arch: remove unused function syscall_set_arguments()

This function appears to have been unused since it was first introduced in
commit 828c365cc8b8 ("tracehook: asm/syscall.h").

Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I8ce04f002903a37c0b6c1d16e9b2a3afa716c097
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

s390/syscall: provide generic system call functions

Provide generic system call functions which should be used whenever a
system call needs to be done from user space. The only in-kernel code
is vdso, which will be converted with a follow on patch.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

s390: convert to generic entry

This patch converts s390 to use the generic entry infrastructure from
kernel/entry/*.

There are a few special things on s390:

- PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't
know about our PIF flags in exit_to_user_mode_loop().

- The old code had several ways to restart syscalls:

a) PIF_SYSCALL_RESTART, which was only set during execve to force a
restart after upgrading a process (usually qemu-kvm) to pgste page
table extensions.

b) PIF_SYSCALL, which is set by do_signal() to indicate that the
current syscall should be restarted. This is changed so that
do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use
PIF_SYSCALL doesn't work with the generic code, and changing it
to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART
more unique.

- On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by
executing a svc instruction on the process stack which causes a fault.
While handling that fault the fault code sets PIF_SYSCALL to hand over
processing to the syscall code on exit to usermode.

The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets
a return value for a syscall. The s390x ptrace ABI uses r2 both for the
syscall number and return value, so ptrace cannot set the syscall number +
return value at the same time. The flag makes handling that a bit easier.
do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET
is set.

CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY.
CR1/7/13 will be checked both on kernel entry and exit to contain the
correct asces.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

s390: fix syscall_get_error for compat processes

If both the tracer and the tracee are compat processes, and gprs[2]
is assigned a value by __poke_user_compat, then the higher 32 bits
of gprs[2] are cleared, IS_ERR_VALUE() always returns false, and
syscall_get_error() always returns 0.

Fix the implementation by sign-extending the value for compat processes
the same way as x86 implementation does.

The bug was exposed to user space by commit 201766a20e30f ("ptrace: add
PTRACE_GET_SYSCALL_INFO request") and detected by strace test suite.

This change fixes strace syscall tampering on s390.

Link: https://lkml.kernel.org/r/20200602180051.GA2427@altlinux.org
Fixes: 753c4dd6a2fa2 ("[S390] ptrace changes")
Cc: Elvira Khabirova <lineprinter@altlinux.org>
Cc: stable@vger.kernel.org # v2.6.28+
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

s390/kernel: convert SYSCALL and PGM_CHECK handlers to .quad

With a relocatable kernel that could reside at any place in memory, the
storage size for the SYSCALL and PGM_CHECK handlers needs to be
increased from .long to .quad.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

syscalls: Remove start and number from syscall_set_arguments() args

After removing the start and count arguments of syscall_get_arguments() it
seems reasonable to remove them from syscall_set_arguments(). Note, as of
today, there are no users of syscall_set_arguments(). But we are told that
there will be soon. But for now, at least make it consistent with
syscall_get_arguments().

Link: http://lkml.kernel.org/r/20190327222014.GA32540@altlinux.org

Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Dave Martin <dave.martin@arm.com>
Cc: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: nios2-dev@lists.rocketboards.org
Cc: openrisc@lists.librecores.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-um@lists.infradead.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linux-arch@vger.kernel.org
Acked-by: Max Filippov <jcmvbkbc@gmail.com> # For xtensa changes
Acked-by: Will Deacon <will.deacon@arm.com> # For the arm64 bits
Reviewed-by: Thomas Gleixner <tglx@linutronix.de> # for x86
Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

syscalls: Remove start and number from syscall_get_arguments() args

At Linux Plumbers, Andy Lutomirski approached me and pointed out that the
function call syscall_get_arguments() implemented in x86 was horribly
written and not optimized for the standard case of passing in 0 and 6 for
the starting index and the number of system calls to get. When looking at
all the users of this function, I discovered that all instances pass in only
0 and 6 for these arguments. Instead of having this function handle
different cases that are never used, simply rewrite it to return the first 6
arguments of a system call.

This should help out the performance of tracing system calls by ptrace,
ftrace and perf.

Link: http://lkml.kernel.org/r/20161107213233.754809394@goodmis.org

Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Dave Martin <dave.martin@arm.com>
Cc: "Dmitry V. Levin" <ldv@altlinux.org>
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@vger.kernel.org
Cc: nios2-dev@lists.rocketboards.org
Cc: openrisc@lists.librecores.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-um@lists.infradead.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linux-arch@vger.kernel.org
Acked-by: Paul Burton <paul.burton@mips.com> # MIPS parts
Acked-by: Max Filippov <jcmvbkbc@gmail.com> # For xtensa changes
Acked-by: Will Deacon <will.deacon@arm.com> # For the arm64 bits
Reviewed-by: Thomas Gleixner <tglx@linutronix.de> # for x86
Reviewed-by: Dmitry V. Levin <ldv@altlinux.org>
Reported-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

syscall_get_arch: add "struct task_struct *" argument

This argument is required to extend the generic ptrace API with
PTRACE_GET_SYSCALL_INFO request: syscall_get_arch() is going
to be called from ptrace_request() along with syscall_get_nr(),
syscall_get_arguments(), syscall_get_error(), and
syscall_get_return_value() functions with a tracee as their argument.

The primary intent is that the triple (audit_arch, syscall_nr, arg1..arg6)
should describe what system call is being called and what its arguments
are.

Reverts: 5e937a9ae913 ("syscall_get_arch: remove useless function arguments")
Reverts: 1002d94d3076 ("syscall.h: fix doc text for syscall_get_arch()")
Reviewed-by: Andy Lutomirski <luto@kernel.org> # for x86
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Paul Burton <paul.burton@mips.com> # MIPS parts
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Kees Cook <keescook@chromium.org> # seccomp parts
Acked-by: Mark Salter <msalter@redhat.com> # for the c6x bit
Cc: Elvira Khabirova <lineprinter@altlinux.org>
Cc: Eugene Syromyatnikov <esyr@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: x86@kernel.org
Cc: linux-alpha@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: nios2-dev@lists.rocketboards.org
Cc: openrisc@lists.librecores.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-um@lists.infradead.org
Cc: linux-xtensa@linux-xtensa.org
Cc: linux-arch@vger.kernel.org
Cc: linux-audit@redhat.com
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Paul Moore <paul@paul-moore.com>

s390: include: Remove redundant license text

Now that the SPDX tag is in all arch/s390/include/ files, that
identifies the license in a specific and legally-defined manner. So the
extra GPL text wording can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text. And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Halil Pasic <pasic@linux.vnet.ibm.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390: add SPDX identifiers to the remaining files

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the remaining arch/s390/ files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/syscalls: Fix out of bounds arguments access

Zorro reported following crash while having enabled
syscall tracing (CONFIG_FTRACE_SYSCALLS):

Unable to handle kernel pointer dereference at virtual ...
Oops: 0011 [#1] SMP DEBUG_PAGEALLOC

SNIP

Call Trace:
([<000000000024d79c>] ftrace_syscall_enter+0xec/0x1d8)
[<00000000001099c6>] do_syscall_trace_enter+0x236/0x2f8
[<0000000000730f1c>] sysc_tracesys+0x1a/0x32
[<000003fffcf946a2>] 0x3fffcf946a2
INFO: lockdep is turned off.
Last Breaking-Event-Address:
[<000000000022dd44>] rb_event_data+0x34/0x40
---[ end trace 8c795f86b1b3f7b9 ]---

The crash happens in syscall_get_arguments function for
syscalls with zero arguments, that will try to access
first argument (args[0]) in event entry, but it's not
allocated.

Bail out of there are no arguments.

Cc: stable@vger.kernel.org
Reported-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/syscalls: simplify syscall_get_arch()

Given that sizeof(long) is now always 8, we can simplify syscall_get_arch()
a bit.
Just another piece I didn't find when removing 31 bit support.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/seccomp: fix error return for filtered system calls

The syscall_set_return_value function of s390 negates the error argument
before storing the value to the return register gpr2. This is incorrect,
the seccomp code already passes the negative error value.
Store the unmodified error value to gpr2.

Signed-off-by: Jan Willeke <willeke@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390: split TIF bits into CIF, PIF and TIF bits

The oi and ni instructions used in entry[64].S to set and clear bits
in the thread-flags are not guaranteed to be atomic in regard to other
CPUs. Split the TIF bits into CPU, pt_regs and thread-info specific
bits. Updates on the TIF bits are done with atomic instructions,
updates on CPU and pt_regs bits are done with non-atomic instructions.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

audit: use uapi/linux/audit.h for AUDIT_ARCH declarations

The syscall.h headers were including linux/audit.h but really only
needed the uapi/linux/audit.h to get the requisite defines. Switch to
the uapi headers.

Signed-off-by: Eric Paris <eparis@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Cc: linux-s390@vger.kernel.org
Cc: x86@kernel.org

syscall_get_arch: remove useless function arguments

Every caller of syscall_get_arch() uses current for the task and no
implementors of the function need args. So just get rid of both of
those things. Admittedly, since these are inline functions we aren't
wasting stack space, but it just makes the prototypes better.

Signed-off-by: Eric Paris <eparis@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Cc: linux390@de.ibm.com
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linux-arch@vger.kernel.org

s390: system call path micro optimization

Add a pointer to the system call table to the thread_info structure.
The TIF_31BIT bit is set or cleared by SET_PERSONALITY exactly once
for the lifetime of a process. With the pointer to the correct system
call table in thread_info the system call code in entry64.S path can
drop the check for TIF_31BIT which saves a couple of instructions.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/seccomp: add support for system call filtering using BPF

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] cleanup trap handling

Move the program interruption code and the translation exception identifier
to the pt_regs structure as 'int_code' and 'int_parm_long' and make the
first level interrupt handler in entry[64].S store the two values. That
makes it possible to drop 'prot_addr' and 'trap_no' from the thread_struct
and to reduce the number of arguments to a lot of functions. Finally
un-inline do_trap. Overall this saves 5812 bytes in the .text section of
the 64 bit kernel.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] add TIF_SYSCALL thread flag

Add an explicit TIF_SYSCALL bit that indicates if a task is inside
a system call. The svc_code in the pt_regs structure is now only
valid if TIF_SYSCALL is set. With this definition TIF_RESTART_SVC
can be replaced with TIF_SYSCALL. Overall do_signal is a bit more
readable and it saves a few lines of code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] signal race with restarting system calls

For a ERESTARTNOHAND/ERESTARTSYS/ERESTARTNOINTR restarting system call
do_signal will prepare the restart of the system call with a rewind of
the PSW before calling get_signal_to_deliver (where the debugger might
take control). For A ERESTART_RESTARTBLOCK restarting system call
do_signal will set -EINTR as return code.
There are two issues with this approach:
1) strace never sees ERESTARTNOHAND, ERESTARTSYS, ERESTARTNOINTR or
ERESTART_RESTARTBLOCK as the rewinding already took place or the
return code has been changed to -EINTR
2) if get_signal_to_deliver does not return with a signal to deliver
the restart via the repeat of the svc instruction is left in place.
This opens a race if another signal is made pending before the
system call instruction can be reexecuted. The original system call
will be restarted even if the second signal would have ended the
system call with -EINTR.

These two issues can be solved by dropping the early rewind of the
system call before get_signal_to_deliver has been called and by using
the TIF_RESTART_SVC magic to do the restart if no signal has to be
delivered. The only situation where the system call restart via the
repeat of the svc instruction is appropriate is when a SA_RESTART
signal is delivered to user space.

Unfortunately this breaks inferior calls by the debugger again. The
system call number and the length of the system call instruction is
lost over the inferior call and user space will see ERESTARTNOHAND/
ERESTARTSYS/ERESTARTNOINTR/ERESTART_RESTARTBLOCK. To correct this a
new ptrace interface is added to save/restore the system call number
and system call instruction length.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] cleanup system call parameter setup

Do the setup of the stack overflow argument for the sixth system
call parameter right before the branch to the system call function.
That simplifies the system call parameter access code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

tracing: Unify arch_syscall_addr() implementations

Most implementations of arch_syscall_addr() are the same, so create a
default version in common code and move the one piece that differs (the
syscall table) to asm/syscall.h. New arch ports don't have to waste
time copying & pasting this simple function.

The s390/sparc versions need to be different, so document why.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1264498803-17278-1-git-send-email-vapier@gentoo.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

[S390] ftrace: add system call tracer support

System call tracer support for s390.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] fix system call parameter functions.

syscall_get_nr() currently returns a valid result only if the call
chain of the traced process includes do_syscall_trace_enter(). But
collect_syscall() can be called for any sleeping task, the result of
syscall_get_nr() in general is completely bogus.

To make syscall_get_nr() work for any sleeping task the traps field
in pt_regs is replace with svcnr - the system call number the process
is executing. If svcnr == 0 the process is not on a system call path.

The syscall_get_arguments and syscall_set_arguments use regs->gprs[2]
for the first system call parameter. This is incorrect since gprs[2]
may have been overwritten with the system call number if the call
chain includes do_syscall_trace_enter. Use regs->orig_gprs2 instead.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] ptrace changes

* System call parameter and result access functions
* Add tracehook calls
* Split syscall_trace into two functions do_syscall_trace_enter and
do_syscall_trace_exit

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>