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SubjectRe: [PATCH v2] perf cs-etm: Improve completeness for kernel address space
Hi all,

On Thu, Jun 20, 2019 at 08:54:28AM +0800, Leo Yan wrote:

[...]

> diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> index 51dd00f65709..cf5906d667aa 100644
> --- a/tools/perf/Makefile.config
> +++ b/tools/perf/Makefile.config
> @@ -418,6 +418,26 @@ ifdef CORESIGHT
> endif
> LDFLAGS += $(LIBOPENCSD_LDFLAGS)
> EXTLIBS += $(OPENCSDLIBS)
> + ARM_PRE_START_SIZE := 0
> + ifeq ($(SRCARCH),arm64)
> + # Extract info from lds:
> + # . = ((((((((0xffffffffffffffff)) - (((1)) << (48)) + 1) + (0)) + (0x08000000))) + (0x08000000))) + 0x00080000;
> + # ARM_PRE_START_SIZE := (0x08000000 + 0x08000000 + 0x00080000)
> + ARM_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)
> + endif
> + ifeq ($(SRCARCH),arm)
> + # 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)
> + endif
> + CFLAGS += -DARM_PRE_START_SIZE="$(ARM_PRE_START_SIZE)"

I did testing for building perf with this patch, this patch is fragile
and easily introduce the building warning:

<command-line>: error: "ARM_PRE_START_SIZE" redefined [-Werror]
<command-line>: note: this is the location of the previous definition

To dismiss this error, I need to change the macro define as below:

+ CFLAGS += -DARM_PRE_START_SIZE=$(ARM_PRE_START_SIZE)

So I sent patch v3 to address this issue and please directly reivew
patch v3. Sorry for spamming.

Thanks,
Leo Yan


> $(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..5fa0be3a3904 100644
> --- a/tools/perf/util/cs-etm.c
> +++ b/tools/perf/util/cs-etm.c
> @@ -613,10 +613,27 @@ 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;
>
> machine = etmq->etm->machine;
>
> - 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.
> + */
> + fixup_kernel_start = etmq->etm->kernel_start - ARM_PRE_START_SIZE;
> +
> + if (address >= fixup_kernel_start) {
> if (machine__is_host(machine))
> return PERF_RECORD_MISC_KERNEL;
> else
> --
> 2.17.1
>

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