Current instruction decoder for uprobe/kprobe handler only handles
branches with delay slots. For compact branches the behaviour is rather
unpredictable - and depending on the encoding of a compact branch
instruction may result in one (or more) of:
- executing an instruction that follows a branch which wasn't in a delay
slot and shouldn't have been executed
- incorrectly emulating a branch leading to a jump to a wrong location
- unexpected branching out of the single-stepped code and never reaching
the breakpoint that should terminate the probe handler
Results of these actions are generally unpredictable, but can end up
with a probed application or kernel crash, so disable placing probes on
compact branches until they are handled properly.
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14336/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Currently both kprobes and uprobes code have definitions of the
insn_has_delay_slot method. Move it to a separate header as an inline
method that each probe-specific method can later use.
No functional change intended, although the methods slightly varied in
the constraints they set for the methods - the uprobes one was chosen as
it is slightly more specific when filtering opcode fields.
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14335/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
#define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.
The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e. using a global
register that may be set to the per cpu base.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
Cc: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull MIPS updates from Ralf Baechle:
o Add basic support for the Mediatek/Ralink Wireless SoC family.
o The Qualcomm Atheros platform is extended by support for the new
QCA955X SoC series as well as a bunch of patches that get the code
ready for OF support.
o Lantiq and BCM47XX platform have a few improvements and bug fixes.
o MIPS has sent a few patches that get the kernel ready for the
upcoming microMIPS support.
o The rest of the series is made up of small bug fixes and cleanups
that relate to various parts of the MIPS code. The biggy in there is
a whitespace cleanup. After I was sent another set of whitespace
cleanup patches I decided it was the time to clean the whitespace
"issues" for once and and that touches many files below arch/mips/.
Fix up silly conflicts, mostly due to whitespace cleanups.
* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus: (105 commits)
MIPS: Quit exporting kernel internel break codes to uapi/asm/break.h
MIPS: remove broken conditional inside vpe loader code
MIPS: SMTC: fix implicit declaration of set_vi_handler
MIPS: early_printk: drop __init annotations
MIPS: Probe for and report hardware virtualization support.
MIPS: ath79: add support for the Qualcomm Atheros AP136-010 board
MIPS: ath79: add USB controller registration code for the QCA955X SoCs
MIPS: ath79: add PCI controller registration code for the QCA955X SoCs
MIPS: ath79: add WMAC registration code for the QCA955X SoCs
MIPS: ath79: register UART for the QCA955X SoCs
MIPS: ath79: add QCA955X specific glue to ath79_device_reset_{set, clear}
MIPS: ath79: add GPIO setup code for the QCA955X SoCs
MIPS: ath79: add IRQ handling code for the QCA955X SoCs
MIPS: ath79: add clock setup code for the QCA955X SoCs
MIPS: ath79: add SoC detection code for the QCA955X SoCs
MIPS: ath79: add early printk support for the QCA955X SoCs
MIPS: ath79: fix WMAC IRQ resource assignment
mips: reserve elfcorehdr
mips: Make sure kernel memory is in iomem
MIPS: ath79: use dynamically allocated USB platform devices
...
I'm not sure why, but the hlist for each entry iterators were conceived
list_for_each_entry(pos, head, member)
The hlist ones were greedy and wanted an extra parameter:
hlist_for_each_entry(tpos, pos, head, member)
Why did they need an extra pos parameter? I'm not quite sure. Not only
they don't really need it, it also prevents the iterator from looking
exactly like the list iterator, which is unfortunate.
Besides the semantic patch, there was some manual work required:
- Fix up the actual hlist iterators in linux/list.h
- Fix up the declaration of other iterators based on the hlist ones.
- A very small amount of places were using the 'node' parameter, this
was modified to use 'obj->member' instead.
- Coccinelle didn't handle the hlist_for_each_entry_safe iterator
properly, so those had to be fixed up manually.
The semantic patch which is mostly the work of Peter Senna Tschudin is here:
@@
iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host;
type T;
expression a,c,d,e;
identifier b;
statement S;
@@
-T b;
<+... when != b
(
hlist_for_each_entry(a,
- b,
c, d) S
|
hlist_for_each_entry_continue(a,
- b,
c) S
|
hlist_for_each_entry_from(a,
- b,
c) S
|
hlist_for_each_entry_rcu(a,
- b,
c, d) S
|
hlist_for_each_entry_rcu_bh(a,
- b,
c, d) S
|
hlist_for_each_entry_continue_rcu_bh(a,
- b,
c) S
|
for_each_busy_worker(a, c,
- b,
d) S
|
ax25_uid_for_each(a,
- b,
c) S
|
ax25_for_each(a,
- b,
c) S
|
inet_bind_bucket_for_each(a,
- b,
c) S
|
sctp_for_each_hentry(a,
- b,
c) S
|
sk_for_each(a,
- b,
c) S
|
sk_for_each_rcu(a,
- b,
c) S
|
sk_for_each_from
-(a, b)
+(a)
S
+ sk_for_each_from(a) S
|
sk_for_each_safe(a,
- b,
c, d) S
|
sk_for_each_bound(a,
- b,
c) S
|
hlist_for_each_entry_safe(a,
- b,
c, d, e) S
|
hlist_for_each_entry_continue_rcu(a,
- b,
c) S
|
nr_neigh_for_each(a,
- b,
c) S
|
nr_neigh_for_each_safe(a,
- b,
c, d) S
|
nr_node_for_each(a,
- b,
c) S
|
nr_node_for_each_safe(a,
- b,
c, d) S
|
- for_each_gfn_sp(a, c, d, b) S
+ for_each_gfn_sp(a, c, d) S
|
- for_each_gfn_indirect_valid_sp(a, c, d, b) S
+ for_each_gfn_indirect_valid_sp(a, c, d) S
|
for_each_host(a,
- b,
c) S
|
for_each_host_safe(a,
- b,
c, d) S
|
for_each_mesh_entry(a,
- b,
c, d) S
)
...+>
[akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c]
[akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c]
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: fix warnings]
[akpm@linux-foudnation.org: redo intrusive kvm changes]
Tested-by: Peter Senna Tschudin <peter.senna@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Having received another series of whitespace patches I decided to do this
once and for all rather than dealing with this kind of patches trickling
in forever.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This patch provides support for kprobes on branch instructions. The branch
instruction at the probed address is actually emulated and not executed
out-of-line like other normal instructions. Instead the delay-slot instruction
is copied and single stepped out of line.
At the time of probe hit, the original branch instruction is evaluated
and the target cp0_epc is computed similar to compute_retrun_epc(). It
is also checked if the delay slot instruction can be skipped, which is
true if there is a NOP in delay slot or branch is taken in case of
branch likely instructions. Once the delay slot instruction is single
stepped the normal execution resume with the cp0_epc updated the earlier
computed cp0_epc as per the branch instructions.
Signed-off-by: Maneesh Soni <manesoni@cisco.com>
Signed-off-by: Victor Kamensky <kamensky@cisco.com>
Cc: David Daney <david.daney@cavium.com>
Cc: ananth@in.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2914/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
As ll/sc instruction are for atomic read-modify-write operations, allowing
probes on top of these insturctions is a bad idea.
Signed-off-by: Victor Kamensky <kamensky@cisco.com>
Signed-off-by: Maneesh Soni <manesoni@cisco.com>
Cc: David Daney <david.daney@cavium.com>
Cc: ananth@in.ibm.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2912/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
