Re: [RFC v3 12/13] kprobes: port .kprobes.text to section range

Masami Hiramatsu
2016-07-25T15:20:15Z

On Fri, 22 Jul 2016 14:24:46 -0700
"Luis R. Rodriguez" <mcgrof@kernel.org> wrote:

> kprobe makes use of two custom sections, each custom section
> is folded into one of the standard Linux sections types as follows,
> it currently relies on the linker script to fold the custom section
> onto the respective Linux section:
>
> type Linux-section custom section name begin end
> table .init.data _kprobe_blacklist __start_kprobe_blacklist __stop_kprobe_blacklist
> range .text .kprobes.text __kprobes_text_start __kprobes_text_end
>
> This ports the .kprobes.text custom section to the standard
> Linux ranges API allowing us remove all the custom kprobe section
> declarations from the linker script.
>
> Tested with CONFIG_KPROBES_SANITY_TEST, it passes with:
>
> Kprobe smoke test: started
> Kprobe smoke test: passed successfully
>
> Then tested CONFIG_SAMPLE_KPROBES on do_fork, and the kprobe bites
> and kicks as expected.
>
> Also ran ./ftracetest with no issues:
>
> $ sudo ./ftracetest
> === Ftrace unit tests ===
> [1] Basic trace file check [PASS]
> [2] Basic test for tracers [PASS]
> [3] Basic trace clock test [PASS]
> [4] Basic event tracing check [PASS]
> [5] event tracing - enable/disable with event level files [PASS]
> [6] event tracing - restricts events based on pid [PASS]
> [7] event tracing - enable/disable with subsystem level files [PASS]
> [8] event tracing - enable/disable with top level files [PASS]
> [9] ftrace - function graph filters with stack tracer [PASS]
> [10] ftrace - function graph filters [PASS]
> [11] ftrace - function profiler with function tracing [PASS]
> [12] Test creation and deletion of trace instances while setting an event[PASS]
> [13] Test creation and deletion of trace instances [PASS]
> [14] Kprobe dynamic event - adding and removing [PASS]
> [15] Kprobe dynamic event - busy event check [PASS]
> [16] Kprobe dynamic event with arguments [PASS]
> [17] Kprobe dynamic event with function tracer [PASS]
> [18] Kretprobe dynamic event with arguments [PASS]
> [19] event trigger - test event enable/disable trigger [PASS]
> [20] event trigger - test trigger filter [PASS]
> [21] event trigger - test histogram modifiers [PASS]
> [22] event trigger - test histogram trigger [PASS]
> [23] event trigger - test multiple histogram triggers [PASS]
> [24] event trigger - test snapshot-trigger [PASS]
> [25] event trigger - test stacktrace-trigger [PASS]
> [26] event trigger - test traceon/off trigger [PASS]
>
> # of passed: 26
> # of failed: 0
> # of unresolved: 0
> # of untested: 0
> # of unsupported: 0
> # of xfailed: 0
> # of undefined(test bug): 0

Looks good to me except for the modpost part.

>
> diff --git a/scripts/Makefile b/scripts/Makefile
> index 1d80897a9644..77a0cc91628c 100644
> --- a/scripts/Makefile
> +++ b/scripts/Makefile
> @@ -10,6 +10,7 @@
> # check-lc_ctype: Used in Documentation/DocBook
>
> HOST_EXTRACFLAGS += -I$(srctree)/tools/include
> +HOST_EXTRACFLAGS += -U__KERNEL__

This looks a add-hoc hack. If we just need SECTION_RNG(SECTION_TEXT, kprobes)
to convert to section name, can we export the definitions outside of _KERNEL_ ?

Thank you,

>
> hostprogs-$(CONFIG_KALLSYMS) += kallsyms
> hostprogs-$(CONFIG_LOGO) += pnmtologo
> diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
> index 8257ef422c0a..76905d4ac0d0 100644
> --- a/scripts/mod/Makefile
> +++ b/scripts/mod/Makefile
> @@ -1,5 +1,7 @@
> OBJECT_FILES_NON_STANDARD := y
>
> +HOST_EXTRACFLAGS += -U__KERNEL__
> +
> hostprogs-y := modpost mk_elfconfig
> always := $(hostprogs-y) empty.o
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 48958d3cec9e..12ddced5df84 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -19,10 +19,16 @@
> #include <stdbool.h>
> #include <errno.h>
> #include "modpost.h"
> +
> #include "../../include/generated/autoconf.h"
> #include "../../include/linux/license.h"
> #include "../../include/linux/export.h"
>
> +#include "../../include/linux/sections.h"
> +#include "../../include/asm-generic/sections.h"
> +#include "../../include/linux/ranges.h"
> +#include "../../include/asm-generic/ranges.h"
> +
> /* Are we using CONFIG_MODVERSIONS? */
> static int modversions = 0;
> /* Warn about undefined symbols? (do so if we have vmlinux) */
> @@ -888,7 +894,7 @@ static void check_section(const char *modname, struct elf_info *elf,
>
> #define DATA_SECTIONS ".data", ".data.rel"
> #define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \
> - ".kprobes.text"
> + SECTION_RNG(SECTION_TEXT, kprobes)
> #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
> ".fixup", ".entry.text", ".exception.text", ".text.*", \
> ".coldtext"
> diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
> index e167592793a7..8381d75235d4 100644
> --- a/scripts/recordmcount.c
> +++ b/scripts/recordmcount.c
> @@ -33,6 +33,11 @@
> #include <string.h>
> #include <unistd.h>
>
> +#include "../../include/linux/sections.h"
> +#include "../../include/asm-generic/sections.h"
> +#include "../../include/linux/ranges.h"
> +#include "../../include/asm-generic/ranges.h"
> +
> #ifndef EM_METAG
> /* Remove this when these make it to the standard system elf.h. */
> #define EM_METAG 174
> @@ -356,7 +361,7 @@ is_mcounted_section_name(char const *const txtname)
> strcmp(".sched.text", txtname) == 0 ||
> strcmp(".spinlock.text", txtname) == 0 ||
> strcmp(".irqentry.text", txtname) == 0 ||
> - strcmp(".kprobes.text", txtname) == 0 ||
> + strcmp(SECTION_RNG(SECTION_TEXT, kprobe), txtname) == 0 ||
> strcmp(".text.unlikely", txtname) == 0;
> }
>
> diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
> index 96e2486a6fc4..f663a7c5d6ab 100755
> --- a/scripts/recordmcount.pl
> +++ b/scripts/recordmcount.pl
> @@ -134,7 +134,7 @@ my %text_sections = (
> ".sched.text" => 1,
> ".spinlock.text" => 1,
> ".irqentry.text" => 1,
> - ".kprobes.text" => 1,
> + ".text.rng.kprobes.any" => 1,
> ".text.unlikely" => 1,
> );
>
> --
> 2.8.4
>

--
Masami Hiramatsu <mhiramat@kernel.org>