PTRACE_GET_SYSCALL_INFO is a generic ptrace API that lets ptracer obtain
details of the syscall the tracee is blocked in.

There are two reasons for a special syscall-related ptrace request.

Firstly, with the current ptrace API there are cases when ptracer cannot
retrieve necessary information about syscalls.  Some examples include:

 * The notorious int-0x80-from-64-bit-task issue. See [1] for details.
   In short, if a 64-bit task performs a syscall through int 0x80, its
   tracer has no reliable means to find out that the syscall was, in
   fact, a compat syscall, and misidentifies it.

 * Syscall-enter-stop and syscall-exit-stop look the same for the
   tracer. Common practice is to keep track of the sequence of
   ptrace-stops in order not to mix the two syscall-stops up. But it is
   not as simple as it looks; for example, strace had a (just recently
   fixed) long-standing bug where attaching strace to a tracee that is
   performing the execve system call led to the tracer identifying the
   following syscall-exit-stop as syscall-enter-stop, which messed up
   all the state tracking.

 * Since the introduction of commit 84d77d3f06e7 ("ptrace: Don't allow
   accessing an undumpable mm"), both PTRACE_PEEKDATA and
   process_vm_readv become unavailable when the process dumpable flag is
   cleared. On such architectures as ia64 this results in all syscall
   arguments being unavailable for the tracer.

Secondly, ptracers also have to support a lot of arch-specific code for
obtaining information about the tracee.  For some architectures, this
requires a ptrace(PTRACE_PEEKUSER, ...) invocation for every syscall
argument and return value.

PTRACE_GET_SYSCALL_INFO returns the following structure:

struct ptrace_syscall_info {
	__u8 op;	/* PTRACE_SYSCALL_INFO_* */
	__u32 arch __attribute__((__aligned__(sizeof(__u32))));
	__u64 instruction_pointer;
	__u64 stack_pointer;
	union {
		struct {
			__u64 nr;
			__u64 args[6];
		} entry;
		struct {
			__s64 rval;
			__u8 is_error;
		} exit;
		struct {
			__u64 nr;
			__u64 args[6];
			__u32 ret_data;
		} seccomp;
	};
};

The structure was chosen according to [2], except for the following
changes:

 * seccomp substructure was added as a superset of entry substructure

 * the type of nr field was changed from int to __u64 because syscall
   numbers are, as a practical matter, 64 bits

 * stack_pointer field was added along with instruction_pointer field
   since it is readily available and can save the tracer from extra
   PTRACE_GETREGS/PTRACE_GETREGSET calls

 * arch is always initialized to aid with tracing system calls such as
   execve()

 * instruction_pointer and stack_pointer are always initialized so they
   could be easily obtained for non-syscall stops

 * a boolean is_error field was added along with rval field, this way
   the tracer can more reliably distinguish a return value from an error
   value

strace has been ported to PTRACE_GET_SYSCALL_INFO.  Starting with
release 4.26, strace uses PTRACE_GET_SYSCALL_INFO API as the preferred
mechanism of obtaining syscall information.

[1] https://lore.kernel.org/lkml/CA+55aFzcSVmdDj9Lh_gdbz1OzHyEm6ZrGPBDAJnywm2LF_eVyg@mail.gmail.com/
[2] https://lore.kernel.org/lkml/CAObL_7GM0n80N7J_DFw_eQyfLyzq+sf4y2AvsCCV88Tb3AwEHA@mail.gmail.com/

This patch (of 7):

All syscall_get_*() and syscall_set_*() functions must be defined as
static inline as on all other architectures, otherwise asm/syscall.h
cannot be included in more than one compilation unit.

This bug has to be fixed in order to extend the generic
ptrace API with PTRACE_GET_SYSCALL_INFO request.

Link: http://lkml.kernel.org/r/20190510152749.GA28558@altlinux.org
Fixes: 1932fbe36e02 ("nds32: System calls handling")
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Reported-by: kbuild test robot <lkp@intel.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Elvira Khabirova <lineprinter@altlinux.org>
Cc: Eugene Syromyatnikov <esyr@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Helge Deller <deller@gmx.de>	[parisc]
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The nds32 implementation of pte_alloc_one_kernel() differs from the
generic in the use of __GFP_RETRY_MAYFAIL flag, which is removed after the
conversion.

The nds32 version of pte_alloc_one() missed the call to
pgtable_page_ctor() and also used __GFP_RETRY_MAYFAIL.  Switching it to
use generic __pte_alloc_one() for the PTE page allocation ensures that
page table constructor is run and the user page tables are allocated with
__GFP_ACCOUNT.

The conversion to the generic version of pte_free_kernel() removes the
NULL check for pte.

The pte_free() version on nds32 is identical to the generic one and can be
simply dropped.

Link: http://lkml.kernel.org/r/1557296232-15361-10-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Guo Ren <ren_guo@c-sky.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Creasey <sammy@sammy.net>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull nds32 fixes from Greentime Hu:

 - fix warning for math-emu

 - fix nds32 fpu exception handling

 - fix nds32 fpu emulation implementation

* tag 'nds32-for-linux-5.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/greentime/linux:
  nds32: add new emulations for floating point instruction
  nds32: Avoid IEX status being incorrectly modified
  math-emu: Use statement expressions to fix Wshift-count-overflow warning

The existing floating point emulations is only available for floating
instruction that possibly issue denormalized input and underflow
exceptions. These existing FPU emulations are not sufficient when IEx
Trap is enabled because some floating point instructions only issue inexact
exception. This patch adds the emulations of such floating point
instructions.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

In order for kernel to capture each denormalized output, the UDF
trapping enable bit is always raised in $fpcsr. Because underflow case will
issue not an underflow exception but also an inexact exception, it causes
that the IEX, IEX cumulative exception, flag in $fpcsr to be raised in each
denormalized output handling. To make the emulation transparent to the
user, the emulator needs to clear the IEX flag in $fpcsr if the result is a
denormalized number. However, if the IEX flag has been raised before this
floating point emulation, this cleanup may be incorrect. To avoid the IEX
flags in $fpcsr be raised in each denormalized output handling, the IEX
trap shall be always enabled.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Acked-by: Greentime Hu <greentime@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>

Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

      GPL-2.0

Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

These generic-y defines do not have the corresponding generic header
in include/asm-generic/, so they are definitely invalid.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Pull nds32 updates from Greentime Hu:

 - Clean up codes and Makefile

 - Fix a vDSO bug

 - Remove useless functions/header files

 - Update git repo path in MAINTAINERS

* tag 'nds32-for-linus-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/greentime/linux:
  nds32: Fix vDSO clock_getres()
  MAINTAINERS: update nds32 git repo path
  nds32: don't export low-level cache flushing routines
  arch: nds32: Kconfig: pedantic formatting
  nds32: fix semicolon code style issue
  nds32: vdso: drop unnecessary cc-ldoption
  nds32: remove unused generic-y += cmpxchg-local.h
  nds32: Use the correct style for SPDX License Identifier
  nds32: remove __virt_to_bus and __bus_to_virt
  nds32: vdso: fix and clean-up Makefile
  nds32: add vmlinux.lds and vdso.so to .gitignore
  nds32: ex-exit: Remove unneeded need_resched() loop
  nds32/io: Remove useless definition of mmiowb()
  nds32: Removed unused thread flag TIF_USEDFPU

Pull nommu generic uaccess updates from Arnd Bergmann:
 "asm-generic: kill <asm/segment.h> and improve nommu generic uaccess helpers

  Christoph Hellwig writes:

     This is a series doing two somewhat interwinded things. It improves
     the asm-generic nommu uaccess helper to optionally be entirely
     generic and not require any arch helpers for the actual uaccess.
     For the generic uaccess.h to actually be generically useful I also
     had to kill off the mess we made of <asm/segment.h>, which really
     shouldn't exist on most architectures"

* tag 'asm-generic-nommu' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  asm-generic: optimize generic uaccess for 8-byte loads and stores
  asm-generic: provide entirely generic nommu uaccess
  arch: mostly remove <asm/segment.h>
  asm-generic: don't include <asm/segment.h> from <asm/uaccess.h>

clock_getres in the vDSO library has to preserve the same behaviour
of posix_get_hrtimer_res().

In particular, posix_get_hrtimer_res() does:
    sec = 0;
    ns = hrtimer_resolution;
and hrtimer_resolution depends on the enablement of the high
resolution timers that can happen either at compile or at run time.

Fix the nds32 vdso implementation of clock_getres keeping a copy of
hrtimer_resolution in vdso data and using that directly.

Cc: Greentime Hu <green.hu@gmail.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>