linux-toradex.git/arch/x86/kernel/entry_32.S, branch v3.2.18

x86-32: Fix endless loop when processing signals for kernel tasks

2012-04-02T16:52:52+00:00

commit 29a2e2836ff9ea65a603c89df217f4198973a74f upstream.

The problem occurs on !CONFIG_VM86 kernels [1] when a kernel-mode task
returns from a system call with a pending signal.

A real-life scenario is a child of 'khelper' returning from a failed
kernel_execve() in ____call_usermodehelper() [ kernel/kmod.c ].
kernel_execve() fails due to a pending SIGKILL, which is the result of
"kill -9 -1" (at least, busybox's init does it upon reboot).

The loop is as follows:

* syscall_exit_work:
 - work_pending:            // start_of_the_loop
 - work_notify_sig:
   - do_notify_resume()
     - do_signal()
       - if (!user_mode(regs)) return;
 - resume_userspace         // TIF_SIGPENDING is still set
 - work_pending             // so we call work_pending => goto
                            // start_of_the_loop

More information can be found in another LKML thread:
http://www.serverphorums.com/read.php?12,457826

[1] the problem was also seen on MIPS.

Signed-off-by: Dmitry Adamushko 
Link: http://lkml.kernel.org/r/1332448765.2299.68.camel@dimm
Cc: Oleg Nesterov 
Cc: Roland McGrath 
Cc: Andrew Morton 
Signed-off-by: H. Peter Anvin 
Signed-off-by: Greg Kroah-Hartman

x86-32: Fix boot with CONFIG_X86_INVD_BUG

2011-08-25T20:27:14+00:00

entry_32.S contained a hardcoded alternative instruction entry, and the
format changed in commit 59e97e4d6fbc ("x86: Make alternative
instruction pointers relative").

Replace the hardcoded entry with the altinstruction_entry macro.  This
fixes the 32-bit boot with CONFIG_X86_INVD_BUG=y.

Reported-and-tested-by: Arnaud Lacombe 
Signed-off-by: Andy Lutomirski 
Cc: Peter Anvin 
Cc: Ingo Molnar 
Signed-off-by: Linus Torvalds

Merge branch 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2011-03-16T17:10:02+00:00

* 'x86-trampoline-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86: Fix binutils-2.21 symbol related build failures
  x86-64, trampoline: Remove unused variable
  x86, reboot: Fix the use of passed arguments in 32-bit BIOS reboot
  x86, reboot: Move the real-mode reboot code to an assembly file
  x86: Make the GDT_ENTRY() macro in  safe for assembly
  x86, trampoline: Use the unified trampoline setup for ACPI wakeup
  x86, trampoline: Common infrastructure for low memory trampolines

Fix up trivial conflicts in arch/x86/kernel/Makefile

Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2011-03-16T01:59:56+00:00

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, binutils, xen: Fix another wrong size directive
  x86: Remove dead config option X86_CPU
  x86: Really print supported CPUs if PROCESSOR_SELECT=y
  x86: Fix a bogus unwind annotation in lib/semaphore_32.S
  um, x86-64: Fix UML build after adding CFI annotations to lib/rwsem_64.S
  x86: Remove unused bits from lib/thunk_*.S
  x86: Use {push,pop}_cfi in more places
  x86-64: Add CFI annotations to lib/rwsem_64.S
  x86, asm: Cleanup unnecssary macros in asm-offsets.c
  x86, system.h: Drop unused __SAVE/__RESTORE macros
  x86: Use bitmap library functions
  x86: Partly unify asm-offsets_{32,64}.c
  x86: Reduce back the alignment of the per-CPU data section

x86: Fix binutils-2.21 symbol related build failures

2011-03-09T09:25:45+00:00

New binutils version 2.21.0.20110302-1 started checking that the symbol
parameter to the .size directive matches the entry name's
symbol parameter, unearthing two mismatches:

  AS      arch/x86/kernel/acpi/wakeup_rm.o
  arch/x86/kernel/acpi/wakeup_rm.S: Assembler messages:
  arch/x86/kernel/acpi/wakeup_rm.S:12: Error: .size expression with symbol `wakeup_code_start' does not evaluate to a constant

  arch/x86/kernel/entry_32.S: Assembler messages:
  arch/x86/kernel/entry_32.S:1421: Error: .size expression with
  symbol `apf_page_fault' does not evaluate to a constant

The problem was discovered while using Debian's binutils
(2.21.0.20110302-1) and experimenting with binutils from
upstream.

Thanks Alexander and H.J. for the vital help.

Signed-off-by: Sedat Dilek 
Cc: Alexander van Heukelum 
Cc: H.J. Lu 
Cc: Len Brown 
Cc: Pavel Machek 
Cc: Rafael J. Wysocki 
LKML-Reference: <1299620364-21644-1-git-send-email-sedat.dilek@gmail.com>
Signed-off-by: Ingo Molnar

x86: Separate out entry text section

2011-03-08T16:22:11+00:00

Put x86 entry code into a separate link section: .entry.text.

Separating the entry text section seems to have performance
benefits - caused by more efficient instruction cache usage.

Running hackbench with perf stat --repeat showed that the change
compresses the icache footprint. The icache load miss rate went
down by about 15%:

 before patch:
         19417627  L1-icache-load-misses      ( +-   0.147% )

 after patch:
         16490788  L1-icache-load-misses      ( +-   0.180% )

The motivation of the patch was to fix a particular kprobes
bug that relates to the entry text section, the performance
advantage was discovered accidentally.

Whole perf output follows:

 - results for current tip tree:

  Performance counter stats for './hackbench/hackbench 10' (500 runs):

         19417627  L1-icache-load-misses      ( +-   0.147% )
       2676914223  instructions             #      0.497 IPC     ( +- 0.079% )
       5389516026  cycles                     ( +-   0.144% )

      0.206267711  seconds time elapsed   ( +-   0.138% )

 - results for current tip tree with the patch applied:

  Performance counter stats for './hackbench/hackbench 10' (500 runs):

         16490788  L1-icache-load-misses      ( +-   0.180% )
       2717734941  instructions             #      0.502 IPC     ( +- 0.079% )
       5414756975  cycles                     ( +-   0.148% )

      0.206747566  seconds time elapsed   ( +-   0.137% )

Signed-off-by: Jiri Olsa 
Cc: Arnaldo Carvalho de Melo 
Cc: Frederic Weisbecker 
Cc: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Nick Piggin 
Cc: Eric Dumazet 
Cc: masami.hiramatsu.pt@hitachi.com
Cc: ananth@in.ibm.com
Cc: davem@davemloft.net
Cc: 2nddept-manager@sdl.hitachi.co.jp
LKML-Reference: <20110307181039.GB15197@jolsa.redhat.com>
Signed-off-by: Ingo Molnar

x86: Use {push,pop}_cfi in more places

2011-02-28T17:06:22+00:00

Cleaning up and shortening code...

Signed-off-by: Jan Beulich 
Cc: Alexander van Heukelum 
LKML-Reference: <4D6BD35002000078000341DA@vpn.id2.novell.com>
Signed-off-by: Ingo Molnar

x86, asm: Cleanup unnecssary macros in asm-offsets.c

2011-02-26T00:37:32+00:00

PAGE_SIZE_asm, PAGE_SHIFT_asm, THREAD_SIZE_asm can be safely removed from 
asm-offsets.c, and be replaced by their non-'_asm' counterparts in the code 
that uses them, since the _AC macro defined in include/linux/const.h makes
PAGE_SIZE/PAGE_SHIFT/THREAD_SIZE work with as.

Signed-off-by: Stratos Psomadakis 
LKML-Reference: <1298666774-17646-2-git-send-email-psomas@cslab.ece.ntua.gr>
Signed-off-by: H. Peter Anvin

KVM: Handle async PF in a guest.

2011-01-12T09:23:16+00:00

When async PF capability is detected hook up special page fault handler
that will handle async page fault events and bypass other page faults to
regular page fault handler. Also add async PF handling to nested SVM
emulation. Async PF always generates exit to L1 where vcpu thread will
be scheduled out until page is available.

Acked-by: Rik van Riel 
Signed-off-by: Gleb Natapov 
Signed-off-by: Marcelo Tosatti

x86, asm: Fix binutils 2.15 build failure

2010-11-18T08:25:11+00:00

Add parentheses around one pushl_cfi argument.

Commit df5d1874 "x86: Use {push,pop}{l,q}_cfi in more places"
caused GNU assembler 2.15 (Debian Sarge) to fail. It is still
failing as of commit 07bd8516 "x86, asm: Restore parentheses
around one pushl_cfi argument". This patch solves build failure
with GNU assembler 2.15.

Signed-off-by: Tetsuo Handa 
Acked-by: Jan Beulich 
Cc: heukelum@fastmail.fm
Cc: hpa@linux.intel.com
LKML-Reference: <201011160445.oAG4jGif079860@www262.sakura.ne.jp>
Signed-off-by: Ingo Molnar