linux-stable.git/arch/x86/boot, branch linux-3.19.y Linux kernel stable tree x86/efi: Avoid triple faults during EFI mixed mode calls 2015-03-06T22:57:42+00:00 Matt Fleming matt.fleming@intel.com 2015-01-13T15:25:00+00:00 c4f934bc8afc2d9ba633c9fc0f0ce593338ecae9 commit 96738c69a7fcdbf0d7c9df0c8a27660011e82a7b upstream. Andy pointed out that if an NMI or MCE is received while we're in the middle of an EFI mixed mode call a triple fault will occur. This can happen, for example, when issuing an EFI mixed mode call while running perf. The reason for the triple fault is that we execute the mixed mode call in 32-bit mode with paging disabled but with 64-bit kernel IDT handlers installed throughout the call. At Andy's suggestion, stop playing the games we currently do at runtime, such as disabling paging and installing a 32-bit GDT for __KERNEL_CS. We can simply switch to the __KERNEL32_CS descriptor before invoking firmware services, and run in compatibility mode. This way, if an NMI/MCE does occur the kernel IDT handler will execute correctly, since it'll jump to __KERNEL_CS automatically. However, this change is only possible post-ExitBootServices(). Before then the firmware "owns" the machine and expects for its 32-bit IDT handlers to be left intact to service interrupts, etc. So, we now need to distinguish between early boot and runtime invocations of EFI services. During early boot, we need to restore the GDT that the firmware expects to be present. We can only jump to the __KERNEL32_CS code segment for mixed mode calls after ExitBootServices() has been invoked. A liberal sprinkling of comments in the thunking code should make the differences in early and late environments more apparent. Reported-by: Andy Lutomirski <luto@amacapital.net> Tested-by: Borislav Petkov <bp@suse.de> Signed-off-by: Matt Fleming <matt.fleming@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 96738c69a7fcdbf0d7c9df0c8a27660011e82a7b upstream.

Andy pointed out that if an NMI or MCE is received while we're in the
middle of an EFI mixed mode call a triple fault will occur. This can
happen, for example, when issuing an EFI mixed mode call while running
perf.

The reason for the triple fault is that we execute the mixed mode call
in 32-bit mode with paging disabled but with 64-bit kernel IDT handlers
installed throughout the call.

At Andy's suggestion, stop playing the games we currently do at runtime,
such as disabling paging and installing a 32-bit GDT for __KERNEL_CS. We
can simply switch to the __KERNEL32_CS descriptor before invoking
firmware services, and run in compatibility mode. This way, if an
NMI/MCE does occur the kernel IDT handler will execute correctly, since
it'll jump to __KERNEL_CS automatically.

However, this change is only possible post-ExitBootServices(). Before
then the firmware "owns" the machine and expects for its 32-bit IDT
handlers to be left intact to service interrupts, etc.

So, we now need to distinguish between early boot and runtime
invocations of EFI services. During early boot, we need to restore the
GDT that the firmware expects to be present. We can only jump to the
__KERNEL32_CS code segment for mixed mode calls after ExitBootServices()
has been invoked.

A liberal sprinkling of comments in the thunking code should make the
differences in early and late environments more apparent.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
x86, build: replace Perl script with Shell script 2015-01-26T21:37:18+00:00 Kees Cook keescook@chromium.org 2015-01-26T20:58:35+00:00 d69911a68c865b152a067feaa45e98e6bb0f655b Commit e6023367d779 ("x86, kaslr: Prevent .bss from overlaping initrd") added Perl to the required build environment. This reimplements in shell the Perl script used to find the size of the kernel with bss and brk added. Signed-off-by: Kees Cook <keescook@chromium.org> Reported-by: Rob Landley <rob@landley.net> Acked-by: Rob Landley <rob@landley.net> Cc: Anca Emanuel <anca.emanuel@gmail.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Junjie Mao <eternal.n08@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Commit e6023367d779 ("x86, kaslr: Prevent .bss from overlaping initrd")
added Perl to the required build environment.  This reimplements in
shell the Perl script used to find the size of the kernel with bss and
brk added.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Rob Landley <rob@landley.net>
Acked-by: Rob Landley <rob@landley.net>
Cc: Anca Emanuel <anca.emanuel@gmail.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Junjie Mao <eternal.n08@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
x86, boot: Skip relocs when load address unchanged 2015-01-20T11:37:23+00:00 Kees Cook keescook@chromium.org 2015-01-16T00:51:46+00:00 f285f4a21c3253887caceed493089ece17579d59 On 64-bit, relocation is not required unless the load address gets changed. Without this, relocations do unexpected things when the kernel is above 4G. Reported-by: Baoquan He <bhe@redhat.com> Signed-off-by: Kees Cook <keescook@chromium.org> Tested-by: Thomas D. <whissi@whissi.de> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jan Beulich <JBeulich@suse.com> Cc: Junjie Mao <eternal.n08@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
On 64-bit, relocation is not required unless the load address gets
changed. Without this, relocations do unexpected things when the kernel
is above 4G.

Reported-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Thomas D. <whissi@whissi.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Junjie Mao <eternal.n08@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
x86/build: Clean auto-generated processor feature files 2014-12-23T14:37:06+00:00 Bjørn Mork bjorn@mork.no 2014-12-23T11:57:43+00:00 280dbc572357eb50184663fc9e4aaf09c8141e9b Commit 9def39be4e96 ("x86: Support compiling out human-friendly processor feature names") made two source file targets conditional. Such conditional targets will not be cleaned automatically by make mrproper. Fix by adding explicit clean-files targets for the two files. Fixes: 9def39be4e96 ("x86: Support compiling out human-friendly processor feature names") Signed-off-by: Bjørn Mork <bjorn@mork.no> Cc: Josh Triplett <josh@joshtriplett.org> Link: http://lkml.kernel.org/r/1419335863-10608-1-git-send-email-bjorn@mork.no Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Commit 9def39be4e96 ("x86: Support compiling out human-friendly
processor feature names") made two source file targets
conditional. Such conditional targets will not be cleaned
automatically by make mrproper.

Fix by adding explicit clean-files targets for the two files.

Fixes: 9def39be4e96 ("x86: Support compiling out human-friendly processor feature names")
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Cc: Josh Triplett <josh@joshtriplett.org>
Link: http://lkml.kernel.org/r/1419335863-10608-1-git-send-email-bjorn@mork.no
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10T20:42:16+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-12-10T20:42:16+00:00 8139548136d966863751a6e5ce8a19d08c4f374a Pull EFI updates from Ingo Molnar: "Changes in this cycle are: - support module unload for efivarfs (Mathias Krause) - another attempt at moving x86 to libstub taking advantage of the __pure attribute (Ard Biesheuvel) - add EFI runtime services section to ptdump (Mathias Krause)" * 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, ptdump: Add section for EFI runtime services efi/x86: Move x86 back to libstub efivarfs: Allow unloading when build as module 
Pull EFI updates from Ingo Molnar:
 "Changes in this cycle are:

   - support module unload for efivarfs (Mathias Krause)

   - another attempt at moving x86 to libstub taking advantage of the
     __pure attribute (Ard Biesheuvel)

   - add EFI runtime services section to ptdump (Mathias Krause)"

* 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, ptdump: Add section for EFI runtime services
  efi/x86: Move x86 back to libstub
  efivarfs: Allow unloading when build as module
Merge branch 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10T20:10:24+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-12-10T20:10:24+00:00 b6444bd0a18eb47343e16749ce80a6ebd521f124 Pull x86 boot and percpu updates from Ingo Molnar: "This tree contains a bootable images documentation update plus three slightly misplaced x86/asm percpu changes/optimizations" * 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86-64: Use RIP-relative addressing for most per-CPU accesses x86-64: Handle PC-relative relocations on per-CPU data x86: Convert a few more per-CPU items to read-mostly ones x86, boot: Document intermediates more clearly 
Pull x86 boot and percpu updates from Ingo Molnar:
 "This tree contains a bootable images documentation update plus three
  slightly misplaced x86/asm percpu changes/optimizations"

* 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86-64: Use RIP-relative addressing for most per-CPU accesses
  x86-64: Handle PC-relative relocations on per-CPU data
  x86: Convert a few more per-CPU items to read-mostly ones
  x86, boot: Document intermediates more clearly
x86: Use $(OBJDUMP) instead of plain objdump 2014-11-23T20:21:53+00:00 Chris Clayton chris2553@googlemail.com 2014-11-22T09:51:10+00:00 e2e68ae688b0a3766cd75aedf4ed4e39be402009 commit e6023367d779 'x86, kaslr: Prevent .bss from overlaping initrd' broke the cross compile of x86. It added a objdump invocation, which invokes the host native objdump and ignores an active cross tool chain. Use $(OBJDUMP) instead which takes the CROSS_COMPILE prefix into account. [ tglx: Massage changelog and use $(OBJDUMP) ] Fixes: e6023367d779 'x86, kaslr: Prevent .bss from overlaping initrd' Signed-off-by: Chris Clayton <chris2553@googlemail.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Borislav Petkov <bp@suse.de> Cc: Junjie Mao <eternal.n08@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: H. Peter Anvin <hpa@linux.intel.com> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/54705C8E.1080400@googlemail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
commit e6023367d779 'x86, kaslr: Prevent .bss from overlaping initrd'
broke the cross compile of x86. It added a objdump invocation, which
invokes the host native objdump and ignores an active cross tool
chain.

Use $(OBJDUMP) instead which takes the CROSS_COMPILE prefix into
account.

[ tglx: Massage changelog and use $(OBJDUMP) ]

Fixes: e6023367d779 'x86, kaslr: Prevent .bss from overlaping initrd'
Signed-off-by: Chris Clayton <chris2553@googlemail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Borislav Petkov <bp@suse.de>
Cc: Junjie Mao <eternal.n08@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/54705C8E.1080400@googlemail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
efi/x86: Move x86 back to libstub 2014-11-11T22:23:11+00:00 Ard Biesheuvel ard.biesheuvel@linaro.org 2014-11-05T16:00:56+00:00 243b6754cd17112bbf0724ed3c13446b48cf6a28 This reverts commit 84be880560fb, which itself reverted my original attempt to move x86 from #include'ing .c files from across the tree to using the EFI stub built as a static library. The issue that affected the original approach was that splitting the implementation into several .o files resulted in the variable 'efi_early' becoming a global with external linkage, which under -fPIC implies that references to it must go through the GOT. However, dealing with this additional GOT entry turned out to be troublesome on some EFI implementations. (GCC's visibility=hidden attribute is supposed to lift this requirement, but it turned out not to work on the 32-bit build.) Instead, use a pure getter function to get a reference to efi_early. This approach results in no additional GOT entries being generated, so there is no need for any changes in the early GOT handling. Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Matt Fleming <matt.fleming@intel.com> 
This reverts commit 84be880560fb, which itself reverted my original
attempt to move x86 from #include'ing .c files from across the tree
to using the EFI stub built as a static library.

The issue that affected the original approach was that splitting
the implementation into several .o files resulted in the variable
'efi_early' becoming a global with external linkage, which under
-fPIC implies that references to it must go through the GOT. However,
dealing with this additional GOT entry turned out to be troublesome
on some EFI implementations. (GCC's visibility=hidden attribute is
supposed to lift this requirement, but it turned out not to work on
the 32-bit build.)

Instead, use a pure getter function to get a reference to efi_early.
This approach results in no additional GOT entries being generated,
so there is no need for any changes in the early GOT handling.

Tested-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
x86-64: Handle PC-relative relocations on per-CPU data 2014-11-04T19:43:14+00:00 Jan Beulich JBeulich@suse.com 2014-11-04T08:50:18+00:00 6d24c5f72dfb26e5fa7f02fa9266dfdbae41adba This is in preparation of using RIP-relative addressing in many of the per-CPU accesses. Signed-off-by: Jan Beulich <jbeulich@suse.com> Link: http://lkml.kernel.org/r/5458A15A0200007800044A9A@mail.emea.novell.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
This is in preparation of using RIP-relative addressing in many of the
per-CPU accesses.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/5458A15A0200007800044A9A@mail.emea.novell.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
x86, boot: Document intermediates more clearly 2014-11-01T21:46:02+00:00 Kees Cook keescook@chromium.org 2014-10-31T16:22:04+00:00 fb7183ef3c016d9067ff83f3ff2455be1818f902 This adds a comment detailing the various intermediate files used to build the bootable decompression image for the x86 kernel. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Cc: Matt Fleming <matt.fleming@intel.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Junjie Mao <eternal.n08@gmail.com> Link: http://lkml.kernel.org/r/20141031162204.GA26268@www.outflux.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 
This adds a comment detailing the various intermediate files used to build
the bootable decompression image for the x86 kernel.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Junjie Mao <eternal.n08@gmail.com>
Link: http://lkml.kernel.org/r/20141031162204.GA26268@www.outflux.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>