linux-stable.git/arch/parisc/kernel/syscall.S, branch v4.8

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

parisc: Improve LWS-CAS performance

2014-05-15T19:12:26+00:00

The attached change significantly improves the performance of the LWS-CAS code
in syscall.S.
This allows a number of packages to build (e.g., zeromq3, gtest and libxs)
that previously failed because slow LWS-CAS performance under contention. In
particular, interrupts taken while the lock was taken degraded performance
significantly.

The change does the following:

1) Disables interrupts around the CAS operation, and
2) Changes the loads and stores to use the ordered completer, "o", on
PA 2.0. "o" and "ma" with a zero offset are equivalent. The latter is
accepted on both PA 1.X and 2.0.

The use of ordered loads and stores probably makes no difference on all
existing hardware, but it seemed pedantically correct. In particular, the CAS
operation must complete before LDCW lock is released. As written before, a
processor could reorder the operations.

I don't believe the period interrupts are disabled is long enough to
significantly increase interrupt latency. For example, the TLB insert code is
longer. Worst case is a memory fault in the CAS operation.

Signed-off-by: John David Anglin 
Cc: stable@vger.kernel.org # 3.13+
Signed-off-by: Helge Deller

parisc: provide macro to create exception table entries

2013-11-07T21:25:33+00:00

Provide a macro ASM_EXCEPTIONTABLE_ENTRY() to create exception table
entries and convert all open-coded places to use that macro.

This patch is a first step toward creating a exception table which only
holds 32bit pointers even on a 64bit kernel. That way in my own kernel
I was able to reduce the in-kernel exception table from 44kB to 22kB.

Signed-off-by: Helge Deller

parisc: document the parisc gateway page

2013-05-06T21:09:10+00:00

Include some documentation about how the parisc gateway page technically
works and how it is used from userspace.

James Bottomley is the original author of this description and it was
copied here out of an email thread from Apr 12 2013 titled:
man2 : syscall.2 : document syscall calling conventions

CC: James Bottomley 
Signed-off-by: Helge Deller