linux-kernel - Re: [git-pull -tip V2] x86: cpu architecture debug code

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Message-Id: <1236779029.2836.33.camel@ht.satnam>
Date:	Wed, 11 Mar 2009 19:13:49 +0530
From:	Jaswinder Singh Rajput <jaswinder@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	"H. Peter Anvin" <hpa@...or.com>, x86 maintainers <x86@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [git-pull -tip V2] x86: cpu architecture debug code

On Wed, 2009-03-11 at 14:13 +0100, Ingo Molnar wrote:
> * Ingo Molnar <mingo@...e.hu> wrote:
> 
> > * Jaswinder Singh Rajput <jaswinder@...nel.org> wrote:
> > 
> > > @@ -472,7 +473,7 @@ static void print_dt(void *seq)
> > >  	print_desc_ptr("GDT", seq, dt);
> > >  
> > >  	/* LDT */
> > > -	store_ldt(ldt);
> > > +	asm volatile("sldt %0" : "=m" (ldt));
> > 
> > this is still wrong.
> 
> As i pointed it out before, we should not open-code an assembly 
> primitive - especially since store_ldt() is available in 
> arch/x86/include/asm/desc.h.
> 
> True, that primitive is not available on CONFIG_PARAVIRT, but 
> that is a bug: the fix is to move the store_ldt() definition 
> outside the CONFIG_PARAVIRT section in desc.h, not to hack 
> around the problem by open-coding assembly code.
> 
> I.e. dont let an uncleanliness and incomplete primitive spread 
> to other code. Fix the primitive and remove the uncleanliness 
> that way.
> 

The following changes since commit 259ef6fcea4046fe24495b1e3631c1b905c531c1:
  Jaswinder Singh Rajput (1):
        x86: cpu architecture debug code

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/jaswinder/linux-2.6-tip-cpu.git master

Jaswinder Singh Rajput (2):
      x86: cpu_debug.c cleanup
      x86: move store_ldt outside the CONFIG_PARAVIRT section

 arch/x86/include/asm/desc.h     |    3 ++-
 arch/x86/kernel/cpu/cpu_debug.c |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

Complete diff:
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index dc27705..ceb17cc 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -91,7 +91,6 @@ static inline int desc_empty(const void *ptr)
 #define store_gdt(dtr) native_store_gdt(dtr)
 #define store_idt(dtr) native_store_idt(dtr)
 #define store_tr(tr) (tr = native_store_tr())
-#define store_ldt(ldt) asm("sldt %0":"=m" (ldt))
 
 #define load_TLS(t, cpu) native_load_tls(t, cpu)
 #define set_ldt native_set_ldt
@@ -112,6 +111,8 @@ static inline void paravirt_free_ldt(struct desc_struct *ldt, unsigned entries)
 }
 #endif	/* CONFIG_PARAVIRT */
 
+#define store_ldt(ldt) asm("sldt %0":"=m" (ldt))
+
 static inline void native_write_idt_entry(gate_desc *idt, int entry,
 					  const gate_desc *gate)
 {
diff --git a/arch/x86/kernel/cpu/cpu_debug.c b/arch/x86/kernel/cpu/cpu_debug.c
index 0bdf4da..9abbcbd 100755
--- a/arch/x86/kernel/cpu/cpu_debug.c
+++ b/arch/x86/kernel/cpu/cpu_debug.c
@@ -23,6 +23,7 @@
 #include <linux/smp.h>
 
 #include <asm/cpu_debug.h>
+#include <asm/paravirt.h>
 #include <asm/system.h>
 #include <asm/traps.h>
 #include <asm/apic.h>
@@ -427,7 +428,7 @@ static void print_tss(void *arg)
 	seq_printf(seq, " CS\t:             %04x\n", seg);
 	asm("movl %%ds,%0" : "=r" (seg));
 	seq_printf(seq, " DS\t:             %04x\n", seg);
-	seq_printf(seq, " SS\t:             %04lx\n", regs->ss);
+	seq_printf(seq, " SS\t:             %04lx\n", regs->ss & 0xffff);
 	asm("movl %%es,%0" : "=r" (seg));
 	seq_printf(seq, " ES\t:             %04x\n", seg);
 	asm("movl %%fs,%0" : "=r" (seg));


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