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/include/asm/vdso.h | 14 ----------- arch/x86/include/asm/vgtod.h | 2 -- arch/x86/include/asm/vsyscall.h | 12 ++-------- arch/x86/include/asm/vvar.h | 52 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 54 insertions(+), 26 deletions(-) create mode 100644 arch/x86/include/asm/vvar.h (limited to 'arch/x86/include') 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 -#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 + 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 -- cgit v1.2.1 From 44259b1abfaa8bb819d25d41d71e8e33e25dd36a Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Mon, 23 May 2011 09:31:28 -0400 Subject: x86-64: Move vread_tsc into a new file with sensible options vread_tsc is short and hot, and it's userspace code so the usual reasons to enable -pg and turn off sibling calls don't apply. (OK, turning off sibling calls has no effect. But it might someday...) As an added benefit, tsc.c is profilable now. 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/%3C99c6d7f5efa3ccb65b4ac6eb443e1ab7bad47d7b.1306156808.git.luto%40mit.edu%3E Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/tsc.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86/include') diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index 83e2efd181e2..9db5583b6d38 100644 --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -51,6 +51,10 @@ extern int unsynchronized_tsc(void); extern int check_tsc_unstable(void); extern unsigned long native_calibrate_tsc(void); +#ifdef CONFIG_X86_64 +extern cycles_t vread_tsc(void); +#endif + /* * Boot-time check whether the TSCs are synchronized across * all CPUs/cores: -- cgit v1.2.1