linux-stable.git/arch/x86/boot, branch linux-3.12.y

x86/build: Build compressed x86 kernels as PIE

2016-10-20T08:49:57+00:00

commit 6d92bc9d483aa1751755a66fee8fb39dffb088c0 upstream.

The 32-bit x86 assembler in binutils 2.26 will generate R_386_GOT32X
relocation to get the symbol address in PIC.  When the compressed x86
kernel isn't built as PIC, the linker optimizes R_386_GOT32X relocations
to their fixed symbol addresses.  However, when the compressed x86
kernel is loaded at a different address, it leads to the following
load failure:

  Failed to allocate space for phdrs

during the decompression stage.

If the compressed x86 kernel is relocatable at run-time, it should be
compiled with -fPIE, instead of -fPIC, if possible and should be built as
Position Independent Executable (PIE) so that linker won't optimize
R_386_GOT32X relocation to its fixed symbol address.

Older linkers generate R_386_32 relocations against locally defined
symbols, _bss, _ebss, _got and _egot, in PIE.  It isn't wrong, just less
optimal than R_386_RELATIVE.  But the x86 kernel fails to properly handle
R_386_32 relocations when relocating the kernel.  To generate
R_386_RELATIVE relocations, we mark _bss, _ebss, _got and _egot as
hidden in both 32-bit and 64-bit x86 kernels.

To build a 64-bit compressed x86 kernel as PIE, we need to disable the
relocation overflow check to avoid relocation overflow errors. We do
this with a new linker command-line option, -z noreloc-overflow, which
got added recently:

 commit 4c10bbaa0912742322f10d9d5bb630ba4e15dfa7
 Author: H.J. Lu 
 Date:   Tue Mar 15 11:07:06 2016 -0700

    Add -z noreloc-overflow option to x86-64 ld

    Add -z noreloc-overflow command-line option to the x86-64 ELF linker to
    disable relocation overflow check.  This can be used to avoid relocation
    overflow check if there will be no dynamic relocation overflow at
    run-time.

The 64-bit compressed x86 kernel is built as PIE only if the linker supports
-z noreloc-overflow.  So far 64-bit relocatable compressed x86 kernel
boots fine even when it is built as a normal executable.

Signed-off-by: H.J. Lu 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
[ Edited the changelog and comments. ]
Signed-off-by: Ingo Molnar 
Cc: Paul Bolle 
Signed-off-by: Jiri Slaby

x86, build: copy ldlinux.c32 to image.iso

2016-07-21T06:36:00+00:00

commit 9c77679cadb118c0aa99e6f88533d91765a131ba upstream.

For newer versions of Syslinux, we need ldlinux.c32 in addition to
isolinux.bin to reside on the boot disk, so if the latter is found,
copy it, too, to the isoimage tree.

Signed-off-by: H. Peter Anvin 
Signed-off-by: Jiri Slaby

efi: fix 32bit kernel boot failed problem using efi

2015-08-05T07:30:32+00:00

3.12 commit 065487a10a22a960bc4e41facb011d10692ef470 ("x86/efi:
Correct EFI boot stub use of code32_start"), upstream commit
7e8213c1f3acc064aef37813a39f13cbfe7c3ce7 imported a bug, which will
cause 32bit kernel boot to fail using EFI method. It should use the
label's address instead of the value stored in the label to calculate
the address of code32_start.

Signed-off-by: Fupan Li 
Reviewed-by: Matt Fleming 
Signed-off-by: Jiri Slaby

x86, boot: Skip relocs when load address unchanged

2015-01-29T14:45:05+00:00

commit f285f4a21c3253887caceed493089ece17579d59 upstream.

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 
Signed-off-by: Kees Cook 
Tested-by: Thomas D. 
Cc: Vivek Goyal 
Cc: Jan Beulich 
Cc: Junjie Mao 
Cc: Andi Kleen 
Link: http://lkml.kernel.org/r/20150116005146.GA4212@www.outflux.net
Signed-off-by: Thomas Gleixner 
Signed-off-by: Jiri Slaby

x86/efi: Include a .bss section within the PE/COFF headers

2014-07-30T16:02:44+00:00

commit c7fb93ec51d462ec3540a729ba446663c26a0505 upstream.

The PE/COFF headers currently describe only the initialised-data
portions of the image, and result in no space being allocated for the
uninitialised-data portions.  Consequently, the EFI boot stub will end
up overwriting unexpected areas of memory, with unpredictable results.

Fix by including a .bss section in the PE/COFF headers (functionally
equivalent to the init_size field in the bzImage header).

Signed-off-by: Michael Brown 
Cc: Thomas Bächler 
Cc: Josh Boyer 
Signed-off-by: Matt Fleming 
Signed-off-by: Jiri Slaby

x86/efi: Correct EFI boot stub use of code32_start

2014-05-15T07:55:20+00:00

commit 7e8213c1f3acc064aef37813a39f13cbfe7c3ce7 upstream.

code32_start should point at the start of the protected mode code, and
*not* at the beginning of the bzImage. This is much easier to do in
assembly so document that callers of make_boot_params() need to fill out
code32_start.

The fallout from this bug is that we would end up relocating the image
but copying the image at some offset, resulting in what appeared to be
memory corruption.

Reported-by: Thomas Bächler 
Signed-off-by: Matt Fleming 
Signed-off-by: Jiri Slaby

x86, build: Pass in additional -mno-mmx, -mno-sse options

2013-12-20T15:49:01+00:00

commit 8b3b005d675726e38bc504d2e35a991e55819155 upstream.

In checkin

    5551a34e5aea x86-64, build: Always pass in -mno-sse

we unconditionally added -mno-sse to the main build, to keep newer
compilers from generating SSE instructions from autovectorization.
However, this did not extend to the special environments
(arch/x86/boot, arch/x86/boot/compressed, and arch/x86/realmode/rm).
Add -mno-sse to the compiler command line for these environments, and
add -mno-mmx to all the environments as well, as we don't want a
compiler to generate MMX code either.

This patch also removes a $(cc-option) call for -m32, since we have
long since stopped supporting compilers too old for the -m32 option,
and in fact hardcode it in other places in the Makefiles.

Reported-by: Kevin B. Smith 
Cc: Sunil K. Pandey 
Signed-off-by: H. Peter Anvin 
Cc: H. J. Lu 
Link: http://lkml.kernel.org/n/tip-j21wzqv790q834n7yc6g80j1@git.kernel.org
Signed-off-by: Greg Kroah-Hartman

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

2013-09-04T16:38:10+00:00

Pull x86 relocation changes from Ingo Molnar:
 "This tree contains a single change, ELF relocation handling in C - one
  of the kernel randomization patches that makes sense even without
  randomization present upstream"

* 'x86-kaslr-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, relocs: Move ELF relocation handling to C

Merge branches 'x86-boot-for-linus' and 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-09-04T16:10:27+00:00

Pull tiny x86 boot cleanups from Ingo Molnar.

* 'x86-boot-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot: Fix a sanity check in printf.c

* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, boot: Fix warning due to undeclared strlen()

x86/boot: Fix a sanity check in printf.c

2013-08-14T09:48:41+00:00

Prior to 9b706aee7d ("x86: trivial printk optimizations") this was
36 because it had 26 characters and 10 digits but now it's just
16 hex digits so the sanity check needs updated.

This function is always called with a valid "base" so it doesn't
make a difference to how the kernel works, it's just a cleanup.

Reported-by: Alexey Petrenko 
Signed-off-by: Dan Carpenter 
Signed-off-by: Ingo Molnar