On 10/08/19 10:21 AM, Leo Yan wrote:
> machine__get_kernel_start() gives out the kernel start address; some
> architectures need to tweak the start address so that can reflect the
> kernel start address correctly. This is not only for x86_64 arch, but
> it is also required by other architectures, e.g. arm/arm64 needs to
> tweak the kernel start address so can include the kernel memory regions
> which are used before the '_stext' symbol.
>
> This patch refactors machine__get_kernel_start() by adding a weak
> arch__fix_kernel_text_start(), any architecture can implement it to
> tweak its specific start address; this also allows the arch specific
> code to be placed into 'arch' folder.
>
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> ---
> tools/perf/arch/x86/util/machine.c | 10 ++++++++++
> tools/perf/util/machine.c | 13 +++++++------
> tools/perf/util/machine.h | 2 ++
> 3 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/arch/x86/util/machine.c b/tools/perf/arch/x86/util/machine.c
> index 1e9ec783b9a1..9f012131534a 100644
> --- a/tools/perf/arch/x86/util/machine.c
> +++ b/tools/perf/arch/x86/util/machine.c
> @@ -101,4 +101,14 @@ int machine__create_extra_kernel_maps(struct machine *machine,
> return ret;
> }
>
> +void arch__fix_kernel_text_start(u64 *start)
> +{
> + /*
> + * On x86_64, PTI entry trampolines are less than the
> + * start of kernel text, but still above 2^63. So leave
> + * kernel_start = 1ULL << 63 for x86_64.
> + */
> + *start = 1ULL << 63;
> +}
That is needed for reporting x86 data on any arch i.e. it is not specific to
the compile-time architecture, it is specific to the perf.data file
architecture, which is what machine__is() compares. So, this looks wrong.
> +
> #endif
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index f6ee7fbad3e4..603518835692 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2671,6 +2671,10 @@ int machine__nr_cpus_avail(struct machine *machine)
> return machine ? perf_env__nr_cpus_avail(machine->env) : 0;
> }
>
> +void __weak arch__fix_kernel_text_start(u64 *start __maybe_unused)
> +{
> +}
> +
> int machine__get_kernel_start(struct machine *machine)
> {
> struct map *map = machine__kernel_map(machine);
> @@ -2687,14 +2691,11 @@ int machine__get_kernel_start(struct machine *machine)
> machine->kernel_start = 1ULL << 63;
> if (map) {
> err = map__load(map);
> - /*
> - * On x86_64, PTI entry trampolines are less than the
> - * start of kernel text, but still above 2^63. So leave
> - * kernel_start = 1ULL << 63 for x86_64.
> - */
> - if (!err && !machine__is(machine, "x86_64"))
> + if (!err)
> machine->kernel_start = map->start;
> }
> +
> + arch__fix_kernel_text_start(&machine->kernel_start);
> return err;
> }
>
> diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h
> index ef803f08ae12..9cb459f4bfbc 100644
> --- a/tools/perf/util/machine.h
> +++ b/tools/perf/util/machine.h
> @@ -278,6 +278,8 @@ void machine__get_kallsyms_filename(struct machine *machine, char *buf,
> int machine__create_extra_kernel_maps(struct machine *machine,
> struct dso *kernel);
>
> +void arch__fix_kernel_text_start(u64 *start);
> +
> /* Kernel-space maps for symbols that are outside the main kernel map and module maps */
> struct extra_kernel_map {
> u64 start;
>
