Commit c6f21243 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 vdso changes from Peter Anvin:
 "This is the revamp of the 32-bit vdso and the associated cleanups.

  This adds timekeeping support to the 32-bit vdso that we already have
  in the 64-bit vdso.  Although 32-bit x86 is legacy, it is likely to
  remain in the embedded space for a very long time to come.

  This removes the traditional COMPAT_VDSO support; the configuration
  variable is reused for simply removing the 32-bit vdso, which will
  produce correct results but obviously suffer a performance penalty.
  Only one beta version of glibc was affected, but that version was
  unfortunately included in one OpenSUSE release.

  This is not the end of the vdso cleanups.  Stefani and Andy have
  agreed to continue work for the next kernel cycle; in fact Andy has
  already produced another set of cleanups that came too late for this
  cycle.

  An incidental, but arguably important, change is that this ensures
  that unused space in the VVAR page is properly zeroed.  It wasn't
  before, and would contain whatever garbage was left in memory by BIOS
  or the bootloader.  Since the VVAR page is accessible to user space
  this had the potential of information leaks"

* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  x86, vdso: Fix the symbol versions on the 32-bit vDSO
  x86, vdso, build: Don't rebuild 32-bit vdsos on every make
  x86, vdso: Actually discard the .discard sections
  x86, vdso: Fix size of get_unmapped_area()
  x86, vdso: Finish removing VDSO32_PRELINK
  x86, vdso: Move more vdso definitions into vdso.h
  x86: Load the 32-bit vdso in place, just like the 64-bit vdsos
  x86, vdso32: handle 32 bit vDSO larger one page
  x86, vdso32: Disable stack protector, adjust optimizations
  x86, vdso: Zero-pad the VVAR page
  x86, vdso: Add 32 bit VDSO time support for 64 bit kernel
  x86, vdso: Add 32 bit VDSO time support for 32 bit kernel
  x86, vdso: Patch alternatives in the 32-bit VDSO
  x86, vdso: Introduce VVAR marco for vdso32
  x86, vdso: Cleanup __vdso_gettimeofday()
  x86, vdso: Replace VVAR(vsyscall_gtod_data) by gtod macro
  x86, vdso: __vdso_clock_gettime() cleanup
  x86, vdso: Revamp vclock_gettime.c
  mm: Add new func _install_special_mapping() to mmap.c
  x86, vdso: Make vsyscall_gtod_data handling x86 generic
  ...
parents 9447dc43 37c97554

Documentation/kernel-parameters.txt

+16 −6
Original line number Diff line number Diff line
@@ -3424,14 +3424,24 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
					of CONFIG_HIGHPTE.



	vdso=		[X86,SH]

			vdso=2: enable compat VDSO (default with COMPAT_VDSO)

			vdso=1: enable VDSO (default)

			On X86_32, this is an alias for vdso32=.  Otherwise:



			vdso=1: enable VDSO (the default)

			vdso=0: disable VDSO mapping



	vdso32=		[X86]

			vdso32=2: enable compat VDSO (default with COMPAT_VDSO)

			vdso32=1: enable 32-bit VDSO (default)

			vdso32=0: disable 32-bit VDSO mapping

	vdso32=		[X86] Control the 32-bit vDSO

			vdso32=1: enable 32-bit VDSO

			vdso32=0 or vdso32=2: disable 32-bit VDSO



			See the help text for CONFIG_COMPAT_VDSO for more

			details.  If CONFIG_COMPAT_VDSO is set, the default is

			vdso32=0; otherwise, the default is vdso32=1.



			For compatibility with older kernels, vdso32=2 is an

			alias for vdso32=0.



			Try vdso32=0 if you encounter an error that says:

			dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!



	vector=		[IA-64,SMP]

			vector=percpu: enable percpu vector domain

arch/x86/Kconfig

+21 −9
Original line number Diff line number Diff line
@@ -107,9 +107,9 @@ config X86 
	select HAVE_ARCH_SOFT_DIRTY

	select CLOCKSOURCE_WATCHDOG

	select GENERIC_CLOCKEVENTS

	select ARCH_CLOCKSOURCE_DATA if X86_64

	select ARCH_CLOCKSOURCE_DATA

	select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)

	select GENERIC_TIME_VSYSCALL if X86_64

	select GENERIC_TIME_VSYSCALL

	select KTIME_SCALAR if X86_32

	select GENERIC_STRNCPY_FROM_USER

	select GENERIC_STRNLEN_USER
@@ -1848,17 +1848,29 @@ config DEBUG_HOTPLUG_CPU0 
	  If unsure, say N.



config COMPAT_VDSO

	def_bool y

	prompt "Compat VDSO support"

	def_bool n

	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"

	depends on X86_32 || IA32_EMULATION

	---help---

	  Map the 32-bit VDSO to the predictable old-style address too.

	  Certain buggy versions of glibc will crash if they are

	  presented with a 32-bit vDSO that is not mapped at the address

	  indicated in its segment table.



	  Say N here if you are running a sufficiently recent glibc

	  version (2.3.3 or later), to remove the high-mapped

	  VDSO mapping and to exclusively use the randomized VDSO.

	  The bug was introduced by f866314b89d56845f55e6f365e18b31ec978ec3a

	  and fixed by 3b3ddb4f7db98ec9e912ccdf54d35df4aa30e04a and

	  49ad572a70b8aeb91e57483a11dd1b77e31c4468.  Glibc 2.3.3 is

	  the only released version with the bug, but OpenSUSE 9

	  contains a buggy "glibc 2.3.2".



	  If unsure, say Y.

	  The symptom of the bug is that everything crashes on startup, saying:

	  dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed!



	  Saying Y here changes the default value of the vdso32 boot

	  option from 1 to 0, which turns off the 32-bit vDSO entirely.

	  This works around the glibc bug but hurts performance.



	  If unsure, say N: if you are compiling your own kernel, you

	  are unlikely to be using a buggy version of glibc.



config CMDLINE_BOOL

	bool "Built-in kernel command line"

arch/x86/include/asm/clocksource.h

+0 −4
Original line number Diff line number Diff line
@@ -3,8 +3,6 @@ 
#ifndef _ASM_X86_CLOCKSOURCE_H

#define _ASM_X86_CLOCKSOURCE_H



#ifdef CONFIG_X86_64



#define VCLOCK_NONE 0  /* No vDSO clock available.	*/

#define VCLOCK_TSC  1  /* vDSO should use vread_tsc.	*/

#define VCLOCK_HPET 2  /* vDSO should use vread_hpet.	*/
@@ -14,6 +12,4 @@ struct arch_clocksource_data { 
	int vclock_mode;

};



#endif /* CONFIG_X86_64 */



#endif /* _ASM_X86_CLOCKSOURCE_H */

arch/x86/include/asm/elf.h

+0 −4
Original line number Diff line number Diff line
@@ -281,16 +281,12 @@ do { \ 


#define STACK_RND_MASK (0x7ff)



#define VDSO_HIGH_BASE		(__fix_to_virt(FIX_VDSO))



#define ARCH_DLINFO		ARCH_DLINFO_IA32(vdso_enabled)



/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */



#else /* CONFIG_X86_32 */



#define VDSO_HIGH_BASE		0xffffe000U /* CONFIG_COMPAT_VDSO address */



/* 1GB for 64bit, 8MB for 32bit */

#define STACK_RND_MASK (test_thread_flag(TIF_ADDR32) ? 0x7ff : 0x3fffff)

arch/x86/include/asm/fixmap.h

+0 −8
Original line number Diff line number Diff line
@@ -40,15 +40,8 @@ 
 */

extern unsigned long __FIXADDR_TOP;

#define FIXADDR_TOP	((unsigned long)__FIXADDR_TOP)



#define FIXADDR_USER_START     __fix_to_virt(FIX_VDSO)

#define FIXADDR_USER_END       __fix_to_virt(FIX_VDSO - 1)

#else

#define FIXADDR_TOP	(VSYSCALL_END-PAGE_SIZE)



/* Only covers 32bit vsyscalls currently. Need another set for 64bit. */

#define FIXADDR_USER_START	((unsigned long)VSYSCALL32_VSYSCALL)

#define FIXADDR_USER_END	(FIXADDR_USER_START + PAGE_SIZE)

#endif
@@ -74,7 +67,6 @@ extern unsigned long __FIXADDR_TOP; 
enum fixed_addresses {

#ifdef CONFIG_X86_32

	FIX_HOLE,

	FIX_VDSO,

#else

	VSYSCALL_LAST_PAGE,

	VSYSCALL_FIRST_PAGE = VSYSCALL_LAST_PAGE

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