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: <stable@vger.kernel.org>
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
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 <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
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 <deller@gmx.de>
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 3bb457af4f
("[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 <ldv@altlinux.org>
Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>
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 <deller@gmx.de>
Cc: stable@vger.kernel.org # v4.5
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 <deller@gmx.de>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: stable@vger.kernel.org # v4.0+
Tested-by: Mike Frysinger <vapier@gentoo.org>
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 <deller@gmx.de>
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: <stable@vger.kernel.org>
Signed-off-by: John David Anglin <dave.anglin>
Signed-off-by: Helge Deller <deller@gmx.de>
The current LWS cas only works correctly for 32bit. The new LWS allows
for CAS operations of variable size.
Signed-off-by: Guy Martin <gmsoft@tuxicoman.be>
Cc: <stable@vger.kernel.org> # 3.13+
Signed-off-by: Helge Deller <deller@gmx.de>
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 <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # 3.13+
Signed-off-by: Helge Deller <deller@gmx.de>
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 <deller@gmx.de>
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 <James.Bottomley@HansenPartnership.com>
Signed-off-by: Helge Deller <deller@gmx.de>
This patch fixes partly PAGE_SIZEs of 16K or 64K by adjusting the
assembler PTE lookup code and the assembler TEMPALIAS code. Furthermore
some data alignments for PAGE_SIZE have been limited to 4K (or less) to
not waste too much memory with greater page sizes. As a side note, the
palo loader can (currently) only handle up to 10 ELF segments which is
fixed with tighter aligning as well.
My testings indicated that the ldci command in the sba iommu coding
needed adjustment by the PAGE_SHIFT value and that the I/O PDIR Page
size was only set to 4K for my machine (C3000).
All this fixes partly the boot, but there are still quite some caching
problems left. Examples are e.g. the symbios logic driver which is
failing:
sym0: <896> rev 0x7 at pci 0000:00:0f.0 irq 69
sym0: PA-RISC Firmware, ID 7, Fast-40, SE, parity checking
CACHE TEST FAILED: DMA error (dstat=0x81).sym0: CACHE INCORRECTLY CONFIGURED.
and the tulip network driver which doesn't seem to work correctly
either:
Sending BOOTP requests .net eth0: Setting full-duplex based on MII#1
link partner capability of 05e1
..... timed out!
Beside those kernel fixes glibc will need fixes too to be able to handle
>4K page sizes.
Signed-off-by: Helge Deller <deller@gmx.de>
1) PTRACE_SYSCALL doesn't work for 64bit process on parisc64.
Compat syscall table is used instead of 64bit one. IMO we should either
refuse to allow PTRACE_SYSCALL for 64bit processes or duplicate the
logics choosing the right syscall table into .Ltracesys.
2) if you have let the tracee run with PTRACE_SYSCALL and
it had stopped, you can use PTRACE_POKEUSR to modify syscall number
(r20) and arguments 1--4 (r26--r23). Modifications will have effect.
However, modifying arguments 5 and 6 (r22 and r21 resp.) works only
when process (32bit one) runs on 64bit host - on 32bit one it has no
effect. AFAICS, the diff below should fix that one.
Signed-off-by: Al Viro <viro@ZenIV.linux.org.uk>
Tested-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Don't bother restoring r28 on syscall restarts; it's clobbered by
syscall anyway. Reuse (now unused) ->orig_r28 as "no restarts allowed"
flag.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1) Gate immediately and save a branch.
2) Fix off by one error in checking entry number.
3) Use sr7 instead of sr3 in error return path as sr3 might not
contain correct value.
4) Enable locking on UP systems to prevent incorrect operation of
the cas_action critical region on page faults.
Tested on several systems, including UP c3750 with 2.6.33.2 kernel.
Signed-off-by: John David Anglin <dave.anglin@nrc-cnrc.gc.ca>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Instead of fiddling with gr[20], restructure code to return whether
or not to -ENOSYS. (Also do a bit of fiddling to let them take
pt_regs directly instead of re-computing it.)
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
This makes parisc use the standard tracehook_report_syscall_entry
and tracehook_report_syscall_exit hooks in <linux/tracehook.h>.
To do this, we need to access current->thread.regs, and to know
whether we're entering or exiting the syscall, so add this to
syscall_trace.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
Document the LWS ABI including implementation notes for
userspace, and comment cleanup.
Remove extraneous .align 16 after lws_lock_start.
Signed-off-by: Carlos O'Donell <carlos@systemhalted.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
This trivial patch fixes the following section warnings on PARISC:
> WARNING: vmlinux.o (.text.1): unexpected section name.
>The (.[number]+) following section name are ld generated and not expected.
> Did you forget to use "ax"/"aw" in a .S file?
> Note that for example <linux/init.h> contains
> section definitions for use in .S files.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
We have the macro _AC() generally available now
so the calculation of PAGE_SIZE can be made
assembler compatible.
Introduce use of _AC() and kill all users of
ASM_PAGE_SIZE.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>
The bug was that we were comparing __NR_syscalls to be greater or equal
to the syscall number stored in %r20. __NR_syscalls is one greater than
the last syscall though, so we're loading one entry beyond the end of the
syscall table, and trying to jump to it.
Fix this by only checking that we're greater, alternatively, we could
have compared to (__NR_Linux_syscalls - 1)
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Amazingly, parisc was the only arch effected by this...
Convert register-sized loads/stores to always be 32-bit for these fields.
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
The LWS debugging code on parisc is wrongly enabled due to a bug in the
use of the preprocessor directives. This debugging code is not thread
safe and causes problems with a recent glibc on SMP kernels.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
- this macro unifies the code to add exception table entries
- additionally use ENTRY()/ENDPROC() at more places
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
ldcw,co should always be used on pa2.0, otherwise the strict cache
width alignment requirement is not relaxed.
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
More work towards supporing multiple page sizes on 64-bit. Convert
some assumptions that 64bit uses 3 level page tables into testing
PT_NLEVELS. Also some BUG() to BUG_ON() conversions and some cleanups
to assembler.
Signed-off-by: Helge Deller <deller@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Add the parisc version of the "mark rodata section read only" patches.
Based on code from and Signed-off-by Arjan van de Ven
<arjan@infradead.org>, Ingo Molnar <mingo@elte.hu>, Andi Kleen <ak@muc.de>,
Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>.
Signed-off-by: Helge Deller <deller@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Document clobbers and args in entry.S and syscall.S.
entry.S: Add comment to indicate that cr27 may recycle and EDEADLOCK
detection is not 100% correct. Since this is only enabled when using
ENABLE_LWS_DEBUG, the user is warned by the comment.
Signed-off-by: Carlos O'Donell <carlos@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Helge Deller