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[S390] mm: add devmem_is_allowed() for STRICT_DEVMEM checking

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Provide the devmem_is_allowed() routine to restrict access to
kernel memory from userspace.
Set the CONFIG_STRICT_DEVMEM config option to switch on checking.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Hendrik Brueckner 2010-11-10 10:05:55 +01:00 committed by Martin Schwidefsky
parent ca768b6631
commit ec6743bb06
2 changed files with 17 additions and 0 deletions
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12
arch/s390/Kconfig.debug
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@ -6,6 +6,18 @@ config TRACE_IRQFLAGS_SUPPORT
source "lib/Kconfig.debug"
config STRICT_DEVMEM
def_bool y
prompt "Filter access to /dev/mem"
---help---
This option restricts access to /dev/mem. If this option is
disabled, you allow userspace access to all memory, including
kernel and userspace memory. Accidental memory access is likely
to be disastrous.
Memory access is required for experts who want to debug the kernel.
If you are unsure, say Y.
config DEBUG_STRICT_USER_COPY_CHECKS
bool "Strict user copy size checks"
---help---

5
arch/s390/include/asm/page.h
View File

@ -130,6 +130,11 @@ struct page;
void arch_free_page(struct page *page, int order);
void arch_alloc_page(struct page *page, int order);
static inline int devmem_is_allowed(unsigned long pfn)
{
return 0;
}
#define HAVE_ARCH_FREE_PAGE
#define HAVE_ARCH_ALLOC_PAGE