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linux/arch/powerpc/include/asm/pte-common.h
Stefan Roese 09597cfe93 powerpc: Don't write protect kernel text with CONFIG_DYNAMIC_FTRACE enabled 
This problem was noticed on an MPC855T platform. Ftrace did oops
when trying to write to the kernel text segment.

Many thanks to Joakim for finding the root cause of this problem.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Joakim Tjernlund <joakim.tjernlund@transmode.se>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2011-04-18 13:08:21 +10:00

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/* Included from asm/pgtable-*.h only ! */
/*
* Some bits are only used on some cpu families... Make sure that all
* the undefined gets a sensible default
*/
#ifndef _PAGE_HASHPTE
#define _PAGE_HASHPTE 0
#endif
#ifndef _PAGE_SHARED
#define _PAGE_SHARED 0
#endif
#ifndef _PAGE_HWWRITE
#define _PAGE_HWWRITE 0
#endif
#ifndef _PAGE_EXEC
#define _PAGE_EXEC 0
#endif
#ifndef _PAGE_ENDIAN
#define _PAGE_ENDIAN 0
#endif
#ifndef _PAGE_COHERENT
#define _PAGE_COHERENT 0
#endif
#ifndef _PAGE_WRITETHRU
#define _PAGE_WRITETHRU 0
#endif
#ifndef _PAGE_4K_PFN
#define _PAGE_4K_PFN 0
#endif
#ifndef _PAGE_SAO
#define _PAGE_SAO 0
#endif
#ifndef _PAGE_PSIZE
#define _PAGE_PSIZE 0
#endif
#ifndef _PMD_PRESENT_MASK
#define _PMD_PRESENT_MASK _PMD_PRESENT
#endif
#ifndef _PMD_SIZE
#define _PMD_SIZE 0
#define PMD_PAGE_SIZE(pmd) bad_call_to_PMD_PAGE_SIZE()
#endif
#ifndef _PAGE_KERNEL_RO
#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)
#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
#endif
#ifndef _PTE_NONE_MASK
#define _PTE_NONE_MASK _PAGE_HPTEFLAGS
#endif
/* Make sure we get a link error if PMD_PAGE_SIZE is ever called on a
* kernel without large page PMD support
*/
#ifndef __ASSEMBLY__
extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
#endif /* __ASSEMBLY__ */
/* Location of the PFN in the PTE. Most 32-bit platforms use the same
* as _PAGE_SHIFT here (ie, naturally aligned).
* Platform who don't just pre-define the value so we don't override it here
*/
#ifndef PTE_RPN_SHIFT
#define PTE_RPN_SHIFT (PAGE_SHIFT)
#endif
/* The mask convered by the RPN must be a ULL on 32-bit platforms with
* 64-bit PTEs
*/
#if defined(CONFIG_PPC32) && defined(CONFIG_PTE_64BIT)
#define PTE_RPN_MAX (1ULL << (64 - PTE_RPN_SHIFT))
#define PTE_RPN_MASK (~((1ULL<<PTE_RPN_SHIFT)-1))
#else
#define PTE_RPN_MAX (1UL << (32 - PTE_RPN_SHIFT))
#define PTE_RPN_MASK (~((1UL<<PTE_RPN_SHIFT)-1))
#endif
/* _PAGE_CHG_MASK masks of bits that are to be preserved across
* pgprot changes
*/
#define _PAGE_CHG_MASK (PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
_PAGE_ACCESSED | _PAGE_SPECIAL)
/* Mask of bits returned by pte_pgprot() */
#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)
/*
* We define 2 sets of base prot bits, one for basic pages (ie,
* cacheable kernel and user pages) and one for non cacheable
* pages. We always set _PAGE_COHERENT when SMP is enabled or
* the processor might need it for DMA coherency.
*/
#define _PAGE_BASE_NC (_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_PSIZE)
#if defined(CONFIG_SMP) || defined(CONFIG_PPC_STD_MMU)
#define _PAGE_BASE (_PAGE_BASE_NC | _PAGE_COHERENT)
#else
#define _PAGE_BASE (_PAGE_BASE_NC)
#endif
/* Permission masks used to generate the __P and __S table,
*
* Note:__pgprot is defined in arch/powerpc/include/asm/page.h
*
* Write permissions imply read permissions for now (we could make write-only
* pages on BookE but we don't bother for now). Execute permission control is
* possible on platforms that define _PAGE_EXEC
*
* Note due to the way vm flags are laid out, the bits are XWR
*/
#define PAGE_NONE __pgprot(_PAGE_BASE)
#define PAGE_SHARED __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW)
#define PAGE_SHARED_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | _PAGE_EXEC)
#define PAGE_COPY __pgprot(_PAGE_BASE | _PAGE_USER)
#define PAGE_COPY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
#define PAGE_READONLY __pgprot(_PAGE_BASE | _PAGE_USER)
#define PAGE_READONLY_X __pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
#define __P000 PAGE_NONE
#define __P001 PAGE_READONLY
#define __P010 PAGE_COPY
#define __P011 PAGE_COPY
#define __P100 PAGE_READONLY_X
#define __P101 PAGE_READONLY_X
#define __P110 PAGE_COPY_X
#define __P111 PAGE_COPY_X
#define __S000 PAGE_NONE
#define __S001 PAGE_READONLY
#define __S010 PAGE_SHARED
#define __S011 PAGE_SHARED
#define __S100 PAGE_READONLY_X
#define __S101 PAGE_READONLY_X
#define __S110 PAGE_SHARED_X
#define __S111 PAGE_SHARED_X
/* Permission masks used for kernel mappings */
#define PAGE_KERNEL __pgprot(_PAGE_BASE | _PAGE_KERNEL_RW)
#define PAGE_KERNEL_NC __pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
_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_RWX)
#define PAGE_KERNEL_RO __pgprot(_PAGE_BASE | _PAGE_KERNEL_RO)
#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
* on platforms where such control is possible.
*/
#if defined(CONFIG_KGDB) || defined(CONFIG_XMON) || defined(CONFIG_BDI_SWITCH) ||\
defined(CONFIG_KPROBES) || defined(CONFIG_DYNAMIC_FTRACE)
#define PAGE_KERNEL_TEXT PAGE_KERNEL_X
#else
#define PAGE_KERNEL_TEXT PAGE_KERNEL_ROX
#endif
/* Make modules code happy. We don't set RO yet */
#define PAGE_KERNEL_EXEC PAGE_KERNEL_X
/*
* Don't just check for any non zero bits in __PAGE_USER, since for book3e
* and PTE_64BIT, PAGE_KERNEL_X contains _PAGE_BAP_SR which is also in
* _PAGE_USER. Need to explicitly match _PAGE_BAP_UR bit in that case too.
*/
#define pte_user(val) ((val & _PAGE_USER) == _PAGE_USER)
/* Advertise special mapping type for AGP */
#define PAGE_AGP (PAGE_KERNEL_NC)
#define HAVE_PAGE_AGP
/* Advertise support for _PAGE_SPECIAL */
#define __HAVE_ARCH_PTE_SPECIAL
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