feng@gmail.com>
To: linux-hyperv@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Cc: Michael Kelley <mikelley@microsoft.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Sasha Levin <sashal@kernel.org>,
xen-devel@lists.xenproject.org,
Stefano Stabellini <sstabellini@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
Matteo Croce <mcroce@redhat.com>
Subject: [RFC 2/6] arm64: vdso: Add support for multiple vDSO data pages
Date: Mon, 16 Dec 2019 08:19:18 +0800 [thread overview]
Message-ID: <20191216001922.23008-3-boqun.feng@gmail.com> (raw)
In-Reply-To: <20191216001922.23008-1-boqun.feng@gmail.com>
Split __vdso_abi::vdso_pages into nr_vdso_{data,code}_pages, so that
__setup_additional_pages() could work with multiple vDSO data pages with
the setup from __vdso_init().
Multiple vDSO data pages are required when running in a virtualized
environment, where the cycles read from cntvct at userspace need to
be adjusted with some data from a page maintained by the hypervisor. For
example, the TSC page in Hyper-V.
This is a prerequisite for vDSO support in ARM64 on Hyper-V.
Signed-off-by: Boqun Feng (Microsoft) <boqun.feng@gmail.com>
---
arch/arm64/kernel/vdso.c | 43 ++++++++++++++++++++++++----------------
1 file changed, 26 insertions(+), 17 deletions(-)
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 354b11e27c07..b9b5ec7a3084 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -50,7 +50,8 @@ struct __vdso_abi {
const char *name;
const char *vdso_code_start;
const char *vdso_code_end;
- unsigned long vdso_pages;
+ unsigned long nr_vdso_data_pages;
+ unsigned long nr_vdso_code_pages;
/* Data Mapping */
struct vm_special_mapping *dm;
/* Code Mapping */
@@ -101,6 +102,8 @@ static int __vdso_init(enum arch_vdso_type arch_index)
{
int i;
struct page **vdso_pagelist;
+ struct page **vdso_code_pagelist;
+ unsigned long nr_vdso_pages;
unsigned long pfn;
if (memcmp(vdso_lookup[arch_index].vdso_code_start, "\177ELF", 4)) {
@@ -108,14 +111,18 @@ static int __vdso_init(enum arch_vdso_type arch_index)
return -EINVAL;
}
- vdso_lookup[arch_index].vdso_pages = (
+ vdso_lookup[arch_index].nr_vdso_data_pages = 1;
+
+ vdso_lookup[arch_index].nr_vdso_code_pages = (
vdso_lookup[arch_index].vdso_code_end -
vdso_lookup[arch_index].vdso_code_start) >>
PAGE_SHIFT;
- /* Allocate the vDSO pagelist, plus a page for the data. */
- vdso_pagelist = kcalloc(vdso_lookup[arch_index].vdso_pages + 1,
- sizeof(struct page *),
+ nr_vdso_pages = vdso_lookup[arch_index].nr_vdso_data_pages +
+ vdso_lookup[arch_index].nr_vdso_code_pages;
+
+ /* Allocate the vDSO pagelist. */
+ vdso_pagelist = kcalloc(nr_vdso_pages, sizeof(struct page *),
GFP_KERNEL);
if (vdso_pagelist == NULL)
return -ENOMEM;
@@ -123,15 +130,17 @@ static int __vdso_init(enum arch_vdso_type arch_index)
/* 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_code_pagelist = vdso_pagelist +
+ vdso_lookup[arch_index].nr_vdso_data_pages;
+
+ for (i = 0; i < vdso_lookup[arch_index].nr_vdso_code_pages; i++)
+ vdso_code_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].dm->pages = vdso_pagelist;
+ vdso_lookup[arch_index].cm->pages = vdso_code_pagelist;
return 0;
}
@@ -141,26 +150,26 @@ static int __setup_additional_pages(enum arch_vdso_type arch_index,
struct linux_binprm *bprm,
int uses_interp)
{
- unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
+ unsigned long vdso_base, vdso_text_len, vdso_data_len;
void *ret;
- vdso_text_len = vdso_lookup[arch_index].vdso_pages << PAGE_SHIFT;
- /* Be sure to map the data page */
- vdso_mapping_len = vdso_text_len + PAGE_SIZE;
+ vdso_data_len = vdso_lookup[arch_index].nr_vdso_data_pages << PAGE_SHIFT;
+ vdso_text_len = vdso_lookup[arch_index].nr_vdso_code_pages << PAGE_SHIFT;
- vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
+ vdso_base = get_unmapped_area(NULL, 0,
+ vdso_data_len + vdso_text_len, 0, 0);
if (IS_ERR_VALUE(vdso_base)) {
ret = ERR_PTR(vdso_base);
goto up_fail;
}
- ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
+ ret = _install_special_mapping(mm, vdso_base, vdso_data_len,
VM_READ|VM_MAYREAD,
vdso_lookup[arch_index].dm);
if (IS_ERR(ret))
goto up_fail;
- vdso_base += PAGE_SIZE;
+ vdso_base += vdso_data_len;
mm->context.vdso = (void *)vdso_base;
ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
VM_READ|VM_EXEC|
--
2.24.0
next prev parent reply other threads:[~2019-12-16 0:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-16 0:19 [RFC 0/6] vDSO support for Hyper-V guest on ARM64 Boqun Feng
2019-12-16 0:19 ` [RFC 1/6] arm64: hyperv: Allow hv_get_raw_timer() definition to be overridden Boqun Feng
2019-12-16 0:19 ` Boqun Feng [this message]
2019-12-16 0:19 ` [RFC 3/6] arm/arm64: clocksource: Introduce vclock_mode Boqun Feng
2019-12-16 0:19 ` [RFC 4/6] arm64: vdso: hyperv: Map tsc page into vDSO if enabled Boqun Feng
2019-12-16 0:19 ` [RFC 5/6] arm64: hyperv: Enable userspace to read cntvct Boqun Feng
2019-12-16 0:19 ` [RFC 6/6] arm64: hyperv: Enable vDSO Boqun Feng
2019-12-17 14:10 ` Vitaly Kuznetsov
2019-12-18 5:47 ` Boqun Feng
2020-01-23 10:48 ` [RFC 0/6] vDSO support for Hyper-V guest on ARM64 Vincenzo Frascino
2020-01-24 6:32 ` Boqun Feng
2020-01-24 10:24 ` Vincenzo Frascino
2020-01-28 5:58 ` Boqun Feng
2020-01-28 11:48 ` Marc Zyngier
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