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Commit 7a59ed41 authored by Stefani Seibold's avatar Stefani Seibold Committed by H. Peter Anvin
Browse files

x86, vdso: Add 32 bit VDSO time support for 32 bit kernel 



This patch add the time support for 32 bit a VDSO to a 32 bit kernel.

For 32 bit programs running on a 32 bit kernel, the same mechanism is
used as for 64 bit programs running on a 64 bit kernel.

Reviewed-by: default avatarAndy Lutomirski <luto@amacapital.net>
Signed-off-by: default avatarStefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-10-git-send-email-stefani@seibold.net


Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
parent b4b541a6

arch/x86/include/asm/vdso.h

+5 −0
Original line number Diff line number Diff line
@@ -2,6 +2,11 @@ 
#define _ASM_X86_VDSO_H



#if defined CONFIG_X86_32 || defined CONFIG_COMPAT



#include <asm/vdso32.h>



extern const char VDSO32_PRELINK[];



/*

 * Given a pointer to the vDSO image, find the pointer to VDSO32_name

 * as that symbol is defined in the vDSO sources or linker script.

arch/x86/include/asm/vdso32.h

0 → 100644
+11 −0
Original line number Diff line number Diff line 
#ifndef _ASM_X86_VDSO32_H

#define _ASM_X86_VDSO32_H



#define VDSO_BASE_PAGE	0

#define VDSO_VVAR_PAGE	1

#define VDSO_HPET_PAGE	2

#define VDSO_PAGES	3

#define VDSO_PREV_PAGES	2

#define VDSO_OFFSET(x)	((x) * PAGE_SIZE)



#endif

arch/x86/vdso/Makefile

+8 −0
Original line number Diff line number Diff line
@@ -146,8 +146,16 @@ KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS)) 
$(vdso32-images:%=$(obj)/%.dbg): KBUILD_AFLAGS = $(KBUILD_AFLAGS_32)

$(vdso32-images:%=$(obj)/%.dbg): asflags-$(CONFIG_X86_64) += -m32



KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS))

KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32))

KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32))

KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32))

KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic

$(vdso32-images:%=$(obj)/%.dbg): KBUILD_CFLAGS = $(KBUILD_CFLAGS_32)



$(vdso32-images:%=$(obj)/%.dbg): $(obj)/vdso32-%.so.dbg: FORCE \

				 $(obj)/vdso32/vdso32.lds \

				 $(obj)/vdso32/vclock_gettime.o \

				 $(obj)/vdso32/note.o \

				 $(obj)/vdso32/%.o

	$(call if_changed,vdso)

arch/x86/vdso/vclock_gettime.c

+69 −7
Original line number Diff line number Diff line
@@ -4,6 +4,9 @@ 
 *

 * Fast user context implementation of clock_gettime, gettimeofday, and time.

 *

 * 32 Bit compat layer by Stefani Seibold <stefani@seibold.net>

 *  sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany

 *

 * The code should have no internal unresolved relocations.

 * Check with readelf after changing.

 */
@@ -12,13 +15,11 @@ 
#define DISABLE_BRANCH_PROFILING



#include <linux/kernel.h>

#include <linux/posix-timers.h>

#include <linux/time.h>

#include <uapi/linux/time.h>

#include <linux/string.h>

#include <asm/vsyscall.h>

#include <asm/fixmap.h>

#include <asm/vgtod.h>

#include <asm/timex.h>

#include <asm/hpet.h>

#include <asm/unistd.h>

#include <asm/io.h>
@@ -26,6 +27,12 @@ 


#define gtod (&VVAR(vsyscall_gtod_data))



extern int __vdso_clock_gettime(clockid_t clock, struct timespec *ts);

extern int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz);

extern time_t __vdso_time(time_t *t);



#ifndef BUILD_VDSO32



static notrace cycle_t vread_hpet(void)

{

	return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + HPET_COUNTER);
@@ -118,6 +125,59 @@ static notrace cycle_t vread_pvclock(int *mode) 
}

#endif



#else



extern u8 hpet_page

	__attribute__((visibility("hidden")));



#ifdef CONFIG_HPET_TIMER

static notrace cycle_t vread_hpet(void)

{

	return readl((const void __iomem *)(&hpet_page + HPET_COUNTER));

}

#endif



notrace static long vdso_fallback_gettime(long clock, struct timespec *ts)

{

	long ret;



	asm(

		"mov %%ebx, %%edx \n"

		"mov %2, %%ebx \n"

		"call VDSO32_vsyscall \n"

		"mov %%edx, %%ebx \n"

		: "=a" (ret)

		: "0" (__NR_clock_gettime), "g" (clock), "c" (ts)

		: "memory", "edx");

	return ret;

}



notrace static long vdso_fallback_gtod(struct timeval *tv, struct timezone *tz)

{

	long ret;



	asm(

		"mov %%ebx, %%edx \n"

		"mov %2, %%ebx \n"

		"call VDSO32_vsyscall \n"

		"mov %%edx, %%ebx \n"

		: "=a" (ret)

		: "0" (__NR_gettimeofday), "g" (tv), "c" (tz)

		: "memory", "edx");

	return ret;

}



#ifdef CONFIG_PARAVIRT_CLOCK



static notrace cycle_t vread_pvclock(int *mode)

{

	*mode = VCLOCK_NONE;

	return 0;

}

#endif



#endif



notrace static cycle_t vread_tsc(void)

{

	cycle_t ret;
@@ -131,7 +191,7 @@ notrace static cycle_t vread_tsc(void) 
	 * but no one has ever seen it happen.

	 */

	rdtsc_barrier();

	ret = (cycle_t)vget_cycles();

	ret = (cycle_t)__native_read_tsc();



	last = gtod->clock.cycle_last;
@@ -152,12 +212,14 @@ notrace static cycle_t vread_tsc(void) 


notrace static inline u64 vgetsns(int *mode)

{

	long v;

	u64 v;

	cycles_t cycles;

	if (gtod->clock.vclock_mode == VCLOCK_TSC)

		cycles = vread_tsc();

#ifdef CONFIG_HPET_TIMER

	else if (gtod->clock.vclock_mode == VCLOCK_HPET)

		cycles = vread_hpet();

#endif

#ifdef CONFIG_PARAVIRT_CLOCK

	else if (gtod->clock.vclock_mode == VCLOCK_PVCLOCK)

		cycles = vread_pvclock(mode);
@@ -189,7 +251,7 @@ notrace static int __always_inline do_realtime(struct timespec *ts) 
	return mode;

}



notrace static int do_monotonic(struct timespec *ts)

notrace static int __always_inline do_monotonic(struct timespec *ts)

{

	unsigned long seq;

	u64 ns;
@@ -284,7 +346,7 @@ int gettimeofday(struct timeval *, struct timezone *) 
 */

notrace time_t __vdso_time(time_t *t)

{

	/* This is atomic on x86_64 so we don't need any locks. */

	/* This is atomic on x86 so we don't need any locks. */

	time_t result = ACCESS_ONCE(gtod->wall_time_sec);



	if (t)

arch/x86/vdso/vdso-layout.lds.S

+22 −0
Original line number Diff line number Diff line
@@ -6,6 +6,24 @@ 


SECTIONS

{

#ifdef BUILD_VDSO32

#include <asm/vdso32.h>



	.hpet_sect : {

		hpet_page = . - VDSO_OFFSET(VDSO_HPET_PAGE);

	} :text :hpet_sect



	.vvar_sect : {

		vvar = . - VDSO_OFFSET(VDSO_VVAR_PAGE);



	/* Place all vvars at the offsets in asm/vvar.h. */

#define EMIT_VVAR(name, offset) vvar_ ## name = vvar + offset;

#define __VVAR_KERNEL_LDS

#include <asm/vvar.h>

#undef __VVAR_KERNEL_LDS

#undef EMIT_VVAR

	} :text :vvar_sect

#endif

	. = SIZEOF_HEADERS;



	.hash		: { *(.hash) }			:text
@@ -61,4 +79,8 @@ PHDRS 
	dynamic		PT_DYNAMIC	FLAGS(4);		/* PF_R */

	note		PT_NOTE		FLAGS(4);		/* PF_R */

	eh_frame_hdr	PT_GNU_EH_FRAME;

#ifdef BUILD_VDSO32

	vvar_sect	PT_NULL		FLAGS(4);		/* PF_R */

	hpet_sect	PT_NULL		FLAGS(4);		/* PF_R */

#endif

}