uaccess: remove CONFIG_SET_FS

There are no remaining callers of set_fs(), so CONFIG_SET_FS
can be removed globally, along with the thread_info field and
any references to it.

This turns access_ok() into a cheaper check against TASK_SIZE_MAX.

As CONFIG_SET_FS is now gone, drop all remaining references to
set_fs()/get_fs(), mm_segment_t, user_addr_max() and uaccess_kernel().

Acked-by: Sam Ravnborg <sam@ravnborg.org> # for sparc32 changes
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Tested-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com> # for arc changes
Acked-by: Stafford Horne <shorne@gmail.com> # [openrisc, asm-generic]
Acked-by: Dinh Nguyen <dinguyen@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

sched,arch: Remove unused TASK_STATE offsets

All 6 architectures define TASK_STATE in asm-offsets, but then never
actually use it. Remove the definitions to make sure they never will.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210611082838.472811363@infradead.org

csky: Fixup gdbmacros.txt with name sp in thread_struct

The gdbmacros.txt use sp in thread_struct, but csky use ksp. This
cause bttnobp fail to excute.

TODO:
- Still couldn't display the contents of stack.

Signed-off-by: Guo Ren <guoren@linux.alibaba.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: Implement ftrace with regs

This patch implements FTRACE_WITH_REGS for csky, which allows a traced
function's arguments (and some other registers) to be captured into a
struct pt_regs, allowing these to be inspected and/or modified.

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

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: Misc headers

This patch adds csky registers' definition, bitops, byteorder,
asm-offsets codes.

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