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SubjectRe: [PATCH 2/3] ftrace/x86: Add support for C version of recordmcount
On Thu, Oct 14, 2010 at 05:00:16PM -0400, Steven Rostedt wrote:
> From: Steven Rostedt <srostedt@redhat.com>
>
> This patch adds the support for the C version of recordmcount and
> compile times show ~ 12% improvement.
>
> After verifying this works, other archs can add:
>
> HAVE_C_MCOUNT_RECORD
>
> in its Kconfig and it will use the C version of recordmcount
> instead of the perl version.
>
While I haven't had the chance to debug this yet, turning it on for SH
blows up immediately:

ftrace: allocating 15200 entries in 30 pages
------------[ cut here ]------------
WARNING: at /home/pmundt/devel/git/sh-2.6/kernel/trace/ftrace.c:1007
Modules linked in:

Pid : 0, Comm: swapper
CPU : 0 Not tainted (2.6.36-05622-g38ab134-dirty #508)

PC is at ftrace_bug+0x78/0x23c
PR is at ftrace_bug+0x74/0x23c
PC : 80064df4 SP : 8056ff70 SR : 400080f0 TEA : c0000004
R0 : 00000001 R1 : 00000001 R2 : 8064d862 R3 : 8056ff64
R4 : 805b47b4 R5 : 00000001 R6 : 00000000 R7 : 00000001
R8 : 803b15d8 R9 : 00000001 R10 : 9fc38be8 R11 : 00000000
R12 : 8064e88c R13 : 8064e880 R14 : 8056ff70
MACH: 00000000 MACL: 003d0900 GBR : 296e1678 PR : 80064df0

Call trace:
[<80066a86>] ftrace_process_locs+0x15a/0x284
[<803b15d8>] dns_query+0x0/0x26c
[<805f6a1a>] ftrace_init+0x112/0x1a8
[<801deec0>] strlen+0x0/0x58
[<8008f098>] get_zeroed_page+0x0/0x34
[<805f0918>] start_kernel+0x3e0/0x480
[<801deec0>] strlen+0x0/0x58
[<801eb388>] debug_smp_processor_id+0x0/0xe4
[<80002132>] _stext+0x132/0x140

Code:
80064dee: mov r9, r5
80064df0: tst r9, r9
80064df2: bt 80064df6
->80064df4: trapa #62
80064df6: bra 80064ef2
80064df8: mov r9, r5
80064dfa: mov.l 80064f68 <ftrace_bug+0x1ec/0x23c>, r1 ! 8064d862 <__warned.27604+0x0/0x1>
80064dfc: mov.b r2, @r1
80064dfe: mov.l 80064f48 <ftrace_bug+0x1cc/0x23c>, r1 ! 8057021c <ftrace_disabled+0x0/0x4>

---[ end trace 4eaa2a86a8e2da22 ]---
ftrace failed to modify [<803b15d8>] dns_query+0x0/0x26c
actual: 02:d1:22:4f
Testing tracer nop: PASSED

Suggestions?


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