linux.git/arch/parisc/kernel/syscall.S, branch v4.11

parisc: Use LINUX_GATEWAY_ADDR define instead of hardcoded value

2016-11-02T22:06:38+00:00

LINUX_GATEWAY_ADDR is defined in unistd.h. Let's use it.

Signed-off-by: Helge Deller

parisc: Ensure consistent state when switching to kernel stack at syscall entry

2016-11-02T22:05:30+00:00

We have one critical section in the syscall entry path in which we switch from
the userspace stack to kernel stack. In the event of an external interrupt, the
interrupt code distinguishes between those two states by analyzing the value of
sr7. If sr7 is zero, it uses the kernel stack. Therefore it's important, that
the value of sr7 is in sync with the currently enabled stack.

This patch now disables interrupts while executing the critical section.  This
prevents the interrupt handler to possibly see an inconsistent state which in
the worst case can lead to crashes.

Interestingly, in the syscall exit path interrupts were already disabled in the
critical section which switches back to the userspace stack.

Cc: 
Signed-off-by: John David Anglin 
Signed-off-by: Helge Deller

parisc: Avoid trashing sr2 and sr3 in LWS code

2016-11-02T22:05:11+00:00

There is no need to trash sr2 and sr3 in the Light-weight syscall (LWS).  sr2
already points to kernel space (it's zero in userspace, otherwise syscalls
wouldn't work), and since the LWS code is executed in userspace, we can simply
ignore to preload sr3.

Signed-off-by: John David Anglin 
Signed-off-by: Helge Deller

parisc: Add syscall tracepoint support

2016-05-22T19:38:47+00:00

This patch adds support for the TIF_SYSCALL_TRACEPOINT on the parisc
architecture. Basically, it calls the appropriate tracepoints on syscall
entry and exit.

Signed-off-by: Helge Deller

parisc: fix a bug when syscall number of tracee is __NR_Linux_syscalls

2016-05-06T13:09:07+00:00

Do not load one entry beyond the end of the syscall table when the
syscall number of a traced process equals to __NR_Linux_syscalls.
Similar bug with regular processes was fixed by commit 3bb457af4fa8
("[PARISC] Fix bug when syscall nr is __NR_Linux_syscalls").

This bug was found by strace test suite.

Cc: stable@vger.kernel.org
Signed-off-by: Dmitry V. Levin 
Acked-by: Helge Deller 
Signed-off-by: Helge Deller

parisc: Fix and enable seccomp filter support

2016-03-31T10:28:38+00:00

The seccomp filter support requires careful handling of task registers.  This
includes reloading of the return value (%r28) and proper syscall exit if
secure_computing() returned -1.

Additionally we need to sign-extend the syscall number from signed 32bit to
signed 64bit in do_syscall_trace_enter() since the ptrace interface only allows
storing 32bit values in compat mode.

Signed-off-by: Helge Deller 
Cc: stable@vger.kernel.org # v4.5

parisc: Fix ptrace syscall number and return value modification

2016-03-01T22:06:07+00:00

Mike Frysinger reported that his ptrace testcase showed strange
behaviour on parisc: It was not possible to avoid a syscall and the
return value of a syscall couldn't be changed.

To modify a syscall number, we were missing to save the new syscall
number to gr20 which is then picked up later in assembly again.

The effect that the return value couldn't be changed is a side-effect of
another bug in the assembly code. When a process is ptraced, userspace
expects each syscall to report entrance and exit of a syscall.  If a
syscall number was given which doesn't exist, we jumped to the normal
syscall exit code instead of informing userspace that the (non-existant)
syscall exits. This unexpected behaviour confuses userspace and thus the
bug was misinterpreted as if we can't change the return value.

This patch fixes both problems and was tested on 64bit kernel with
32bit userspace.

Signed-off-by: Helge Deller 
Cc: Mike Frysinger 
Cc: stable@vger.kernel.org  # v4.0+
Tested-by: Mike Frysinger

parisc: Use long branch to do_syscall_trace_exit

2015-11-22T11:23:02+00:00

Use the 22bit instead of the 17bit branch instruction on a 64bit kernel
to reach the do_syscall_trace_exit function from the gateway page.
A huge page enabled kernel may need the additional branch distance bits.

Signed-off-by: Helge Deller

parisc: Use double word condition in 64bit CAS operation

2015-09-08T14:15:54+00:00

The attached change fixes the condition used in the "sub" instruction.
A double word comparison is needed.  This fixes the 64-bit LWS CAS
operation on 64-bit kernels.

I can now enable 64-bit atomic support in GCC.

Cc: 
Signed-off-by: John David Anglin 
Signed-off-by: Helge Deller

parisc: Implement new LWS CAS supporting 64 bit operations.

2014-09-13T20:40:48+00:00

The current LWS cas only works correctly for 32bit. The new LWS allows
for CAS operations of variable size.

Signed-off-by: Guy Martin 
Cc:  # 3.13+
Signed-off-by: Helge Deller