Unaligned exception handler is needed in configurations with hardware
support for unaligned access when the load/store exception handler is
enabled because such configurations would still raise an exception on
unaligned access through the instruction bus.
Fixes: f29cf77609 ("xtensa: add load/store exception handler")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
In the absence of other debug facilities dumping user code around the
unhandled exception address may help debugging the issue.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Minimal stack alignment on xtensa is 16 bytes, having stack dump in
32-byte lines may be visually misleading as the stack frame border may
be in the middle of the line.
Arrange stack dump in 16-byte lines. Mark lines at stack frame borders
with arrows.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Memory attached to instruction bus of the xtensa CPU is only accessible
for a limited subset of opcodes. Other opcodes generate an exception
with the load/store error cause code. This property complicates use of
such systems. Provide a handler that recognizes and transparently fixes
such exceptions. The following opcodes are recognized when used outside
of FLIX bundles: l32i, l32i.n, l16ui, l16si, l8ui.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Currently slow handler for unaligned access exception is not installed
when CPU has hardware support for unaligned access. However some opcodes
(e.g. l32ai, s32ri, s32c1i) would still raise unaligned access exception
even on such CPUs. In that case instead of SIGBUS and a diagnostic entry
in the kernel log the faulting process would receive SIGILL.
Always install slow handler for unaligned access exception to fix that.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
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>
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>
Drop 'extern' from all function declarations and move those that need to
be visible from traps.c to traps.h. Add 'asmlinkage' to declarations of
fucntions defined in assembly. Add 'static' to declarations and
definitions only used locally. Add argument names in declarations.
Drop unused second argument from do_multihit and do_page_fault.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Context tracking call must be done after hardirq tracking call,
otherwise lockdep_assert_irqs_disabled called from rcu_eqs_exit gives
a warning. To avoid context tracking logic duplication for IRQ/exception
entry paths move trace_hardirqs_off call back to common entry code.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Many xtensa CPU cores without full MMU still have memory protection
features capable of raising exceptions for invalid instruction
fetches/data access. Allow handling such exceptions. This improves
behavior of processes that pass invalid memory pointers to syscalls in
noMMU configs: in case of exception the kernel instead of killing the
process is now able to return -EINVAL from a syscall.
Introduce CONFIG_PFAULT that controls whether protection fault code is
enabled and register handlers for common memory protection exceptions
when it is enabled.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
There are two big uses of do_exit. The first is it's design use to be
the guts of the exit(2) system call. The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.
Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure. In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.
Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.
As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Pull exit cleanups from Eric Biederman:
"While looking at some issues related to the exit path in the kernel I
found several instances where the code is not using the existing
abstractions properly.
This set of changes introduces force_fatal_sig a way of sending a
signal and not allowing it to be caught, and corrects the misuse of
the existing abstractions that I found.
A lot of the misuse of the existing abstractions are silly things such
as doing something after calling a no return function, rolling BUG by
hand, doing more work than necessary to terminate a kernel thread, or
calling do_exit(SIGKILL) instead of calling force_sig(SIGKILL).
In the review a deficiency in force_fatal_sig and force_sig_seccomp
where ptrace or sigaction could prevent the delivery of the signal was
found. I have added a change that adds SA_IMMUTABLE to change that
makes it impossible to interrupt the delivery of those signals, and
allows backporting to fix force_sig_seccomp
And Arnd found an issue where a function passed to kthread_run had the
wrong prototype, and after my cleanup was failing to build."
* 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (23 commits)
soc: ti: fix wkup_m3_rproc_boot_thread return type
signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed
signal: Replace force_sigsegv(SIGSEGV) with force_fatal_sig(SIGSEGV)
exit/r8188eu: Replace the macro thread_exit with a simple return 0
exit/rtl8712: Replace the macro thread_exit with a simple return 0
exit/rtl8723bs: Replace the macro thread_exit with a simple return 0
signal/x86: In emulate_vsyscall force a signal instead of calling do_exit
signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig
signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails
exit/syscall_user_dispatch: Send ordinary signals on failure
signal: Implement force_fatal_sig
exit/kthread: Have kernel threads return instead of calling do_exit
signal/s390: Use force_sigsegv in default_trap_handler
signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.
signal/vm86_32: Replace open coded BUG_ON with an actual BUG_ON
signal/sparc: In setup_tsb_params convert open coded BUG into BUG
signal/powerpc: On swapcontext failure force SIGSEGV
signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL)
signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT
signal/sparc32: Remove unreachable do_exit in do_sparc_fault
...
After a cleanup the function show_regs doesn't use variable wmask but
still computes it. Drop it.
Fixes: 8d7e8240e6 ("[XTENSA] Clean up elf-gregset.")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
There's no need in window overflow/underflow/alloca exception handlers
or window spill code when neither kernel nor userspace support windowed
registers. Don't build or link it.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Sebastian Andrzej SiewiorandPeter Zijlstra
Randy DunlapandMax Filippov
Yang LiandMax Filippov
Eric W. Biederman
Linus Torvalds