The xol_free_insn_slot()->waitqueue_active() check is buggy. We
need mb() after we set the conditon for wait_event(), or
xol_take_insn_slot() can miss the wakeup.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134036.GA4799@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Change xol_add_vma() to use _install_special_mapping(), this way
we can name the vma installed by uprobes. Currently it looks
like private anonymous mapping, this is confusing and
complicates the debugging. With this change /proc/$pid/maps
reports "[uprobes]".
As a side effect this will cause core dumps to include the XOL vma
and I think this is good; this can help to debug the problem if
the app crashed because it was probed.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134033.GA4796@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
install_special_mapping(pages) expects that "pages" is the zero-
terminated array while xol_add_vma() passes &area->page, this
means that special_mapping_fault() can wrongly use the next
member in xol_area (vaddr) as "struct page *".
Fortunately, this area is not expandable so pgoff != 0 isn't
possible (modulo bugs in special_mapping_vmops), but still this
does not look good.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Pratyush Anand <panand@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134031.GA4789@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The previous change documents that cleanup_return_instances()
can't always detect the dead frames, the stack can grow. But
there is one special case which imho worth fixing:
arch_uretprobe_is_alive() can return true when the stack didn't
actually grow, but the next "call" insn uses the already
invalidated frame.
Test-case:
#include <stdio.h>
#include <setjmp.h>
jmp_buf jmp;
int nr = 1024;
void func_2(void)
{
if (--nr == 0)
return;
longjmp(jmp, 1);
}
void func_1(void)
{
setjmp(jmp);
func_2();
}
int main(void)
{
func_1();
return 0;
}
If you ret-probe func_1() and func_2() prepare_uretprobe() hits
the MAX_URETPROBE_DEPTH limit and "return" from func_2() is not
reported.
When we know that the new call is not chained, we can do the
more strict check. In this case "sp" points to the new ret-addr,
so every frame which uses the same "sp" must be dead. The only
complication is that arch_uretprobe_is_alive() needs to know was
it chained or not, so we add the new RP_CHECK_CHAIN_CALL enum
and change prepare_uretprobe() to pass RP_CHECK_CALL only if
!chained.
Note: arch_uretprobe_is_alive() could also re-read *sp and check
if this word is still trampoline_vaddr. This could obviously
improve the logic, but I would like to avoid another
copy_from_user() especially in the case when we can't avoid the
false "alive == T" positives.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134028.GA4786@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86 doesn't care (so far), but as Pratyush Anand pointed
out other architectures might want why arch_uretprobe_is_alive()
was called and use different checks depending on the context.
Add the new argument to distinguish 2 callers.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134026.GA4779@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Change prepare_uretprobe() to flush the !arch_uretprobe_is_alive()
return_instance's. This is not needed correctness-wise, but can help
to avoid the failure caused by MAX_URETPROBE_DEPTH.
Note: in this case arch_uretprobe_is_alive() can be false
positive, the stack can grow after longjmp(). Unfortunately, the
kernel can't 100% solve this problem, but see the next patch.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134023.GA4776@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Test-case:
#include <stdio.h>
#include <setjmp.h>
jmp_buf jmp;
void func_2(void)
{
longjmp(jmp, 1);
}
void func_1(void)
{
if (setjmp(jmp))
return;
func_2();
printf("ERR!! I am running on the caller's stack\n");
}
int main(void)
{
func_1();
return 0;
}
fails if you probe func_1() and func_2() because
handle_trampoline() assumes that the probed function should must
return and hit the bp installed be prepare_uretprobe(). But in
this case func_2() does not return, so when func_1() returns the
kernel uses the no longer valid return_instance of func_2().
Change handle_trampoline() to unwind ->return_instances until we
know that the next chain is alive or NULL, this ensures that the
current chain is the last we need to report and free.
Alternatively, every return_instance could use unique
trampoline_vaddr, in this case we could use it as a key. And
this could solve the problem with sigaltstack() automatically.
But this approach needs more changes, and it puts the "hard"
limit on MAX_URETPROBE_DEPTH. Plus it can not solve another
problem partially fixed by the next patch.
Note: this change has no effect on !x86, the arch-agnostic
version of arch_uretprobe_is_alive() just returns "true".
TODO: as documented by the previous change, arch_uretprobe_is_alive()
can be fooled by sigaltstack/etc.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134021.GA4773@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add the x86 specific version of arch_uretprobe_is_alive()
helper. It returns true if the stack frame mangled by
prepare_uretprobe() is still on stack. So if it returns false,
we know that the probed function has already returned.
We add the new return_instance->stack member and change the
generic code to initialize it in prepare_uretprobe, but it
should be equally useful for other architectures.
TODO: this assumes that the probed application can't use
multiple stacks (say sigaltstack). We will try to improve
this logic later.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134018.GA4766@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add the new "weak" helper, arch_uretprobe_is_alive(), used by
the next patches. It should return true if this return_instance
is still valid. The arch agnostic version just always returns
true.
The patch exports "struct return_instance" for the architectures
which want to override this hook. We can also cleanup
prepare_uretprobe() if we pass the new return_instance to
arch_uretprobe_hijack_return_addr().
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134016.GA4762@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
No functional changes, preparation.
Add the new helper, find_next_ret_chain(), which finds the first
!chained entry and returns its ->next. Yes, it is suboptimal. We
probably want to turn ->chained into ->start_of_this_chain
pointer and avoid another loop. But this needs the boring
changes in dup_utask(), so lets do this later.
Change the main loop in handle_trampoline() to unwind the stack
until ri is equal to the pointer returned by this new helper.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134013.GA4755@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Turn the last pr_warn() in uprobes.c into uprobe_warn().
While at it:
- s/kzalloc/kmalloc, we initialize every member of 'ri'
- remove the pointless comment above the obvious code
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134010.GA4752@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1. It doesn't make sense to continue if handle_trampoline()
fails, change handle_swbp() to always return after this call.
2. Turn pr_warn() into uprobe_warn(), and change
handle_trampoline() to send SIGILL on failure. It is pointless to
return to user mode with the corrupted instruction_pointer() which
we can't restore.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134008.GA4745@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We can simplify uprobe_free_utask() and handle_uretprobe_chain()
if we add a simple helper which does put_uprobe/kfree and
returns the ->next return_instance.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134006.GA4740@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cosmetic. Add the new trivial helper, get_uprobe(). It matches
put_uprobe() we already have and we can simplify a couple of its
users.
Tested-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Anton Arapov <arapov@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150721134003.GA4736@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull drm updates from Dave Airlie:
"Highlights:
- AMD KFD driver merge
This is the AMD HSA interface for exposing a lowlevel interface for
GPGPU use. They have an open source userspace built on top of this
interface, and the code looks as good as it was going to get out of
tree.
- Initial atomic modesetting work
The need for an atomic modesetting interface to allow userspace to
try and send a complete set of modesetting state to the driver has
arisen, and been suffering from neglect this past year. No more,
the start of the common code and changes for msm driver to use it
are in this tree. Ongoing work to get the userspace ioctl finished
and the code clean will probably wait until next kernel.
- DisplayID 1.3 and tiled monitor exposed to userspace.
Tiled monitor property is now exposed for userspace to make use of.
- Rockchip drm driver merged.
- imx gpu driver moved out of staging
Other stuff:
- core:
panel - MIPI DSI + new panels.
expose suggested x/y properties for virtual GPUs
- i915:
Initial Skylake (SKL) support
gen3/4 reset work
start of dri1/ums removal
infoframe tracking
fixes for lots of things.
- nouveau:
tegra k1 voltage support
GM204 modesetting support
GT21x memory reclocking work
- radeon:
CI dpm fixes
GPUVM improvements
Initial DPM fan control
- rcar-du:
HDMI support added
removed some support for old boards
slave encoder driver for Analog Devices adv7511
- exynos:
Exynos4415 SoC support
- msm:
a4xx gpu support
atomic helper conversion
- tegra:
iommu support
universal plane support
ganged-mode DSI support
- sti:
HDMI i2c improvements
- vmwgfx:
some late fixes.
- qxl:
use suggested x/y properties"
* 'drm-next' of git://people.freedesktop.org/~airlied/linux: (969 commits)
drm: sti: fix module compilation issue
drm/i915: save/restore GMBUS freq across suspend/resume on gen4
drm: sti: correctly cleanup CRTC and planes
drm: sti: add HQVDP plane
drm: sti: add cursor plane
drm: sti: enable auxiliary CRTC
drm: sti: fix delay in VTG programming
drm: sti: prepare sti_tvout to support auxiliary crtc
drm: sti: use drm_crtc_vblank_{on/off} instead of drm_vblank_{on/off}
drm: sti: fix hdmi avi infoframe
drm: sti: remove event lock while disabling vblank
drm: sti: simplify gdp code
drm: sti: clear all mixer control
drm: sti: remove gpio for HDMI hot plug detection
drm: sti: allow to change hdmi ddc i2c adapter
drm/doc: Document drm_add_modes_noedid() usage
drm/i915: Remove '& 0xffff' from the mask given to WA_REG()
drm/i915: Invert the mask and val arguments in wa_add() and WA_REG()
drm: Zero out DRM object memory upon cleanup
drm/i915/bdw: Fix the write setting up the WIZ hashing mode
...
Both register and unregister call build_map_info() in order to create the
list of mappings before installing or removing breakpoints for every mm
which maps file backed memory. As such, there is no reason to hold the
i_mmap_rwsem exclusively, so share it and allow concurrent readers to
build the mapping data.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The i_mmap_mutex is a close cousin of the anon vma lock, both protecting
similar data, one for file backed pages and the other for anon memory. To
this end, this lock can also be a rwsem. In addition, there are some
important opportunities to share the lock when there are no tree
modifications.
This conversion is straightforward. For now, all users take the write
lock.
[sfr@canb.auug.org.au: update fremap.c]
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
x86 call do_notify_resume on paranoid returns if TIF_UPROBE is set but
not on non-paranoid returns. I suspect that this is a mistake and that
the code only works because int3 is paranoid.
Setting _TIF_NOTIFY_RESUME in the uprobe code was probably a workaround
for the x86 bug. With that bug fixed, we can remove _TIF_NOTIFY_RESUME
from the uprobes code.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These patches rework memcg charge lifetime to integrate more naturally
with the lifetime of user pages. This drastically simplifies the code and
reduces charging and uncharging overhead. The most expensive part of
charging and uncharging is the page_cgroup bit spinlock, which is removed
entirely after this series.
Here are the top-10 profile entries of a stress test that reads a 128G
sparse file on a freshly booted box, without even a dedicated cgroup (i.e.
executing in the root memcg). Before:
15.36% cat [kernel.kallsyms] [k] copy_user_generic_string
13.31% cat [kernel.kallsyms] [k] memset
11.48% cat [kernel.kallsyms] [k] do_mpage_readpage
4.23% cat [kernel.kallsyms] [k] get_page_from_freelist
2.38% cat [kernel.kallsyms] [k] put_page
2.32% cat [kernel.kallsyms] [k] __mem_cgroup_commit_charge
2.18% kswapd0 [kernel.kallsyms] [k] __mem_cgroup_uncharge_common
1.92% kswapd0 [kernel.kallsyms] [k] shrink_page_list
1.86% cat [kernel.kallsyms] [k] __radix_tree_lookup
1.62% cat [kernel.kallsyms] [k] __pagevec_lru_add_fn
After:
15.67% cat [kernel.kallsyms] [k] copy_user_generic_string
13.48% cat [kernel.kallsyms] [k] memset
11.42% cat [kernel.kallsyms] [k] do_mpage_readpage
3.98% cat [kernel.kallsyms] [k] get_page_from_freelist
2.46% cat [kernel.kallsyms] [k] put_page
2.13% kswapd0 [kernel.kallsyms] [k] shrink_page_list
1.88% cat [kernel.kallsyms] [k] __radix_tree_lookup
1.67% cat [kernel.kallsyms] [k] __pagevec_lru_add_fn
1.39% kswapd0 [kernel.kallsyms] [k] free_pcppages_bulk
1.30% cat [kernel.kallsyms] [k] kfree
As you can see, the memcg footprint has shrunk quite a bit.
text data bss dec hex filename
37970 9892 400 48262 bc86 mm/memcontrol.o.old
35239 9892 400 45531 b1db mm/memcontrol.o
This patch (of 4):
The memcg charge API charges pages before they are rmapped - i.e. have an
actual "type" - and so every callsite needs its own set of charge and
uncharge functions to know what type is being operated on. Worse,
uncharge has to happen from a context that is still type-specific, rather
than at the end of the page's lifetime with exclusive access, and so
requires a lot of synchronization.
Rewrite the charge API to provide a generic set of try_charge(),
commit_charge() and cancel_charge() transaction operations, much like
what's currently done for swap-in:
mem_cgroup_try_charge() attempts to reserve a charge, reclaiming
pages from the memcg if necessary.
mem_cgroup_commit_charge() commits the page to the charge once it
has a valid page->mapping and PageAnon() reliably tells the type.
mem_cgroup_cancel_charge() aborts the transaction.
This reduces the charge API and enables subsequent patches to
drastically simplify uncharging.
As pages need to be committed after rmap is established but before they
are added to the LRU, page_add_new_anon_rmap() must stop doing LRU
additions again. Revive lru_cache_add_active_or_unevictable().
[hughd@google.com: fix shmem_unuse]
[hughd@google.com: Add comments on the private use of -EAGAIN]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add WARN_ON's into uprobe_unregister() and uprobe_apply() to ensure
that nobody tries to play with the dead uprobe/consumer. This helps
to catch the bugs like the one fixed by the previous patch.
In the longer term we should fix this poorly designed interface.
uprobe_register() should return "struct uprobe *" which should be
passed to apply/unregister. Plus other semantic changes, see the
changelog in commit 41ccba029e.
Link: http://lkml.kernel.org/p/20140627170140.GA18322@redhat.com
Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Pull more perf updates from Ingo Molnar:
"A second round of perf updates:
- wide reaching kprobes sanitization and robustization, with the hope
of fixing all 'probe this function crashes the kernel' bugs, by
Masami Hiramatsu.
- uprobes updates from Oleg Nesterov: tmpfs support, corner case
fixes and robustization work.
- perf tooling updates and fixes from Jiri Olsa, Namhyung Ki, Arnaldo
et al:
* Add support to accumulate hist periods (Namhyung Kim)
* various fixes, refactorings and enhancements"
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits)
perf: Differentiate exec() and non-exec() comm events
perf: Fix perf_event_comm() vs. exec() assumption
uprobes/x86: Rename arch_uprobe->def to ->defparam, minor comment updates
perf/documentation: Add description for conditional branch filter
perf/x86: Add conditional branch filtering support
perf/tool: Add conditional branch filter 'cond' to perf record
perf: Add new conditional branch filter 'PERF_SAMPLE_BRANCH_COND'
uprobes: Teach copy_insn() to support tmpfs
uprobes: Shift ->readpage check from __copy_insn() to uprobe_register()
perf/x86: Use common PMU interrupt disabled code
perf/ARM: Use common PMU interrupt disabled code
perf: Disable sampled events if no PMU interrupt
perf: Fix use after free in perf_remove_from_context()
perf tools: Fix 'make help' message error
perf record: Fix poll return value propagation
perf tools: Move elide bool into perf_hpp_fmt struct
perf tools: Remove elide setup for SORT_MODE__MEMORY mode
perf tools: Fix "==" into "=" in ui_browser__warning assignment
perf tools: Allow overriding sysfs and proc finding with env var
perf tools: Consider header files outside perf directory in tags target
...
Pull ARM updates from Russell King:
- Major clean-up of the L2 cache support code. The existing mess was
becoming rather unmaintainable through all the additions that others
have done over time. This turns it into a much nicer structure, and
implements a few performance improvements as well.
- Clean up some of the CP15 control register tweaks for alignment
support, moving some code and data into alignment.c
- DMA properties for ARM, from Santosh and reviewed by DT people. This
adds DT properties to specify bus translations we can't discover
automatically, and to indicate whether devices are coherent.
- Hibernation support for ARM
- Make ftrace work with read-only text in modules
- add suspend support for PJ4B CPUs
- rework interrupt masking for undefined instruction handling, which
allows us to enable interrupts earlier in the handling of these
exceptions.
- support for big endian page tables
- fix stacktrace support to exclude stacktrace functions from the
trace, and add save_stack_trace_regs() implementation so that kprobes
can record stack traces.
- Add support for the Cortex-A17 CPU.
- Remove last vestiges of ARM710 support.
- Removal of ARM "meminfo" structure, finally converting us solely to
memblock to handle the early memory initialisation.
* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (142 commits)
ARM: ensure C page table setup code follows assembly code (part II)
ARM: ensure C page table setup code follows assembly code
ARM: consolidate last remaining open-coded alignment trap enable
ARM: remove global cr_no_alignment
ARM: remove CPU_CP15 conditional from alignment.c
ARM: remove unused adjust_cr() function
ARM: move "noalign" command line option to alignment.c
ARM: provide common method to clear bits in CPU control register
ARM: 8025/1: Get rid of meminfo
ARM: 8060/1: mm: allow sub-architectures to override PCI I/O memory type
ARM: 8066/1: correction for ARM patch 8031/2
ARM: 8049/1: ftrace/add save_stack_trace_regs() implementation
ARM: 8065/1: remove last use of CONFIG_CPU_ARM710
ARM: 8062/1: Modify ldrt fixup handler to re-execute the userspace instruction
ARM: 8047/1: rwsem: use asm-generic rwsem implementation
ARM: l2c: trial at enabling some Cortex-A9 optimisations
ARM: l2c: add warnings for stuff modifying aux_ctrl register values
ARM: l2c: print a warning with L2C-310 caches if the cache size is modified
ARM: l2c: remove old .set_debug method
ARM: l2c: kill L2X0_AUX_CTRL_MASK before anyone else makes use of this
...
tmpfs is widely used but as Denys reports shmem_aops doesn't have
->readpage() and thus you can't probe a binary on this filesystem.
As Hugh suggested we can use shmem_read_mapping_page() in this case,
just we need to check shmem_mapping() if ->readpage == NULL.
Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140519184136.GB6750@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
copy_insn() fails with -EIO if ->readpage == NULL, but this error
is not propagated unless uprobe_register() path finds ->mm which
already mmaps this file. In this case (say) "perf record" does not
actually install the probe, but the user can't know about this.
Move this check into uprobe_register() so that this problem can be
detected earlier and reported to user.
Note: this is still not perfect,
- copy_insn() and arch_uprobe_analyze_insn() should be called
by uprobe_register() but this is not simple, we need vm_file
for read_mapping_page() (although perhaps we can pass NULL),
and we need ->mm for is_64bit_mm() (although this logic is
broken anyway).
- uprobe_register() should be called by create_trace_uprobe(),
not by probe_event_enable(), so that an error can be detected
at "perf probe -x" time. This also needs more changes in the
core uprobe code, uprobe register/unregister interface was
poorly designed from the very beginning.
Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140519184054.GA6750@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
After instruction write into xol area, on ARM V7
architecture code need to flush dcache and icache to sync
them up for given set of addresses. Having just
'flush_dcache_page(page)' call is not enough - it is
possible to have stale instruction sitting in icache
for given xol area slot address.
Introduce arch_uprobe_ixol_copy weak function
that by default calls uprobes copy_to_page function and
than flush_dcache_page function and on ARM define new one
that handles xol slot copy in ARM specific way
flush_uprobe_xol_access function shares/reuses implementation
with/of flush_ptrace_access function and takes care of writing
instruction to user land address space on given variety of
different cache types on ARM CPUs. Because
flush_uprobe_xol_access does not have vma around
flush_ptrace_access was split into two parts. First that
retrieves set of condition from vma and common that receives
those conditions as flags.
Note ARM cache flush function need kernel address
through which instruction write happened, so instead
of using uprobes copy_to_page function changed
code to explicitly map page and do memcpy.
Note arch_uprobe_copy_ixol function, in similar way as
copy_to_user_page function, has preempt_disable/preempt_enable.
Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: David A. Long <dave.long@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
If the probed insn triggers a trap, ->si_addr = regs->ip is technically
correct, but this is not what the signal handler wants; we need to pass
the address of the probed insn, not the address of xol slot.
Add the new arch-agnostic helper, uprobe_get_trap_addr(), and change
fill_trap_info() and math_error() to use it. !CONFIG_UPROBES case in
uprobes.h uses a macro to avoid include hell and ensure that it can be
compiled even if an architecture doesn't define instruction_pointer().
Test-case:
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
extern void probe_div(void);
void sigh(int sig, siginfo_t *info, void *c)
{
int passed = (info->si_addr == probe_div);
printf(passed ? "PASS\n" : "FAIL\n");
_exit(!passed);
}
int main(void)
{
struct sigaction sa = {
.sa_sigaction = sigh,
.sa_flags = SA_SIGINFO,
};
sigaction(SIGFPE, &sa, NULL);
asm (
"xor %ecx,%ecx\n"
".globl probe_div; probe_div:\n"
"idiv %ecx\n"
);
return 0;
}
it fails if probe_div() is probed.
Note: show_unhandled_signals users should probably use this helper too,
but we need to cleanup them first.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Hugh says:
The one I noticed was that it forgets all about memcg (because
it was copied from KSM, and there the replacement page has already
been charged to a memcg). See how mm/memory.c do_anonymous_page()
does a mem_cgroup_charge_anon().
Hopefully not a big problem, uprobes is a system-wide thing and only
root can insert the probes. But I agree, should be fixed anyway.
Add mem_cgroup_{un,}charge_anon() into uprobe_write_opcode(). To simplify
the error handling (and avoid the new "uncharge" label) the patch also
moves anon_vma_prepare() up before we alloc/charge the new page.
While at it fix the comment about ->mmap_sem, it is held for write.
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
valid_vma() rejects the VM_SHARED vmas, but this still allows to insert
a probe into the MAP_SHARED but not VM_MAYWRITE vma.
Currently this is fine, such a mapping doesn't really differ from the
private read-only mmap except mprotect(PROT_WRITE) won't work. However,
get_user_pages(FOLL_WRITE | FOLL_FORCE) doesn't allow to COW in this
case, and it would be safer to follow the same conventions as mm even
if currently this happens to work.
After the recent cda540ace6 "mm: get_user_pages(write,force) refuse
to COW in shared areas" only uprobes can insert an anon page into the
shared file-backed area, lets stop this and change valid_vma() to check
VM_MAYSHARE instead.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Currently the error from arch_uprobe_post_xol() is silently ignored.
This doesn't look good and this can lead to the hard-to-debug problems.
1. Change handle_singlestep() to loudly complain and send SIGILL.
Note: this only affects x86, ppc/arm can't fail.
2. Change arch_uprobe_post_xol() to call arch_uprobe_abort_xol() and
avoid TF games if it is going to return an error.
This can help to to analyze the problem, if nothing else we should
not report ->ip = xol_slot in the core-file.
Note: this means that handle_riprel_post_xol() can be called twice,
but this is fine because it is idempotent.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
UPROBE_COPY_INSN, UPROBE_SKIP_SSTEP, and uprobe->flags must die. This
patch kills UPROBE_SKIP_SSTEP. I never understood why it was added;
not only it doesn't help, it harms.
It can only help to avoid arch_uprobe_skip_sstep() if it was already
called before and failed. But this is ugly, if we want to know whether
we can emulate this instruction or not we should do this analysis in
arch_uprobe_analyze_insn(), not when we hit this probe for the first
time.
And in fact this logic is simply wrong. arch_uprobe_skip_sstep() can
fail or not depending on the task/register state, if this insn can be
emulated but, say, put_user() fails we need to xol it this time, but
this doesn't mean we shouldn't try to emulate it when this or another
thread hits this bp next time.
And this is the actual reason for this change. We need to emulate the
"call" insn, but push(return-address) can obviously fail.
Per-arch notes:
x86: __skip_sstep() can only emulate "rep;nop". With this
change it will be called every time and most probably
for no reason.
This will be fixed by the next changes. We need to
change this suboptimal code anyway.
arm: Should not be affected. It has its own "bool simulate"
flag checked in arch_uprobe_skip_sstep().
ppc: Looks like, it can emulate almost everything. Does it
actually need to record the fact that emulate_step()
failed? Hopefully not. But if yes, it can add the ppc-
specific flag into arch_uprobe.
TODO: rename arch_uprobe_skip_sstep() to arch_uprobe_emulate_insn(),
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: David A. Long <dave.long@linaro.org>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Allow arches to decided to ignore a probe hit. ARM will use this to
only call handlers if the conditions to execute a conditionally executed
instruction are satisfied.
Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
triggers by Tom Zanussi. A trigger is a way to enable an action when an
event is hit. The actions are:
o trace on/off - enable or disable tracing
o snapshot - save the current trace buffer in the snapshot
o stacktrace - dump the current stack trace to the ringbuffer
o enable/disable events - enable or disable another event
Namhyung Kim added updates to the tracing uprobes code. Having the
uprobes add support for fetch methods.
The rest are various bug fixes with the new code, and minor ones for
the old code.
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Merge tag 'trace-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing updates from Steven Rostedt:
"This pull request has a new feature to ftrace, namely the trace event
triggers by Tom Zanussi. A trigger is a way to enable an action when
an event is hit. The actions are:
o trace on/off - enable or disable tracing
o snapshot - save the current trace buffer in the snapshot
o stacktrace - dump the current stack trace to the ringbuffer
o enable/disable events - enable or disable another event
Namhyung Kim added updates to the tracing uprobes code. Having the
uprobes add support for fetch methods.
The rest are various bug fixes with the new code, and minor ones for
the old code"
* tag 'trace-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (38 commits)
tracing: Fix buggered tee(2) on tracing_pipe
tracing: Have trace buffer point back to trace_array
ftrace: Fix synchronization location disabling and freeing ftrace_ops
ftrace: Have function graph only trace based on global_ops filters
ftrace: Synchronize setting function_trace_op with ftrace_trace_function
tracing: Show available event triggers when no trigger is set
tracing: Consolidate event trigger code
tracing: Fix counter for traceon/off event triggers
tracing: Remove double-underscore naming in syscall trigger invocations
tracing/kprobes: Add trace event trigger invocations
tracing/probes: Fix build break on !CONFIG_KPROBE_EVENT
tracing/uprobes: Add @+file_offset fetch method
uprobes: Allocate ->utask before handler_chain() for tracing handlers
tracing/uprobes: Add support for full argument access methods
tracing/uprobes: Fetch args before reserving a ring buffer
tracing/uprobes: Pass 'is_return' to traceprobe_parse_probe_arg()
tracing/probes: Implement 'memory' fetch method for uprobes
tracing/probes: Add fetch{,_size} member into deref fetch method
tracing/probes: Move 'symbol' fetch method to kprobes
tracing/probes: Implement 'stack' fetch method for uprobes
...
Add calls to the new mmu_notifier_invalidate_range() function to all
places in the VMM that need it.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Jay Cornwall <Jay.Cornwall@amd.com>
Cc: Oded Gabbay <Oded.Gabbay@amd.com>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
uprobe_trace_print() and uprobe_perf_print() need to pass the additional
info to call_fetch() methods, currently there is no simple way to do this.
current->utask looks like a natural place to hold this info, but we need
to allocate it before handler_chain().
This is a bit unfortunate, perhaps we will find a better solution later,
but this is simple and should work right now.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
1. Don't include asm/uprobes.h unconditionally, we only need
it if CONFIG_UPROBES.
2. Move the definition of "struct xol_area" into uprobes.c.
Perhaps we should simply kill struct uprobes_state, it buys
nothing.
3. Kill the dummy definition of uprobe_get_swbp_addr(), nobody
except handle_swbp() needs it.
4. Purely cosmetic, but move the decl of uprobe_get_swbp_addr()
up, close to other __weak helpers.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
arch_uprobe should be opaque as much as possible to the generic
code, but currently it assumes that insn/ixol must be u8[] of the
known size. Remove this unnecessary dependency, we can use "&" and
and sizeof() with the same effect.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
uprobe_task->vaddr is a bit strange. The generic code uses it only
to pass the additional argument to arch_uprobe_pre_xol(), and since
it is always equal to instruction_pointer() this looks even more
strange.
And both utask->vaddr and and utask->autask have the same scope,
they only have the meaning when the task executes the probed insn
out-of-line, so it is safe to reuse both in UTASK_RUNNING state.
This all means that logically ->vaddr belongs to arch_uprobe_task
and we should probably move it there, arch_uprobe_pre_xol() can
record instruction_pointer() itself.
OTOH, it is also used by uprobe_copy_process() and dup_xol_work()
for another purpose, this doesn't look clean and doesn't allow to
move this member into arch_uprobe_task.
This patch adds the union with 2 anonymous structs into uprobe_task.
The first struct is autask + vaddr, this way we "almost" move vaddr
into autask.
The second struct has 2 new members for uprobe_copy_process() paths:
->dup_xol_addr which can be used instead ->vaddr, and ->dup_xol_work
which can be used to avoid kmalloc() and simplify the code.
Note that this union will likely have another member(s), we need
something like "private_data_for_handlers" so that the tracing
handlers could use it to communicate with call_fetch() methods.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
1. copy_insn() doesn't look very nice, all calculations are
confusing and it is not immediately clear why do we read
the 2nd page first.
2. The usage of inode->i_size is wrong on 32-bit machines.
3. "Instruction at end of binary" logic is simply wrong, it
doesn't handle the case when uprobe->offset > inode->i_size.
In this case "bytes" overflows, and __copy_insn() writes to
the memory outside of uprobe->arch.insn.
Yes, uprobe_register() checks i_size_read(), but this file
can be truncated after that. All i_size checks are racy, we
do this only to catch the obvious mistakes.
Change copy_insn() to call __copy_insn() in a loop, simplify
and fix the bytes/nbytes calculations.
Note: we do not care if we read extra bytes after inode->i_size
if we got the valid page. This is fine because the task gets the
same page after page-fault, and arch_uprobe_analyze_insn() can't
know how many bytes were actually read anyway.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Commit aa59c53fd4 "uprobes: Change uprobe_copy_process() to dup
xol_area" has a stupid typo, we need to setup t->utask->vaddr but
the code wrongly uses current->utask.
Even with this bug dup_xol_work() works "in practice", but only
because get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE) likely
returns the same address every time.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
set_swbp() and set_orig_insn() are __weak, but this is pointless
because write_opcode() is static.
Export write_opcode() as uprobe_write_opcode() for the upcoming
arm port, this way it can actually override set_swbp() and use
__opcode_to_mem_arm(bpinsn) instead if UPROBE_SWBP_INSN.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Currently xol_get_insn_slot() assumes that we should simply copy
arch_uprobe->insn[] which is (ignoring arch_uprobe_analyze_insn)
just the copy of the original insn.
This is not true for arm which needs to create another insn to
execute it out-of-line.
So this patch simply adds the new member, ->ixol into the union.
This doesn't make any difference for x86 and powerpc, but arm
can divorce insn/ixol and initialize the correct xol insn in
arch_uprobe_analyze_insn().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Turn module_init() into __initcall() and kill module_exit().
This code can't be compiled as a module so these module_*()
calls only add the confusion, especially if arch-dependant
code needs its own initialization hooks.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
uprobe_copy_process() does nothing if the child shares ->mm with
the forking process, but there is a special case: CLONE_VFORK.
In this case it would be more correct to do dup_utask() but avoid
dup_xol(). This is not that important, the child should not unwind
its stack too much, this can corrupt the parent's stack, but at
least we need this to allow to ret-probe __vfork() itself.
Note: in theory, it would be better to check task_pt_regs(p)->sp
instead of CLONE_VFORK, we need to dup_utask() if and only if the
child can return from the function called by the parent. But this
needs the arch-dependant helper, and I think that nobody actually
does clone(same_stack, CLONE_VM).
Reported-by: Martin Cermak <mcermak@redhat.com>
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
This finally fixes the serious bug in uretprobes: a forked child
crashes if the parent called fork() with the pending ret probe.
Trivial test-case:
# perf probe -x /lib/libc.so.6 __fork%return
# perf record -e probe_libc:__fork perl -le 'fork || print "OK"'
(the child doesn't print "OK", it is killed by SIGSEGV)
If the child returns from the probed function it actually returns
to trampoline_vaddr, because it got the copy of parent's stack
mangled by prepare_uretprobe() when the parent entered this func.
It crashes because a) this address is not mapped and b) until the
previous change it doesn't have the proper->return_instances info.
This means that uprobe_copy_process() has to create xol_area which
has the trampoline slot, and its vaddr should be equal to parent's
xol_area->vaddr.
Unfortunately, uprobe_copy_process() can not simply do
__create_xol_area(child, xol_area->vaddr). This could actually work
but perf_event_mmap() doesn't expect the usage of foreign ->mm. So
we offload this to task_work_run(), and pass the argument via not
yet used utask->vaddr.
We know that this vaddr is fine for install_special_mapping(), the
necessary hole was recently "created" by dup_mmap() which skips the
parent's VM_DONTCOPY area, and nobody else could use the new mm.
Unfortunately, this also means that we can not handle the errors
properly, we obviously can not abort the already completed fork().
So we simply print the warning if GFP_KERNEL allocation (the only
possible reason) fails.
Reported-by: Martin Cermak <mcermak@redhat.com>
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
uprobe_copy_process() assumes that the new child doesn't need
->utask, it should be allocated by demand.
But this is not true if the forking task has the pending ret-
probes, the child should report them as well and thus it needs
the copy of parent's ->return_instances chain. Otherwise the
child crashes when it returns from the probed function.
Alternatively we could cleanup the child's stack, but this needs
per-arch changes and this is not what we want. At least systemtap
expects a .return in the child too.
Note: this change alone doesn't fix the problem, see the next
change.
Reported-by: Martin Cermak <mcermak@redhat.com>
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Currently xol_add_vma() uses get_unmapped_area() for area->vaddr,
but the next patches need to use the fixed address. So this patch
adds the new "vaddr" argument to __create_xol_area() which should
be used as area->vaddr if it is nonzero.
xol_add_vma() doesn't bother to verify that the predefined addr is
not used, insert_vm_struct() should fail if find_vma_links() detects
the overlap with the existing vma.
Also, __create_xol_area() doesn't need __GFP_ZERO to allocate area.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
No functional changes, preparation.
Extract the code which actually allocates/installs the new area
into the new helper, __create_xol_area().
While at it remove the unnecessary "ret = ENOMEM" and "ret = 0"
in xol_add_vma(), they both have no effect.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Oleg Nesterov