Ld knows about 2 kinds of symbols,  absolute and section
relative.  Section relative symbols symbols change value
when a section is moved and absolute symbols do not.

Currently in the linker script we have several labels
marking the beginning and ending of sections that
are outside of sections, making them absolute symbols.
Having a mixture of absolute and section relative
symbols refereing to the same data is currently harmless
but it is confusing.

This must be done carefully as newer revs of ld do not place
symbols that appear in sections without data and instead
ld makes those symbols global :(

My ultimate goal is to build a relocatable kernel.  The
safest and least intrusive technique is to generate
relocation entries so the kernel can be relocated at load
time.  The only penalty would be an increase in the size
of the kernel binary.  The problem is that if absolute and
relocatable symbols are not properly specified absolute symbols
will be relocated or section relative symbols won't be, which
is fatal.

The practical motivation is that when generating kernels that
will run from a reserved area for analyzing what caused
a kernel panic, it is simpler if you don't need to hard code
the physical memory location they will run at, especially
for the distributions.

[AK: and merged:]

o Also put a message so that in future people can be aware of it and
  avoid introducing absolute symbols.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

This network ioctl wasn't handled before.

Reported by Alexandra.Kossovsky@oktetlabs.ru (Alexandra Kossovsky)
Signed-off-by: NAndi Kleen <ak@suse.de>

On modern systems RAM errors don't cause NMIs, but it's usually
caused by PCI SERR. Mention PCI instead of RAM in the printk.

Reported by r_hayashi@ctc-g.co.jp (Ryutaro Hayashi)

Cc:  r_hayashi@ctc-g.co.jp
Signed-off-by: NAndi Kleen <ak@suse.de>

Resending as I believe the discussion about them established they were
correct.
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Currently the idle loop has two nested loops -- one high level
in cpu_idle and in some low level idle functions another one.

Looping in the low level idle functions breaks the idle notifiers
because interrupts waking up sleep states need to execute
exit_idle() which is only in cpu_idle().

So don't do that, only loop in cpu_idle(). This only removes
code.

In some cases e.g. poll_idle the idle loop is a little longer
now because cpu_idle checks more things. I hope that isn't a problem
ACPI idle doesn't change behaviour because it never looped anyways.

Cc: len.brown@intel.com
Cc: eranian@hpl.hp.com
Signed-off-by: NAndi Kleen <ak@suse.de>

This patch fixes the math emulator, which had not been adjusted
to match the changed struct pt_regs.

AK: extracted from larger patch by Jeremy.
Signed-off-by: NAndi Kleen <ak@suse.de>

Signed-off-by: NJeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NAndi Kleen <ak@suse.de>

Use the pcurrent field in the PDA to implement the "current" macro.  This ends
up compiling down to a single instruction to get the current task.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Use the cpu_number in the PDA to implement raw_smp_processor_id.  This is a
little simpler than using thread_info, though the cpu field in thread_info
cannot be removed since it is used for things other than getting the current
CPU in common code.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

sys_vm86 uses a struct kernel_vm86_regs, which is identical to pt_regs, but
adds an extra space for all the segment registers.  Previously this structure
was completely independent, so changes in pt_regs had to be reflected in
kernel_vm86_regs.  This changes just embeds pt_regs in kernel_vm86_regs, and
makes the appropriate changes to vm86.c to deal with the new naming.

Also, since %gs is dealt with differently in the kernel, this change adjusts
vm86.c to reflect this.

While making these changes, I also cleaned up some frankly bizarre code which
was added when auditing was added to sys_vm86.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

There are a few places where the change in struct pt_regs and the use of %gs
affect the userspace ABI.  These are primarily debugging interfaces where
thread state can be inspected or extracted.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

This patch is the meat of the PDA change.  This patch makes several related
changes:

1: Most significantly, %gs is now used in the kernel.  This means that on
   entry, the old value of %gs is saved away, and it is reloaded with
   __KERNEL_PDA.

2: entry.S constructs the stack in the shape of struct pt_regs, and this
   is passed around the kernel so that the process's saved register
   state can be accessed.

   Unfortunately struct pt_regs doesn't currently have space for %gs
   (or %fs). This patch extends pt_regs to add space for gs (no space
   is allocated for %fs, since it won't be used, and it would just
   complicate the code in entry.S to work around the space).

3: Because %gs is now saved on the stack like %ds, %es and the integer
   registers, there are a number of places where it no longer needs to
   be handled specially; namely context switch, and saving/restoring the
   register state in a signal context.

4: And since kernel threads run in kernel space and call normal kernel
   code, they need to be created with their %gs == __KERNEL_PDA.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

When a CPU is brought up, a PDA and GDT are allocated for it.  The GDT's
__KERNEL_PDA entry is pointed to the allocated PDA memory, so that all
references using this segment descriptor will refer to the PDA.

This patch rearranges CPU initialization a bit, so that the GDT/PDA are set up
as early as possible in cpu_init().  Also for secondary CPUs, GDT+PDA are
preallocated and initialized so all the secondary CPU needs to do is set up
the ldt and load %gs.  This will be important once smp_processor_id() and
current use the PDA.

In all cases, the PDA is set up in head.S, before a CPU starts running C code,
so the PDA is always available.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Matt Tolentino <matthew.e.tolentino@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

This patch has the basic definitions of struct i386_pda, and the segment
selector in the GDT.

asm-i386/pda.h is more or less a direct copy of asm-x86_64/pda.h.  The most
interesting difference is the use of _proxy_pda, which is used to give gcc a
model for the actual memory operations on the real pda structure.  No actual
reference is ever made to _proxy_pda, so it is never defined.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Use asm-offsets for the offsets of registers into the pt_regs struct, rather
than having hard-coded constants

I left the constants in the comments of entry.S because they're useful for
reference; the code in entry.S is very dependent on the layout of pt_regs,
even when using asm-offsets.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Keith Owens <kaos@ocs.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

This patch:
- makes ret_from_sys_call no longer global (all external users were
  previously switched to use int_ret_from_sys_call)
- adjusts placement of a CFI_{REMEMBER,RESTORE}_STATE pair to better
  fit logic flow
- eliminates an unnecessary pair of CFI_{REMEMBER,RESTORE}_STATE
- glues together function- and unwinder-wise the previously separate
  system_call and int_ret_from_sys_call function fragments
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Fix

BUG: using smp_processor_id() in preemptible [00000001] code:

in backtracer on preemptible debug kernels.

Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NAndi Kleen <ak@suse.de>

- add Intel Precise-Event Based sampling (PEBS) related MSR
- add Intel Data Save (DS) Area related MSR
- add Intel Core microarchitecure performance counter MSRs
Signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Add o the x86-64 tree a bunch of MSRs related to performance
monitoring for the processors based on Intel Core microarchitecture.
It also adds some architectural MSRs for PEBS. A similar patch for i386 will
follow.

changelog:
	- add Intel Precise-Event Based sampling (PEBS) related MSR
	- add Intel Data Save (DS) Area related MSR
	- add Intel Core microarchitecure performance counter MSRs
Signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

ioremap must be balanced by an iounmap and failing to do so can result
in a memory leak.

Tested (compilation only):
- using allmodconfig
- making sure the files are compiling without any warning/error due to
new changes
Signed-off-by: NAmol Lad <amol@verismonetworks.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Signed-off-by: NAmol Lad <amol@verismonetworks.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Insert the Local APIC and IO APIC(s) into the resource tree.  It allows the
APIC resources to be visible within /proc/iomem.  The patch also takes into
account IO APIC(s) mapped in the PCI space by deferring the insertion until
after PCI has allocated its necessary resources.
Signed-off-by: NAaron Durbin <adurbin@google.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

i386 port of the sLeAZY-fpu feature.  Chuck reports that this gives him a +/-
0.4% improvement on his simple benchmark

x86_64 description follows:

Right now the kernel on x86-64 has a 100% lazy fpu behavior: after *every*
context switch a trap is taken for the first FPU use to restore the FPU
context lazily.  This is of course great for applications that have very
sporadic or no FPU use (since then you avoid doing the expensive save/restore
all the time).  However for very frequent FPU users...  you take an extra trap
every context switch.

The patch below adds a simple heuristic to this code: After 5 consecutive
context switches of FPU use, the lazy behavior is disabled and the context
gets restored every context switch.  If the app indeed uses the FPU, the trap
is avoided.  (the chance of the 6th time slice using FPU after the previous 5
having done so are quite high obviously).

After 256 switches, this is reset and lazy behavior is returned (until there
are 5 consecutive ones again).  The reason for this is to give apps that do
longer bursts of FPU use still the lazy behavior back after some time.
Signed-off-by: NChuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NAndi Kleen <ak@suse.de>

Clean up the espfix code:

- Introduced PER_CPU() macro to be used from asm
- Introduced GET_DESC_BASE() macro to be used from asm
- Rewrote the fixup code in asm, as calling a C code with the altered %ss
  appeared to be unsafe
- No longer altering the stack from a .fixup section
- 16bit per-cpu stack is no longer used, instead the stack segment base
  is patched the way so that the high word of the kernel and user %esp
  are the same.
- Added the limit-patching for the espfix segment. (Chuck Ebbert)

[jeremy@goop.org: use the x86 scaling addressing mode rather than shifting]
Signed-off-by: NStas Sergeev <stsp@aknet.ru>
Signed-off-by: NAndi Kleen <ak@suse.de>
Acked-by: NZachary Amsden <zach@vmware.com>
Acked-by: NChuck Ebbert <76306.1226@compuserve.com>
Acked-by: NJan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NJeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

When a spinlock lockup occurs, arrange for the NMI code to emit an all-cpu
backtrace, so we get to see which CPU is holding the lock, and where.

Cc: Andi Kleen <ak@muc.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NAndi Kleen <ak@suse.de>

This patch removes the default_ldt[] array, as it has been unused since
iBCS stopped being supported.  This means it is now possible to actually
set an empty LDT segment.

In order to deal with this, the set_ldt_desc/load_LDT pair has been
replaced with a single set_ldt() operation which is responsible for both
setting up the LDT descriptor in the GDT, and reloading the LDT register.
If there are no LDT entries, the LDT register is loaded with a NULL
descriptor.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Acked-by: NZachary Amsden <zach@vmware.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Here is a patch (used by perfmon2) to detect the presence of the Precise Event
Based Sampling (PEBS) feature for i386.  The patch also adds the cpu_has_pebs
macro.

- adds X86_FEATURE_PEBS

- adds cpu_has_pebs to test for X86_FEATURE_PEBS
Signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Here is a patch (used by perfmon2) that renames X86_FEATURE_DTES to
X86_FEATURE_DS to match Intel's documentation for the Debug Store save area on
i386.  The patch also adds cpu_has_ds.

- rename X86_FEATURE_DTES to X86_FEATURE_DS to match documentation

- adds cpu_has_ds to test for X86_FEATURE_DS
Signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

inline function cpu_mask_to_apicid in smp.h is duplicated with macro
in mach_apic.h.
Signed-off-by: NYinghai Lu <yinghai.lu@amd.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Here is a patch (used by perfmon2) to detect the presence of the
Precise Event Based Sampling (PEBS) feature for Intel 64-bit processors.
The patch also adds the cpu_has_pebs macro.

changelog:
	- adds X86_FEATURE_PEBS
	- adds cpu_has_pebs to test for X86_FEATURE_PEBS
Signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Here is a patch (used by perfmon2) that renamed X86_FEATURE_DTES
to X86_FEATURE_DS to match Intel's documentation for the Debug Store
save area. The patch also adds cpu_has_ds.

changelog:
	- rename X86_FEATURE_DTES to X86_FEATURE_DS to match documentation
	- adds cpu_has_ds to test for X86_FEATURE_DS
Signed-off-by: Nstephane eranian <eranian@hpl.hp.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Follows i386.

Based on patch from some folks at Google (MikeW, Edward G.?), but
completely redone by AK.
Signed-off-by: NAndi Kleen <ak@suse.de>

This just got removed on x86-64, do the same on 32bit.
It always annoyed me when this ate a line of oops output pushing
interesting stuff off the screen.
Signed-off-by: NDave Jones <davej@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Fix __must_check warnings in i386/math-emu.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAndi Kleen <ak@suse.de>

The unwinder has some extra newlines, which eat up loads of screen
space when it spews. (See https://bugzilla.redhat.com/bugzilla/attachment.cgi?id=137900
for a nasty example).

warning_symbol-> and warning-> already printk a newline, so don't add one
in the strings passed to them.

[AK: redone for new code]
Signed-off-by: NDave Jones <davej@redhat.com>
Signed-off-by: NAndi Kleen <ak@suse.de>

Andrew complained about > 80 character lines in the new unwinder.
Fix that.
Signed-off-by: NAndi Kleen <ak@suse.de>

Fix checks that failed to realize that values are 4-kB-unit-sized (note the
format strings in this same diff context which *do* realize the unit size,
via appended "000"!).  Also fix an incorrect below-1MB area check (as
gathered from Jan Beulich's unapplied patch at
http://www.ussg.iu.edu/hypermail/linux/kernel/0411.1/1378.html ) Update
mtrr_add_page() docu to make 4-kB-sized calculation more obvious.

Given several further items mentioned in Jan's patch mail, all in all MTRR
code seems surprisingly buggy, for a surprisingly long period of time (many
years).  Further work/investigation would be useful.

TBD Note that my patch is pretty much UNTESTED, since I can only verify that it
TBD successfully boots my machine, but I cannot test against actual buggy
TBD hardware which would require these (formerly broken) checks.  Long -mm
TBD simmering would make sense, especially since these now-working checks might
TBD turn out to have adverse effects on unaffected hardware.
Signed-off-by: NAndreas Mohr <andi@lisas.de>
Signed-off-by: NAndi Kleen <ak@suse.de>
Acked-by: NJan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>

Signed-off-by: NAndi Kleen <ak@suse.de>

Signed-off-by: NAndi Kleen <ak@suse.de>