This implements a few trace points across events that are deemed
interesting. This implements a number of trace points:
- The page fault handler / TLB miss
- IPC calls
- Kernel thread creation
The original LTTng patch had the slow-path instrumented, which
fails to account for the vast majority of events. In general
placing this in the fast-path is not a huge performance hit, as
we don't take page faults for kernel addresses.
The other bits of interest are some of the other trap handlers, as
well as the syscall entry/exit (which is better off being handled
through the tracehook API). Most of the other trap handlers are corner
cases where alternate means of notification exist, so there is little
value in placing extra trace points in these locations.
Based on top of the points provided both by the LTTng instrumentation
patch as well as the patch shipping in the ST-Linux tree, albeit in a
stripped down form.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This fixes a problem in the code which copies the vmalloc portion of the
kernel's page table into the current user space page table. The addition
of the four level page table code breaks on folded page tables, because
the pud level is always present (although folded). This updates the code
to use the same style of updates for the pud as is used for the pgd
level.
Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
The current kernel behaviour is to reenable interrupts unconditionally
when taking a page fault. This patch changes this to only enable them
if interrupts were previously enabled.
It also fixes a problem seen with this fix in place: the kernel previously
flushed the vsyscall page when handling a signal, which is not only
unncessary, but caused a possible sleep with interrupts disabled.
Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This acts as a reversion of 1c6b2ca5e0 in
the case of UP SH-4, where we still have the risk of a multiple hit
between the slow and fast paths. As seen on SH7780.
Signed-off-by: Hideo Saito <saito@densan.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
The idea is that we want to get rid of the in/out/readb/writeb callbacks from
the machvec and replace that with simple inline read and write operations to
memory. Fast and simple for most hardware devices (think pci).
Some devices require special treatment though - like 16-bit only CF devices -
so we need to have some method to hook in callbacks.
This patch makes it possible to add a per-device trap generating filter. This
way we can get maximum performance of sane hardware - which doesn't need this
filter - and crappy hardware works but gets punished by a performance hit.
V2 changes things around a bit and replaces io access callbacks with a
simple minimum_bus_width value. In the future we can add stride as well.
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
