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authorIngo Molnar <mingo@elte.hu>2008-04-17 20:05:36 +0200
committerIngo Molnar <mingo@elte.hu>2008-04-17 20:05:36 +0200
commitc33fa9f5609e918824446ef9a75319d4a802f1f4 (patch)
treeab711865ba14d4e3d21c2e480e8b113fc73e08a2
parent4b119e21d0c66c22e8ca03df05d9de623d0eb50f (diff)
downloadlinux-stericsson-c33fa9f5609e918824446ef9a75319d4a802f1f4.tar.gz
uaccess: add probe_kernel_write()
add probe_kernel_read() and probe_kernel_write(). Uninlined and restricted to kernel range memory only, as suggested by Linus. Signed-off-by: Ingo Molnar <mingo@elte.hu> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--include/linux/uaccess.h22
-rw-r--r--mm/Makefile2
-rw-r--r--mm/maccess.c49
3 files changed, 72 insertions, 1 deletions
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 975c963e5789..fec6decfb983 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -84,4 +84,26 @@ static inline unsigned long __copy_from_user_nocache(void *to,
ret; \
})
+/*
+ * probe_kernel_read(): safely attempt to read from a location
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from
+ * @size: size of the data chunk
+ *
+ * Safely read from address @src to the buffer at @dst. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+extern long probe_kernel_read(void *dst, void *src, size_t size);
+
+/*
+ * probe_kernel_write(): safely attempt to write to a location
+ * @dst: address to write to
+ * @src: pointer to the data that shall be written
+ * @size: size of the data chunk
+ *
+ * Safely write to address @dst from the buffer at @src. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+extern long probe_kernel_write(void *dst, void *src, size_t size);
+
#endif /* __LINUX_UACCESS_H__ */
diff --git a/mm/Makefile b/mm/Makefile
index a5b0dd93427a..18c143b3c46c 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -8,7 +8,7 @@ mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \
vmalloc.o
obj-y := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
- page_alloc.o page-writeback.o pdflush.o \
+ maccess.o page_alloc.o page-writeback.o pdflush.o \
readahead.o swap.o truncate.o vmscan.o \
prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
page_isolation.o $(mmu-y)
diff --git a/mm/maccess.c b/mm/maccess.c
new file mode 100644
index 000000000000..24f81b971403
--- /dev/null
+++ b/mm/maccess.c
@@ -0,0 +1,49 @@
+/*
+ * Access kernel memory without faulting.
+ */
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/mm.h>
+
+/**
+ * probe_kernel_read(): safely attempt to read from a location
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from
+ * @size: size of the data chunk
+ *
+ * Safely read from address @src to the buffer at @dst. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+long probe_kernel_read(void *dst, void *src, size_t size)
+{
+ long ret;
+
+ pagefault_disable();
+ ret = __copy_from_user_inatomic(dst,
+ (__force const void __user *)src, size);
+ pagefault_enable();
+
+ return ret ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
+
+/**
+ * probe_kernel_write(): safely attempt to write to a location
+ * @dst: address to write to
+ * @src: pointer to the data that shall be written
+ * @size: size of the data chunk
+ *
+ * Safely write to address @dst from the buffer at @src. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+long probe_kernel_write(void *dst, void *src, size_t size)
+{
+ long ret;
+
+ pagefault_disable();
+ ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
+ pagefault_enable();
+
+ return ret ? -EFAULT : 0;
+}
+EXPORT_SYMBOL_GPL(probe_kernel_write);