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SubjectRe: [PATCH 22/31] perf tools: Add BPF_PROLOGUE config options for further patches
On Tue, Sep 01, 2015 at 06:59:48AM +0000, Wang Nan wrote:
> If both LIBBPF and DWARF are detected, it is possible to create prologue
> for eBPF programs to help them accessing kernel data. HAVE_BPF_PROLOGUE
> and CONFIG_BPF_PROLOGUE is added as flags for this feature.
>
> PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET indicates an architecture
> supports converting name of a register to its offset in
> 'struct pt_regs'. Without this support, BPF_PROLOGUE should be turned off.
>
> HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET is introduced as the corresponding
> CFLAGS of PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET.
>
> Signed-off-by: Wang Nan <wangnan0@huawei.com>
> Cc: Alexei Starovoitov <ast@plumgrid.com>
> Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: He Kuang <hekuang@huawei.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kaixu Xia <xiakaixu@huawei.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Cc: Zefan Li <lizefan@huawei.com>
> Cc: pi3orama@163.com
> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> Link: http://lkml.kernel.org/n/1436445342-1402-33-git-send-email-wangnan0@huawei.com
> [wawngnan:
> - Introduce new CFLAGS to control BPF prologue and arch_get_reg_info()
> separately.
> - Rename ARCH_GET_REG_INFO to ARCH_REGS_QUERY_REGISTER_OFFSET,
> arch_get_reg_info() to regs_query_register_offset(), change its API accordingly
> to make it similar to kernel's regs_query_register_offset().
> ]
> ---
> tools/perf/config/Makefile | 17 +++++++++++++++++
> tools/perf/util/include/dwarf-regs.h | 8 ++++++++
> 2 files changed, 25 insertions(+)
>
> diff --git a/tools/perf/config/Makefile b/tools/perf/config/Makefile
> index 38a4144..33785a1 100644
> --- a/tools/perf/config/Makefile
> +++ b/tools/perf/config/Makefile
> @@ -110,6 +110,11 @@ FEATURE_CHECK_CFLAGS-bpf = -I. -I$(srctree)/tools/include -I$(srctree)/arch/$(AR
> # include ARCH specific config
> -include $(src-perf)/arch/$(ARCH)/Makefile
>
> +ifneq ($(origin PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET), undefined)

Why not just using

ifdef PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET

?


> + CFLAGS += -DHAVE_ARCH_REGS_QUERY_REGISTER_OFFSET
> +endif
> +
> +
> include $(src-perf)/config/utilities.mak
> ifeq ($(call get-executable,$(FLEX)),)
> @@ -314,6 +319,18 @@ ifndef NO_LIBELF
> CFLAGS += -DHAVE_LIBBPF_SUPPORT
> $(call detected,CONFIG_LIBBPF)
> endif
> +
> + ifndef NO_DWARF
> + ifneq ($(origin PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET), undefined)

Ditto.

Thanks,
Namhyung


> + CFLAGS += -DHAVE_BPF_PROLOGUE
> + $(call detected,CONFIG_BPF_PROLOGUE)
> + else
> + msg := $(warning BPF prologue is not supported by architecture $(ARCH), missing regs_query_register_offset());
> + endif
> + else
> + msg := $(warning DWARF support is off, BPF prologue is disabled);
> + endif
> +
> endif # NO_LIBBPF
> endif # NO_LIBELF
>
> diff --git a/tools/perf/util/include/dwarf-regs.h b/tools/perf/util/include/dwarf-regs.h
> index 8f14965..07c644e 100644
> --- a/tools/perf/util/include/dwarf-regs.h
> +++ b/tools/perf/util/include/dwarf-regs.h
> @@ -5,4 +5,12 @@
> const char *get_arch_regstr(unsigned int n);
> #endif
>
> +#ifdef HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET
> +/*
> + * Arch should support fetching the offset of a register in pt_regs
> + * by its name. See kernel's regs_query_register_offset in
> + * arch/xxx/kernel/ptrace.c.
> + */
> +int regs_query_register_offset(const char *name);
> +#endif
> #endif
> --
> 1.8.3.4
>


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