[
Ingo, Thomas or H.Peter,
I believe this is all set to go now. I updated those patches that Linus
commented on and I don't believe there are any more issues. I ran this
through several tests (although some of my tests are failing due to
bugs introduced by others in 4.11-rc2). You can take this as a patch
series, or you can pull from my tree defined below. It's based on 4.11-rc2
as I noticed that tip/x86/core is rather outdated, and Linus is fine with
basing off of his tagged releases.
]
With the issues of gcc screwing around with the mcount stack frame causing
function graph tracer to panic on x86_32, and with Linus saying that we
should start deprecating mcount (at least on x86), I figured that x86_32
needs to support fentry.
First, I renamed mcount_64.S to ftrace_64.S. As we want to get away from
mcount, having the ftrace code in a file called mcount seems rather backwards.
Next I moved the ftrace code out of entry_32.S. It's not in entry_64.S
and it does not belong in entry_32.S.
I noticed that the x86_32 code has the same issue as the x86_64 did
in the past with respect to a stack frame. I fixed that just for the main
ftrace_caller. The ftrace_regs_caller is rather special, and so is
function graph tracing.
I realized the ftrace_regs_caller code was complex due to me aggressively
saving flags, even though I could still do push, lea and mov without
changing them. That made the logic a little nicer.
Finally I added the fentry code.
I tested this with an older compiler (for mcount) with and without
FRAME_POINTER set. I also did it with a new compiler (with fentry), with and
without FRAME_POINTER. I tested function tracing, stack tracing, function_graph
tracing, and kprobes (as that uses the ftrace_regs_caller).
Please pull (or take the patch series) from:
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
tip/x86/ftrace
Head SHA1: e086b1da846b8e53f4de11e38d02d05b1ec5db58
Steven Rostedt (VMware) (6):
ftrace/x86_64: Rename mcount_64.S to ftrace_64.S
ftrace/x86_32: Move the ftrace specific code out of entry_32.S
ftrace/x86_32: Add stack frame pointer to ftrace_caller
ftrace/x86_32: Clean up ftrace_regs_caller
ftrace/x86_32: Add -mfentry support to x86_32 with DYNAMIC_FTRACE set
ftrace/x86: Use Makefile logic instead of #ifdef for compiling ftrace_*.o
----
Changes since v3:
* Changed comment about regs being skipped (Josh Poimboeuf)
* Change subject line to fix typo (Josh Poimboeuf)
arch/x86/Kconfig | 2 +-
arch/x86/entry/entry_32.S | 169 ------------------
arch/x86/kernel/Makefile | 5 +-
arch/x86/kernel/ftrace_32.S | 246 +++++++++++++++++++++++++++
arch/x86/kernel/{mcount_64.S => ftrace_64.S} | 4 -
5 files changed, 250 insertions(+), 176 deletions(-)
create mode 100644 arch/x86/kernel/ftrace_32.S
rename arch/x86/kernel/{mcount_64.S => ftrace_64.S} (99%)
Diff against v3:
diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S
index 4d52e0d49e26..de50c9084d16 100644
--- a/arch/x86/kernel/ftrace_32.S
+++ b/arch/x86/kernel/ftrace_32.S
@@ -167,7 +167,7 @@ GLOBAL(ftrace_regs_call)
popl %gs
/* use lea to not affect flags */
- lea 3*4(%esp), %esp /* Skip orig_ax, ip and flags */
+ lea 3*4(%esp), %esp /* Skip orig_ax, ip and cs */
jmp .Lftrace_ret
#else /* ! CONFIG_DYNAMIC_FTRACE */
