diff options
author | Andy Lutomirski <luto@MIT.EDU> | 2011-05-23 15:31:24 +0200 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2011-05-24 14:51:28 +0200 |
commit | 8c49d9a74bac5ea3f18480307057241b808fcc0c (patch) | |
tree | a9d2d8160ca37e9292e605cf3cdd85b29646c4b7 /arch/x86/include/asm | |
parent | Merge branch 'sh-latest' of git://git.kernel.org/pub/scm/linux/kernel/git/let... (diff) | |
download | linux-8c49d9a74bac5ea3f18480307057241b808fcc0c.tar.xz linux-8c49d9a74bac5ea3f18480307057241b808fcc0c.zip |
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/include/asm')
-rw-r--r-- | arch/x86/include/asm/vdso.h | 14 | ||||
-rw-r--r-- | arch/x86/include/asm/vgtod.h | 2 | ||||
-rw-r--r-- | arch/x86/include/asm/vsyscall.h | 12 | ||||
-rw-r--r-- | arch/x86/include/asm/vvar.h | 52 |
4 files changed, 54 insertions, 26 deletions
diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h index 9064052b73de..bb0522850b74 100644 --- a/arch/x86/include/asm/vdso.h +++ b/arch/x86/include/asm/vdso.h @@ -1,20 +1,6 @@ #ifndef _ASM_X86_VDSO_H #define _ASM_X86_VDSO_H -#ifdef CONFIG_X86_64 -extern const char VDSO64_PRELINK[]; - -/* - * Given a pointer to the vDSO image, find the pointer to VDSO64_name - * as that symbol is defined in the vDSO sources or linker script. - */ -#define VDSO64_SYMBOL(base, name) \ -({ \ - extern const char VDSO64_##name[]; \ - (void *)(VDSO64_##name - VDSO64_PRELINK + (unsigned long)(base)); \ -}) -#endif - #if defined CONFIG_X86_32 || defined CONFIG_COMPAT extern const char VDSO32_PRELINK[]; diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h index 3d61e204826f..646b4c1ca695 100644 --- a/arch/x86/include/asm/vgtod.h +++ b/arch/x86/include/asm/vgtod.h @@ -23,8 +23,6 @@ struct vsyscall_gtod_data { struct timespec wall_to_monotonic; struct timespec wall_time_coarse; }; -extern struct vsyscall_gtod_data __vsyscall_gtod_data -__section_vsyscall_gtod_data; extern struct vsyscall_gtod_data vsyscall_gtod_data; #endif /* _ASM_X86_VGTOD_H */ diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h index d0983d255fbd..d55597351f6a 100644 --- a/arch/x86/include/asm/vsyscall.h +++ b/arch/x86/include/asm/vsyscall.h @@ -16,27 +16,19 @@ enum vsyscall_num { #ifdef __KERNEL__ #include <linux/seqlock.h> -#define __section_vgetcpu_mode __attribute__ ((unused, __section__ (".vgetcpu_mode"), aligned(16))) -#define __section_jiffies __attribute__ ((unused, __section__ (".jiffies"), aligned(16))) - /* Definitions for CONFIG_GENERIC_TIME definitions */ -#define __section_vsyscall_gtod_data __attribute__ \ - ((unused, __section__ (".vsyscall_gtod_data"),aligned(16))) -#define __section_vsyscall_clock __attribute__ \ - ((unused, __section__ (".vsyscall_clock"),aligned(16))) #define __vsyscall_fn \ __attribute__ ((unused, __section__(".vsyscall_fn"))) notrace #define VGETCPU_RDTSCP 1 #define VGETCPU_LSL 2 -extern int __vgetcpu_mode; -extern volatile unsigned long __jiffies; - /* kernel space (writeable) */ extern int vgetcpu_mode; extern struct timezone sys_tz; +#include <asm/vvar.h> + extern void map_vsyscall(void); #endif /* __KERNEL__ */ diff --git a/arch/x86/include/asm/vvar.h b/arch/x86/include/asm/vvar.h new file mode 100644 index 000000000000..341b3559452b --- /dev/null +++ b/arch/x86/include/asm/vvar.h @@ -0,0 +1,52 @@ +/* + * vvar.h: Shared vDSO/kernel variable declarations + * Copyright (c) 2011 Andy Lutomirski + * Subject to the GNU General Public License, version 2 + * + * A handful of variables are accessible (read-only) from userspace + * code in the vsyscall page and the vdso. They are declared here. + * Some other file must define them with DEFINE_VVAR. + * + * In normal kernel code, they are used like any other variable. + * In user code, they are accessed through the VVAR macro. + * + * Each of these variables lives in the vsyscall page, and each + * one needs a unique offset within the little piece of the page + * reserved for vvars. Specify that offset in DECLARE_VVAR. + * (There are 896 bytes available. If you mess up, the linker will + * catch it.) + */ + +/* Offset of vars within vsyscall page */ +#define VSYSCALL_VARS_OFFSET (3072 + 128) + +#if defined(__VVAR_KERNEL_LDS) + +/* The kernel linker script defines its own magic to put vvars in the + * right place. + */ +#define DECLARE_VVAR(offset, type, name) \ + EMIT_VVAR(name, VSYSCALL_VARS_OFFSET + offset) + +#else + +#define DECLARE_VVAR(offset, type, name) \ + static type const * const vvaraddr_ ## name = \ + (void *)(VSYSCALL_START + VSYSCALL_VARS_OFFSET + (offset)); + +#define DEFINE_VVAR(type, name) \ + type __vvar_ ## name \ + __attribute__((section(".vsyscall_var_" #name), aligned(16))) + +#define VVAR(name) (*vvaraddr_ ## name) + +#endif + +/* DECLARE_VVAR(offset, type, name) */ + +DECLARE_VVAR(0, volatile unsigned long, jiffies) +DECLARE_VVAR(8, int, vgetcpu_mode) +DECLARE_VVAR(128, struct vsyscall_gtod_data, vsyscall_gtod_data) + +#undef DECLARE_VVAR +#undef VSYSCALL_VARS_OFFSET |