linux.git/arch/powerpc/kernel/process.c, branch v2.6.25

[POWERPC] Fix missed hardware breakpoints across multiple threads

2008-03-28T11:51:02+00:00

There is a bug in the powerpc DABR (data access breakpoint) handling,
which can result in us missing breakpoints if several threads are trying
to break on the same address.

The circumstances are that do_page_fault() calls do_dabr(), this clears
the DABR (sets it to 0) and sets up the signal which will report to
userspace that the DABR was hit. The do_signal() code will restore the DABR
value on the way out to userspace.

If we reschedule before calling do_signal(), __switch_to() will check the
cached DABR value and compare it to the new thread's value, if they match
we don't set the DABR in hardware.

So if two threads have the same DABR value, and we schedule from one to
the other after taking the interrupt for the first thread hitting the DABR,
the second thread will run without the DABR set in hardware.

The cleanest fix is to move the cache update into set_dabr(), that way we
can't forget to do it.

Reported-by: Jan Kratochvil 
Signed-off-by: Michael Ellerman 
Signed-off-by: Paul Mackerras

[POWERPC] Fix PMU + soft interrupt disable bug

2008-03-19T23:14:55+00:00

Since the PMU is an NMI now, it can come at any time we are only soft
disabled.  We must hard disable around the two places we allow the kernel
stack SLB and r1 to go out of sync.  Otherwise the PMU exception can
force a kernel stack SLB into another slot, which can lead to it
getting evicted, which can lead to a nasty unrecoverable SLB miss
in the exception entry code.

Signed-off-by: Anton Blanchard 
Acked-by: Benjamin Herrenschmidt 
Acked-by: Olof Johansson 
Signed-off-by: Paul Mackerras

[POWERPC] Fix DEBUG_PREEMPT warning when warning

2008-02-14T11:11:00+00:00

The powerpc show_regs prints CPU using smp_processor_id: change that to
raw_smp_processor_id, so that when it's showing a WARN_ON backtrace without
preemption disabled, DEBUG_PREEMPT doesn't mess up that warning with its own.

Signed-off-by: Hugh Dickins 
Signed-off-by: Paul Mackerras

[POWERPC] Fix hardware IRQ time accounting problem.

2007-12-06T05:08:59+00:00

The commit fa13a5a1f25f671d084d8884be96fc48d9b68275 (sched: restore
deterministic CPU accounting on powerpc), unconditionally calls
update_process_tick() in system context.  In the deterministic
accounting case this is the correct thing to do.  However, in the
non-deterministic accounting case we need to not do this, since doing
this results in the time accounted as hardware irq time being
artificially elevated.

Also this collapses 2 consecutive '#ifdef CONFIG_VIRT_CPU_ACCOUNTING'
checks in time.h into one for neatness.

Signed-off-by: Tony Breeds 
Signed-off-by: Paul Mackerras

sched: restore deterministic CPU accounting on powerpc

2007-11-09T21:39:38+00:00

Since powerpc started using CONFIG_GENERIC_CLOCKEVENTS, the
deterministic CPU accounting (CONFIG_VIRT_CPU_ACCOUNTING) has been
broken on powerpc, because we end up counting user time twice: once in
timer_interrupt() and once in update_process_times().

This fixes the problem by pulling the code in update_process_times
that updates utime and stime into a separate function called
account_process_tick.  If CONFIG_VIRT_CPU_ACCOUNTING is not defined,
there is a version of account_process_tick in kernel/timer.c that
simply accounts a whole tick to either utime or stime as before.  If
CONFIG_VIRT_CPU_ACCOUNTING is defined, then arch code gets to
implement account_process_tick.

This also lets us simplify the s390 code a bit; it means that the s390
timer interrupt can now call update_process_times even when
CONFIG_VIRT_CPU_ACCOUNTING is turned on, and can just implement a
suitable account_process_tick().

account_process_tick() now takes the task_struct * as an argument.
Tested both with and without CONFIG_VIRT_CPU_ACCOUNTING.

Signed-off-by: Paul Mackerras 
Signed-off-by: Ingo Molnar

Use helpers to obtain task pid in printks (arch code)

2007-10-19T18:53:43+00:00

One of the easiest things to isolate is the pid printed in kernel log.
There was a patch, that made this for arch-independent code, this one makes
so for arch/xxx files.

It took some time to cross-compile it, but hopefully these are all the
printks in arch code.

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Pavel Emelyanov 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: add Altivec/VMX state to coredumps

2007-10-17T15:42:44+00:00

Update dump_task_altivec() (which has so far never been put to use) so that
it dumps the Altivec/VMX registers (VR[0] - VR[31], VSCR and VRSAVE) in the
same format as the ptrace get_vrregs(), and add the appropriate glue
typedef and #defines to make it work.

A new note type of NT_PPC_VMX was chosen to be 0x100 (arbitrarily) because
it allows the low range values to be used for more generic purposes and
0x100 seems an adequate starting point for PowerPC extensions.

Signed-off-by: Mark Nelson 
Signed-off-by: Paul Mackerras 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Andi Kleen 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[POWERPC] Use 1TB segments

2007-10-12T04:05:17+00:00

This makes the kernel use 1TB segments for all kernel mappings and for
user addresses of 1TB and above, on machines which support them
(currently POWER5+, POWER6 and PA6T).

We detect that the machine supports 1TB segments by looking at the
ibm,processor-segment-sizes property in the device tree.

We don't currently use 1TB segments for user addresses < 1T, since
that would effectively prevent 32-bit processes from using huge pages
unless we also had a way to revert to using 256MB segments.  That
would be possible but would involve extra complications (such as
keeping track of which segment size was used when HPTEs were inserted)
and is not addressed here.

Parts of this patch were originally written by Ben Herrenschmidt.

Signed-off-by: Paul Mackerras

Merge branch 'linux-2.6' into for-2.6.24

2007-10-03T05:33:17+00:00

[POWERPC] Make instruction dumping work in real mode

2007-10-03T01:48:44+00:00

On non-book-E, exceptions execute in real mode.  If a fault happens
that leads to a register dump, the kernel currently prints XXXXXXXX
because it doesn't realize that PC is a physical address.

This patch checks whether instruction address translation is turned
on, and if not converts PC into a virtual address.

Signed-off-by: Scott Wood 
Acked-by: Kumar Gala 
Acked-by: Olof Johansson 
Signed-off-by: Paul Mackerras