On Tue, Jun 20, 2017 at 14:02:02 +0300, Lluís Vilanova wrote:
> Jayanto Minocha writes:
>
> > Hi,
> > I think there have been a few threads on the mailing list regarding tracing
> > guest virtual addresses for load and store instructions, but I have been
> > unable to get it to work. I am trying this for an AArch64 machine, and am
> > using the softmmu.
>
> > The tracing infrastructure provides the following event:
>
> > vcpu tcg guest_mem_before(...).
>
> > But that is only used to instrument the cpu_ld/cpu_st macros, which is only
> > called in the case of a tlb miss.
>
> > I've been going over the archives, and it looks like I need to instrument
> > tcg_out_tlb_load. Am I on the right path ?
>
> That event should trace all guest memory accesses performed by the CPU. If you
> found any case where this does not hold, it is likely a bug and I'd appreciate
> it if you can point me to the smallest possible failing example.
I'm having trouble with this as well, although I'm pretty sure I must be doing
something wrong (never used the tracing infrastructure before). Here's what
I'm doing:
$ git show --pretty=short
commit e85c0d14014514a2f0faeae5b4c23fab5b234de4
Merge: 65a0e3e 7f3cf2d
Author: Peter Maydell <peter.mayd...@linaro.org>
Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging
$ git diff
diff --git a/accel/tcg/trace-events b/accel/tcg/trace-events
index 2de8359..385a462 100644
--- a/accel/tcg/trace-events
+++ b/accel/tcg/trace-events
@@ -2,7 +2,7 @@
# TCG related tracing (mostly disabled by default)
# cpu-exec.c
-disable exec_tb(void *tb, uintptr_t pc) "tb:%p pc=0x%"PRIxPTR
+exec_tb(void *tb, uintptr_t pc) "tb:%p pc=0x%"PRIxPTR
disable exec_tb_nocache(void *tb, uintptr_t pc) "tb:%p pc=0x%"PRIxPTR
disable exec_tb_exit(void *last_tb, unsigned int flags) "tb:%p flags=%x"
diff --git a/trace-events b/trace-events
index bae63fd..7df49a3 100644
--- a/trace-events
+++ b/trace-events
@@ -106,7 +106,7 @@ vcpu guest_cpu_reset(void)
#
# Mode: user, softmmu
# Targets: TCG(all)
-disable vcpu tcg guest_mem_before(TCGv vaddr, uint8_t info) "info=%d",
"vaddr=0x%016"PRIx64" info=%d"
+vcpu tcg guest_mem_before(TCGv vaddr, uint8_t info) "info=%d",
"vaddr=0x%016"PRIx64" info=%d"
# @num: System call number.
# @arg*: System call argument value.
$ mkdir build
$ cd build
$ ../configure --target-list=arm-softmmu,x86_64-linux-user
--enable-trace-backends=simple && make -j 12
[...]
$ cat ../ev
guest_mem_before_exec
guest_mem_before_trans
exec_tb
$ x86_64-linux-user/qemu-x86_64 -trace events=../ev /bin/date
Tue Jun 20 13:11:49 EDT 2017
$ ls -lt | head | grep trace
-rw-rw-r-- 1 cota cota 169721 Jun 20 13:11 trace-2150
$ scripts/simpletrace.py trace-events-all trace-2150
exec_tb 0.000 pid=2150 tb=0x7f5896667010 pc=0x4000801cc0
exec_tb 21.648 pid=2150 tb=0x7f5896667088 pc=0x4000805c00
[...]
100% of the file is exec_tb lines, i.e. no memory references whatsoever.
Similar results with arm-softmmu.
Thanks,
Emilio
