linux-toradex.git/arch/arm/kernel/ftrace.c, branch v4.10

ftrace: Add return address pointer to ftrace_ret_stack

2016-08-24T10:15:14+00:00

Storing this value will help prevent unwinders from getting out of sync
with the function graph tracer ret_stack.  Now instead of needing a
stateful iterator, they can compare the return address pointer to find
the right ret_stack entry.

Note that an array of 50 ftrace_ret_stack structs is allocated for every
task.  So when an arch implements this, it will add either 200 or 400
bytes of memory usage per task (depending on whether it's a 32-bit or
64-bit platform).

Signed-off-by: Josh Poimboeuf 
Acked-by: Steven Rostedt 
Cc: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Byungchul Park 
Cc: Denys Vlasenko 
Cc: Frederic Weisbecker 
Cc: H. Peter Anvin 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Nilay Vaish 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/a95cfcc39e8f26b89a430c56926af0bb217bc0a1.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

ARM: kprobes: enable OPTPROBES for ARM 32

2015-01-13T16:10:17+00:00

This patch introduce kprobeopt for ARM 32.

Limitations:
 - Currently only kernel compiled with ARM ISA is supported.

 - Offset between probe point and optinsn slot must not larger than
   32MiB. Masami Hiramatsu suggests replacing 2 words, it will make
   things complex. Futher patch can make such optimization.

Kprobe opt on ARM is relatively simpler than kprobe opt on x86 because
ARM instruction is always 4 bytes aligned and 4 bytes long. This patch
replace probed instruction by a 'b', branch to trampoline code and then
calls optimized_callback(). optimized_callback() calls opt_pre_handler()
to execute kprobe handler. It also emulate/simulate replaced instruction.

When unregistering kprobe, the deferred manner of unoptimizer may leave
branch instruction before optimizer is called. Different from x86_64,
which only copy the probed insn after optprobe_template_end and
reexecute them, this patch call singlestep to emulate/simulate the insn
directly. Futher patch can optimize this behavior.

Signed-off-by: Wang Nan 
Acked-by: Masami Hiramatsu 
Cc: Will Deacon 
Reviewed-by: Jon Medhurst (Tixy) 
Signed-off-by: Jon Medhurst

ARM: mm: allow text and rodata sections to be read-only

2014-10-16T21:38:54+00:00

This introduces CONFIG_DEBUG_RODATA, making kernel text and rodata
read-only. Additionally, this splits rodata from text so that rodata can
also be NX, which may lead to wasted memory when aligning to SECTION_SIZE.
The read-only areas are made writable during ftrace updates and kexec.

Signed-off-by: Kees Cook 
Tested-by: Laura Abbott 
Acked-by: Nicolas Pitre

ARM: 8022/1: ftrace: work with CONFIG_DEBUG_SET_MODULE_RONX

2014-04-23T00:24:31+00:00

Make ftrace work with CONFIG_DEBUG_SET_MODULE_RONX by making module text
writable around the place where ftrace does its work, like it is done on
x86 in the patch which introduced CONFIG_DEBUG_SET_MODULE_RONX,
84e1c6bb38eb ("x86: Add RO/NX protection for loadable kernel modules").

Tested-by: Mitchel Humpherys 
Signed-off-by: Rabin Vincent 
Signed-off-by: Russell King

ftrace: Do not pass data to ftrace_dyn_arch_init

2014-03-07T15:06:14+00:00

As the data parameter is not really used by any ftrace_dyn_arch_init,
remove that from ftrace_dyn_arch_init. This also removes the addr
local variable from ftrace_init which is now unused.

Note the documentation was imprecise as it did not suggest to set
(*data) to 0.

Link: http://lkml.kernel.org/r/1393268401-24379-4-git-send-email-jslaby@suse.cz

Cc: Frederic Weisbecker 
Cc: Ingo Molnar 
Cc: linux-arch@vger.kernel.org
Signed-off-by: Jiri Slaby 
Signed-off-by: Steven Rostedt

ftrace: Pass retval through return in ftrace_dyn_arch_init()

2014-03-07T15:06:13+00:00

No architecture uses the "data" parameter in ftrace_dyn_arch_init() in any
way, it just sets the value to 0. And this is used as a return value
in the caller -- ftrace_init, which just checks the retval against
zero.

Note there is also "return 0" in every ftrace_dyn_arch_init.  So it is
enough to check the retval and remove all the indirect sets of data on
all archs.

Link: http://lkml.kernel.org/r/1393268401-24379-3-git-send-email-jslaby@suse.cz

Cc: linux-arch@vger.kernel.org
Signed-off-by: Jiri Slaby 
Signed-off-by: Steven Rostedt

ARM: 7468/1: ftrace: Trace function entry before updating index

2012-07-31T09:30:42+00:00

Commit 722b3c74695377d11d18a52f3da08114d37f3f37 modified x86 ftrace to
avoid tracing all functions called from irqs when function graph was
used with a filter.  Port the same fix to ARM.

Acked-by: Steven Rostedt 
Signed-off-by: Colin Cross 
Signed-off-by: Russell King

ARM: 7331/1: extract out insn generation code from ftrace

2012-03-24T09:38:55+00:00

Extract out the instruction generation code so that it can be used
for jump labels too.

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

ARM: 7330/1: ftrace: use canonical Thumb-2 wide instruction format

2012-03-24T09:38:54+00:00

As commit 592201a9f15 (ARM: Thumb-2: Support Thumb-2 in undefined
instruction handler) says:

    32-bit Thumb instructions are specified in the form:
        ((first_half << 16 ) | second_half)
    which matches the layout used by the ARM ARM.

Convert the ftrace code to use the same format to avoid the usage of
different formats in kernel code.

Acked-by: Dave Martin 
Signed-off-by: Rabin Vincent 
Signed-off-by: Russell King

ARM: 7351/1: ftrace: remove useless memory checks

2012-03-24T09:38:54+00:00

Before replacing an instruction, the ftrace code determines what the old
instruction should be and verifies that that's what's really there in
memory before replacing it.  This is useful if for example a bug in
mcountrecord causes it to record wrong locations.

However, in cases where we replace call sites in entry-common.S, these
checks are not needed.  For these, we currently just memcpy() the memory
content and then "verify" it -- this is quite useless and can be
removed.

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