linux.git/arch/powerpc/kernel/misc_64.S, branch v2.6.30

powerpc: Disable VSX or current process in giveup_fpu/altivec

2009-04-07T05:18:59+00:00

When we call giveup_fpu, we need to need to turn off VSX for the
current process.  If we don't, on return to userspace it may execute a
VSX instruction before the next FP instruction, and not have its
register state refreshed correctly from the thread_struct.  Ditto for
altivec.

This caused a bug where an unaligned lfs or stfs results in
fix_alignment calling giveup_fpu so it can use the FPRs (in order to
do a single <-> double conversion), and then returning to userspace
with FP off but VSX on.  Then if a VSX instruction is executed, before
another FP instruction, it will proceed without another exception and
hence have the incorrect register state for VSX registers 0-31.

   lfs unaligned   <- alignment exception turns FP off but leaves VSX on

   VSX instruction <- no exception since VSX on, hence we get the
                      wrong VSX register values for VSX registers 0-31,
                      which overlap the FPRs.

Signed-off-by: Michael Neuling 
Signed-off-by: Paul Mackerras

powerpc: Kexec exit should not use magic numbers

2008-10-31T05:11:44+00:00

Commit 54622f10a6aabb8bb2bdacf3dd070046f03dc246 ("powerpc: Support for
relocatable kdump kernel") added a magic flag value in a register to
tell purgatory that it should be a panic kernel.  This part is wrong
and is reverted by this commit.

The kernel gets a list of memory blocks and a entry point from user space.
Its job is to copy the blocks into place and then branch to the designated
entry point (after turning "off" the mmu).

The user space tool inserts a trampoline, called purgatory, that runs
before the user supplied code.   Its job is to establish the entry
environment for the new kernel or other application based on the contents
of memory.  The purgatory code is compiled and embedded in the tool,
where it is later patched using the elf symbol table using elf symbols.

Since the tool knows it is creating a purgatory that will run after a
kernel crash, it should just patch purgatory (or the kernel directly)
if something needs to happen.

Signed-off-by: Milton Miller 
Signed-off-by: Paul Mackerras

powerpc: Support for relocatable kdump kernel

2008-10-22T04:01:22+00:00

This adds relocatable kernel support for kdump. With this one can
use the same regular kernel to capture the kdump. A signature (0xfeed1234)
is passed in r6 from panic code to the next kernel through kexec_sequence
and purgatory code. The signature is used to differentiate between
kdump kernel and non-kdump kernels.

The purgatory code compares the signature and sets the __kdump_flag in
head_64.S.  During the boot up, kernel code checks __kdump_flag and if it
is set, the kernel will behave as relocatable kdump kernel. This kernel
will boot at the address where it was loaded by kexec-tools ie. at the
address reserved through crashkernel boot parameter.

CONFIG_CRASH_DUMP depends on CONFIG_RELOCATABLE option to build kdump
kernel as relocatable. So the same kernel can be used as production and
kdump kernel.

This patch incorporates the changes suggested by Paul Mackerras to avoid
GOT use and to avoid two copies of the code.

Signed-off-by: Paul Mackerras 
Signed-off-by: Mohan Kumar M 
Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix error path in kernel_thread function

2008-10-10T04:55:18+00:00

The powerpc 32-bit and 64-bit kernel_thread functions don't properly
propagate errors being returned by the clone syscall.  (In the case of
error, the syscall exit code returns a positive errno in r3 and sets
the CR0[SO] bit.)

This patch fixes that by negating r3 if CR0[SO] is set after the syscall.

Signed-off-by: Josh Poimboeuf 
Signed-off-by: Josh Boyer 
Acked-by: Paul Mackerras 
Signed-off-by: Benjamin Herrenschmidt

powerpc: fix giveup_vsx to save registers correctly

2008-07-15T02:29:23+00:00

giveup_vsx didn't save the FPU and VMX regsiters.  Change it to be
like giveup_fpr/altivec which save these registers.

Also update call sites where FPU and VMX are already saved to use the
original giveup_vsx (renamed to __giveup_vsx).

Signed-off-by: Michael Neuling 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Add VSX context save/restore, ptrace and signal support

2008-07-01T01:28:50+00:00

This patch extends the floating point save and restore code to use the
VSX load/stores when VSX is available.  This will make FP context
save/restore marginally slower on FP only code, when VSX is available,
as it has to load/store 128bits rather than just 64bits.

Mixing FP, VMX and VSX code will get constant architected state.

The signals interface is extended to enable access to VSR 0-31
doubleword 1 after discussions with tool chain maintainers.  Backward
compatibility is maintained.

The ptrace interface is also extended to allow access to VSR 0-31 full
registers.

Signed-off-by: Michael Neuling 
Signed-off-by: Paul Mackerras

[POWERPC] Clean up misc_64.S

2008-04-24T10:58:03+00:00

* Removed get_msr(), get_srr0(), and get_srr1() - not used anywhere
* Use STACK_FRAME_OVERHEAD instead of magic number

Signed-off-by: Kumar Gala 
Signed-off-by: Paul Mackerras

[POWERPC] kernel_execve is identical in 32 and 64 bit

2007-12-11T02:34:39+00:00

so consolidate it into misc.S.

Signed-off-by: Stephen Rothwell 
Signed-off-by: Paul Mackerras

[POWERPC] kexec: Send slaves to new kernel earlier

2007-06-25T06:55:16+00:00

With this, when kexec-ing, we copy the code and start the slaves on
their journey to the next kernel's spin loop as soon as we copy the
kexec image into place.

The kernel doesn't know exactly which slaves are spinning in
kexec_wait.  This allows us to pass more than max-cpus to the
next kernel.  But it also means that we might leave some behind.

Moving the code here means they have the time it takes us to
clear the hash table to wake up and move on.  Moving the code
any earlier would reuqire walking the image description to
search for the code, which could span multiple pages.

Signed-off-by: Milton Miller 
Signed-off-by: Paul Mackerras

[POWERPC] pasemi: UART udbg support

2007-02-07T03:03:22+00:00

Early debug output for PA Semi UART. Uses the 2.05 CI real mode ops.

Signed-off-by: Olof Johansson 
Signed-off-by: Paul Mackerras