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SubjectRe: [PATCH 2/4] Add NR_syscalls for x86_64
On Tue, Aug 25, 2009 at 10:25:52PM -0400, Steven Rostedt wrote:
> On Tue, 25 Aug 2009, Jason Baron wrote:
>
> > On Tue, Aug 25, 2009 at 09:40:05AM -0400, Jason Baron wrote:
> > >
> > > 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
>
> Why not? A define is not a problem until it is used. Is something in
> asm-offsets.c using NR_syscalls?
>
> > 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)
>
>
> Ug, yuck yuck yuck. Sometimes "it works" is not good enough ;-)
>
> How about just adding in asm/unistd.h
>
> #ifdef __KERNEL__
> # ifdef CONFIG_X86_32
> # include "unistd_32.h"
> # else
> # include "unistd_64.h"
> +# define NR_syscalls (__NR_syscall_max + 1)
> # endif
> #else
> # ifdef __i386__
> # include "unistd_32.h"
> # else
> # include "unistd_64.h"
> # endif
> #endif
>
> And if this is a problem because asm-offset_64.c includes asm/unistd.h,
> then make it just include unistd_64.h.
>
> Or am I missing something?
>
> -- Steve
>
>

ok, so using the above patch gives me:

CC arch/x86/kernel/ftrace.o
arch/x86/kernel/ftrace.c: In function ‘syscall_nr_to_meta’:
arch/x86/kernel/ftrace.c:497:35: error: ‘__NR_syscall_max’ undeclared
(first use in this function)
arch/x86/kernel/ftrace.c:497:35: error: (Each undeclared identifier is
reported only once
arch/x86/kernel/ftrace.c:497:35: error: for each function it appears
in.)
arch/x86/kernel/ftrace.c: In function ‘syscall_name_to_nr’:
arch/x86/kernel/ftrace.c:510:19: error: ‘__NR_syscall_max’ undeclared
(first use in this function)
arch/x86/kernel/ftrace.c: In function ‘arch_init_ftrace_syscalls’:
arch/x86/kernel/ftrace.c:536:7: error: ‘__NR_syscall_max’ undeclared
(first use in this function)
make[2]: *** [arch/x86/kernel/ftrace.o] Error 1
make[1]: *** [arch/x86/kernel] Error 2
make: *** [arch/x86] Error 2


That is the the first time, I encounter a 'NR_syscalls' usage, we error, b/c
unistd.h does not include 'asm/asm-offsets.h'. If I add an #include of
'asm/asm-offsets.h' to ftrace.c the compile is fine. But the point of
this was to the 'NR_syscalls' definition just from the unistd.h file...
I'll see if I can come up with a simpler patch.

thanks,

-Jason

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