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  1. 01 5月, 2016 10 次提交
  3. 27 4月, 2016 1 次提交
    • C
      powerpc: Add support for userspace P9 copy paste · 8a649045
      由 Chris Smart 提交于 
      The copy paste facility introduced in POWER9 provides an optimised
mechanism for a userspace application to copy a cacheline. This is
provided by a pair of instructions, copy and paste, while a third,
cp_abort (copy paste abort), provides a clean up of the state in case of
a failure.

The copy instruction will read a 128 byte cacheline and store it in an
internal buffer. The subsequent paste instruction will store this
internal buffer to memory and set a CR field if the paste succeeds.

Since the state of the copy paste buffer is internal (and not
architecturally visible), in the unlikely event of a context switch, the
state cannot be stored and the paste should therefore fail.

The cp_abort instruction exists to fail and clean up any such
interrupted copy paste sequence and is to be called by the kernel as
part of the context switch. Doing so prevents data from a preceding copy
in one process leaking into the paste of another.

This code enables use of the cp_abort instruction if a supported
processor is detected.

NOTE: this is for userspace only, not in kernel, and does not deal
with KVM guests.

Patch created with much assistance from Michael Neuling
<mikey@neuling.org>
Signed-off-by: NChris Smart <chris@distroguy.com>
Reviewed-by: NCyril Bur <cyrilbur@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      8a649045
  5. 14 4月, 2016 2 次提交
  7. 11 4月, 2016 3 次提交
  9. 29 3月, 2016 1 次提交
  11. 16 3月, 2016 1 次提交
  13. 12 3月, 2016 8 次提交
  15. 10 3月, 2016 3 次提交
  17. 09 3月, 2016 6 次提交
  19. 08 3月, 2016 1 次提交
  21. 07 3月, 2016 4 次提交
    • T
      powerpc/ftrace: Add support for -mprofile-kernel ftrace ABI · 15308664
      由 Torsten Duwe 提交于 
      The gcc switch -mprofile-kernel defines a new ABI for calling _mcount()
very early in the function with minimal overhead.

Although mprofile-kernel has been available since GCC 3.4, there were
bugs which were only fixed recently. Currently it is known to work in
GCC 4.9, 5 and 6.

Additionally there are two possible code sequences generated by the
flag, the first uses mflr/std/bl and the second is optimised to omit the
std. Currently only gcc 6 has the optimised sequence. This patch
supports both sequences.

Initial work started by Vojtech Pavlik, used with permission.

Key changes:
 - rework _mcount() to work for both the old and new ABIs.
 - implement new versions of ftrace_caller() and ftrace_graph_caller()
   which deal with the new ABI.
 - updates to __ftrace_make_nop() to recognise the new mcount calling
   sequence.
 - updates to __ftrace_make_call() to recognise the nop'ed sequence.
 - implement ftrace_modify_call().
 - updates to the module loader to surpress the toc save in the module
   stub when calling mcount with the new ABI.
Reviewed-by: NBalbir Singh <bsingharora@gmail.com>
Signed-off-by: NTorsten Duwe <duwe@suse.de>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      15308664
    • M
      powerpc/module: Mark module stubs with a magic value · f17c4e01
      由 Michael Ellerman 提交于 
      When a module is loaded, calls out to the kernel go via a stub which is
generated at runtime. One of these stubs is used to call _mcount(),
which is the default target of tracing calls generated by the compiler
with -pg.

If dynamic ftrace is enabled (which it typically is), another stub is
used to call ftrace_caller(), which is the target of tracing calls when
ftrace is actually active.

ftrace then wants to disable the calls to _mcount() at module startup,
and enable/disable the calls to ftrace_caller() when enabling/disabling
tracing - all of these it does by patching the code.

As part of that code patching, the ftrace code wants to confirm that the
branch it is about to modify, is in fact a call to a module stub which
calls _mcount() or ftrace_caller().

Currently it does that by inspecting the instructions and confirming
they are what it expects. Although that works, the code to do it is
pretty intricate because it requires lots of knowledge about the exact
format of the stub.

We can make that process easier by marking the generated stubs with a
magic value, and then looking for that magic value. Altough this is not
as rigorous as the current method, I believe it is sufficient in
practice.
Reviewed-by: NBalbir Singh <bsingharora@gmail.com>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      f17c4e01
    • M
      powerpc/module: Only try to generate the ftrace_caller() stub once · 136cd345
      由 Michael Ellerman 提交于 
      Currently we generate the module stub for ftrace_caller() at the bottom
of apply_relocate_add(). However apply_relocate_add() is potentially
called more than once per module, which means we will try to generate
the ftrace_caller() stub multiple times.

Although the current code deals with that correctly, ie. it only
generates a stub the first time, it would be clearer to only try to
generate the stub once.

Note also on first reading it may appear that we generate a different
stub for each section that requires relocation, but that is not the
case. The code in stub_for_addr() that searches for an existing stub
uses sechdrs[me->arch.stubs_section], ie. the single stub section for
this module.

A cleaner approach is to only generate the ftrace_caller() stub once,
from module_finalize(). Although the original code didn't check to see
if the stub was actually generated correctly, it seems prudent to add a
check, so do that. And an additional benefit is we can clean the ifdefs
up a little.

Finally we must propagate the const'ness of some of the pointers passed
to module_finalize(), but that is also an improvement.
Reviewed-by: NBalbir Singh <bsingharora@gmail.com>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      136cd345
    • M
      powerpc: Create a helper for getting the kernel toc value · a5cab83c
      由 Michael Ellerman 提交于 
      Move the logic to work out the kernel toc pointer into a header. This is
a good cleanup, and also means we can use it elsewhere in future.
Reviewed-by: NKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Reviewed-by: NBalbir Singh <bsingharora@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Tested-by: NKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
      a5cab83c