[PATCH 1/3] X86: make VDSO data support multiple pages

Shaohua Li
2014-12-08T03:03:54Z

Currently vdso data is one page. Next patches will add per-cpu data to
vdso, which requires several pages if CPU number is big. This makes VDSO
data support multiple pages.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Shaohua Li <shli@fb.com>
---
arch/x86/include/asm/vvar.h | 6 +++++-
arch/x86/kernel/asm-offsets.c | 5 +++++
arch/x86/kernel/vmlinux.lds.S | 4 +---
arch/x86/vdso/vdso-layout.lds.S | 5 +++--
arch/x86/vdso/vma.c | 3 ++-
5 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/vvar.h b/arch/x86/include/asm/vvar.h
index 5d2b9ad..fcbe621 100644
--- a/arch/x86/include/asm/vvar.h
+++ b/arch/x86/include/asm/vvar.h
@@ -47,7 +47,11 @@ extern char __vvar_page;
DECLARE_VVAR(0, volatile unsigned long, jiffies)
DECLARE_VVAR(16, int, vgetcpu_mode)
DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data)
-
+/*
+ * you must update VVAR_TOTAL_SIZE to reflect all of the variables we're
+ * stuffing into the vvar area. Don't change any of the above without
+ * also changing this math of VVAR_TOTAL_SIZE
+ */
#undef DECLARE_VVAR

#endif
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 9f6b934..0ab31a9 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -16,6 +16,7 @@
#include <asm/sigframe.h>
#include <asm/bootparam.h>
#include <asm/suspend.h>
+#include <asm/vgtod.h>

#ifdef CONFIG_XEN
#include <xen/interface/xen.h>
@@ -71,4 +72,8 @@ void common(void) {

BLANK();
DEFINE(PTREGS_SIZE, sizeof(struct pt_regs));
+
+ BLANK();
+ DEFINE(VVAR_TOTAL_SIZE,
+ ALIGN(128 + sizeof(struct vsyscall_gtod_data), PAGE_SIZE));
}
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 49edf2d..8b11307 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -168,11 +168,9 @@ SECTIONS
* Pad the rest of the page with zeros. Otherwise the loader
* can leave garbage here.
*/
- . = __vvar_beginning_hack + PAGE_SIZE;
+ . = __vvar_beginning_hack + VVAR_TOTAL_SIZE;
} :data

- . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE);
-
/* Init code and data - will be freed after init */
. = ALIGN(PAGE_SIZE);
.init.begin : AT(ADDR(.init.begin) - LOAD_OFFSET) {
diff --git a/arch/x86/vdso/vdso-layout.lds.S b/arch/x86/vdso/vdso-layout.lds.S
index de2c921..acaf8ce 100644
--- a/arch/x86/vdso/vdso-layout.lds.S
+++ b/arch/x86/vdso/vdso-layout.lds.S
@@ -1,4 +1,5 @@
#include <asm/vdso.h>
+#include <asm/asm-offsets.h>

/*
* Linker script for vDSO. This is an ELF shared object prelinked to
@@ -25,7 +26,7 @@ SECTIONS
* segment.
*/

- vvar_start = . - 2 * PAGE_SIZE;
+ vvar_start = . - (VVAR_TOTAL_SIZE + PAGE_SIZE);
vvar_page = vvar_start;

/* Place all vvars at the offsets in asm/vvar.h. */
@@ -35,7 +36,7 @@ SECTIONS
#undef __VVAR_KERNEL_LDS
#undef EMIT_VVAR

- hpet_page = vvar_start + PAGE_SIZE;
+ hpet_page = vvar_start + VVAR_TOTAL_SIZE;

. = SIZEOF_HEADERS;

diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 970463b..fc37067 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -16,6 +16,7 @@
#include <asm/vdso.h>
#include <asm/page.h>
#include <asm/hpet.h>
+#include <asm/asm-offsets.h>

#if defined(CONFIG_X86_64)
unsigned int __read_mostly vdso64_enabled = 1;
@@ -150,7 +151,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
ret = remap_pfn_range(vma,
text_start + image->sym_vvar_page,
__pa_symbol(&__vvar_page) >> PAGE_SHIFT,
- PAGE_SIZE,
+ VVAR_TOTAL_SIZE,
PAGE_READONLY);

if (ret)
--
1.8.1