Revert "csky: Add support for restartable sequence"

This reverts commit 9866d141a0977ace974400bf1f793dfc163409ce.

The csky rseq support has been merged without ever notifying the rseq
maintainers, and without any of the required asssembler glue in the rseq
selftests, which means it is entirely untested.

It is also derived from a non-upstream riscv patch which has known bugs.

The assembly part of this revert should be carefully reviewed by the
architecture maintainer because it touches code which has changed since
the merge of the reverted patch.

The rseq selftests assembly glue should be introduced at the same time
as the architecture rseq support. Without the presence of any test, I
recommend reverting rseq support from csky for now.

Link: https://lore.kernel.org/lkml/1257037909.25426.1626705790861.JavaMail.zimbra@efficios.com/
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-csky@vger.kernel.org

Revert "csky: Fixup CONFIG_DEBUG_RSEQ"

This reverts commit f36e0aab6f1f78d770ce859df3f07a9c5763ce5f.

The csky rseq support has been merged without ever notifying the rseq
maintainers, and without any of the required asssembler glue in the rseq
selftests, which means it is entirely untested.

It is also derived from a non-upstream riscv patch which has known bugs.

The assembly part of this revert should be carefully reviewed by the
architecture maintainer because it touches code which has changed since
the merge of the reverted patch.

The rseq selftests assembly glue should be introduced at the same time
as the architecture rseq support. Without the presence of any test, I
recommend reverting rseq support from csky for now.

Link: https://lore.kernel.org/lkml/1257037909.25426.1626705790861.JavaMail.zimbra@efficios.com/
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-csky@vger.kernel.org

context_tracking: Split user tracking Kconfig

Context tracking is going to be used not only to track user transitions
but also idle/IRQs/NMIs. The user tracking part will then become a
separate feature. Prepare Kconfig for that.

[ frederic: Apply Max Filippov feedback. ]

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>

context_tracking: Rename context_tracking_user_enter/exit() to user_enter/exit_callable()

context_tracking_user_enter() and context_tracking_user_exit() are
ASM callable versions of user_enter() and user_exit() for architectures
that didn't manage to check the context tracking static key from ASM.
Change those function names to better reflect their purpose.

[ frederic: Apply Max Filippov feedback. ]

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@sony.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Cc: Yu Liao <liaoyu15@huawei.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Paul Gortmaker<paul.gortmaker@windriver.com>
Cc: Alex Belits <abelits@marvell.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>

irq: csky: perform irqentry in entry code

In preparation for removing HANDLE_DOMAIN_IRQ_IRQENTRY, have arch/csky
perform all the irqentry accounting in its entry code. As arch/csky uses
GENERIC_IRQ_MULTI_HANDLER, we can use generic_handle_arch_irq() to do
so.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

csky: Remove duplicate include in arch/csky/kernel/entry.S

'asm/setup.h' included in 'arch/csky/kernel/entry.S' is duplicated.

Signed-off-by: Zhang Yunkai <zhang.yunkai@zte.com.cn>
Signed-off-by: Guo Ren <guoren@kernel.org>

csky: Fixup do_page_fault parent irq status

We must succeed parent's context irq status in page fault handler.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Remove prologue of page fault handler in entry.S

There is a prologue on page fault handler which marking pages dirty
and/or accessed in page attributes, but all of these have been
handled in handle_pte_fault.

- Add flush_tlb_one in vmalloc page fault instead of prologue.
- Using cmxchg_fixup C codes in do_page_fault instead of ASM one.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Add memory layout 2.5G(user):1.5G(kernel)

There are two ways for translating va to pa for csky:
- Use TLB(Translate Lookup Buffer) and PTW (Page Table Walk)
- Use SSEG0/1 (Simple Segment Mapping)

We use tlb mapping 0-2G and 3G-4G virtual address area and SSEG0/1
are for 2G-2.5G and 2.5G-3G translation. We could disable SSEG0
to use 2G-2.5G as TLB user mapping.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Add context tracking support

This patch support context tracking with no hz full.

Here is the test result with dynticks-testing (see tick_stop):

cat /sys/kernel/debug/tracing/per_cpu/cpu0/trace
tracer: nop

entries-in-buffer/entries-written: 356/356 #P:1

_-----=> irqs-off
/ _----=> need-resched
| / _---=> hardirq/softirq
|| / _--=> preempt-depth
||| / delay
TASK-PID CPU# |||| TIMESTAMP FUNCTION
| | | |||| | |
...
sleep-192 [000] d.h. 167.088270: hrtimer_expire_entry: hrtimer=(ptrval) function=tick_sched_timer now=166436355700
sleep-192 [000] d.h. 167.092279: hrtimer_expire_entry: hrtimer=(ptrval) function=tick_sched_timer now=166440365700
<idle>-0 [000] d.h2 167.096492: hrtimer_expire_entry: hrtimer=(ptrval) function=tick_sched_timer now=166444578400
<idle>-0 [000] d..1 167.097876: tick_stop: success=1 dependency=NONE
^^^^^^^^^
<idle>-0 [000] d.h1 168.818206: hrtimer_expire_entry: hrtimer=(ptrval) function=tick_sched_timer now=168166280900
kworker/u2:0-7 [000] .... 168.821760: workqueue_execute_start: work struct (ptrval): function wb_workfn
kworker/u2:0-7 [000] d.h1 168.824464: hrtimer_expire_entry: hrtimer=(ptrval) function=tick_sched_timer now=168172547100
kworker/0:1-18 [000] .... 168.825053: workqueue_execute_start: work struct (ptrval): function vmstat_update
kworker/0:1-18 [000] .... 168.825238: workqueue_execute_start: work struct (ptrval): function vmstat_shepherd
kworker/0:1-18 [000] .... 168.825516: workqueue_execute_start: work struct (ptrval): function neigh_periodic_work
<idle>-0 [000] d..1 168.826121: tick_stop: success=1 dependency=NONE
kworker/u2:0-7 [000] .... 169.377327: workqueue_execute_start: work struct (ptrval): function flush_to_ldisc
<idle>-0 [000] d..1 169.379832: tick_stop: success=1 dependency=NONE
kworker/u2:0-7 [000] .... 169.607935: workqueue_execute_start: work struct (ptrval): function flush_to_ldisc
kworker/u2:0-7 [000] d.h1 169.608148: hrtimer_expire_entry: hrtimer=(ptrval) function=tick_sched_timer now=168956235500
<idle>-0 [000] d..1 169.608654: tick_stop: success=1 dependency=NONE

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Greentime Hu <greentime.hu@sifive.com>
Cc: Arnd Bergmann <arnd@arndb.de>

csky: Add SECCOMP_FILTER supported

secure_computing() is called first in syscall_trace_enter() so that
a system call will be aborted quickly without doing succeeding syscall
tracing if seccomp rules want to deny that system call.

TODO:
- Update https://github.com/seccomp/libseccomp csky support

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@arndb.de>

csky: Fixup CONFIG_DEBUG_RSEQ

Put the rseq_syscall check point at the prologue of the syscall
will break the a0 ... a7. This will casue system call bug when
DEBUG_RSEQ is enabled.

So move it to the epilogue of syscall, but before syscall_trace.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Coding convention in entry.S

There is no fixup or feature in the patch, we only cleanup with:

- Remove unnecessary reg used (r11, r12), just use r9 & r10 &
syscallid regs as temp useage.
- Add _TIF_SYSCALL_WORK and _TIF_WORK_MASK to gather macros.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Fixup abiv2 syscall_trace break a4 & a5

Current implementation could destory a4 & a5 when strace, so we need to get them
from pt_regs by SAVE_ALL.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Fixup CONFIG_PREEMPT panic

log:
[    0.13373200] Calibrating delay loop...
[    0.14077600] ------------[ cut here ]------------
[    0.14116700] WARNING: CPU: 0 PID: 0 at kernel/sched/core.c:3790 preempt_count_add+0xc8/0x11c
[    0.14348000] DEBUG_LOCKS_WARN_ON((preempt_count() < 0))Modules linked in:
[    0.14395100] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0 #7
[    0.14410800]
[    0.14427400] Call Trace:
[    0.14450700] [<807cd226>] dump_stack+0x8a/0xe4
[    0.14473500] [<80072792>] __warn+0x10e/0x15c
[    0.14495900] [<80072852>] warn_slowpath_fmt+0x72/0xc0
[    0.14518600] [<800a5240>] preempt_count_add+0xc8/0x11c
[    0.14544900] [<807ef918>] _raw_spin_lock+0x28/0x68
[    0.14572600] [<800e0eb8>] vprintk_emit+0x84/0x2d8
[    0.14599000] [<800e113a>] vprintk_default+0x2e/0x44
[    0.14625100] [<800e2042>] vprintk_func+0x12a/0x1d0
[    0.14651300] [<800e1804>] printk+0x30/0x48
[    0.14677600] [<80008052>] lockdep_init+0x12/0xb0
[    0.14703800] [<80002080>] start_kernel+0x558/0x7f8
[    0.14730000] [<800052bc>] csky_start+0x58/0x94
[    0.14756600] irq event stamp: 34
[    0.14775100] hardirqs last  enabled at (33): [<80067370>] ret_from_exception+0x2c/0x72
[    0.14793700] hardirqs last disabled at (34): [<800e0eae>] vprintk_emit+0x7a/0x2d8
[    0.14812300] softirqs last  enabled at (32): [<800655b0>] __do_softirq+0x578/0x6d8
[    0.14830800] softirqs last disabled at (25): [<8007b3b8>] irq_exit+0xec/0x128

The preempt_count of reg could be destroyed after csky_do_IRQ without reload
from memory.

After reference to other architectures (arm64, riscv), we move preempt entry
into ret_from_exception and disable irq at the beginning of
ret_from_exception instead of RESTORE_ALL.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reported-by: Lu Baoquan <lu.baoquan@intellif.com>

csky: Fixup remove unnecessary save/restore PSR code

All processes' PSR could success from SETUP_MMU, so need set it
in INIT_THREAD again.

And use a3 instead of r7 in __switch_to for code convention.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Fixup remove duplicate irq_disable

Interrupt has been disabled in __schedule() with local_irq_disable()
and enabled in finish_task_switch->finish_lock_switch() with
local_irq_enabled(), So needn't to disable irq here.

Signed-off-by: Liu Yibin <jiulong@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Add uprobes support

This patch adds support for uprobes on csky architecture.

Just like kprobe, it support single-step and simulate instructions.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>

csky: Enable LOCKDEP_SUPPORT

Lockdep is needed by proving the spinlocks and rwlocks. Currently,
we only put trace_hardirqs_on/off with csky_irq and
ret_from_exception.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

csky: Add support for restartable sequence

Copied and adapted from vincent's patch, but modified for csky.

ref:
https://lore.kernel.org/linux-riscv/1572919114-3886-3-git-send-email-vincent.chen@sifive.com/raw

Add calls to rseq_signal_deliver(), rseq_handle_notify_resume() and
rseq_syscall() to introduce RSEQ support.

1. Call the rseq_handle_notify_resume() function on return to userspace
if TIF_NOTIFY_RESUME thread flag is set.

2. Call the rseq_signal_deliver() function to fixup on the pre-signal
frame when a signal is delivered on top of a restartable sequence
critical section.

3. Check that system calls are not invoked from within rseq critical
sections by invoking rseq_signal() from ret_from_syscall(). With
CONFIG_DEBUG_RSEQ, such behavior results in termination of the
process with SIGSEGV.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>

sched/rt, csky: Use CONFIG_PREEMPTION

CONFIG_PREEMPTION is selected by CONFIG_PREEMPT and by CONFIG_PREEMPT_RT.
Both PREEMPT and PREEMPT_RT require the same functionality which today
depends on CONFIG_PREEMPT.

Switch the entry code over to use CONFIG_PREEMPTION.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Guo Ren <guoren@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20191015191821.11479-7-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

csky: entry: Remove unneeded need_resched() loop

Since the enabling and disabling of IRQs within preempt_schedule_irq()
is contained in a need_resched() loop, we don't need the outer arch
code loop.

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

csky: Fixup add zero_fp fixup perf backtrace panic

We need set fp zero to let backtrace know the end. The patch fixup perf
callchain panic problem, because backtrace didn't know what is the end
of fp.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reported-by: Mao Han <han_mao@c-sky.com>

csky: Use va_pa_offset instead of phys_offset

The name of phys_offset is so common for global export and it may
conflict with some local name. So change phys_offset to va_pa_offset
which also used by riscv.

Also use __pa() and __va() instead of using phys_offset directly.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Arnd Bergmann <arnd@arndb.de>

csky: Support dynamic start physical address

Before this patch csky-linux need CONFIG_RAM_BASE to determine start
physical address. Now we use phys_offset variable to replace the macro
of PHYS_OFFSET and we setup phys_offset with real physical address which
is determined during startup in head.S.

With this patch we needn't re-compile kernel for different start
physical address. ie: 0x0 / 0xc0000000 start physical address could use
the same vmlinux, be care different start address must be 512MB aligned.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Arnd Bergmann <arnd@arndb.de>

csky: Reconstruct signal processing

Linux kernel has provided some apis for arch signal's implementation.
For example:
restore_saved_sigmask()
set_current_blocked()
restore_altstack()

But in last version of csky signal.c didn't use them and some codes are
confusing, so reconstruct signal.c with reference to riscv's code.

Now csky signal.c implementation are very close to riscv and we can
get the following benefits:
- Clear code structure
- The signal code of riscv and csky can be reviewed together
- Promoting the unification of arch's signal implementation

Also modified the related code in entry.S

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Arnd Bergmann <arnd@arndb.de>

csky: Use in_syscall & forget_syscall instead of r11_sig

We could use regs->sr 16-24 bits to detect syscall: VEC_TRAP0 and
r11_sig is no necessary for current implementation.

In this patch, we implement the in_syscall and forget_syscall which are
inspired from arm & nds32, but csky pt_regs has no syscall_num element
and we just set zero to regs->sr's vector-bits-field instead.

For ret_from_fork, current task was forked from parent which is in syscall
progress and its regs->sr has been already setted with VEC_TRAP0. See:
arch/csky/kernel/process.c: copy_thread()

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

csky: Update syscall_trace_enter/exit implementation

Previous syscall_trace implementation couldn't support AUDITSYSCALL and
SYSCALL_TRACEPOINTS. Now we redesign it to support audit_syscall
and syscall_tracepoints just like other archs'.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Arnd Bergmann <arnd@arndb.de>

csky: remove unused members in processor.h

Cleanup struct cpuinfo_csky and struct thread_struct, remove all esp0
related code. We could get pt_regs from sp and backtrace could use fp
in switch_stack.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

csky: fixup save hi,lo,dspcr regs in switch_stack.

HI, LO, DSPCR registers are 807/810 related regs and no need for 610/860.
All of the regs must be saved in pt_regs and switch_stack. This patch
fixup saving dspcr reg in switch_stack and pt_regs.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

csky: remove syscall_exit_work

Remove syscall_exit_work and union all to ret_from_exception.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>

csky: Exception handling and mm-fault

This patch adds exception handling code, cpuinfo and mm-fault code.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>