Hi all!

        As part of the VAMOS[0] research project at the University of
Erlangen we are looking at multiple integrity errors in linux'
configuration system.

	      I've been running a check on the arch/powerpc sourcetree
	      for
config Items not defined in Kconfig and found5 such chases. Sourcecode
blocks depending on these Items are not reachable from a vanilla
kernel -- dead code. I've seen such dead blocks made on purpose
e.g. while integrating new features into the kernel but generally
they're just useless. 

	Each of the patches in this patchset removes on such dead
config Item, I'd be glad if you consider applying them. I've been
doing deeper analysis of such issues before and can do so again but
I'm not so sure they were fastly usefull. However I've done a
testbuild on ppc with allmodconfig so it should at least build.

        Please keep me informed of this patch getting confirmed /
merged so we can keep track of it.

Regards

        Christoph Egger

[0] http://vamos1.informatik.uni-erlangen.de/

Christoph Egger (5):
  Removing dead BOOK3E_MMU_TLB_STATS
  Removing dead CONFIG_HIGHPTE
  Removing dead CONFIG_SMP_750
  Removing dead CONFIG_SERIAL_TEXT_DEBUG
  Removing dead CONFIG_PPC47x

 arch/powerpc/include/asm/exception-64e.h |   38 ------------------------------
 arch/powerpc/kernel/head_40x.S           |   19 ---------------
 arch/powerpc/mm/44x_mmu.c                |    4 ---
 arch/powerpc/mm/pgtable_32.c             |    4 ---
 arch/powerpc/mm/tlb_hash32.c             |    4 ---
 arch/powerpc/mm/tlb_low_64e.S            |    9 -------
 6 files changed, 0 insertions(+), 78 deletions(-)

--

[ message continues ]

BOOK3E_MMU_TLB_STATS doesn't exist in Kconfig, therefore removing all
references for it from the source code.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
---
 arch/powerpc/include/asm/exception-64e.h |   38 ------------------------------
 arch/powerpc/mm/tlb_low_64e.S            |    9 -------
 2 files changed, 0 insertions(+), 47 deletions(-)

diff --git a/arch/powerpc/include/asm/exception-64e.h b/arch/powerpc/include/asm/exception-64e.h
index 6d53f31..db74814 100644
--- a/arch/powerpc/include/asm/exception-64e.h
+++ b/arch/powerpc/include/asm/exception-64e.h
@@ -65,14 +65,7 @@
 #define EX_TLB_MMUCR0	(12 * 8) /* Level 0 */
 #define EX_TLB_MAS1	(12 * 8) /* Level 0 */
 #define EX_TLB_MAS2	(13 * 8) /* Level 0 */
-#ifdef CONFIG_BOOK3E_MMU_TLB_STATS
-#define EX_TLB_R8	(14 * 8)
-#define EX_TLB_R9	(15 * 8)
-#define EX_TLB_LR	(16 * 8)
-#define EX_TLB_SIZE	(17 * 8)
-#else
 #define EX_TLB_SIZE	(14 * 8)
-#endif
 
 #define	START_EXCEPTION(label)						\
 	.globl exc_##label##_book3e;					\
@@ -157,36 +150,6 @@ exc_##label##_book3e:
 	addi	r11,r13,PACA_EXTLB;					    \
 	TLB_MISS_RESTORE(r11)
 
-#ifdef CONFIG_BOOK3E_MMU_TLB_STATS
-#define TLB_MISS_PROLOG_STATS						    \
-	mflr	r10;							    \
-	std	r8,EX_TLB_R8(r12);					    \
-	std	r9,EX_TLB_R9(r12);					    \
-	std	r10,EX_TLB_LR(r12);
-#define TLB_MISS_RESTORE_STATS					            \
-	ld	r16,EX_TLB_LR(r12);					    \
-	ld	r9,EX_TLB_R9(r12);					    \
-	ld	r8,EX_TLB_R8(r12);					    \
-	mtlr	r16;
-#define TLB_MISS_STATS_D(name)						    \
-	addi	r9,r13,MMSTAT_DSTATS+name;				    \
-	bl	.tlb_stat_inc;
-#define TLB_MISS_STATS_I(name)						    \
-	addi	r9,r13,MMSTAT_ISTATS+name;				    \
-	bl	.tlb_stat_inc;
-#define TLB_MISS_STATS_X(name)						    \
-	ld	r8,PACA_EXTLB+EX_TLB_ESR(r13);				    \
-	cmpdi	cr2,r8,-1;						    \
-	beq	cr2,61f;						    \
-	addi	r9,r13,MMSTAT_DSTATS+name;				    \
-	b	62f;							    \
-61:	addi	r9,r13,MMSTAT_ISTATS+name;				    \
-62:	bl	.tlb_stat_inc;
-#define ...
[ message continues ]

Heh, thanks but no :-)

I want to keep that code here, until we hook it up again. It was hooked
up properly in some internal stuff that didn't go upstream for some
reason and I need to fix that.

Cheers,


--

[ message continues ]

CONFIG_HIGHPTE doesn't exist in Kconfig, therefore removing all
references for it from the source code.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
---
 arch/powerpc/mm/pgtable_32.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 9fc02dc..34347b2 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -115,11 +115,7 @@ pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
 {
 	struct page *ptepage;
 
-#ifdef CONFIG_HIGHPTE
-	gfp_t flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_REPEAT | __GFP_ZERO;
-#else
 	gfp_t flags = GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO;
-#endif
 
 	ptepage = alloc_pages(flags, 0);
 	if (!ptepage)
-- 
1.6.3.3

--

[ message continues ]

CONFIG_SMP_750 doesn't exist in Kconfig, therefore removing all
references for it from the source code.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
---
 arch/powerpc/mm/tlb_hash32.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/mm/tlb_hash32.c b/arch/powerpc/mm/tlb_hash32.c
index 8aaa8b7..925fecb 100644
--- a/arch/powerpc/mm/tlb_hash32.c
+++ b/arch/powerpc/mm/tlb_hash32.c
@@ -94,11 +94,7 @@ void tlb_flush(struct mmu_gather *tlb)
  * the cache operations on the bus.  Hence we need to use an IPI
  * to get the other CPU(s) to invalidate their TLBs.
  */
-#ifdef CONFIG_SMP_750
-#define FINISH_FLUSH	smp_send_tlb_invalidate(0)
-#else
 #define FINISH_FLUSH	do { } while (0)
-#endif
 
 static void flush_range(struct mm_struct *mm, unsigned long start,
 			unsigned long end)
-- 
1.6.3.3

--

[ message continues ]

Yeah, we don't support SMP on 750 at the moment.  This code was carried over
from the arch/ppc days, and that code was present pre-git.  I think we can
drop it, but I'll leave that up to Ben.  Maybe he has crazy plans for a 750 SMP
board.

--

[ message continues ]

Nope :-) Though it would be nice to also remove the call sites too and
thus remove the macro entirely.

Cheers,


--

[ message continues ]

SOmething like below?

-----
From: Christoph Egger <siccegge@cs.fau.de>
Subject: [PATCH 3/5] Removing dead CONFIG_SMP_750

CONFIG_SMP_750 doesn't exist in Kconfig, therefore removing all
references for it from the source code.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>

diff --git a/arch/powerpc/mm/tlb_hash32.c b/arch/powerpc/mm/tlb_hash32.c
index 8aaa8b7..09c7820 100644
--- a/arch/powerpc/mm/tlb_hash32.c
+++ b/arch/powerpc/mm/tlb_hash32.c
@@ -94,11 +94,6 @@ void tlb_flush(struct mmu_gather *tlb)
  * the cache operations on the bus.  Hence we need to use an IPI
  * to get the other CPU(s) to invalidate their TLBs.
  */
-#ifdef CONFIG_SMP_750
-#define FINISH_FLUSH   smp_send_tlb_invalidate(0)
-#else
-#define FINISH_FLUSH   do { } while (0)
-#endif
 
 static void flush_range(struct mm_struct *mm, unsigned long start,
                        unsigned long end)
@@ -138,7 +133,6 @@ static void flush_range(struct mm_struct *mm, unsigned long start,
 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 {
        flush_range(&init_mm, start, end);
-       FINISH_FLUSH;
 }
 EXPORT_SYMBOL(flush_tlb_kernel_range);
 
@@ -162,7 +156,6 @@ void flush_tlb_mm(struct mm_struct *mm)
         */
        for (mp = mm->mmap; mp != NULL; mp = mp->vm_next)
                flush_range(mp->vm_mm, mp->vm_start, mp->vm_end);
-       FINISH_FLUSH;
 }
 EXPORT_SYMBOL(flush_tlb_mm);
 
@@ -179,7 +172,6 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long vmaddr)
        pmd = pmd_offset(pud_offset(pgd_offset(mm, vmaddr), vmaddr), vmaddr);
        if (!pmd_none(*pmd))
                flush_hash_pages(mm->context.id, vmaddr, pmd_val(*pmd), 1);
-       FINISH_FLUSH;
 }
 EXPORT_SYMBOL(flush_tlb_page);
 
@@ -192,6 +184,5 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
                     unsigned long end)
 {
        flush_range(vma->vm_mm, start, end);
-       FINISH_FLUSH;
 }
 EXPORT_SYMBOL(flush_tlb_range);
-- ...
[ message continues ]

Excellent. Thanks. I'll add that to the batch I'm preparing for Linus.

Cheers,


--

[ message continues ]

CONFIG_SERIAL_TEXT_DEBUG doesn't exist in Kconfig, therefore removing all
references for it from the source code.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
---
 arch/powerpc/kernel/head_40x.S |   19 -------------------
 1 files changed, 0 insertions(+), 19 deletions(-)

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index a90625f..1a10e4d 100644
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -939,25 +939,6 @@ initial_mmu:
 	tlbwe	r4,r0,TLB_DATA		/* Load the data portion of the entry */
 	tlbwe	r3,r0,TLB_TAG		/* Load the tag portion of the entry */
 
-#if defined(CONFIG_SERIAL_TEXT_DEBUG) && defined(SERIAL_DEBUG_IO_BASE)
-
-	/* Load a TLB entry for the UART, so that ppc4xx_progress() can use
-	 * the UARTs nice and early.  We use a 4k real==virtual mapping. */
-
-	lis	r3,SERIAL_DEBUG_IO_BASE@h
-	ori	r3,r3,SERIAL_DEBUG_IO_BASE@l
-	mr	r4,r3
-	clrrwi	r4,r4,12
-	ori	r4,r4,(TLB_WR|TLB_I|TLB_M|TLB_G)
-
-	clrrwi	r3,r3,12
-	ori	r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K))
-
-	li	r0,0			/* TLB slot 0 */
-	tlbwe	r4,r0,TLB_DATA
-	tlbwe	r3,r0,TLB_TAG
-#endif /* CONFIG_SERIAL_DEBUG_TEXT && SERIAL_DEBUG_IO_BASE */
-
 	isync
 
 	/* Establish the exception vector base
-- 
1.6.3.3

--

[ message continues ]

It would be better to conver this to work with CONFIG_PPC_EARLY_DEBUG and
CONFIG_PPC_EARLY_DEBUG_40x.  I'd rather just leave this for now until we can
get it switched over.

--

[ message continues ]

CONFIG_PPC47x doesn't exist in Kconfig, therefore removing all
references for it from the source code.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
---
 arch/powerpc/mm/44x_mmu.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/mm/44x_mmu.c b/arch/powerpc/mm/44x_mmu.c
index d8c6efb..f70da7e 100644
--- a/arch/powerpc/mm/44x_mmu.c
+++ b/arch/powerpc/mm/44x_mmu.c
@@ -76,11 +76,7 @@ static void __init ppc44x_pin_tlb(unsigned int virt, unsigned int phys)
 		"tlbwe	%1,%3,%5\n"
 		"tlbwe	%0,%3,%6\n"
 	:
-#ifdef CONFIG_PPC47x
-	: "r" (PPC47x_TLB2_S_RWX),
-#else
 	: "r" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G),
-#endif
 	  "r" (phys),
 	  "r" (virt | PPC44x_TLB_VALID | PPC44x_TLB_256M),
 	  "r" (entry),
-- 
1.6.3.3

--

[ message continues ]

CONFIG_PPC47x should actually be spelled CONFIG_PPC_47x as reported by
Andreas Schwab.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
---
 arch/powerpc/mm/44x_mmu.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/mm/44x_mmu.c b/arch/powerpc/mm/44x_mmu.c
index d8c6efb..f70da7e 100644
--- a/arch/powerpc/mm/44x_mmu.c
+++ b/arch/powerpc/mm/44x_mmu.c
@@ -76,11 +76,11 @@ static void __init ppc44x_pin_tlb(unsigned int virt, unsigned int phys)
 		"tlbwe	%1,%3,%5\n"
 		"tlbwe	%0,%3,%6\n"
 	:
-#ifdef CONFIG_PPC47x
+#ifdef CONFIG_PPC_47x
 	: "r" (PPC47x_TLB2_S_RWX),
 #else
 	: "r" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G),
 #endif
 	  "r" (phys),
 	  "r" (virt | PPC44x_TLB_VALID | PPC44x_TLB_256M),
 	  "r" (entry),
-- 
1.6.3.3

--

[ message continues ]

Thanks, I'll pull this one in and get it merged.

--

[ message continues ]

I pulled your tree along with a couple of other things. I'll do a few
tests tomorrow before sending to Linus.

Cheers,


--

[ message continues ]

(cc's trimmed and rpjday added)


Are you aware of


--

[ message continues ]

Yes, we are. These scripts aim at a very similar goal.  However, we are
using a more sound approach that actually involves parsing CPP
statements and the kconfig language and checking the resulting
constraints with SAT solving tools.  This way, we get way more precise
results.

You can read about our approach in [1].

[1] http://portal.acm.org/citation.cfm?id=1629732

-- 
Reinhard Tartler                     Department of Computer Science IV
Martensstr 1, 91058 Erlangen Germany, University of Erlangen-Nuremberg
            http://www4.informatik.uni-erlangen.de/~tartler
--

[ message continues ]