From 8c49d9a74bac5ea3f18480307057241b808fcc0c Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Mon, 23 May 2011 09:31:24 -0400 Subject: 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 Cc: Andi Kleen Cc: Linus Torvalds Cc: "David S. Miller" Cc: Eric Dumazet Cc: Peter Zijlstra Cc: Borislav Petkov Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E Signed-off-by: Thomas Gleixner --- arch/x86/vdso/Makefile | 2 +- arch/x86/vdso/vclock_gettime.c | 3 +-- arch/x86/vdso/vdso.lds.S | 7 ------- arch/x86/vdso/vextern.h | 16 ---------------- arch/x86/vdso/vgetcpu.c | 3 +-- arch/x86/vdso/vma.c | 27 --------------------------- arch/x86/vdso/vvar.c | 12 ------------ 7 files changed, 3 insertions(+), 67 deletions(-) delete mode 100644 arch/x86/vdso/vextern.h delete mode 100644 arch/x86/vdso/vvar.c (limited to 'arch/x86/vdso') diff --git a/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile index b6552b189bc..a651861f7e8 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 ee55754cc3c..0b873d455bd 100644 --- a/arch/x86/vdso/vclock_gettime.c +++ b/arch/x86/vdso/vclock_gettime.c @@ -22,9 +22,8 @@ #include #include #include -#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 4e5dd3b4de7..81f250011f7 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 1683ba2ae3e..00000000000 --- a/arch/x86/vdso/vextern.h +++ /dev/null @@ -1,16 +0,0 @@ -#ifndef VEXTERN -#include -#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 9fbc6b20026..5463ad55857 100644 --- a/arch/x86/vdso/vgetcpu.c +++ b/arch/x86/vdso/vgetcpu.c @@ -11,14 +11,13 @@ #include #include #include -#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 4b5d26f108b..7abd2be0f9b 100644 --- a/arch/x86/vdso/vma.c +++ b/arch/x86/vdso/vma.c @@ -15,9 +15,6 @@ #include #include -#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 1b7e703684f..00000000000 --- 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 -#include -#include -#include -#include - -#define VEXTERN(x) typeof (__ ## x) *const vdso_ ## x = (void *)VMAGIC; -#include "vextern.h" -- cgit v1.2.3-70-g09d2