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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, May 06, 2019 at 06:31:03PM +0200, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > This patch adds a simple test, that calls the uname syscall with a > tagged user pointer as an argument. Without the kernel accepting tagged > user pointers the test fails with EFAULT. That's probably sufficient for a simple example. Something we could add to Documentation maybe is a small library that can be LD_PRELOAD'ed so that you can run a lot more tests like LTP. We could add this to selftests but I think it's too glibc specific. --------------------8<------------------------------------ #include #define TAG_SHIFT (56) #define TAG_MASK (0xffUL << TAG_SHIFT) void *__libc_malloc(size_t size); void __libc_free(void *ptr); void *__libc_realloc(void *ptr, size_t size); void *__libc_calloc(size_t nmemb, size_t size); static void *tag_ptr(void *ptr) { unsigned long tag = rand() & 0xff; if (!ptr) return ptr; return (void *)((unsigned long)ptr | (tag << TAG_SHIFT)); } static void *untag_ptr(void *ptr) { return (void *)((unsigned long)ptr & ~TAG_MASK); } void *malloc(size_t size) { return tag_ptr(__libc_malloc(size)); } void free(void *ptr) { __libc_free(untag_ptr(ptr)); } void *realloc(void *ptr, size_t size) { return tag_ptr(__libc_realloc(untag_ptr(ptr), size)); } void *calloc(size_t nmemb, size_t size) { return tag_ptr(__libc_calloc(nmemb, size)); } _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel