kernel-hacking-2024-linux-s.../arch/arc/include/asm/page.h
Vineet Gupta 3abc944802 ARC: [mm] Make stack/heap Non-executable by default
1. For VM_EXEC based delayed dcache/icache flush, reduces the number of
   flushes.

2. Makes this security feature ON by default rather than OFF before.

3. Applications can use mprotect() to selectively override this.

4. ELF binaries have a GNU_STACK segment which can easily override the
   kernel default permissions.
   For nested-functions/trampolines, gcc already auto-enables executable
   stack in elf. Others needing this can use -Wl,-z,execstack option.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
2013-06-22 19:23:20 +05:30

109 lines
3 KiB
C

/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef __ASM_ARC_PAGE_H
#define __ASM_ARC_PAGE_H
#include <uapi/asm/page.h>
#ifndef __ASSEMBLY__
#define get_user_page(vaddr) __get_free_page(GFP_KERNEL)
#define free_user_page(page, addr) free_page(addr)
#define clear_page(paddr) memset((paddr), 0, PAGE_SIZE)
#define copy_page(to, from) memcpy((to), (from), PAGE_SIZE)
struct vm_area_struct;
struct page;
#define __HAVE_ARCH_COPY_USER_HIGHPAGE
void copy_user_highpage(struct page *to, struct page *from,
unsigned long u_vaddr, struct vm_area_struct *vma);
void clear_user_page(void *to, unsigned long u_vaddr, struct page *page);
#undef STRICT_MM_TYPECHECKS
#ifdef STRICT_MM_TYPECHECKS
/*
* These are used to make use of C type-checking..
*/
typedef struct {
unsigned long pte;
} pte_t;
typedef struct {
unsigned long pgd;
} pgd_t;
typedef struct {
unsigned long pgprot;
} pgprot_t;
typedef unsigned long pgtable_t;
#define pte_val(x) ((x).pte)
#define pgd_val(x) ((x).pgd)
#define pgprot_val(x) ((x).pgprot)
#define __pte(x) ((pte_t) { (x) })
#define __pgd(x) ((pgd_t) { (x) })
#define __pgprot(x) ((pgprot_t) { (x) })
#define pte_pgprot(x) __pgprot(pte_val(x))
#else /* !STRICT_MM_TYPECHECKS */
typedef unsigned long pte_t;
typedef unsigned long pgd_t;
typedef unsigned long pgprot_t;
typedef unsigned long pgtable_t;
#define pte_val(x) (x)
#define pgd_val(x) (x)
#define pgprot_val(x) (x)
#define __pte(x) (x)
#define __pgprot(x) (x)
#define pte_pgprot(x) (x)
#endif
#define ARCH_PFN_OFFSET (CONFIG_LINUX_LINK_BASE >> PAGE_SHIFT)
#define pfn_valid(pfn) (((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
/*
* __pa, __va, virt_to_page (ALERT: deprecated, don't use them)
*
* These macros have historically been misnamed
* virt here means link-address/program-address as embedded in object code.
* So if kernel img is linked at 0x8000_0000 onwards, 0x8010_0000 will be
* 128th page, and virt_to_page( ) will return the struct page corresp to it.
* mem_map[ ] is an array of struct page for each page frame in the system
*
* Independent of where linux is linked at, link-addr = physical address
* So the old macro __pa = vaddr + PAGE_OFFSET - CONFIG_LINUX_LINK_BASE
* would have been wrong in case kernel is not at 0x8zs
*/
#define __pa(vaddr) ((unsigned long)vaddr)
#define __va(paddr) ((void *)((unsigned long)(paddr)))
#define virt_to_page(kaddr) \
(mem_map + ((__pa(kaddr) - CONFIG_LINUX_LINK_BASE) >> PAGE_SHIFT))
#define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
/* Default Permissions for stack/heaps pages (Non Executable) */
#define VM_DATA_DEFAULT_FLAGS (VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE)
#define WANT_PAGE_VIRTUAL 1
#include <asm-generic/memory_model.h> /* page_to_pfn, pfn_to_page */
#include <asm-generic/getorder.h>
#endif /* !__ASSEMBLY__ */
#endif