From c33fa9f5609e918824446ef9a75319d4a802f1f4 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 17 Apr 2008 20:05:36 +0200 Subject: 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 Reviewed-by: Thomas Gleixner --- mm/Makefile | 2 +- mm/maccess.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 50 insertions(+), 1 deletion(-) create mode 100644 mm/maccess.c (limited to 'mm') 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 +#include +#include + +/** + * 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); -- cgit v1.2.3