csky: Fixup -Wmissing-prototypes warning

Cleanup the warnings:

arch/csky/kernel/ptrace.c:320:16: error: no previous prototype for 'syscall_trace_enter' [-Werror=missing-prototypes]
arch/csky/kernel/ptrace.c:336:17: error: no previous prototype for 'syscall_trace_exit' [-Werror=missing-prototypes]
arch/csky/kernel/setup.c:116:34: error: no previous prototype for 'csky_start' [-Werror=missing-prototypes]
arch/csky/kernel/signal.c:255:17: error: no previous prototype for 'do_notify_resume' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:150:15: error: no previous prototype for 'do_trap_unknown' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:152:15: error: no previous prototype for 'do_trap_zdiv' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:154:15: error: no previous prototype for 'do_trap_buserr' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:157:17: error: no previous prototype for 'do_trap_misaligned' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:168:17: error: no previous prototype for 'do_trap_bkpt' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:187:17: error: no previous prototype for 'do_trap_illinsn' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:210:17: error: no previous prototype for 'do_trap_fpe' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:220:17: error: no previous prototype for 'do_trap_priv' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:230:17: error: no previous prototype for 'trap_c' [-Werror=missing-prototypes]
arch/csky/kernel/traps.c:57:13: error: no previous prototype for 'trap_init' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:12:5: error: no previous prototype for '__vdso_clock_gettime64' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:18:5: error: no previous prototype for '__vdso_gettimeofday' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:24:5: error: no previous prototype for '__vdso_clock_getres' [-Werror=missing-prototypes]
arch/csky/kernel/vdso/vgettimeofday.c:6:5: error: no previous prototype for '__vdso_clock_gettime' [-Werror=missing-prototypes]
arch/csky/mm/fault.c:187:17: error: no previous prototype for 'do_page_fault' [-Werror=missing-prototypes]

Link: https://lore.kernel.org/lkml/20230810141947.1236730-17-arnd@kernel.org/
Reported-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>

csky: Fixup compile error

: error: C++ style comments are not allowed in ISO C90
// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
^
error: (this will be reported only once per input file)

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

csky: Optimize the trap processing flow

- Seperate different trap functions
- Add trap_no()
- Remove panic code print
- Redesign die_if_kerenl to die with riscv's
- Print exact trap info for app segment fault

[ 17.389321] gzip[126]: unhandled signal 11 code 0x3 at 0x0007835a in busybox[8000+d4000]
[ 17.393882]
[ 17.393882] CURRENT PROCESS:
[ 17.393882]
[ 17.394309] COMM=gzip PID=126
[ 17.394513] TEXT=00008000-000db2e4 DATA=000dcf14-000dd1ad BSS=000dd1ad-000ff000
[ 17.395499] USER-STACK=7f888e50 KERNEL-STACK=bf130300
[ 17.395499]
[ 17.396801] PC: 0x0007835a (0x7835a)
[ 17.397048] LR: 0x000058b4 (0x58b4)
[ 17.397285] SP: 0xbe519f68
[ 17.397555] orig_a0: 0x00002852
[ 17.397886] PSR: 0x00020341
[ 17.398356] a0: 0x00002852 a1: 0x000f2f5a a2: 0x0000d7ae a3: 0x0000005d
[ 17.399289] r4: 0x000de150 r5: 0x00000002 r6: 0x00000102 r7: 0x00007efa
[ 17.399800] r8: 0x7f888bc4 r9: 0x00000001 r10: 0x000002eb r11: 0x0000aac1
[ 17.400166] r12: 0x00002ef2 r13: 0x00000007 r15: 0x000058b4
[ 17.400531] r16: 0x0000004c r17: 0x00000031 r18: 0x000f5816 r19: 0x000e8068
[ 17.401006] r20: 0x000f5818 r21: 0x000e8068 r22: 0x000f5918 r23: 0x90000000
[ 17.401721] r24: 0x00000031 r25: 0x000000c8 r26: 0x00000000 r27: 0x00000000
[ 17.402199] r28: 0x2ac2a000 r29: 0x00000000 r30: 0x00000000 tls: 0x2aadbaa8
[ 17.402686] hi: 0x00120340 lo: 0x7f888bec
/etc/init.ci/ntfs3g_run: line 61: 126 Segmentation fault gzip -c -9 /mnt/test.bin > /mnt/test_bin.gz

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

csky: Add support for function error injection

Inspired by the commit 42d038c4fb00 ("arm64: Add support for function
error injection"), this patch supports function error injection for
csky.

This patch mainly support two functions: one is regs_set_return_value()
which is used to overwrite the return value; the another function is
override_function_with_return() which is to override the probed
function returning and jump to its caller.

Test log:

cd /sys/kernel/debug/fail_function/
echo sys_clone > inject
echo 100 > probability
echo 1 > interval
ls /
[ 108.644163] FAULT_INJECTION: forcing a failure.
[ 108.644163] name fail_function, interval 1, probability 100, space 0, times 1
[ 108.647799] CPU: 0 PID: 104 Comm: sh Not tainted 5.8.0-rc5+ #46
[ 108.648384] Call Trace:
[ 108.649339] [<8005eed4>] walk_stackframe+0x0/0xf0
[ 108.649679] [<8005f16a>] show_stack+0x32/0x5c
[ 108.649927] [<8040f9d2>] dump_stack+0x6e/0x9c
[ 108.650271] [<80406f7e>] should_fail+0x15e/0x1ac
[ 108.650720] [<80118ba8>] fei_kprobe_handler+0x28/0x5c
[ 108.651519] [<80754110>] kprobe_breakpoint_handler+0x144/0x1cc
[ 108.652289] [<8005d6da>] trap_c+0x8e/0x110
[ 108.652816] [<8005ce8c>] csky_trap+0x5c/0x70
-sh: can't fork: Invalid argument

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

csky: Fixup calltrace panic

The implementation of show_stack will panic with wrong fp:

addr = *fp++;

because the fp isn't checked properly.

The current implementations of show_stack, wchan and stack_trace
haven't been designed properly, so just deprecate them.

This patch is a reference to riscv's way, all codes are modified from
arm's. The patch is passed with:

- cat /proc/<pid>/stack
- cat /proc/<pid>/wchan
- echo c > /proc/sysrq-trigger

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

csky: Add kprobes supported

This patch enable kprobes, kretprobes, ftrace interface. It utilized
software breakpoint and single step debug exceptions, instructions
simulation on csky.

We use USR_BKPT replace origin instruction, and the kprobe handler
prepares an excutable memory slot for out-of-line execution with a
copy of the original instruction being probed. Most of instructions
could be executed by single-step, but some instructions need origin
pc value to execute and we need software simulate these instructions.

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

csky: Implement ptrace regs and stack API

Needed for kprobes support. Copied and adapted from Patrick's patch,
but it has been modified for csky's pt_regs.

ref:
https://lore.kernel.org/linux-riscv/1572919114-3886-2-git-send-email-vincent.chen@sifive.com/raw

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Patrick Staehlin <me@packi.ch>

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: Add non-uapi asm/ptrace.h namespace

Move #ifdef __KERNEL__ code in the uapi namespace to non-uapi
include/asm/ptrace.h namespace and remove #ifdef __KERNEL__ in
include/asm/ptrace.h. Seperate ptrace.h in uapi and non-uapi is more
common and clear.

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