Skip to content

cloud-kernel
cloud-kernel

openanolis / cloud-kernel
大约 1 年 前同步成功

通知 158
Star 36
Fork 7
cloud-kernel
cloud-kernel

体验新版 GitCode，发现更多精彩内容 >>

切换分支/标签
  1. 30 10月, 2010 5 次提交
    • S
      jump label: Add work around to i386 gcc asm goto bug · 45f81b1c
      由 Steven Rostedt 提交于 
      On i386 (not x86_64) early implementations of gcc would have a bug
with asm goto causing it to produce code like the following:

(This was noticed by Peter Zijlstra)

   56 pushl 0
   67 nopl         jmp 0x6f
      popl
      jmp 0x8c

   6f              mov
                   test
                   je 0x8c

   8c mov
      call *(%esp)

The jump added in the asm goto skipped over the popl that matched
the pushl 0, which lead up to a quick crash of the system when
the jump was enabled. The nopl is defined in the asm goto () statement
and when tracepoints are enabled, the nop changes to a jump to the label
that was specified by the asm goto. asm goto is suppose to tell gcc that
the code in the asm might jump to an external label. Here gcc obviously
fails to make that work.

The bug report for gcc is here:

  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46226

The bug only appears on x86 when not compiled with
-maccumulate-outgoing-args. This option is always set on x86_64 and it
is also the work around for a function graph tracer i386 bug.
(See commit: 746357d6)
This explains why the bug only showed up on i386 when function graph
tracer was not enabled.

This patch now adds a CONFIG_JUMP_LABEL option that is default
off instead of using jump labels by default. When jump labels are
enabled, the -maccumulate-outgoing-args will be used (causing a
slightly larger kernel image on i386). This option will exist
until we have a way to detect if the gcc compiler in use is safe
to use on all configurations without the work around.

Note, there exists such a test, but for now we will keep the enabling
of jump label as a manual option.

Archs that know the compiler is safe with asm goto, may choose to
select JUMP_LABEL and enable it by default.
Reported-by: NIngo Molnar <mingo@elte.hu>
Cause-discovered-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Baron <jbaron@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: David Miller <davem@davemloft.net>
Cc: Richard Henderson <rth@redhat.com>
LKML-Reference: <1288028746.3673.11.camel@laptop>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      45f81b1c
    • H
      x86, ftrace: Use safe noops, drop trap test · 2d1d7126
      由 H. Peter Anvin 提交于 
      Always use a safe 5-byte noop sequence.  Drop the trap test, since it
is known to return false negatives on some virtualization platforms on
32 bits.  The resulting code is both simpler and safer.

Cc: Daniel Drake <dsd@laptop.org>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      2d1d7126
    • D
      jump_label: Fix unaligned traps on sparc. · f0daed02
      由 David Miller 提交于 
      The vmlinux.lds.h knobs to emit the __jump_table section in the main
kernel image takes care to align the section, but this doesn't help
for the __jump_table section that gets emitted into modules.

Fix the resulting lack of section alignment by explicitly specifying
it in the assembler.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
LKML-Reference: <20101023.110624.226758370.davem@davemloft.net>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      f0daed02
    • S
      jump label: Make arch_jump_label_text_poke_early() optional · 95bcd683
      由 Steven Rostedt 提交于 
      Some archs do not need to do anything special for jump labels on
startup (like MIPS).  This patch adds a weak function stub for
arch_jump_label_text_poke_early();

Cc: Jason Baron <jbaron@redhat.com>
Cc: David Miller <davem@davemloft.net>
Cc: David Daney <ddaney@caviumnetworks.com>
Suggested-by: NThomas Gleixner <tglx@linutronix.de>
LKML-Reference: <1286218615-24011-2-git-send-email-ddaney@caviumnetworks.com>
LKML-Reference: <20101015201037.703989993@goodmis.org>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      95bcd683
    • S
      jump label: Fix error with preempt disable holding mutex · de31c3ca
      由 Steven Rostedt 提交于 
      Kprobes and jump label were having a race between mutexes that
was fixed by reordering the jump label. But this reordering
moved the jump label mutex into a preempt disable location.

This patch does a little fiddling to move the grabbing of
the jump label mutex from inside the preempt disable section
and still keep the order correct between the mutex and the
kprobes lock.
Reported-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
      de31c3ca
  3. 28 10月, 2010 35 次提交