linux-stable.git/arch/x86/kernel/process_32.c, branch linux-3.16.y

x86/process: Consolidate and simplify switch_to_xtra() code

2019-05-22T22:15:16+00:00

commit ff16701a29cba3aafa0bd1656d766813b2d0a811 upstream.

Move the conditional invocation of __switch_to_xtra() into an inline
function so the logic can be shared between 32 and 64 bit.

Remove the handthrough of the TSS pointer and retrieve the pointer directly
in the bitmap handling function. Use this_cpu_ptr() instead of the
per_cpu() indirection.

This is a preparatory change so integration of conditional indirect branch
speculation optimization happens only in one place.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Andy Lutomirski 
Cc: Linus Torvalds 
Cc: Jiri Kosina 
Cc: Tom Lendacky 
Cc: Josh Poimboeuf 
Cc: Andrea Arcangeli 
Cc: David Woodhouse 
Cc: Tim Chen 
Cc: Andi Kleen 
Cc: Dave Hansen 
Cc: Casey Schaufler 
Cc: Asit Mallick 
Cc: Arjan van de Ven 
Cc: Jon Masters 
Cc: Waiman Long 
Cc: Greg KH 
Cc: Dave Stewart 
Cc: Kees Cook 
Link: https://lkml.kernel.org/r/20181125185005.280855518@linutronix.de
[bwh: Backported to 3.16:
 - Use init_tss instead of cpu_tss_rw
 - __switch_to() still uses the tss variable, so don't delete it
 - Adjust context]
Signed-off-by: Ben Hutchings

x86/process: Don't mix user/kernel regs in 64bit __show_regs()

2018-12-16T22:09:11+00:00

commit 9fe6299dde587788f245e9f7a5a1b296fad4e8c7 upstream.

When the kernel.print-fatal-signals sysctl has been enabled, a simple
userspace crash will cause the kernel to write a crash dump that contains,
among other things, the kernel gsbase into dmesg.

As suggested by Andy, limit output to pt_regs, FS_BASE and KERNEL_GS_BASE
in this case.

This also moves the bitness-specific logic from show_regs() into
process_{32,64}.c.

Fixes: 45807a1df9f5 ("vdso: print fatal signals")
Signed-off-by: Jann Horn 
Signed-off-by: Thomas Gleixner 
Cc: "H. Peter Anvin" 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Greg Kroah-Hartman 
Link: https://lkml.kernel.org/r/20180831194151.123586-1-jannh@google.com
[bwh: Backported to 3.16:
 - Keep using user_mode_vm() to in 32-bit show_regs()
 - Also update call to __show_regs() in kmemcheck
 - Don't add redundant rdmsrl()s in 64-bit __show_regs()
 - Adjust filenames, context]
Signed-off-by: Ben Hutchings

x86: Keep thread_info on thread stack in x86_32

2014-03-07T00:56:55+00:00

x86_64 uses a per_cpu variable kernel_stack to always point to
the thread stack of current. This is where the thread_info is stored
and is accessed from this location even when the irq or exception stack
is in use. This removes the complexity of having to maintain the
thread info on the stack when interrupts are running and having to
copy the preempt_count and other fields to the interrupt stack.

x86_32 uses the old method of copying the thread_info from the thread
stack to the exception stack just before executing the exception.

Having the two different requires #ifdefs and also the x86_32 way
is a bit of a pain to maintain. By converting x86_32 to the same
method of x86_64, we can remove #ifdefs, clean up the x86_32 code
a little, and remove the overhead of the copy.

Cc: Andrew Morton 
Cc: Peter Zijlstra 
Cc: Brian Gerst 
Signed-off-by: Steven Rostedt 
Link: http://lkml.kernel.org/r/20110806012354.263834829@goodmis.org
Link: http://lkml.kernel.org/r/20140206144321.852942014@goodmis.org
Signed-off-by: H. Peter Anvin

x86: Delete non-required instances of include

2014-01-07T05:25:18+00:00

None of these files are actually using any __init type directives
and hence don't need to include .  Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.

[ hpa: undid incorrect removal from arch/x86/kernel/head_32.S ]

Signed-off-by: Paul Gortmaker 
Link: http://lkml.kernel.org/r/1389054026-12947-1-git-send-email-paul.gortmaker@windriver.com
Signed-off-by: H. Peter Anvin

x86: move fpu_counter into ARCH specific thread_struct

2013-11-13T03:09:13+00:00

Only a couple of arches (sh/x86) use fpu_counter in task_struct so it can
be moved out into ARCH specific thread_struct, reducing the size of
task_struct for other arches.

Compile tested i386_defconfig + gcc 4.7.3

Signed-off-by: Vineet Gupta 
Acked-by: Ingo Molnar 
Cc: Paul Mundt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched, x86: Provide a per-cpu preempt_count implementation

2013-09-25T12:07:57+00:00

Convert x86 to use a per-cpu preemption count. The reason for doing so
is that accessing per-cpu variables is a lot cheaper than accessing
thread_info variables.

We still need to save/restore the actual preemption count due to
PREEMPT_ACTIVE so we place the per-cpu __preempt_count variable in the
same cache-line as the other hot __switch_to() variables such as
current_task.

NOTE: this save/restore is required even for !PREEMPT kernels as
cond_resched() also relies on preempt_count's PREEMPT_ACTIVE to ignore
task_struct::state.

Also rename thread_info::preempt_count to ensure nobody is
'accidentally' still poking at it.

Suggested-by: Linus Torvalds 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/n/tip-gzn5rfsf8trgjoqx8hyayy3q@git.kernel.org
Signed-off-by: Ingo Molnar

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