powerpc/mm: Cleanup handling of execute permission

This is an attempt at cleaning up a bit the way we handle execute
permission on powerpc. _PAGE_HWEXEC is gone, _PAGE_EXEC is now only
defined by CPUs that can do something with it, and the myriad of
#ifdef's in the I$/D$ coherency code is reduced to 2 cases that
hopefully should cover everything.

The logic on BookE is a little bit different than what it was though
not by much. Since now, _PAGE_EXEC will be set by the generic code
for executable pages, we need to filter out if they are unclean and
recover it. However, I don't expect the code to be more bloated than
it already was in that area due to that change.

I could boast that this brings proper enforcing of per-page execute
permissions to all BookE and 40x but in fact, we've had that now for
some time as a side effect of my previous rework in that area (and
I didn't even know it :-) We would only enable execute permission if
the page was cache clean and we would only cache clean it if we took
and exec fault. Since we now enforce that the later only work if
VM_EXEC is part of the VMA flags, we de-fact already enforce per-page
execute permissions... Unless I missed something

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/pgtable-ppc32.h

@@ -186,7 +186,7 @@ static inline unsigned long pte_update(pte_t *p,
 #endif /* !PTE_ATOMIC_UPDATES */
 
 #ifdef CONFIG_44x
-	if ((old & _PAGE_USER) && (old & _PAGE_HWEXEC))
+	if ((old & _PAGE_USER) && (old & _PAGE_EXEC))
 		icache_44x_need_flush = 1;
 #endif
 	return old;
@@ -217,7 +217,7 @@ static inline unsigned long long pte_update(pte_t *p,
 #endif /* !PTE_ATOMIC_UPDATES */
 
 #ifdef CONFIG_44x
-	if ((old & _PAGE_USER) && (old & _PAGE_HWEXEC))
+	if ((old & _PAGE_USER) && (old & _PAGE_EXEC))
 		icache_44x_need_flush = 1;
 #endif
 	return old;
@@ -267,8 +267,7 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm,
 static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
 {
 	unsigned long bits = pte_val(entry) &
-		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW |
-		 _PAGE_HWEXEC | _PAGE_EXEC);
+		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
 	pte_update(ptep, 0, bits);
 }
 

arch/powerpc/include/asm/pgtable-ppc64.h

@@ -313,8 +313,7 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr,
 static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
 {
 	unsigned long bits = pte_val(entry) &
-		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW |
-		 _PAGE_EXEC | _PAGE_HWEXEC);
+		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
 
 #ifdef PTE_ATOMIC_UPDATES
 	unsigned long old, tmp;

arch/powerpc/include/asm/pte-40x.h

@@ -46,7 +46,7 @@
 #define	_PAGE_RW	0x040	/* software: Writes permitted */
 #define	_PAGE_DIRTY	0x080	/* software: dirty page */
 #define _PAGE_HWWRITE	0x100	/* hardware: Dirty & RW, set in exception */
-#define _PAGE_HWEXEC	0x200	/* hardware: EX permission */
+#define _PAGE_EXEC	0x200	/* hardware: EX permission */
 #define _PAGE_ACCESSED	0x400	/* software: R: page referenced */
 
 #define _PMD_PRESENT	0x400	/* PMD points to page of PTEs */

arch/powerpc/include/asm/pte-44x.h

@@ -78,7 +78,7 @@
 #define _PAGE_PRESENT	0x00000001		/* S: PTE valid */
 #define _PAGE_RW	0x00000002		/* S: Write permission */
 #define _PAGE_FILE	0x00000004		/* S: nonlinear file mapping */
-#define _PAGE_HWEXEC	0x00000004		/* H: Execute permission */
+#define _PAGE_EXEC	0x00000004		/* H: Execute permission */
 #define _PAGE_ACCESSED	0x00000008		/* S: Page referenced */
 #define _PAGE_DIRTY	0x00000010		/* S: Page dirty */
 #define _PAGE_SPECIAL	0x00000020		/* S: Special page */

arch/powerpc/include/asm/pte-8xx.h

@@ -36,7 +36,6 @@
 /* These five software bits must be masked out when the entry is loaded
  * into the TLB.
  */
-#define _PAGE_EXEC	0x0008	/* software: i-cache coherency required */
 #define _PAGE_GUARDED	0x0010	/* software: guarded access */
 #define _PAGE_DIRTY	0x0020	/* software: page changed */
 #define _PAGE_RW	0x0040	/* software: user write access allowed */

arch/powerpc/include/asm/pte-book3e.h

@@ -37,12 +37,13 @@
 #define _PAGE_WRITETHRU	0x800000 /* W: cache write-through */
 
 /* "Higher level" linux bit combinations */
-#define _PAGE_EXEC	_PAGE_BAP_SX /* Can be executed from potentially */
-#define _PAGE_HWEXEC	_PAGE_BAP_UX /* .. and was cache cleaned */
-#define _PAGE_RW	(_PAGE_BAP_SW | _PAGE_BAP_UW) /* User write permission */
-#define _PAGE_KERNEL_RW	(_PAGE_BAP_SW | _PAGE_BAP_SR | _PAGE_DIRTY)
-#define _PAGE_KERNEL_RO	(_PAGE_BAP_SR)
-#define _PAGE_USER	(_PAGE_BAP_UR | _PAGE_BAP_SR) /* Can be read */
+#define _PAGE_EXEC		_PAGE_BAP_UX /* .. and was cache cleaned */
+#define _PAGE_RW		(_PAGE_BAP_SW | _PAGE_BAP_UW) /* User write permission */
+#define _PAGE_KERNEL_RW		(_PAGE_BAP_SW | _PAGE_BAP_SR | _PAGE_DIRTY)
+#define _PAGE_KERNEL_RO		(_PAGE_BAP_SR)
+#define _PAGE_KERNEL_RWX	(_PAGE_BAP_SW | _PAGE_BAP_SR | _PAGE_DIRTY | _PAGE_BAP_SX)
+#define _PAGE_KERNEL_ROX	(_PAGE_BAP_SR | _PAGE_BAP_SX)
+#define _PAGE_USER		(_PAGE_BAP_UR | _PAGE_BAP_SR) /* Can be read */
 
 #define _PAGE_HASHPTE	0
 #define _PAGE_BUSY	0

arch/powerpc/include/asm/pte-common.h

@@ -13,9 +13,6 @@
 #ifndef _PAGE_HWWRITE
 #define _PAGE_HWWRITE	0
 #endif
-#ifndef _PAGE_HWEXEC
-#define _PAGE_HWEXEC	0
-#endif
 #ifndef _PAGE_EXEC
 #define _PAGE_EXEC	0
 #endif
@@ -48,10 +45,16 @@
 #define PMD_PAGE_SIZE(pmd)	bad_call_to_PMD_PAGE_SIZE()
 #endif
 #ifndef _PAGE_KERNEL_RO
-#define _PAGE_KERNEL_RO	0
+#define _PAGE_KERNEL_RO		0
+#endif
+#ifndef _PAGE_KERNEL_ROX
+#define _PAGE_KERNEL_ROX	(_PAGE_EXEC)
 #endif
 #ifndef _PAGE_KERNEL_RW
-#define _PAGE_KERNEL_RW	(_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE)
+#define _PAGE_KERNEL_RW		(_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE)
+#endif
+#ifndef _PAGE_KERNEL_RWX
+#define _PAGE_KERNEL_RWX	(_PAGE_DIRTY | _PAGE_RW | _PAGE_HWWRITE | _PAGE_EXEC)
 #endif
 #ifndef _PAGE_HPTEFLAGS
 #define _PAGE_HPTEFLAGS _PAGE_HASHPTE
@@ -96,8 +99,7 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
 #define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
 			 _PAGE_WRITETHRU | _PAGE_ENDIAN | _PAGE_4K_PFN | \
 			 _PAGE_USER | _PAGE_ACCESSED | \
-			 _PAGE_RW | _PAGE_HWWRITE | _PAGE_DIRTY | \
-			 _PAGE_EXEC | _PAGE_HWEXEC)
+			 _PAGE_RW | _PAGE_HWWRITE | _PAGE_DIRTY | _PAGE_EXEC)
 
 /*
  * We define 2 sets of base prot bits, one for basic pages (ie,
@@ -154,11 +156,9 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
 				 _PAGE_NO_CACHE)
 #define PAGE_KERNEL_NCG	__pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
 				 _PAGE_NO_CACHE | _PAGE_GUARDED)
-#define PAGE_KERNEL_X	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RW | _PAGE_EXEC | \
-				 _PAGE_HWEXEC)
+#define PAGE_KERNEL_X	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RWX)
 #define PAGE_KERNEL_RO	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RO)
-#define PAGE_KERNEL_ROX	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RO | _PAGE_EXEC | \
-				 _PAGE_HWEXEC)
+#define PAGE_KERNEL_ROX	__pgprot(_PAGE_BASE | _PAGE_KERNEL_ROX)
 
 /* Protection used for kernel text. We want the debuggers to be able to
  * set breakpoints anywhere, so don't write protect the kernel text

arch/powerpc/include/asm/pte-fsl-booke.h

@@ -23,7 +23,7 @@
 #define _PAGE_FILE	0x00002	/* S: when !present: nonlinear file mapping */
 #define _PAGE_RW	0x00004	/* S: Write permission (SW) */
 #define _PAGE_DIRTY	0x00008	/* S: Page dirty */
-#define _PAGE_HWEXEC	0x00010	/* H: SX permission */
+#define _PAGE_EXEC	0x00010	/* H: SX permission */
 #define _PAGE_ACCESSED	0x00020	/* S: Page referenced */
 
 #define _PAGE_ENDIAN	0x00040	/* H: E bit */

arch/powerpc/include/asm/pte-hash32.h

@@ -26,7 +26,6 @@
 #define _PAGE_WRITETHRU	0x040	/* W: cache write-through */
 #define _PAGE_DIRTY	0x080	/* C: page changed */
 #define _PAGE_ACCESSED	0x100	/* R: page referenced */
-#define _PAGE_EXEC	0x200	/* software: i-cache coherency required */
 #define _PAGE_RW	0x400	/* software: user write access allowed */
 #define _PAGE_SPECIAL	0x800	/* software: Special page */
 

arch/powerpc/kernel/head_44x.S

@@ -497,7 +497,7 @@ tlb_44x_patch_hwater_D:
 	mtspr	SPRN_MMUCR,r12
 
 	/* Make up the required permissions */
-	li	r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_HWEXEC
+	li	r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
 
 	/* Compute pgdir/pmd offset */
 	rlwinm 	r12, r10, PPC44x_PGD_OFF_SHIFT, PPC44x_PGD_OFF_MASK_BIT, 29

arch/powerpc/kernel/head_fsl_booke.S

@@ -643,7 +643,7 @@ interrupt_base:
 
 4:
 	/* Make up the required permissions */
-	li	r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_HWEXEC
+	li	r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
 
 	FIND_PTE
 	andc.	r13,r13,r11		/* Check permission */
@@ -742,7 +742,7 @@ finish_tlb_load:
 #endif
 	mtspr	SPRN_MAS2, r12
 
-	li	r10, (_PAGE_HWEXEC | _PAGE_PRESENT)
+	li	r10, (_PAGE_EXEC | _PAGE_PRESENT)
 	rlwimi	r10, r11, 31, 29, 29	/* extract _PAGE_DIRTY into SW */
 	and	r12, r11, r10
 	andi.	r10, r11, _PAGE_USER	/* Test for _PAGE_USER */

arch/powerpc/mm/40x_mmu.c

@@ -105,7 +105,7 @@ unsigned long __init mmu_mapin_ram(void)
 
 	while (s >= LARGE_PAGE_SIZE_16M) {
 		pmd_t *pmdp;
-		unsigned long val = p | _PMD_SIZE_16M | _PAGE_HWEXEC | _PAGE_HWWRITE;
+		unsigned long val = p | _PMD_SIZE_16M | _PAGE_EXEC | _PAGE_HWWRITE;
 
 		pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
 		pmd_val(*pmdp++) = val;
@@ -120,7 +120,7 @@ unsigned long __init mmu_mapin_ram(void)
 
 	while (s >= LARGE_PAGE_SIZE_4M) {
 		pmd_t *pmdp;
-		unsigned long val = p | _PMD_SIZE_4M | _PAGE_HWEXEC | _PAGE_HWWRITE;
+		unsigned long val = p | _PMD_SIZE_4M | _PAGE_EXEC | _PAGE_HWWRITE;
 
 		pmdp = pmd_offset(pud_offset(pgd_offset_k(v), v), v);
 		pmd_val(*pmdp) = val;