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authorAndy Lutomirski <luto@MIT.EDU>2011-05-23 09:31:24 -0400
committerThomas Gleixner <tglx@linutronix.de>2011-05-24 14:51:28 +0200
commit8c49d9a74bac5ea3f18480307057241b808fcc0c (patch)
treea9d2d8160ca37e9292e605cf3cdd85b29646c4b7 /arch/x86/vdso
parentd762f4383100c2a87b1a3f2d678cd3b5425655b4 (diff)
downloadlinux-8c49d9a74bac5ea3f18480307057241b808fcc0c.tar.bz2
x86-64: Clean up vdso/kernel shared variables
Variables that are shared between the vdso and the kernel are currently a bit of a mess. They are each defined with their own magic, they are accessed differently in the kernel, the vsyscall page, and the vdso, and one of them (vsyscall_clock) doesn't even really exist. This changes them all to use a common mechanism. All of them are delcared in vvar.h with a fixed address (validated by the linker script). In the kernel (as before), they look like ordinary read-write variables. In the vsyscall page and the vdso, they are accessed through a new macro VVAR, which gives read-only access. The vdso is now loaded verbatim into memory without any fixups. As a side bonus, access from the vdso is faster because a level of indirection is removed. While we're at it, pack jiffies and vgetcpu_mode into the same cacheline. Signed-off-by: Andy Lutomirski <luto@mit.edu> Cc: Andi Kleen <andi@firstfloor.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Borislav Petkov <bp@amd64.org> Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/vdso')
-rw-r--r--arch/x86/vdso/Makefile2
-rw-r--r--arch/x86/vdso/vclock_gettime.c3
-rw-r--r--arch/x86/vdso/vdso.lds.S7
-rw-r--r--arch/x86/vdso/vextern.h16
-rw-r--r--arch/x86/vdso/vgetcpu.c3
-rw-r--r--arch/x86/vdso/vma.c27
-rw-r--r--arch/x86/vdso/vvar.c12
7 files changed, 3 insertions, 67 deletions
diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index b6552b189bcd..a651861f7e8e 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -11,7 +11,7 @@ vdso-install-$(VDSO32-y) += $(vdso32-images)
# files to link into the vdso
-vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o vvar.o
+vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o
# files to link into kernel
obj-$(VDSO64-y) += vma.o vdso.o
diff --git a/arch/x86/vdso/vclock_gettime.c b/arch/x86/vdso/vclock_gettime.c
index ee55754cc3c5..0b873d455bda 100644
--- a/arch/x86/vdso/vclock_gettime.c
+++ b/arch/x86/vdso/vclock_gettime.c
@@ -22,9 +22,8 @@
#include <asm/hpet.h>
#include <asm/unistd.h>
#include <asm/io.h>
-#include "vextern.h"
-#define gtod vdso_vsyscall_gtod_data
+#define gtod (&VVAR(vsyscall_gtod_data))
notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)
{
diff --git a/arch/x86/vdso/vdso.lds.S b/arch/x86/vdso/vdso.lds.S
index 4e5dd3b4de7f..81f250011f71 100644
--- a/arch/x86/vdso/vdso.lds.S
+++ b/arch/x86/vdso/vdso.lds.S
@@ -28,10 +28,3 @@ VERSION {
}
VDSO64_PRELINK = VDSO_PRELINK;
-
-/*
- * Define VDSO64_x for each VEXTERN(x), for use via VDSO64_SYMBOL.
- */
-#define VEXTERN(x) VDSO64_ ## x = vdso_ ## x;
-#include "vextern.h"
-#undef VEXTERN
diff --git a/arch/x86/vdso/vextern.h b/arch/x86/vdso/vextern.h
deleted file mode 100644
index 1683ba2ae3e8..000000000000
--- a/arch/x86/vdso/vextern.h
+++ /dev/null
@@ -1,16 +0,0 @@
-#ifndef VEXTERN
-#include <asm/vsyscall.h>
-#define VEXTERN(x) \
- extern typeof(x) *vdso_ ## x __attribute__((visibility("hidden")));
-#endif
-
-#define VMAGIC 0xfeedbabeabcdefabUL
-
-/* Any kernel variables used in the vDSO must be exported in the main
- kernel's vmlinux.lds.S/vsyscall.h/proper __section and
- put into vextern.h and be referenced as a pointer with vdso prefix.
- The main kernel later fills in the values. */
-
-VEXTERN(jiffies)
-VEXTERN(vgetcpu_mode)
-VEXTERN(vsyscall_gtod_data)
diff --git a/arch/x86/vdso/vgetcpu.c b/arch/x86/vdso/vgetcpu.c
index 9fbc6b20026b..5463ad558573 100644
--- a/arch/x86/vdso/vgetcpu.c
+++ b/arch/x86/vdso/vgetcpu.c
@@ -11,14 +11,13 @@
#include <linux/time.h>
#include <asm/vsyscall.h>
#include <asm/vgtod.h>
-#include "vextern.h"
notrace long
__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
{
unsigned int p;
- if (*vdso_vgetcpu_mode == VGETCPU_RDTSCP) {
+ if (VVAR(vgetcpu_mode) == VGETCPU_RDTSCP) {
/* Load per CPU data from RDTSCP */
native_read_tscp(&p);
} else {
diff --git a/arch/x86/vdso/vma.c b/arch/x86/vdso/vma.c
index 4b5d26f108bb..7abd2be0f9b9 100644
--- a/arch/x86/vdso/vma.c
+++ b/arch/x86/vdso/vma.c
@@ -15,9 +15,6 @@
#include <asm/proto.h>
#include <asm/vdso.h>
-#include "vextern.h" /* Just for VMAGIC. */
-#undef VEXTERN
-
unsigned int __read_mostly vdso_enabled = 1;
extern char vdso_start[], vdso_end[];
@@ -26,20 +23,10 @@ extern unsigned short vdso_sync_cpuid;
static struct page **vdso_pages;
static unsigned vdso_size;
-static inline void *var_ref(void *p, char *name)
-{
- if (*(void **)p != (void *)VMAGIC) {
- printk("VDSO: variable %s broken\n", name);
- vdso_enabled = 0;
- }
- return p;
-}
-
static int __init init_vdso_vars(void)
{
int npages = (vdso_end - vdso_start + PAGE_SIZE - 1) / PAGE_SIZE;
int i;
- char *vbase;
vdso_size = npages << PAGE_SHIFT;
vdso_pages = kmalloc(sizeof(struct page *) * npages, GFP_KERNEL);
@@ -54,20 +41,6 @@ static int __init init_vdso_vars(void)
copy_page(page_address(p), vdso_start + i*PAGE_SIZE);
}
- vbase = vmap(vdso_pages, npages, 0, PAGE_KERNEL);
- if (!vbase)
- goto oom;
-
- if (memcmp(vbase, "\177ELF", 4)) {
- printk("VDSO: I'm broken; not ELF\n");
- vdso_enabled = 0;
- }
-
-#define VEXTERN(x) \
- *(typeof(__ ## x) **) var_ref(VDSO64_SYMBOL(vbase, x), #x) = &__ ## x;
-#include "vextern.h"
-#undef VEXTERN
- vunmap(vbase);
return 0;
oom:
diff --git a/arch/x86/vdso/vvar.c b/arch/x86/vdso/vvar.c
deleted file mode 100644
index 1b7e703684f9..000000000000
--- a/arch/x86/vdso/vvar.c
+++ /dev/null
@@ -1,12 +0,0 @@
-/* Define pointer to external vDSO variables.
- These are part of the vDSO. The kernel fills in the real addresses
- at boot time. This is done because when the vdso is linked the
- kernel isn't yet and we don't know the final addresses. */
-#include <linux/kernel.h>
-#include <linux/time.h>
-#include <asm/vsyscall.h>
-#include <asm/timex.h>
-#include <asm/vgtod.h>
-
-#define VEXTERN(x) typeof (__ ## x) *const vdso_ ## x = (void *)VMAGIC;
-#include "vextern.h"