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SubjectRe: [PATCH] perf cs-etm: Improve completeness for kernel address space
On Mon, 24 Jun 2019 at 13:00, Arnaldo Carvalho de Melo
<arnaldo.melo@gmail.com> wrote:
>
> Em Thu, Jun 20, 2019 at 08:58:29AM +0800, Leo Yan escreveu:
> > Hi Mathieu,
> >
> > On Wed, Jun 19, 2019 at 11:49:44AM -0600, Mathieu Poirier wrote:
> >
> > [...]
> >
> > > > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > > > index 51dd00f65709..4776c2c1fb6d 100644
> > > > --- a/tools/perf/Makefile.config
> > > > +++ b/tools/perf/Makefile.config
> > > > @@ -418,6 +418,30 @@ ifdef CORESIGHT
> > > > endif
> > > > LDFLAGS += $(LIBOPENCSD_LDFLAGS)
> > > > EXTLIBS += $(OPENCSDLIBS)
> > > > + ifneq ($(wildcard $(srctree)/arch/arm64/kernel/vmlinux.lds),)
> > > > + # Extract info from lds:
> > > > + # . = ((((((((0xffffffffffffffff)) - (((1)) << (48)) + 1) + (0)) + (0x08000000))) + (0x08000000))) + 0x00080000;
> > > > + # ARM64_PRE_START_SIZE := (0x08000000 + 0x08000000 + 0x00080000)
> > > > + ARM64_PRE_START_SIZE := $(shell egrep ' \. \= \({8}0x[0-9a-fA-F]+\){2}' \
> > > > + $(srctree)/arch/arm64/kernel/vmlinux.lds | \
> > > > + sed -e 's/[(|)|.|=|+|<|;|-]//g' -e 's/ \+/ /g' -e 's/^[ \t]*//' | \
> > > > + awk -F' ' '{print "("$$6 "+" $$7 "+" $$8")"}' 2>/dev/null)
> > > > + else
> > > > + ARM64_PRE_START_SIZE := 0
> > > > + endif
> > > > + CFLAGS += -DARM64_PRE_START_SIZE="$(ARM64_PRE_START_SIZE)"
> > > > + ifneq ($(wildcard $(srctree)/arch/arm/kernel/vmlinux.lds),)
> > > > + # Extract info from lds:
> > > > + # . = ((0xC0000000)) + 0x00208000;
> > > > + # ARM_PRE_START_SIZE := 0x00208000
> > > > + ARM_PRE_START_SIZE := $(shell egrep ' \. \= \({2}0x[0-9a-fA-F]+\){2}' \
> > > > + $(srctree)/arch/arm/kernel/vmlinux.lds | \
> > > > + sed -e 's/[(|)|.|=|+|<|;|-]//g' -e 's/ \+/ /g' -e 's/^[ \t]*//' | \
> > > > + awk -F' ' '{print "("$$2")"}' 2>/dev/null)
> > > > + else
> > > > + ARM_PRE_START_SIZE := 0
> > > > + endif
> > > > + CFLAGS += -DARM_PRE_START_SIZE="$(ARM_PRE_START_SIZE)"
> > > > $(call detected,CONFIG_LIBOPENCSD)
> > > > ifdef CSTRACE_RAW
> > > > CFLAGS += -DCS_DEBUG_RAW
> > > > diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
> > > > index 0c7776b51045..ae831f836c70 100644
> > > > --- a/tools/perf/util/cs-etm.c
> > > > +++ b/tools/perf/util/cs-etm.c
> > > > @@ -613,10 +613,34 @@ static void cs_etm__free(struct perf_session *session)
> > > > static u8 cs_etm__cpu_mode(struct cs_etm_queue *etmq, u64 address)
> > > > {
> > > > struct machine *machine;
> > > > + u64 fixup_kernel_start = 0;
> > > > + const char *arch;
> > > >
> > > > machine = etmq->etm->machine;
> > > > + arch = perf_env__arch(machine->env);
> > > >
> > > > - if (address >= etmq->etm->kernel_start) {
> > > > + /*
> > > > + * Since arm and arm64 specify some memory regions prior to
> > > > + * 'kernel_start', kernel addresses can be less than 'kernel_start'.
> > > > + *
> > > > + * For arm architecture, the 16MB virtual memory space prior to
> > > > + * 'kernel_start' is allocated to device modules, a PMD table if
> > > > + * CONFIG_HIGHMEM is enabled and a PGD table.
> > > > + *
> > > > + * For arm64 architecture, the root PGD table, device module memory
> > > > + * region and BPF jit region are prior to 'kernel_start'.
> > > > + *
> > > > + * To reflect the complete kernel address space, compensate these
> > > > + * pre-defined regions for kernel start address.
> > > > + */
> > > > + if (!strcmp(arch, "arm64"))
> > > > + fixup_kernel_start = etmq->etm->kernel_start -
> > > > + ARM64_PRE_START_SIZE;
> > > > + else if (!strcmp(arch, "arm"))
> > > > + fixup_kernel_start = etmq->etm->kernel_start -
> > > > + ARM_PRE_START_SIZE;
> > >
> > > I will test your work but from a quick look wouldn't it be better to
> > > have a single define name here? From looking at the modifications you
> > > did to Makefile.config there doesn't seem to be a reason to have two.
> >
> > Thanks for suggestion. I changed to use single define
> > ARM_PRE_START_SIZE and sent patch v2 [1].
> >
> > If possible, please test patch v2.
> >
> > Thanks,
> > Leo Yan
>
> So just for the record, I'm waiting for Mathieu on this one, i.e. for
> him to test/ack v3.

Right, please give me some time to test this. As Leo indicated the
procedure is time consuming.

Thanks,
Mathieu

>
> - Arnaldo
>
> > [1] https://lore.kernel.org/linux-arm-kernel/20190620005428.20883-1-leo.yan@linaro.org/T/#u
> >
> > > > +
> > > > + if (address >= fixup_kernel_start) {
> > > > if (machine__is_host(machine))
> > > > return PERF_RECORD_MISC_KERNEL;
> > > > else
> > > > --
> > > > 2.17.1
> > > >
>
> --
>
> - Arnaldo

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