linux-stable.git/arch/x86/tools, branch linux-3.6.y Linux kernel stable tree x86/decoder: Fix bsr/bsf/jmpe decoding with operand-size prefix 2012-06-06T06:54:18+00:00 Masami Hiramatsu masami.hiramatsu.pt@hitachi.com 2012-06-04T15:09:11+00:00 436d03faf6961b30e13b2d0967aea9d772d6cf44 Fix the x86 instruction decoder to decode bsr/bsf/jmpe with operand-size prefix (66h). This fixes the test case failure reported by Linus, attached below. bsf/bsr/jmpe have a special encoding. Opcode map in Intel Software Developers Manual vol2 says they have TZCNT/LZCNT variants if it has F3h prefix. However, there is no information if it has other 66h or F2h prefixes. Current instruction decoder supposes that those are bad instructions, but it actually accepts at least operand-size prefixes. H. Peter Anvin further explains: " TZCNT/LZCNT are F3 + BSF/BSR exactly because the F2 and F3 prefixes have historically been no-ops with most instructions. This allows software to unconditionally use the prefixed versions and get TZCNT/LZCNT on the processors that have them if they don't care about the difference. " This fixes errors reported by test_get_len: Warning: arch/x86/tools/test_get_len found difference at <em_bsf>:ffffffff81036d87 Warning: ffffffff81036de5: 66 0f bc c2 bsf %dx,%ax Warning: objdump says 4 bytes, but insn_get_length() says 3 Warning: arch/x86/tools/test_get_len found difference at <em_bsr>:ffffffff81036ea6 Warning: ffffffff81036f04: 66 0f bd c2 bsr %dx,%ax Warning: objdump says 4 bytes, but insn_get_length() says 3 Warning: decoded and checked 13298882 instructions with 2 warnings Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Reported-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: <yrl.pp-manager.tt@hitachi.com> Link: http://lkml.kernel.org/r/20120604150911.22338.43296.stgit@localhost.localdomain Signed-off-by: Ingo Molnar <mingo@kernel.org> 
Fix the x86 instruction decoder to decode bsr/bsf/jmpe with
operand-size prefix (66h). This fixes the test case failure
reported by Linus, attached below.

bsf/bsr/jmpe have a special encoding. Opcode map in
Intel Software Developers Manual vol2 says they have
TZCNT/LZCNT variants if it has F3h prefix. However, there
is no information if it has other 66h or F2h prefixes.
Current instruction decoder supposes that those are
bad instructions, but it actually accepts at least
operand-size prefixes.

H. Peter Anvin further explains:

 " TZCNT/LZCNT are F3 + BSF/BSR exactly because the F2 and
   F3 prefixes have historically been no-ops with most instructions.
   This allows software to unconditionally use the prefixed versions
   and get TZCNT/LZCNT on the processors that have them if they don't
   care about the difference. "

This fixes errors reported by test_get_len:

  Warning: arch/x86/tools/test_get_len found difference at <em_bsf>:ffffffff81036d87
  Warning: ffffffff81036de5:	66 0f bc c2          	bsf    %dx,%ax
  Warning: objdump says 4 bytes, but insn_get_length() says 3
  Warning: arch/x86/tools/test_get_len found difference at <em_bsr>:ffffffff81036ea6
  Warning: ffffffff81036f04:	66 0f bd c2          	bsr    %dx,%ax
  Warning: objdump says 4 bytes, but insn_get_length() says 3
  Warning: decoded and checked 13298882 instructions with 2 warnings

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <yrl.pp-manager.tt@hitachi.com>
Link: http://lkml.kernel.org/r/20120604150911.22338.43296.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-05-30T03:14:53+00:00 Linus Torvalds torvalds@linux-foundation.org 2012-05-30T03:14:53+00:00 731a7378b81c2f5fa88ca1ae20b83d548d5613dc Pull x86 trampoline rework from H. Peter Anvin: "This code reworks all the "trampoline"/"realmode" code (various bits that need to live in the first megabyte of memory, most but not all of which runs in real mode at some point) in the kernel into a single object. The main reason for doing this is that it eliminates the last place in the kernel where we needed pages to be mapped RWX. This code separates all that code into proper R/RW/RX pages." Fix up conflicts in arch/x86/kernel/Makefile (mca removed next to reboot code), and arch/x86/kernel/reboot.c (reboot code moved around in one branch, modified in this one), and arch/x86/tools/relocs.c (mostly same code came in earlier due to working around the ld bugs just before the 3.4 release). Also remove stale x86-relocs entry from scripts/.gitignore as per Peter Anvin. * commit '61f5446169046c217a5479517edac3a890c3bee7': (36 commits) x86, realmode: Move end signature into header.S x86, relocs: When printing an error, say relative or absolute x86, relocs: More relocations which may end up as absolute x86, relocs: Workaround for binutils 2.22.52.0.1 section bug xen-acpi-processor: Add missing #include <xen/xen.h> acpi, bgrd: Add missing <linux/io.h> to drivers/acpi/bgrt.c x86, realmode: Change EFER to a single u64 field x86, realmode: Move kernel/realmode.c to realmode/init.c x86, realmode: Move not-common bits out of trampoline_common.S x86, realmode: Mask out EFER.LMA when saving trampoline EFER x86, realmode: Fix no cache bits test in reboot_32.S x86, realmode: Make sure all generated files are listed in targets x86, realmode: build fix: remove duplicate build x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline x86, realmode: fixes compilation issue in tboot.c x86, realmode: move relocs from scripts/ to arch/x86/tools x86, realmode: header for trampoline code x86, realmode: flattened rm hierachy x86, realmode: don't copy real_mode_header x86, realmode: fix 64-bit wakeup sequence ... 
Pull x86 trampoline rework from H. Peter Anvin:
 "This code reworks all the "trampoline"/"realmode" code (various bits
  that need to live in the first megabyte of memory, most but not all of
  which runs in real mode at some point) in the kernel into a single
  object.  The main reason for doing this is that it eliminates the last
  place in the kernel where we needed pages to be mapped RWX.  This code
  separates all that code into proper R/RW/RX pages."

Fix up conflicts in arch/x86/kernel/Makefile (mca removed next to reboot
code), and arch/x86/kernel/reboot.c (reboot code moved around in one
branch, modified in this one), and arch/x86/tools/relocs.c (mostly same
code came in earlier due to working around the ld bugs just before the
3.4 release).

Also remove stale x86-relocs entry from scripts/.gitignore as per Peter
Anvin.

* commit '61f5446169046c217a5479517edac3a890c3bee7': (36 commits)
  x86, realmode: Move end signature into header.S
  x86, relocs: When printing an error, say relative or absolute
  x86, relocs: More relocations which may end up as absolute
  x86, relocs: Workaround for binutils 2.22.52.0.1 section bug
  xen-acpi-processor: Add missing #include <xen/xen.h>
  acpi, bgrd: Add missing <linux/io.h> to drivers/acpi/bgrt.c
  x86, realmode: Change EFER to a single u64 field
  x86, realmode: Move kernel/realmode.c to realmode/init.c
  x86, realmode: Move not-common bits out of trampoline_common.S
  x86, realmode: Mask out EFER.LMA when saving trampoline EFER
  x86, realmode: Fix no cache bits test in reboot_32.S
  x86, realmode: Make sure all generated files are listed in targets
  x86, realmode: build fix: remove duplicate build
  x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline
  x86, realmode: fixes compilation issue in tboot.c
  x86, realmode: move relocs from scripts/ to arch/x86/tools
  x86, realmode: header for trampoline code
  x86, realmode: flattened rm hierachy
  x86, realmode: don't copy real_mode_header
  x86, realmode: fix 64-bit wakeup sequence
  ...
x86, relocs: Add jiffies and jiffies_64 to the relative whitelist 2012-05-24T14:16:18+00:00 H. Peter Anvin hpa@zytor.com 2012-05-24T14:01:38+00:00 ea17e7414bc62e8d3bde8d08e3df1d921c518c17 The symbol jiffies is created in the linker script as an alias to jiffies_64. Unfortunately this is done outside any section, and apparently GNU ld 2.21 doesn't carry the section with it, so we end up with an absolute symbol and therefore a broken kernel. Add jiffies and jiffies_64 to the whitelist. The most disturbing bit with this discovery is that it shows that we have had multiple linker bugs in this area crossing multiple generations, and have been silently building bad kernels for some time. Link: http://lkml.kernel.org/r/20120524171604.0d98284f3affc643e9714470@canb.auug.org.au Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: <stable@vger.kernel.org> v3.4 
The symbol jiffies is created in the linker script as an alias to
jiffies_64.  Unfortunately this is done outside any section, and
apparently GNU ld 2.21 doesn't carry the section with it, so we end up
with an absolute symbol and therefore a broken kernel.

Add jiffies and jiffies_64 to the whitelist.

The most disturbing bit with this discovery is that it shows that we
have had multiple linker bugs in this area crossing multiple
generations, and have been silently building bad kernels for some time.

Link: http://lkml.kernel.org/r/20120524171604.0d98284f3affc643e9714470@canb.auug.org.au
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org> v3.4
x86-32, relocs: Whitelist more symbols for ld bug workaround 2012-05-23T21:02:34+00:00 H. Peter Anvin hpa@zytor.com 2012-05-23T21:02:34+00:00 fd952815307f0f272bf49fd364a7fd2f9992bc42 As noted in checkin: a3e854d95 x86, relocs: Workaround for binutils 2.22.52.0.1 section bug ld version 2.22.52.0.[12] can incorrectly promote relative symbols to absolute, if the output section they appear in is otherwise empty. Since checkin: 6520fe55 x86, realmode: 16-bit real-mode code support for relocs tool we actually check for this and error out rather than silently creating a kernel which will malfunction if relocated. Ingo found a configuration in which __start_builtin_fw triggered the warning. Go through the linker script sources and look for more symbols that could plausibly get bogusly promoted to absolute, and add them to the whitelist. In general, if the following error triggers: Invalid absolute R_386_32 relocation: <symbol> ... then we should verify that <symbol> is really meant to be relocated, and add it and any related symbols manually to the S_REL regexp. Please note that 6520fe55 does not introduce the error, only the check for the error -- without 6520fe55 this version of ld will simply produce a corrupt kernel if CONFIG_RELOCATABLE is set on x86-32. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: <stable@vger.kernel.org> v3.4 
As noted in checkin:

a3e854d95 x86, relocs: Workaround for binutils 2.22.52.0.1 section bug

ld version 2.22.52.0.[12] can incorrectly promote relative symbols to
absolute, if the output section they appear in is otherwise empty.

Since checkin:

6520fe55 x86, realmode: 16-bit real-mode code support for relocs tool

we actually check for this and error out rather than silently creating
a kernel which will malfunction if relocated.

Ingo found a configuration in which __start_builtin_fw triggered the
warning.

Go through the linker script sources and look for more symbols that
could plausibly get bogusly promoted to absolute, and add them to the
whitelist.

In general, if the following error triggers:

	Invalid absolute R_386_32 relocation: <symbol>

... then we should verify that <symbol> is really meant to be
relocated, and add it and any related symbols manually to the S_REL
regexp.

Please note that 6520fe55 does not introduce the error, only the check
for the error -- without 6520fe55 this version of ld will simply
produce a corrupt kernel if CONFIG_RELOCATABLE is set on x86-32.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org> v3.4
x86, relocs: When printing an error, say relative or absolute 2012-05-19T02:50:02+00:00 H. Peter Anvin hpa@linux.intel.com 2012-05-18T16:52:01+00:00 24ab82bd9bf18f3efc69a131d73577940941e1b7 When the relocs tool throws an error, let the error message say if it is an absolute or relative symbol. This should make it a lot more clear what action the programmer needs to take and should help us find the reason if additional symbol bugs show up. Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: <stable@vger.kernel.org> 
When the relocs tool throws an error, let the error message say if it
is an absolute or relative symbol.  This should make it a lot more
clear what action the programmer needs to take and should help us find
the reason if additional symbol bugs show up.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@vger.kernel.org>
x86, relocs: Workaround for binutils 2.22.52.0.1 section bug 2012-05-19T02:50:00+00:00 H. Peter Anvin hpa@linux.intel.com 2012-05-18T07:24:09+00:00 a3e854d95a76862cd37937e0b0438f540536771a GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from section-relative to absolute if they are in a section of zero length. This turns the symbols __init_begin and __init_end into absolute symbols. Let the relocs program know that those should be treated as relative symbols. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: H.J. Lu <hjl.tools@gmail.com> Cc: <stable@vger.kernel.org> Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com> 
GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from
section-relative to absolute if they are in a section of zero length.
This turns the symbols __init_begin and __init_end into absolute
symbols.  Let the relocs program know that those should be treated as
relative symbols.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: <stable@vger.kernel.org>
Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
x86, realmode: 16-bit real-mode code support for relocs tool 2012-05-19T02:49:40+00:00 H. Peter Anvin hpa@linux.intel.com 2012-05-08T18:22:24+00:00 6520fe5564acf07ade7b18a1272db1184835c487 A new option is added to the relocs tool called '--realmode'. This option causes the generation of 16-bit segment relocations and 32-bit linear relocations for the real-mode code. When the real-mode code is moved to the low-memory during kernel initialization, these relocation entries can be used to relocate the code properly. In the assembly code 16-bit segment relocations must be relative to the 'real_mode_seg' absolute symbol. Linear relocations must be relative to a symbol prefixed with 'pa_'. 16-bit segment relocation is used to load cs:ip in 16-bit code. Linear relocations are used in the 32-bit code for relocatable data references. They are declared in the linker script of the real-mode code. The relocs tool is moved to arch/x86/tools/relocs.c, and added new target archscripts that can be used to build scripts needed building an architecture. be compiled before building the arch/x86 tree. [ hpa: accelerating this because it detects invalid absolute relocations, a serious bug in binutils 2.22.52.0.x which currently produces bad kernels. ] Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.com Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@vger.kernel.org> 
A new option is added to the relocs tool called '--realmode'.
This option causes the generation of 16-bit segment relocations
and 32-bit linear relocations for the real-mode code. When
the real-mode code is moved to the low-memory during kernel
initialization, these relocation entries can be used to
relocate the code properly.

In the assembly code 16-bit segment relocations must be relative
to the 'real_mode_seg' absolute symbol. Linear relocations must be
relative to a symbol prefixed with 'pa_'.

16-bit segment relocation is used to load cs:ip in 16-bit code.
Linear relocations are used in the 32-bit code for relocatable
data references. They are declared in the linker script of the
real-mode code.

The relocs tool is moved to arch/x86/tools/relocs.c, and added new
target archscripts that can be used to build scripts needed building
an architecture.  be compiled before building the arch/x86 tree.

[ hpa: accelerating this because it detects invalid absolute
  relocations, a serious bug in binutils 2.22.52.0.x which currently
  produces bad kernels. ]

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@vger.kernel.org>
x86, relocs: When printing an error, say relative or absolute 2012-05-18T16:52:01+00:00 H. Peter Anvin hpa@linux.intel.com 2012-05-18T16:52:01+00:00 8a3b947c40cb36100f316ac0d433f4ae554ee4cc When the relocs tool throws an error, let the error message say if it is an absolute or relative symbol. This should make it a lot more clear what action the programmer needs to take. Signed-off-by: H. Peter Anvin <hpa@zytor.com> 
When the relocs tool throws an error, let the error message say if it
is an absolute or relative symbol.  This should make it a lot more
clear what action the programmer needs to take.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
x86, relocs: More relocations which may end up as absolute 2012-05-18T15:31:44+00:00 H. Peter Anvin hpa@linux.intel.com 2012-05-18T15:31:44+00:00 c54a354c1835e7412a53458891b9ea05361b4e8a GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from section-relative to absolute if they are in a section of zero length. This turns the symbols __init_begin and __init_end into absolute symbols. Let the relocs program know that those should be treated as relative symbols. This bug is exposed by checkin 433de739bbc2 x86, realmode: 16-bit real-mode code support for relocs tool only in the sense that that checkin changes the relocs tool to report an error instead of silently generating a kernel which is broken if relocated. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: H.J. Lu <hjl.tools@gmail.com> Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com> 
GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from
section-relative to absolute if they are in a section of zero length.
This turns the symbols __init_begin and __init_end into absolute
symbols.  Let the relocs program know that those should be treated as
relative symbols.

This bug is exposed by checkin

433de739bbc2 x86, realmode: 16-bit real-mode code support for relocs tool

only in the sense that that checkin changes the relocs tool to report
an error instead of silently generating a kernel which is broken if
relocated.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
x86, relocs: Workaround for binutils 2.22.52.0.1 section bug 2012-05-18T07:24:09+00:00 H. Peter Anvin hpa@linux.intel.com 2012-05-18T07:24:09+00:00 bea3f8781e30d0abc0bd0da80aa528d44c71959e GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from section-relative to absolute if they are in a section of zero length. This turns the symbols __init_begin and __init_end into absolute symbols. Let the relocs program know that those should be treated as relative symbols. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Cc: H.J. Lu <hjl.tools@gmail.com> 
GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from
section-relative to absolute if they are in a section of zero length.
This turns the symbols __init_begin and __init_end into absolute
symbols.  Let the relocs program know that those should be treated as
relative symbols.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: H.J. Lu <hjl.tools@gmail.com>