linux-toradex.git/arch/arm/kernel/ftrace.c, branch v5.0

ARM: function_graph: Simplify with function_graph_enter()

2018-11-28T01:29:52+00:00

The function_graph_enter() function does the work of calling the function
graph hook function and the management of the shadow stack, simplifying the
work done in the architecture dependent prepare_ftrace_return().

Have ARM use the new code, and remove the shadow stack management as well as
having to set up the trace structure.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack
is used.

Cc: Russell King 
Cc: linux-arm-kernel@lists.infradead.org
Cc: stable@kernel.org
Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu 
Signed-off-by: Steven Rostedt (VMware)

ARM: 8788/1: ftrace: remove old mcount support

2018-09-19T09:44:50+00:00

Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6")
raised the minimum GCC version to 4.6. Old mcount is only required for
GCC versions older than 4.4.0. Hence old mcount support can be dropped
too.

Signed-off-by: Stefan Agner 
Signed-off-by: Russell King

ARM: 8678/1: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS

2017-06-18T21:25:16+00:00

The DYNAMIC_FTRACE_WITH_REGS configuration makes it possible for a
ftrace operation to specify if registers need to saved/restored by
the ftrace handler. This is needed by kgraft and possibly other
ftrace-based tools, and the ARM architecture is currently lacking
this feature. It would also be the first step to support the
"Kprobes-on-ftrace" optimization on ARM.

This patch introduces a new ftrace handler that stores the registers
on the stack before calling the next stage. The registers are restored
from the stack before going back to the instrumented function.

A side-effect of this patch is to activate the support for
ftrace_modify_call() as it defines ARCH_SUPPORTS_FTRACE_OPS for the
ARM architecture.

Signed-off-by: Abel Vesa 
Signed-off-by: Russell King

Merge branch 'akpm' (patches from Andrew)

2017-05-09T01:17:56+00:00

Merge more updates from Andrew Morton:

 - the rest of MM

 - various misc things

 - procfs updates

 - lib/ updates

 - checkpatch updates

 - kdump/kexec updates

 - add kvmalloc helpers, use them

 - time helper updates for Y2038 issues. We're almost ready to remove
   current_fs_time() but that awaits a btrfs merge.

 - add tracepoints to DAX

* emailed patches from Andrew Morton : (114 commits)
  drivers/staging/ccree/ssi_hash.c: fix build with gcc-4.4.4
  selftests/vm: add a test for virtual address range mapping
  dax: add tracepoint to dax_insert_mapping()
  dax: add tracepoint to dax_writeback_one()
  dax: add tracepoints to dax_writeback_mapping_range()
  dax: add tracepoints to dax_load_hole()
  dax: add tracepoints to dax_pfn_mkwrite()
  dax: add tracepoints to dax_iomap_pte_fault()
  mtd: nand: nandsim: convert to memalloc_noreclaim_*()
  treewide: convert PF_MEMALLOC manipulations to new helpers
  mm: introduce memalloc_noreclaim_{save,restore}
  mm: prevent potential recursive reclaim due to clearing PF_MEMALLOC
  mm/huge_memory.c: deposit a pgtable for DAX PMD faults when required
  mm/huge_memory.c: use zap_deposited_table() more
  time: delete CURRENT_TIME_SEC and CURRENT_TIME
  gfs2: replace CURRENT_TIME with current_time
  apparmorfs: replace CURRENT_TIME with current_time()
  lustre: replace CURRENT_TIME macro
  fs: ubifs: replace CURRENT_TIME_SEC with current_time
  fs: ufs: use ktime_get_real_ts64() for birthtime
  ...

arm: use set_memory.h header

2017-05-09T00:15:13+00:00

set_memory_* functions have moved to set_memory.h.  Switch to this
explicitly

Link: http://lkml.kernel.org/r/1488920133-27229-3-git-send-email-labbott@redhat.com
Signed-off-by: Laura Abbott 
Acked-by: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ARM: 8668/1: ftrace: Fix dynamic ftrace with DEBUG_RODATA and !FRAME_POINTER

2017-04-20T10:19:43+00:00

The support for dynamic ftrace with CONFIG_DEBUG_RODATA involves
overriding the weak arch_ftrace_update_code() with a variant which makes
the kernel text writable around the patching.

This override was however added under the CONFIG_OLD_MCOUNT ifdef, and
CONFIG_OLD_MCOUNT is only enabled if frame pointers are enabled.

This leads to non-functional dynamic ftrace (ftrace triggers a
WARN_ON()) when CONFIG_DEBUG_RODATA is enabled and CONFIG_FRAME_POINTER
is not.

Move the override out of that ifdef and into the CONFIG_DYNAMIC_FTRACE
ifdef where it belongs.

Fixes: 80d6b0c2eed2a ("ARM: mm: allow text and rodata sections to be read-only")
Suggested-by: Nicolai Stange 
Suggested-by: Rabin Vincent 
Signed-off-by: Abel Vesa 
Acked-by: Rabin Vincent 
Signed-off-by: Russell King

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