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    SubjectRe: [PATCH 2/4] Add NR_syscalls for x86_64
    On Tue, Aug 25, 2009 at 09:40:05AM -0400, Jason Baron wrote:
    > > > On Mon, Aug 24, 2009 at 05:40:18PM -0400, Jason Baron wrote:
    > > > > Add a dynamic definition of NR_syscalls for x86_64. This is used in the
    > > > > syscall events tracing code.
    > > > >
    > > > > Signed-off-by: Jason Baron <jbaron@redhat.com>
    > > > >
    > > > > ---
    > > > > include/linux/ftrace.h | 5 +++++
    > > > > 1 files changed, 5 insertions(+), 0 deletions(-)
    > > > >
    > > > > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
    > > > > index dc3b132..3bd94ee 100644
    > > > > --- a/include/linux/ftrace.h
    > > > > +++ b/include/linux/ftrace.h
    > > > > @@ -14,6 +14,11 @@
    > > > >
    > > > > #include <asm/ftrace.h>
    > > > >
    > > > > +#ifdef CONFIG_X86_64
    > > > > +#include <asm/asm-offsets.h>
    > > > > +#define NR_syscalls (__NR_syscall_max + 1)
    > > > > +#endif
    > > > > +
    > > >
    > > >
    > > > I'd rather see this in arch/x86/include/unistd_64.h, since
    > > > NR_syscalls seems to be the defined in unistd.h in all archs.
    > > >
    > > > That also makes a unified way to retrieve this number for
    > > > other users.
    > > >
    > >
    > > Yes, NR_syscalls should be included there.
    > >
    > > -- Steve
    >
    > right, for x86_64, unistd.h is included to generate __NR_syscall_max
    > which is then used for NR_syscalls. So I did initially try it there, but
    > there were dependency problems. I'll see what I can come up with...
    >
    > thanks,
    >
    > -Jason

    ok, since unistd_64.h is used to generate offsets.c, which eventually
    generates, asm/asm-offsets.h, which defines, __NR_syscall_max, we can't
    just put #define of NR_syscalls in unistd_64.h. However, it seems the
    only point in time that unistd_64.h can not depend upon __NR_syscall_max,
    is before asm/asm-offsets.h is defined. Thus, the patch below passes in
    a '-DCREATE_OFFSETS' during the creation of asm/asm-offsets.h, so that
    we do not include it before it exists. The patch is hacky but works.
    thoughts?

    Signed-off-by: Jason Baron <jbaron@redhat.com>

    ---

    Kbuild | 2 +-
    arch/x86/include/asm/unistd_64.h | 6 ++++++
    scripts/Makefile.build | 4 ++++
    3 files changed, 11 insertions(+), 1 deletions(-)


    diff --git a/Kbuild b/Kbuild
    index f056b4f..5f43d4d 100644
    --- a/Kbuild
    +++ b/Kbuild
    @@ -78,7 +78,7 @@ endef
    arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c \
    $(obj)/$(bounds-file) FORCE
    $(Q)mkdir -p $(dir $@)
    - $(call if_changed_dep,cc_s_c)
    + $(call if_changed_dep,cc_s_c_define_offset)

    $(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
    $(call cmd,offsets)
    diff --git a/arch/x86/include/asm/unistd_64.h b/arch/x86/include/asm/unistd_64.h
    index 900e161..70c0c3d 100644
    --- a/arch/x86/include/asm/unistd_64.h
    +++ b/arch/x86/include/asm/unistd_64.h
    @@ -688,6 +688,12 @@ __SYSCALL(__NR_perf_counter_open, sys_perf_counter_open)
    #endif /* __NO_STUBS */

    #ifdef __KERNEL__
    +
    +#ifndef CREATE_OFFSETS
    +#include <asm/asm-offsets.h>
    +#define NR_syscalls (__NR_syscall_max + 1)
    +#endif
    +
    /*
    * "Conditional" syscalls
    *
    diff --git a/scripts/Makefile.build b/scripts/Makefile.build
    index 5c4b7a4..4177858 100644
    --- a/scripts/Makefile.build
    +++ b/scripts/Makefile.build
    @@ -145,6 +145,10 @@ $(multi-objs-y:.o=.lst) : modname = $(modname-multi)
    quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
    cmd_cc_s_c = $(CC) $(c_flags) -fverbose-asm -S -o $@ $<

    +quiet_cmd_cc_s_c_define_offset = CC $(quiet_modtag) $@
    +cmd_cc_s_c_define_offset = $(CC) $(c_flags) -DCREATE_OFFSETS \
    + -fverbose-asm -S -o $@ $<
    +
    $(obj)/%.s: $(src)/%.c FORCE
    $(call if_changed_dep,cc_s_c)






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