mbox series

[RFC,0/4] Nop out the preceding mflr with -mprofile-kernel

Message ID cover.1558115654.git.naveen.n.rao@linux.vnet.ibm.com (mailing list archive)
Headers show
Series Nop out the preceding mflr with -mprofile-kernel | expand

Message

Naveen N. Rao May 17, 2019, 7:02 p.m. UTC 
On powerpc64, -mprofile-kernel results in two instructions being 
emitted: 'mflr r0' and 'bl _mcount'. So far, we were only nop'ing out 
the branch to _mcount(). This series implements an approach to also nop 
out the preceding mflr.

Patches 1-3 are generic changes. Patch 2 is a fix for x86, but has not 
been tested. Patch 4 implements the changes for powerpc64.


- Naveen

Naveen N. Rao (4):
  ftrace: Expose flags used for ftrace_replace_code()
  x86/ftrace: Fix use of flags in ftrace_replace_code()
  ftrace: Expose __ftrace_replace_code()
  powerpc/ftrace: Additionally nop out the preceding mflr with
    -mprofile-kernel

 arch/powerpc/kernel/trace/ftrace.c | 188 +++++++++++++++++++++++++----
 arch/x86/kernel/ftrace.c           |   3 +-
 include/linux/ftrace.h             |   6 +
 kernel/trace/ftrace.c              |  13 +-
 4 files changed, 178 insertions(+), 32 deletions(-)