[PATCH 2/4] KVM: Use __print_hex() for kvm_emulate_insn tracepoint

Namhyung Kim
2012-06-27T00:45:51Z

From: Namhyung Kim <namhyung.kim@lge.com>

The kvm_emulate_insn tracepoint used __print_insn()
for printing its instructions. However it makes the
format of the event hard to parse as it reveals TP
internals.

Fortunately, kernel provides __print_hex for almost
same purpose, we can use it instead of open coding
it. The user-space can be changed to parse it later.

That means raw kernel tracing will not be affected
by this change:

# cd /sys/kernel/debug/tracing/
# cat events/kvm/kvm_emulate_insn/format
name: kvm_emulate_insn
ID: 29
format:
...
print fmt: "%x:%llx:%s (%s)%s", REC->csbase, REC->rip, __print_hex(REC->insn, REC->len), \
__print_symbolic(REC->flags, { 0, "real" }, { (1 << 0) | (1 << 1), "vm16" }, \
{ (1 << 0), "prot16" }, { (1 << 0) | (1 << 2), "prot32" }, { (1 << 0) | (1 << 3), "prot64" }), \
REC->failed ? " failed" : ""

# echo 1 > events/kvm/kvm_emulate_insn/enable
# cat trace
# tracer: nop
#
# entries-in-buffer/entries-written: 2183/2183 #P:12
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
qemu-kvm-1782 [002] ...1 140.931636: kvm_emulate_insn: 0:c102fa25:89 10 (prot32)
qemu-kvm-1781 [004] ...1 140.931637: kvm_emulate_insn: 0:c102fa25:89 10 (prot32)

Cc: kvm@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-wfw6y3b9ugtey8snaow9nmg5@git.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
arch/x86/kvm/trace.h | 12 +-----------
include/trace/ftrace.h | 1 +
2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
index 911d2641f14c..62d02e3c3ed6 100644
--- a/arch/x86/kvm/trace.h
+++ b/arch/x86/kvm/trace.h
@@ -710,16 +710,6 @@ TRACE_EVENT(kvm_skinit,
__entry->rip, __entry->slb)
);

-#define __print_insn(insn, ilen) ({ \
- int i; \
- const char *ret = p->buffer + p->len; \
- \
- for (i = 0; i < ilen; ++i) \
- trace_seq_printf(p, " %02x", insn[i]); \
- trace_seq_printf(p, "%c", 0); \
- ret; \
- })
-
#define KVM_EMUL_INSN_F_CR0_PE (1 << 0)
#define KVM_EMUL_INSN_F_EFL_VM (1 << 1)
#define KVM_EMUL_INSN_F_CS_D (1 << 2)
@@ -786,7 +776,7 @@ TRACE_EVENT(kvm_emulate_insn,

TP_printk("%x:%llx:%s (%s)%s",
__entry->csbase, __entry->rip,
- __print_insn(__entry->insn, __entry->len),
+ __print_hex(__entry->insn, __entry->len),
__print_symbolic(__entry->flags,
kvm_trace_symbol_emul_flags),
__entry->failed ? " failed" : ""
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 769724944fc6..c6bc2faaf261 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -571,6 +571,7 @@ static inline void ftrace_test_probe_##call(void) \

#undef __print_flags
#undef __print_symbolic
+#undef __print_hex
#undef __get_dynamic_array
#undef __get_str

--
1.7.10.2