kernel.git/arch/x86/vdso, branch linux-3.17.y

arm64,ia64,ppc,s390,sh,tile,um,x86,mm: remove default gate area

2014-08-08T22:57:27Z

The core mm code will provide a default gate area based on FIXADDR_USER_START and FIXADDR_USER_END if !defined(__HAVE_ARCH_GATE_AREA) && defined(AT_SYSINFO_EHDR). This default is only useful for ia64. arm64, ppc, s390, sh, tile, 64-bit UML, and x86_32 have their own code just to disable it. arm, 32-bit UML, and x86_64 have gate areas, but they have their own implementations. This gets rid of the default and moves the code into ia64. This should save some code on architectures without a gate area: it's now possible to inline the gate_area functions in the default case. Signed-off-by: Andy Lutomirski Acked-by: Nathan Lynch Acked-by: H. Peter Anvin Acked-by: Benjamin Herrenschmidt [in principle] Acked-by: Richard Weinberger [for um] Acked-by: Will Deacon [for arm64] Cc: Catalin Marinas Cc: Will Deacon Cc: Tony Luck Cc: Fenghua Yu Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: Chris Metcalf Cc: Jeff Dike Cc: Richard Weinberger Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Nathan Lynch Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

x86/vdso: Set VM_MAYREAD for the vvar vma

2014-07-25T23:32:53Z

The VVAR area can, obviously, be read; that is kind of the point. AFAIK this has no effect whatsoever unless x86 suddenly turns into a nommu architecture. Nonetheless, not setting it is suspicious. Reported-by: Nathan Lynch Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/e4c8bf4bc2725bda22c4a4b7d0c82adcd8f8d9b8.1406330779.git.luto@amacapital.net Signed-off-by: H. Peter Anvin

x86, vdso: Get rid of the fake section mechanism

2014-07-11T23:58:07Z

Now that we can tolerate extra things dangling off the end of the vdso image, we can strip the vdso the old fashioned way rather than using an overcomplicated custom stripping algorithm. This is a partial reversion of: 6f121e5 x86, vdso: Reimplement vdso.so preparation in build-time C Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/50e01ed6dcc0575d20afd782f9fe98d5ee3e2d8a.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin

x86, vdso: Move the vvar area before the vdso text

2014-07-11T23:57:51Z

Putting the vvar area after the vdso text is rather complicated: it only works of the total length of the vdso text mapping is known at vdso link time, and the linker doesn't allow symbol addresses to depend on the sizes of non-allocatable data after the PT_LOAD segment. Moving the vvar area before the vdso text will allow is to safely map non-allocatable data after the vdso text, which is a nice simplification. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/156c78c0d93144ff1055a66493783b9e56813983.1405040914.git.luto@amacapital.net Signed-off-by: H. Peter Anvin

x86-32, vdso: Fix vDSO build error due to missing align_vdso_addr()

2014-07-10T23:06:04Z

Relying on static functions used just once to get inlined (and subsequently have dead code paths eliminated) is wrong: Compilers are free to decide whether they do this, regardless of optimization level. With this not happening for vdso_addr() (observed with gcc 4.1.x), an unresolved reference to align_vdso_addr() causes the build to fail. [ hpa: vdso_addr() is never actually used on x86-32, as calculate_addr in map_vdso() is always false. It ought to be possible to clean this up further, but this fixes the immediate problem. ] Signed-off-by: Jan Beulich Link: http://lkml.kernel.org/r/53B5863B02000078000204D5@mail.emea.novell.com Acked-by: Andy Lutomirski Tested-by: Boris Ostrovsky Tested-by: Andrew Morton Signed-off-by: H. Peter Anvin

x86-64, vdso: Fix vDSO build breakage due to empty .rela.dyn

2014-07-10T22:59:56Z

Certain ld versions (observed with 2.20.0) put an empty .rela.dyn section into shared object files, breaking the assumption on the number of sections to be copied to the final output. Simply discard any empty SHT_REL and SHT_RELA sections to address this. Signed-off-by: Jan Beulich Link: http://lkml.kernel.org/r/53B5861E02000078000204D1@mail.emea.novell.com Acked-by: Andy Lutomirski Tested-by: Boris Ostrovsky Tested-by: Andrew Morton Signed-off-by: H. Peter Anvin

x86/vdso: Error out in vdso2c if DT_RELA is present

2014-06-24T20:53:57Z

vdso2c was checking for various types of relocations to detect when the vdso had undefined symbols or was otherwise dependent on relocation at load time. Undefined symbols in the vdso would fail if accessed at runtime, and certain implementation errors (e.g. branch profiling or incorrect symbol visibilities) could result in data access through the GOT that requires relocations. This could be as simple as: extern char foo; return foo; Without some kind of visibility control, the compiler would assume that foo could be interposed at load time and would generate a relocation. x86-64 and x32 (as opposed to i386) use explicit-addent (RELA) instead of implicit-addent (REL) relocations for data access, and vdso2c forgot to detect those. Whether these bad relocations would actually fail at runtime depends on what the linker sticks in the unrelocated references. Nonetheless, these relocations have no business existing in the vDSO and should be fixed rather than silently ignored. This error could trigger on some configurations due to branch profiling. The previous patch fixed that. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/74ef0c00b4d2a3b573e00a4113874e62f772e348.1403642755.git.luto@amacapital.net Signed-off-by: H. Peter Anvin

x86/vdso: Move DISABLE_BRANCH_PROFILING into the vdso makefile

2014-06-24T20:53:00Z

DISABLE_BRANCH_PROFILING turns off branch profiling (i.e. a redefinition of 'if'). Branch profiling depends on a bunch of kernel-internal symbols and generates extra output sections, none of which are useful or functional in the vDSO. It's currently turned off for vclock_gettime.c, but vgetcpu.c also triggers branch profiling, so just turn it off in the makefile. This fixes the build on some configurations: the vdso could contain undefined symbols, and the fake section table overflowed due to ftrace's added sections. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/bf1ec29e03b2bbc081f6dcaefa64db1c3a83fb21.1403642755.git.luto@amacapital.net Signed-off-by: H. Peter Anvin

x86/vdso: Create .build-id links for unstripped vdso files

2014-06-20T20:18:49Z

With this change, doing 'make vdso_install' and telling gdb: set debug-file-directory /lib/modules/KVER/vdso will enable vdso debugging with symbols. This is useful for testing, but kernel RPM builds will probably want to manually delete these symlinks or otherwise do something sensible when they strip the vdso/*.so files. If ld does not support --build-id, then the symlinks will not be created. Note that kernel packagers that use vdso_install may need to adjust their packaging scripts to accomdate this change. For example, Fedora's scripts create build-id symlinks themselves in a different location, so the spec should probably be updated to remove the symlinks created by make vdso_install. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/a424b189ce3ced85fe1e82d032a20e765e0fe0d3.1403291930.git.luto@amacapital.net Signed-off-by: H. Peter Anvin

x86/vdso: Remove some redundant in-memory section headers

2014-06-19T22:45:26Z

.data doesn't need to be separate from .rodata: they're both readonly. .altinstructions and .altinstr_replacement aren't needed by anything except vdso2c; strip them from the final image. While we're at it, rather than aligning the actual executable text, just shove some unused-at-runtime data in between real data and text. My vdso image is still above 4k, but I'm disinclined to try to trim it harder for 3.16. For future trimming, I suspect that these sections could be moved to later in the file and dropped from the in-memory image: .gnu.version and .gnu.version_d (this may lose versions in gdb) .eh_frame (should be harmless) .eh_frame_hdr (I'm not really sure) .hash (AFAIK nothing needs this section header) Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/2e96d0c49016ea6d026a614ae645e93edd325961.1403129369.git.luto@amacapital.net Signed-off-by: H. Peter Anvin