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powerpc/mm: Cleanup handling of execute permission v2

PATCH In review Benjamin Herrenschmidt 2 participants 2 messages Aug 19, 2009 – Sep 11, 2009 PowerPC

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Benjamin Herrenschmidt

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PATCH 1/1 powerpc/mm: Cleanup handling of execute permission v2

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 <[email protected]>

---

This version restores the missing (oops) cache flush in ptep_set_access_flags() which broke BookE.

arch/powerpc/include/asm/pgtable-ppc32.h +3 -4
index c9ff9d7..f2c52e2 100644
@@ -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 +1 -2
index 200ec2d..806abe7 100644
@@ -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 +1 -1
index 07630fa..6c3e1f4 100644
@@ -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 +1 -1
index 37e98bc..4192b9b 100644
@@ -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 +0 -1
index 8c6e312..94e9797 100644
@@ -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 +7 -6
index 1d27c77..9800565 100644
@@ -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 +11 -11
index 8bb6464..c3b6507 100644
@@ -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 +1 -1
index 10820f5..ce8a9e9 100644
@@ -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 +0 -1
index 16e571c..4aad413 100644
@@ -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 +1 -1
index 656cfb2..711368b 100644
@@ -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 +2 -2
index eca8048..2c5af52 100644
@@ -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 +2 -2
index 29954dc..f5e7b9c 100644
@@ -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;
arch/powerpc/mm/pgtable.c +116 -51

210 lines not on this page · raw message

arch/powerpc/mm/pgtable_32.c +1 -1
index 5422169..cb96cb2 100644
@@ -142,7 +142,7 @@ ioremap_flags(phys_addr_t addr, unsigned long size, unsigned long flags)
 		flags |= _PAGE_DIRTY | _PAGE_HWWRITE;
 
 	/* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
-	flags &= ~(_PAGE_USER | _PAGE_EXEC | _PAGE_HWEXEC);
+	flags &= ~(_PAGE_USER | _PAGE_EXEC);
 
 	return __ioremap_caller(addr, size, flags, __builtin_return_address(0));
 }
arch/powerpc/mm/tlb_low_64e.S +2 -2
index 10d524d..cd92f62 100644
@@ -133,7 +133,7 @@
 
 	/* We do the user/kernel test for the PID here along with the RW test
 	 */
-	li	r11,_PAGE_PRESENT|_PAGE_HWEXEC	/* Base perm */
+	li	r11,_PAGE_PRESENT|_PAGE_EXEC	/* Base perm */
 	oris	r11,r11,_PAGE_ACCESSED@h
 
 	cmpldi	cr0,r15,0			/* Check for user region */

@@ -256,7 +256,7 @@ normal_tlb_miss_done:
 
 normal_tlb_miss_access_fault:
 	/* We need to check if it was an instruction miss */
-	andi.	r10,r11,_PAGE_HWEXEC
+	andi.	r10,r11,_PAGE_EXEC
 	bne	1f
 	ld	r14,EX_TLB_DEAR(r12)
 	ld	r15,EX_TLB_ESR(r12)
Signature · 1 line
1.6.1.2.14.gf26b5
Acked-by on v1 1/1
#1 lore raw
Quoted 21 lines · Benjamin Herrenschmidt

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

Quoted 1 line
Signed-off-by Benjamin Herrenschmidt <[email protected]>
Acked-by David Gibson <[email protected]>
Signature · 4 lines
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson