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: Michal 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: Jason 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Michal 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: Steven 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: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal 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: Michal 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: Michal Simek <monstr@monstr.eu>
Saving is done in SAVE_STATE macros that's why another save discard
previous saved value.
This change has no effect to normal programs because they ends in any exception
and they are killed. On the other side has effect on debugging.
Signed-off-by: Michal Simek <monstr@monstr.eu>
Previous patch d63678d607d0e37ec7abe5ceb545d7e8aab956a4 clear
it for noMMU kernel. This one do it for MMU.
Correct noMMU version
Signed-off-by: Michal Simek <monstr@monstr.eu>
The prototypes in syscalls.h all make sense for
microblaze, but for some of them, the actual implementation
in sys_microblaze.c needs to be adapted.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michal Simek <monstr@monstr.eu>
When legacy signal handling is disabled, the
arch/microblaze/kernel/signal.c implementation can
be much simpler, as most of it is handled generically
from kernel/signal.c.
This is also a prerequisite for using the generic
asm/unistd.h, which does not provide __NR_sigreturn,
because this macro is referenced by the current signal.c
implementation.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michal Simek <monstr@monstr.eu>
