linux.git/arch/arm/kernel/stacktrace.c, branch v5.1

ARM: probes: avoid adding kprobes to sensitive kernel-entry/exit code

2017-12-17T22:14:21+00:00

Avoid adding kprobes to any of the kernel entry/exit or startup
assembly code, or code in the identity-mapped region.  This code does
not conform to the standard C conventions, which means that the
expectations of the kprobes code is not forfilled.

Placing kprobes at some of these locations results in the kernel trying
to return to userspace addresses while retaining the CPU in kernel mode.

Tested-by: Naresh Kamboju 
Signed-off-by: Russell King

ARM: 8691/1: Export save_stack_trace_tsk()

2017-09-09T15:26:42+00:00

The kernel watchdog is a great debugging tool for finding tasks that
consume a disproportionate amount of CPU time in contiguous chunks. One
can imagine building a similar watchdog for arbitrary driver threads
using save_stack_trace_tsk() and print_stack_trace(). However, this is
not viable for dynamically loaded driver modules on ARM platforms
because save_stack_trace_tsk() is not exported for those architectures.
Export save_stack_trace_tsk() for the ARM architecture to align with
x86 and support various debugging use cases such as arbitrary driver
thread watchdog timers.

Signed-off-by: Dustin Brown 
Signed-off-by: Russell King

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:34+00:00

We are going to split  out of , which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder  file that just
maps to  to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

ARM: 8172/1: Use current_stack_pointer in save_stack_trace_tsk

2014-11-13T23:58:03+00:00

Use the global current_stack_pointer to get the value of the stack pointer.
This change supports being able to compile the kernel with both gcc and clang.

Signed-off-by: Behan Webster 
Reviewed-by: Mark Charlebois 
Reviewed-by: Jan-Simon Möller 
Acked-by: Will Deacon 
Acked-by: Nicolas Pitre 
Signed-off-by: Russell King

ARM: 8049/1: ftrace/add save_stack_trace_regs() implementation

2014-05-30T00:12:32+00:00

When configure kprobe events of ftrace with "stacktrace" option enabled
in arm, there is no stacktrace was recorded after the kprobe event was
triggered. The root cause is no save_stack_trace_regs() function implemented.

Implement the save_stack_trace_regs() function in arm, then ftrace will
call this architecture-related function to record the stacktrace into
ring buffer.

After this fix, stacktrace can be recorded, for example:

 # mount -t debugfs nodev /sys/kernel/debug
 # echo "p:netrx net_rx_action" >> /sys/kernel/debug/tracing/kprobe_events
 # echo 1 > /sys/kernel/debug/tracing/events/kprobes/netrx/enable
 # echo 1 > /sys/kernel/debug/tracing/options/stacktrace
 # echo 1 > /sys/kernel/debug/tracing/tracing_on
 # ping 127.0.0.1 -c 1
 # echo 0 > /sys/kernel/debug/tracing/tracing_on

 # cat /sys/kernel/debug/tracing/trace
 # tracer: nop
 #
 # entries-in-buffer/entries-written: 12/12   #P:1
 #
 #                              _-----=> irqs-off
 #                             / _----=> need-resched
 #                            | / _---=> hardirq/softirq
 #                            || / _--=> preempt-depth
 #                            ||| /     delay
 #           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
 #              | |       |   ||||       |         |
             <------ missing some entries ---------------->
             ping-1200  [000] dNs1   667.603250: netrx: (net_rx_action+0x0/0x1f8)
             ping-1200  [000] dNs1   667.604738: 
  => net_rx_action
  => do_softirq
  => local_bh_enable
  => ip_finish_output
  => ip_output
  => ip_local_out
  => ip_send_skb
  => ip_push_pending_frames
  => raw_sendmsg
  => inet_sendmsg
  => sock_sendmsg
  => SyS_sendto
  => ret_fast_syscall

Signed-off-by: Lin Yongting 
Acked-by: Steven Rostedt 
Signed-off-by: Russell King

ARM: stacktrace: include exception PC value in stacktrace output

2014-05-22T15:33:24+00:00

When we unwind through an exception stack, include the saved PC value
into the stack trace: this fills in an otherwise missed functions from
the trace (as indicated below):

 [] fec_enet_interrupt+0xa0/0xe8
 [] handle_irq_event_percpu+0x68/0x228
 [] handle_irq_event+0x4c/0x6c
 [] handle_fasteoi_irq+0xac/0x198
 [] generic_handle_irq+0x4c/0x60
 [] handle_IRQ+0x40/0x98
 [] gic_handle_irq+0x30/0x64
 [] __irq_svc+0x40/0x50
 [] __do_softirq+0xe0/0x2fc		<====
 [] irq_exit+0xb0/0x100
 [] handle_IRQ+0x44/0x98
 [] gic_handle_irq+0x30/0x64
 [] __irq_svc+0x40/0x50
 [] arch_cpu_idle+0x30/0x38		<====
 [] cpu_startup_entry+0xac/0x214
 [] rest_init+0x68/0x80
 [] start_kernel+0x2fc/0x358

Signed-off-by: Russell King

ARM: stacktrace: avoid listing stacktrace functions in stacktrace

2014-05-22T15:33:19+00:00

While debugging the FEC ethernet driver using stacktrace, it was noticed
that the stacktraces always begin as follows:

 [] save_stack_trace_tsk+0x0/0x98
 [] save_stack_trace+0x24/0x28
 ...

This is because the stack trace code includes the stack frames for itself.
This is incorrect behaviour, and also leads to "skip" doing the wrong
thing (which is the number of stack frames to avoid recording.)

Perversely, it does the right thing when passed a non-current thread.  Fix
this by ensuring that we have a known constant number of frames above the
main stack trace function, and always skip these.

Cc: 
Signed-off-by: Russell King

ARM: 7913/1: fix framepointer check in unwind_frame

2013-12-09T23:24:33+00:00

This patch fixes corner case when (fp + 4) overflows unsigned long,
for example: fp = 0xFFFFFFFF -> fp + 4 == 3.

Cc: 
Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Russell King

arm: convert core files from module.h to export.h

2011-10-31T23:30:49+00:00

Many of the core ARM kernel files are not modules, but just
including module.h for exporting symbols.  Now these files can
use the lighter footprint export.h for this role.

There are probably lots more, but ARM files of mach-* and plat-*
don't get coverage via a simple yesconfig build.  They will have
to be cleaned up and tested via using their respective configs.

Signed-off-by: Paul Gortmaker

ARM: fix /proc/$PID/stack on SMP

2011-01-15T09:27:04+00:00

Rabin Vincent reports:
| On SMP, this BUG() in save_stack_trace_tsk() can be easily triggered
| from user space by reading /proc/$PID/stack, where $PID is any pid but
| the current process:
|
|	if (tsk != current) {
| #ifdef CONFIG_SMP
|		/*
|		 * What guarantees do we have here that 'tsk'
|		 * is not running on another CPU?
|		 */
|		BUG();
| #else

Fix this by replacing the BUG() with an entry to terminate the stack
trace, returning an empty trace - I'd rather not expose the dwarf
unwinder to a volatile stack of a running thread.

Reported-by: Rabin Vincent 
Tested-by: Rabin Vincent 
Signed-off-by: Russell King