linux-kernel - Re: [PATCH 2/4] Add NR_syscalls for x86

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Date:	Wed, 26 Aug 2009 10:39:26 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jason Baron <jbaron@...hat.com>
cc:	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org, x86@...nel.org, lethal@...ux-sh.org,
	mingo@...e.hu, laijs@...fujitsu.com, peterz@...radead.org,
	mathieu.desnoyers@...ymtl.ca, jiayingz@...gle.com,
	mbligh@...gle.com, lizf@...fujitsu.com, jistone@...hat.com,
	tglx@...utronix.de, hpa@...or.com
Subject: Re: [PATCH 2/4] Add NR_syscalls for x86_64


On Wed, 26 Aug 2009, Jason Baron wrote:
> > > 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.

Then add the asm/asm-offests.h to the x86_64 define in unistd.h and have 
the asm-offset_64.c only include the unistd_64.h file. Would that work?

-- Steve

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