show_stack dumps raw stack contents which may trigger an unnecessary
KASAN report. Fix it by copying stack contents to a temporary buffer
with __memcpy and then printing that buffer instead of passing stack
pointer directly to the print_hex_dump.

Cc: stable@vger.kernel.org
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

bad_vaddr, bad_uaddr and error_code fields are set but never read by the
xtensa arch-specific code. Drop them. Also drop the commented out info
field.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Return boolean values ("true" or "false") instead of 1 or 0 from bool
function. This fixes the following warnings from coccicheck:

./arch/xtensa/kernel/traps.c:304:10-11: WARNING: return of 0/1 in
function 'check_div0' with return type bool

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Message-Id: <20220518230953.112266-1-yang.lee@linux.alibaba.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

When call0 userspace ABI support by probing is enabled instructions that
cause illegal instruction exception when PS.WOE is clear are retried
with PS.WOE set before calling c-level exception handler. Record user pc
at which PS.WOE was set in the fast exception handler and clear PS.WOE
in the c-level exception handler if we get there from the same address.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

On xtensa cores wihout hardware division option division support
functions from libgcc react to division by 0 attempt by executing
illegal instruction followed by the characters 'DIV0'. Recognize this
pattern in illegal instruction exception handler and convert it to
division by 0.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Add c-level handler for the division by zero exception and kill the task
if it was thrown from the kernel space or send SIGFPE otherwise.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Current coprocessor support on xtensa only works correctly on
uniprocessor configurations. Make it work on SMP too and keep it lazy.

Make coprocessor_owner array per-CPU and move it to struct exc_table for
easy access from the fast_coprocessor exception handler. Allow task to
have live coprocessors only on single CPU, record this CPU number in the
struct thread_info::cp_owner_cpu. Change struct thread_info::cpenable
meaning to be 'coprocessors live on cp_owner_cpu'.
Introduce C-level coprocessor exception handler that flushes and
releases live coprocessors of the task taking 'coprocessor disabled'
exception and call it from the fast_coprocessor handler when the task
has live coprocessors on other CPU.
Make coprocessor_flush_all and coprocessor_release_all work correctly
when called from any CPU by sending IPI to the cp_owner_cpu. Add
function coprocessor_flush_release_all to do flush followed by release
atomically. Add function local_coprocessors_flush_release_all to flush
and release all coprocessors on the local CPU and use it to flush
coprocessor contexts from the CPU that goes offline.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

In order to let drivers use xtensa coprocessors on behalf of the calling
process the kernel must handle coprocessor exceptions from the kernel
mode the same way as from the user mode.

This is not sufficient to allow using coprocessors transparently in IRQ
or softirq context. Should such users exist they must be aware of the
context and do the right thing, e.g. preserve the coprocessor state and
resore it after use.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Use xtensa_set_sr instead of inline assembly.
Rename local variable exc_table in early_trap_init to avoid conflict
with per-CPU variable of the same name.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Exception handlers are currently passed as void pointers because they
may have one or two parameters. Only two handlers uses the second
parameter and it is available in the struct pt_regs anyway. Make all
handlers have only one parameter, introduce xtensa_exception_handler
type for handlers and use it in trap_set_handler.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>