linux-stable.git/arch/x86/kernel/process_64.c, branch linux-3.12.y

x86/iopl/64: Properly context-switch IOPL on Xen PV

2016-04-11T14:43:58+00:00

commit b7a584598aea7ca73140cb87b40319944dd3393f upstream.

On Xen PV, regs->flags doesn't reliably reflect IOPL and the
exit-to-userspace code doesn't change IOPL.  We need to context
switch it manually.

I'm doing this without going through paravirt because this is
specific to Xen PV.  After the dust settles, we can merge this with
the 32-bit code, tidy up the iopl syscall implementation, and remove
the set_iopl pvop entirely.

Fixes XSA-171.

Reviewewd-by: Jan Beulich 
Signed-off-by: Andy Lutomirski 
Cc: Andrew Cooper 
Cc: Andy Lutomirski 
Cc: Boris Ostrovsky 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: David Vrabel 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Jan Beulich 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/693c3bd7aeb4d3c27c92c622b7d0f554a458173c.1458162709.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
[ kamal: backport to 3.19-stable: no X86_FEATURE_XENPV so just call
  xen_pv_domain() directly ]
Acked-by: Andy Lutomirski 
Signed-off-by: Kamal Mostafa 
Signed-off-by: Jiri Slaby

x86/ldt: Make modify_ldt synchronous

2015-08-25T14:57:00+00:00

commit 37868fe113ff2ba814b3b4eb12df214df555f8dc upstream.

modify_ldt() has questionable locking and does not synchronize
threads.  Improve it: redesign the locking and synchronize all
threads' LDTs using an IPI on all modifications.

This will dramatically slow down modify_ldt in multithreaded
programs, but there shouldn't be any multithreaded programs that
care about modify_ldt's performance in the first place.

This fixes some fallout from the CVE-2015-5157 fixes.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Borislav Petkov 
Cc: Andrew Cooper 
Cc: Andy Lutomirski 
Cc: Boris Ostrovsky 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Jan Beulich 
Cc: Konrad Rzeszutek Wilk 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Sasha Levin 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/4c6978476782160600471bd865b318db34c7b628.1438291540.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Jiri Slaby

x86/dumpstack: Fix printk_address for direct addresses

2014-03-12T12:25:40+00:00

commit 5f01c98859073cb512b01d4fad74b5f4e047be0b upstream.

Consider a kernel crash in a module, simulated the following way:

 static int my_init(void)
 {
         char *map = (void *)0x5;
         *map = 3;
         return 0;
 }
 module_init(my_init);

When we turn off FRAME_POINTERs, the very first instruction in
that function causes a BUG. The problem is that we print IP in
the BUG report using %pB (from printk_address). And %pB
decrements the pointer by one to fix printing addresses of
functions with tail calls.

This was added in commit 71f9e59800e5ad4 ("x86, dumpstack: Use
%pB format specifier for stack trace") to fix the call stack
printouts.

So instead of correct output:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000005
  IP: [] my_init+0x0/0x10 [pb173]

We get:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000005
  IP: [] 0xffffffffa0151fff

To fix that, we use %pS only for stack addresses printouts (via
newly added printk_stack_address) and %pB for regs->ip (via
printk_address). I.e. we revert to the old behaviour for all
except call stacks. And since from all those reliable is 1, we
remove that parameter from printk_address.

Signed-off-by: Jiri Slaby 
Cc: Namhyung Kim 
Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: "H. Peter Anvin" 
Cc: joe@perches.com
Cc: jirislaby@gmail.com
Link: http://lkml.kernel.org/r/1382706418-8435-1-git-send-email-jslaby@suse.cz
Signed-off-by: Ingo Molnar 
Signed-off-by: Jiri Slaby

x86, asmlinkage: Make several variables used from assembler/linker script visible

2013-08-06T21:20:13+00:00

Plus one function, load_gs_index().

Signed-off-by: Andi Kleen 
Link: http://lkml.kernel.org/r/1375740170-7446-10-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin

x86, asmlinkage: Make 32bit/64bit __switch_to visible

2013-08-06T21:18:30+00:00

This function is called from inline assembler, so has to be visible.

Signed-off-by: Andi Kleen 
Link: http://lkml.kernel.org/r/1375740170-7446-6-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin

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

2013-07-02T23:25:06+00:00

Pull x86 debug update from Ingo Molnar:
 "Misc debuggability improvements:

   - Optimize the x86 CPU register printout a bit
   - Expose the tboot TXT log via debugfs
   - Small do_debug() cleanup"

* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tboot: Provide debugfs interfaces to access TXT log
  x86: Remove weird PTR_ERR() in do_debug
  x86/debug: Only print out DR registers if they are not power-on defaults

x86, flags: Rename X86_EFLAGS_BIT1 to X86_EFLAGS_FIXED

2013-06-25T23:25:32+00:00

Bit 1 in the x86 EFLAGS is always set.  Name the macro something that
actually tries to explain what it is all about, rather than being a
tautology.

Signed-off-by: H. Peter Anvin 
Cc: Rusty Russell 
Cc: Gleb Natapov 
Cc: Paolo Bonzini 
Link: http://lkml.kernel.org/n/tip-f10rx5vjjm6tfnt8o1wseb3v@git.kernel.org

x86/debug: Only print out DR registers if they are not power-on defaults

2013-06-19T12:33:59+00:00

The DR registers are rarely useful when decoding oopses.
With screen real estate during oopses at a premium, we can save
two lines by only printing out these registers when they are set
to something other than they power-on state.

Signed-off-by: Dave Jones 
Acked-by: Borislav Petkov 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20130618160911.GA24487@redhat.com
Signed-off-by: Ingo Molnar

dump_stack: unify debug information printed by show_regs()

2013-05-01T00:04:02+00:00

show_regs() is inherently arch-dependent but it does make sense to print
generic debug information and some archs already do albeit in slightly
different forms.  This patch introduces a generic function to print debug
information from show_regs() so that different archs print out the same
information and it's much easier to modify what's printed.

show_regs_print_info() prints out the same debug info as dump_stack()
does plus task and thread_info pointers.

* Archs which didn't print debug info now do.

  alpha, arc, blackfin, c6x, cris, frv, h8300, hexagon, ia64, m32r,
  metag, microblaze, mn10300, openrisc, parisc, score, sh64, sparc,
  um, xtensa

* Already prints debug info.  Replaced with show_regs_print_info().
  The printed information is superset of what used to be there.

  arm, arm64, avr32, mips, powerpc, sh32, tile, unicore32, x86

* s390 is special in that it used to print arch-specific information
  along with generic debug info.  Heiko and Martin think that the
  arch-specific extra isn't worth keeping s390 specfic implementation.
  Converted to use the generic version.

Note that now all archs print the debug info before actual register
dumps.

An example BUG() dump follows.

 kernel BUG at /work/os/work/kernel/workqueue.c:4841!
 invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
 Modules linked in:
 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ #7
 Hardware name: empty empty/S3992, BIOS 080011  10/26/2007
 task: ffff88007c85e040 ti: ffff88007c860000 task.ti: ffff88007c860000
 RIP: 0010:[]  [] init_workqueues+0x4/0x6
 RSP: 0000:ffff88007c861ec8  EFLAGS: 00010246
 RAX: ffff88007c861fd8 RBX: ffffffff824466a8 RCX: 0000000000000001
 RDX: 0000000000000046 RSI: 0000000000000001 RDI: ffffffff8234a07a
 RBP: ffff88007c861ec8 R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff8234a07a
 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 FS:  0000000000000000(0000) GS:ffff88007dc00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
 CR2: ffff88015f7ff000 CR3: 00000000021f1000 CR4: 00000000000007f0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Stack:
  ffff88007c861ef8 ffffffff81000312 ffffffff824466a8 ffff88007c85e650
  0000000000000003 0000000000000000 ffff88007c861f38 ffffffff82335e5d
  ffff88007c862080 ffffffff8223d8c0 ffff88007c862080 ffffffff81c47760
 Call Trace:
  [] do_one_initcall+0x122/0x170
  [] kernel_init_freeable+0x9b/0x1c8
  [] ? rest_init+0x140/0x140
  [] kernel_init+0xe/0xf0
  [] ret_from_fork+0x7c/0xb0
  [] ? rest_init+0x140/0x140
  ...

v2: Typo fix in x86-32.

v3: CPU number dropped from show_regs_print_info() as
    dump_stack_print_info() has been updated to print it.  s390
    specific implementation dropped as requested by s390 maintainers.

Signed-off-by: Tejun Heo 
Acked-by: David S. Miller 
Acked-by: Jesper Nilsson 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: Bjorn Helgaas 
Cc: Fengguang Wu 
Cc: Mike Frysinger 
Cc: Vineet Gupta 
Cc: Sam Ravnborg 
Acked-by: Chris Metcalf 		[tile bits]
Acked-by: Richard Kuo 		[hexagon bits]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86/process: Change %8s to %s for pr_warn() in release_thread()

2013-01-24T17:11:03+00:00

the length of dead_task->comm[] is 16 (TASK_COMM_LEN)
on pr_warn(), it is not meaningful to use %8s for task->comm[].

So change it to %s, since the line is not solid anyway.

Additional information:

 %8s  limit the width, not for the original string output length
      if name length is more than 8, it still can be fully displayed.
      if name length is less than 8, the ' ' will be filled before name.

 %.8s truly limit the original string output length (precision)

Signed-off-by: Chen Gang 
Link: http://lkml.kernel.org/n/tip-nridm1zvreai1tgfLjuexDmd@git.kernel.org
Signed-off-by: Ingo Molnar