r16 and r17 should be saved across interrupt and exception handling.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Signal code uses r3 value which saved in restore_sigcontext to
rt_sigframe but it require to be zeroed. If is not zero rt_sigframe
contains wrong values.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Do not save return registers before rt_sigreturn is called.
_user_exception(syscall handler) already setup return address
that's why it is removed from rt_sigreturn_wrapper.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Kgdb uses brki r16, 0x18 instruction to call
low level _debug_exception function which save
current state to pt_regs and call microblaze_kgdb_break
function. _debug_exception should be called only from
the kernel space. User space calling is not supported
because user application debugging uses different handling.

pt_regs_to_gdb_regs loads additional special registers
which can't be changed

 * Enable KGDB in Kconfig
 * Remove ancient not-tested KGDB support
 * Remove ancient _debug_exception code from entry.S

Only MMU KGDB support is supported.
Signed-off-by: NMichal Simek <monstr@monstr.eu>
CC: Jason Wessel <jason.wessel@windriver.com>
CC: John Williams <john.williams@petalogix.com>
CC: Edgar E. Iglesias <edgar.iglesias@petalogix.com>
CC: linux-kernel@vger.kernel.org
Acked-by: NJason Wessel <jason.wessel@windriver.com>

This is the first patch which add support for
user application debugging through brki rX, 0x18 vector.

This patch has side effect which also remove security issue
to use brki rX, 0x18 to freeze kernel.

Support for old gdb support via priviledged exception
(brk r0, r0) is still there. It will be remove in future.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

We need to save instruction and the latest Microblaze shouldn't
have any problem with it.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Syscall can be called only from userspace that's why
we don't need to check which space kernel come from.

Kernel syscall calling is not check and shouldn't come
throught this part of code.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

We can save one more instruction if PT_MODE is saved in delay slot
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Save instructions by using delay slot and
clear UMS only if kernel comes from user space.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Saving some instructions. Clear VMS bit if kernel comes
from kernel space.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Saving instructions by adding 2/3 addik instructions to one.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Saving instruction with delay slot usage.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

This change save one instruction if kernel comes from kernel
space.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Separate reg saving and mode setting.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

SAVE_STATE macro could be used by other rutines too.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

We are not working with values from MSR that's why
we can discard it and use r11 for different purpose without
saving/restoring.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Remove set_vms because UMS is cleared and VMS is already setup.
Optimize function calling which save one additional instruction.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

VMS is always setup because VM mode was before
exception/syscall/interrupt. Kernel continues in kernel mode
that's why we have to clear UMS bit if kernel comes from
user space.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

PT_MODE stores information if kernel comes from user
or kernel space. If come from user space, PT_MODE
contains 0. If come from kernel store, PT_MODE contains
non zero value. We don't need to save value 1. I am using
r1 register which contains non zero value.
This change save one additional instruction.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

SAVE_STATE macro could be used for user_exception
or interrupt functions.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

We don't need to save r0 to PT_R0. It could be additional
operation.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

We don't need to save R11 register. There is easy way
to use only R1 which is saved and restore later.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

BIP is already setup.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Keep together all arguments for send_sig function.
Move returning address to delay slot which is executed.
Remove additional send_sig loading. I am using IMM part of
rtbd instruction with r0.

old solution:
addik r11, r0, send_sig
rtbd r11, 0
nop

new solution:
rtbd r0, send_sig
nop

There is one instruction saving.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

It is necessary to setup BIP and EE and clear EIP
only for unaligned exception handler. The rest of
hw exception handlers don't require it.
HW exception occured and we are not in virtual mode.
That's why we can do operations protected by EIP.
Interrupt, next hw exception or syscall can't occur.

EIP is cleared by rted.

This change speedup page_fault hw exception handler
which is critical path.

There is also necessary to save R11 content before
flag setup for unaligned exception.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

la is translated to addik by toolchain.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

SAVE_STATE macro is used in hw exceptions high level handling
functions. Hw exception doesn't disable IRQ that's why we don't
need to reenable it.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Remove code duplicity and move it to SAVE_STATE macro.
There is no impact on performance.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

We don't need to protect by BIP whole ret_from_trap/ret_from_exc code.
Only restoring from user/hw exception should be covered.
If BIP is setup, IRQ can't occur.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

There is a way howto remove Kernel Mode variable. It is easier
to parse UMS bit in MSR to find out if I come from kernel or user
space. Loading MSR content should be in one cycle and loading
PER_CPU variable depends on memory state.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

We can save two instruction when MSR_VMS and MSR_UMS
are setup in one instruction.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Save and restore R3/R4 registers in macros. This change
help to cleanup entry.S.

In ret_from_trap function we are saving returning value from
syscall to pt_regs on stack that's why we don't need to save and
restore these values before kernel functions (schedule, do_signal).
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Jump behind macro. We don't want to execute nop instruction again.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Implement intelligent backtracing by searching for stack frame creation,
and emitting only return addresses. Use print_hex_dump() to display the
entire binary kernel stack.

Limitation: MMU kernels are not currently able to trace beyond a system trap
(interrupt, syscall, etc.). It is the intent of this patch to provide
infrastructure that can be extended to add this capability later.

Changes from V1:
* Removed checks in find_frame_creation() that prevented location of the frame
  creation instruction in heavily optimized code
* Various formatting/commenting/file location tweaks per review comments
* Dropped Kconfig option to enable STACKTRACE as something logically separate
Signed-off-by: NSteven J. Magnani <steve@digidescorp.com>

sys_clone syscall ignored args which this patch mapped to args
which are passing from glibc.

Here is the origin problem description.

"I ran the static libgcc tests (very few of them are there, they are
mostly dynamically linked) and some of  them fail with an assertion in
fork() system call (tid != pid), I looked at the microblaze/entry.S
file and it looks suspicious (ignores arguments 3-5)"

Arg mapping should be:
glibc ARCH_FORK(...) -> do_fork(...)
r5 -> r5   (clone_flags)
r6  -> r6 (stack_start, use parent->stack if NULL)
pt_regs -> r7 (pt_regs)
r7 -> r8 (stack_size)
r8 -> r9 (parent_tidptr)
r9 -> r10 (child_tidptr)
Signed-off-by: NJohn Williams <john.williams@petalogix.com>
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Signed-off-by: NMichal Simek <monstr@monstr.eu>

Signed-off-by: NMichal Simek <monstr@monstr.eu>

There is possible to save r3/r4 at the beggining of user part
before calling handlers and at the end restore it.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

This patch add core PREEMPT support for Microblaze.
I tried to trace it via tracers and I was able to see any output.

I also added low level debug functions to see if that code is called.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Generic rt_sigsuspend syscalls doesn't need any asm wrapper.
Signed-off-by: NMichal Simek <monstr@monstr.eu>